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Mike BradyandGitHub 39da3d3cf2 Update AirPlay 2 service options in release notes [skip ci]

Enhanced AirPlay 2 build options and improved input format change delivery.

2026-06-03 14:55:28 +01:00

254 KiB

Raw Blame History

Version 5.1-dev-17-g9b16ff92

Bug Fixes

Set locales in the test clients shairport-sync-dbus-test-client and shairport-sync-mpris-test-client so that they can deal with non-ASCII characters, e.g. accented characters, properly.

Version 5.1-dev-15-g2d89d2bf

Bug Fixes

Fix a race condition that was allowing a TEARDOWN request to close the next connection rather than the current one.
Fix a compilation bug when build for Classic operation only.

Version 5.1-dev

Enhancements

Enable the AirPlay 2 build to provide pure classic AirPlay either optionally or automatically if NQPTP is not running, as follows:

Add a new command-line option -—service-type=<type> and an equivalent configuration entry service_type = "<type>"; in the general section of the configuration file, where <type> can be "auto", "classic" or "airplay2":
1. "auto" (default) means that the service will be AirPlay 2 if NQPTP is running. If NQPTP is not running, classic AirPlay service will be provided and (Classic) will be appended to the default AirPlay service name visible to AirPlay clients like Apple Music, for example RaspberryPi3B (Classic).
2. "classic" means the service will be classic AirPlay (aka AirPlay 1).
3. "airplay2" means the service will be the modern AirPlay 2. In this case, as distinct from "auto", if NQPTP is not running, Shairport Sync will log an error and terminate.
In the systemd service file, NQPTP is now a Want rather than a Require. If it's present, it will be launched before Shairport Sync.

Improve the delivery of input format changes and emit sdsc metadata tokens when changes occur.
Emit new format information in the log if statistics is enabled.

Docker Changes

Support for linux/arm/v6 has been dropped, as Docker is no longer supported on that architecture.
NQPTP is not started in the AirPlay 2 Docker image if --service-type=classic or --service-type=airplay1 is in the command line options at the end of the docker run command. This is to ensure that ports 319 and 320 are left alone when the AirPlay 2 image is set to provide Classic service only. Note that setting the configuration file service_type to classic will not prevent NQPTP from starting up -- you must use the command line option.
A new dev target has been added. It is a large image containing the custom-built FFmpeg library, NQPTP, Avahi and D-Bus along with the Shairport Sync source and all necessary development tools. When started, Avahi, D-Bus and NQPTP are all installed and running. The bash shell has also been added and is entered.

Stability Improvements

Reorganise session preemption to fully terminate the existing session before starting a new one. This should address some reports that Shairport Sync occasionally crashes and restarts when a new play session interrupts an existing one.
Don't delay closing the event port to wait for it to be closed at the client end.
Add a safe_socket_close() function to ensure sockets are fully closed. Use -1 to designate closed rather than 0, to prevent attempts to reclose sockets, which was causing mayhem. Sincere thanks to Will Laws for taking a very careful look at some of the problems this was causing, and to microfix for reporting the issue.
Re-order FFmpeg decommissioning during teardown.

Version 5.0.5-dev-15-g3cbc4b18

Bug Fixes – Classic AirPlay Remote Control (Updated)

A significant Classic AirPlay Remote Control bug was found: in Classic AirPlay mode, the DACP command port was being incorrectly reported to the Remote Control system, causing it not to function!

This has been fixed, and remote control has been restored for Classic AirPlay. Please check the D-Bus interface for the RemoteControl suite -- most all of these now work. The AdvancedRemoteControl suite also works with the macOS Music App but only in Classic AirPlay.

MQTT remote control commands and some MPRIS commands should now also work, although the MPRIS interface is quite incomplete.
The dapo metadata token now correctly reports the DACP port as a character string, and reports a DACP port of "0" when the DACP port is or becomes invalid.

Version 5.0.5-dev-12-g9d102497

Enhancements

Setting a password now works with AirPlay 2 as well as Classic AirPlay. Use the password setting in the general section of the configuration file or the --password="<password>" command line option to set a password.
Update information about the password and interpolation (aka "stuffing") command line settings.

Version 5.0.5-dev-10-g4b020a6b

Enhancements

Experimentally allow up to 31 audio channels. This is up from a previous maximum of eight. The ALSA system allows up to 32 channels, one more than Shairport Sync can handle, so let's see...

Unfortunately, this can not be tested due to a lack of suitable output devices, so if anyone can test it out, it would be appreciated.

Thanks to 24fpsDaVinci for the issue.

Upmixing

"Upmixing" adds channels to an audio stream, e.g. you could upmix stereo (two channels) to 5.1 surround sound (six channels) by copying and blending the stereo channels to drive the extra surround channels. The FFmpeg resampler used by Shairport Sync does implement upmixing, but by default it just copies the source channels to their equivalent channels in the output, leaving the extra channels silent.

So, while Shairport Sync does technically implement upmixing, it makes no audible difference. Maybe in the future, upmixing matrices will be added, but it is not a priority just now.

Thanks to iliaspapan for enquiring about this.

Version 5.0.5-dev-7-g3a1bfd71

Docker Updates

Update Docker images to use Alpine 3.23.4 (up from build 20250108).
Update Docker images to use FFmpeg 8.1 (up from 7.1).

Other Updates

Fix some benign compiler warnings coming from the updated compiler in Ubuntu 26.04.

Version 5.0.5-dev-2-g2400aae4

This is effectively 5.0.4-dev-9-g68b6d4df.

Version 5.0.4-dev-9-g68b6d4df

Bug Fix

Fixed missing configuration mapping parameter in PulseAudio backend initialisation. This bug would prevent the PulseAudio backend from initialising, preventing Shairport Sync from working.

Version 5.0.4-dev-5-g936b8387

New Features

AirPlay 2 Passwords. Until now, you could set a password only for Classic AirPlay. Now, setting a password is effective for both AirPlay 2 and Classic AirPlay.
Metadata multicast is now optional, so can, in principle, be omitted. This is still experimental.
DACP support is optional and can, in principle, be omitted. This is still experimental.

Bug Fixes and Stability Improvements

Calls to some libraries have been made uncancellable in order to improve application stability when terminating or when pre-empting an active play session. These changes are not yet complete.

Other Changes

Some rationalisation of source files is being undertaken.

Version 5.0.3-dev-4-g07ca1891

Release

This is effectively release 5.0.3

Bug Fix

Make code using getifaddrs() uncancellable to prevent a mysterious Unexpected error 9 on netlink descriptor error. Thanks to microfx for reporting the issue.

Version 5.0.3-dev

Small Changes

Add warnings if string or boolean configuration parameters were present but not strings.
Improve behaviour when there is a large timing uncertainty/granularity and a large audio buffer. e.g. on some virtual machines.
Make the SoxR delay checker thread behave better when being cancelled.
Remove some debug messages, quieten some others, add a few.

Version 5.0.1+-38-gf784e463

Build Update

The Apple ALAC Decoder can no longer be included in an AirPlay 2 build. The reason is that FFmpeg -- used instead -- deals comprehensively with ALAC, AAC, multichannel, mixdown and rate transcoding and is well maintained.

The Apple ALAC Decoder is known to have security issues and is no longer maintained. This update prevents it from being included in Shairport Sync for AirPlay 2.

Version 5.0.1+-36-g6729802d

Update

The Shairport Sync systemd service file has been updated as follows:
- It uses POSIX shell parameter expansion functionality to prevent adding leading space in option values.
- It adds nqptp.service to the After and Requires options when building for Airplay 2.
Many thanks to mikelei8291 for the PR.

Version 5.0.1+-32-g20a87fef

Build Bugfix

Fix a bug at the .configure... stage of a build of Classic Shairport Sync whereby the UUID library was incorrectly required if the FFmpeg library was being used. (The wording on a few associated warning messages was also fixed.) Thanks to phexian for the report.

Dependabot Update

A Dependabot update to a building tool was added.

Version 5.0.1+-23-g7fb3506e

Documentation Update

Fixed dead link to the online man page. Thanks to CornelisJ for the report.

Version 5.0.1+-13-ga14517d7

Change

When built for AirPlay 2, add pw=true to the Bonjour raop properties if the classic AirPlay password is set. This might help with Owntone compatibility.

Version 5.0.1+-11-g07546c35

Changes

Turn off yet more currently-irrelevant debug messages by setting their level to 4, meaning they will never be displayed.
Use NULL instead of 0 to check for the presence of a classic AirPlay password. Makes no difference, but type-wise it is less misleading.

Version 5.0.1+-8-gb09fd400

Bug Fix

Defer rather than delete blocks of audio that are too far into the future, and also check for a valid clock when checking the timing of blocks. This is to attempt to deal with an unexpected situation where the timing of blocks of incoming audio seems to suddenly jump into the distant future, as if audio from the skipped-over interval has been dropped. Can this be classified as a bug fix? Who knows!

Changes

Turn off some more currently-irrelevant debug messages by setting their level to 4, meaning they will never be displayed.

Version 5.0.1+-2-g22f283fe

Bug Fix

Update the D-Bus test client to refer to shairport_sync_get_loudness_enabled rather than shairport_sync_get_loudness. thankt to flatsiedatsie for the bug report.

Other Changes

Turn off many currently-irrelevant debug messages by setting their level to 4, meaning they will never be displayed.

Version 5.0-post-dev-13-g5893eabf

The MQTT client in Shairport Sync has a Home-Assistant-specific configuration key called object_id used to define the entity's unique ID for HA. The term object_id has been deprecated by HA in favour of a new term: defauly_entity_id. This has now been added to Shairport Sync's MQTT client.

The deprecated object_id term will be removed in a future release. Thanks to Markus Reiter for the PR.

Version 5.0-post-dev-10-g3888999d

Remove requirement for the mosquitto service to be running when Shairport Sync is built with the --with-mqtt-client configuration flag. The service does not, in fact, need to be running in every case. This reverses a change made in PR at Version 5.0-dev-161.

Thanks to David Crook for the bug report.

Version 5.0-post-dev-6-gd32d5cb9

Fix handling of missing const type qualifier and some follow-on warnings. Thanks to Rudi Heitbaum for the PR.

Version 5.0-post-dev-1-g963380a8

This is essentially release Version 5.0 or 5.0.0.

Version 5.0-dev-168-g846e0e3d

MQTT Enhancement

Add a new publish_retain boolean option to the MQTT section of the configuration file (normally /etc/shairport-sync.conf).

When enabled, published MQTT messages will have the retain flag set, so that the MQTT broker stores the last message per topic and new subscribers receive the most recent value immediately.

Thanks to lululombard for the PR.

Dependabot Update

A Dependabot update to some image building tools was added.

Version 5.0-dev-161-g5b3659c2

Bug Fix

Fix an MQTT warning and simplify building the systemd startup script. The warning occured if Shairport Sync was built with MQTT support. For that case, the startup script omitted stating that the mosquitto service was required and had to be active before starting Shairport Sync.

Thanks to hvilleneuve29 for the PR.

Dependabot Update

A Dependabot update to some image building tools was added.

Version 5.0-dev-155-g45063d10

Bug Fix

Finally! Add Carl Johnson's suggestion to only consider interfaces that are up, running and not loopback interfaces for a valid MAC address. Thanks to Carl for his suggestion and for his gentle reminder.

Versions 5.0-dev-153-g525e49cd, 5.0-dev-151-g16b6534a and 5.0-dev-146-g691d71f3

Updates

Tighten up the checking of arguments given to debug(), inform(), warn() and die() to avoid silly errors. No known issues, but better sure than sorry. Thanks to ejurgensen for the PR which prompted the review.

Version 5.0-dev-142-gfcacc4e5

Updates

Continuing to address some issues with AutoMix on AirPlay, skipping tracks, and other unreported issues, this update represents some "housekeeping" -- cleaning up some old code based on a better (?) understanding of protocols.

Your bug reports are welcome.

Here are some of the details:
- Cleaned up get_play_lock() and release_play_lock() stuff and placed them in the right places for AP2, AP1 compatibiity and Classic AP.
- Fixed the setting of flags and GID in Bonjour.
- The principal_conn is correctly released when terminating a listener loop.
- The airplay_stream_type is correctly set for a classic airplay session.
- Moved NQPTP clock setup and start from Setup Phase 1 to Setup Phase 2.
- Stopped a player thread from resetting the NTPTP client clock when it finishes.
- Modified and greatly simplified the TEARDOWN handling in AP2 mode.
- Allowed threads to 'naturally' terminate when ports are closed by the client.
- Improved clearing of flush requests in new play sessions.
- Added, but disabled, code to remove previously decoded buffers of data from the player if replacement buffers come in later. (This happens when input changes from AAC to ALAC on the fly, and it's unclear whether this is an AirPlay 2 implementation bug or not.) It's unclear which buffers should have primacy -- the older ones or the newer ones -- so for simplicity new buffers that would replace buffers that are already decoded are simply dropped.

Version 5.0-dev-106-gec0016fb

Bug Fix

Fix a bug in the PulseAudio backend so that PA_ERR_NODATA returns "No latency data yet". Thanks to Vladimir Shakov for the report and fix.

Version 5.0-dev-100-ga1238882

Bug Fix

Fixed a bug whereby Shairport Sync would not work with mbedtls library from version 3.4 (present on recent versions of Linux, e.g. Debian 13...).

Many thanks to Christian Beier for finding the bug and for fixing it.

Version 5.0-dev-93-g1417cd6f

Bug Fix

Ensure old flush requests are deleted when a new play session starts. Thanks to saujanyashah for the report.

Version 5.0-dev-87-ge12a3ed7

Updates -- This is Significant

To address some issues around AutoMix on AirPlay, a long-overdue rebuild of the buffered audio processor and been done, using everything we have figured out until now. It implements a cleaner method to handle both immediate and deferred flush requests. Lots of old flags and redundant code have been removed. Some diagnostics have been left in the code. The changes are pretty far-reaching, and it is possible that new issues have been inadventently introduced and old ones revived. Please let us know if you discover any issue, especially if you can readily cause the issue to occur. As you may know, it can be difficult to determine if an issue is caused by AirPlay 2 itself or by Shairport Sync.

Version 5.0-dev-83-g38592252

Enhancements

Convolution Update. The convolution system is now multithreaded and works on stereo and multichannel audio at 48k and 44.1k.
- Multiple impulse response (IR) files can now be provided to the convolution system through a new setting: convolution_ir_files (the old setting: convolution_ir_file is now deprecated). When convolution starts, Shairport Sync will look for an IR file with a sample rate matching the input (44.1k or 48k) and channel count. If an exact match can not be found, it will start again and look for a single-channel IR file with the matching rate. It will always choose the first match in the file list supplied with the convolution_ir_files setting or the D-Bus method.
- Multithreading of convolution processing is now possible -- use the convolution_thread_pool_size setting to set the number of threads to use during convolution. (Note: high levels of multicore operation can cause audible power supply noise on some systems, due to rapid power switching or frequency-ramping of CPU cores.)
- The HiFi-LoFi FFT convolver has been updated to the latest available.
Loudness Update. The loudness code now works with stereo and multichannel audio at 48k and 44.1k.

Deprecations

The Jack audio backend is deprecated and will be removed in the future. It seems to be very little used, and most of its functionality is now available through PipeWire.

Configuration File and D-Bus Changes

A new convolution_thread_pool_size configuration file setting has been added, defaulting to 1. This is not available in the D-Bus interface.
The convolution setting is deprecated -- use convolution_enabled instead.
The convolution_max_length setting is deprecated -- use convolution_max_length_in_seconds instead.
The convolution_ir_file setting is deprecated -- use convolution_ir_files (i.e. plural!) instead.
The loudness setting is deprecated -- use loudness_enabled instead.
Corresponding D-Bus methods and properties have been updated.

Bug Fix

Fix an FFmpeg deprecation warning.

Version 5.0-dev-65-g8545938d

Enhancement

Add a new command-line argument dbus_default_message_bus which can be system or session. This becomes the default message bus used both by the D-Bus native service and the MPRIS service. In its absence, the default is to use the system message bus. Example of use:
```
$ shairport-sync ... --dbus_default_message_bus=session ....
```
Add a warning if a convolution impulse response file can not be read, e.g. due to a bad path name or a permissions error.

Bug fix

If the native D-Bus interface is active and a convolution impulse response file is specified, don't open it a second time on startup. (BTW, this is not known to have caused any problems.)

Version 5.0-dev-50-g10700356

Docker Update

Add an ENABLE_AVAHI environment variable to enable or disable avahi and dbus processes in the Docker image. The default is to enable both, an has always been the case. Thanks to Adam Oleksy for the PR.

Version 5.0-dev-47-g03fb1d69

Tiny Update

Remove a redundant s6-overlay directory from the docker etc subdirectory. The directory was obsolete and wasn't copied into Docker images anyway...
Various Dependabot updates.

Version 5.0-dev-39-g77d0deec

Dependabot Updates

A number of deferred Dependabot-originated updates have been accepted. They all relate to (limited) automated testing and Docker image creation.

Version 5.0-dev-34-ga5a54621

Bug Fix

Fixed a bug whereby the volume setting was ignored if the input was not at 44100 FPS and the loudness DSP setting was enabled. Thanks to microfx for the report and for helping to track down the issue.

Version 5.0-dev-25-ge05448ae

Bug Fixes and Enhancements

A convenience script user-service-install.sh has been added to install a systemd user service startup script.
- Associated with this, a user service startup script is no longer installed at the # make install step in a systemd based Linux. This is because:
  - The user service startup script would be owned by root and therefore would not be editable or removable by the user,
  - The user service startup script would be only be installed correctly if the command was $ sudo make install and would not work properly if the command was # make install because the script would be installed in the wrong place.
- Update the BUILD.md guide to reflect the introduction of the new script.
- Thanks to petcol for their help and persistence in identifying and resolving this problem.
Ignore empty configuration setting strings. Specifically, log a warning and behave as if the configuration setting was not given. Thanks to mantheman for the initial report.
Add a disconnect command to the MQTT interface. Thanks to Jordan Zucker for the PR.
In the Docker images, remove any left-over pid files before starting the D-Bus and Avahi services. Thanks to Kir Belevich for the report.

Version 5.0-dev

This is a major update adding exciting new features and improvements to Shairport Sync:

48k operation;
48k lossless stereo from Apple devices e.g. Homepod mini, Apple TV 4K;
48k 5.1 and 7.1 surround sound from Apple devices e.g. Homepod mini, Apple TV 4K;
Full FFmpeg integration for flexibility and security;
Multichannel ALSA, PipeWire, PulseAudio, FreeBSD, stdout and unix pipe output backends;
Flexible, controllable, automatic matching of output format to input format;
Improved synchronization;
A new "vernier" resampling and interpolation method for low-power CPUs;
Lower powered devices operation, including the original Raspberry Pi B;
Reduced Docker image sizes;
A systemd user startup script.
Many bug fixes.

44.1k operation is retained.

Deprecation Note The stand-alone ALAC decoder by John Hammerton, used in all versions of Shairport Sync until now, and Apple's own ALAC decoder, optional for Shairport Sync, are now deprecated due to maintainance and security issues. You may find it be necessary to use one of them (for classic AirPlay reception only) in devices with very restricted storage, but security considerations mean that these decoders will be fully dropped in future.

Warning: This is a breaking update. That means you probably can not simply update an existing installation of Shairport Sync without a little bit of work. To update correctly you must:

Remove the Shairport Sync device from Apple Home -- you can add it back later;
Review the list of libraries needed for building Shairport Sync, as there are some extras -- see the updated BUILD.md guide;
Review configuration flags when building Shairport Sync -- some names have changed, e.g. --with-systemd becomes --with-systemd-startup;
Fully delete and reinstall Shairport Sync and NQPTP, along with all their service files;
Review and update settings:
- Some of the names of the setting sections have changed, e.g. the pa section becomes the pulseaudio section;
- The behaviour of Shairport Sync backends has changed, e.g. rates and channel counts can change dynamically.

Version 4.3.7-dev-24-gbc5001eb

This is effectively release 4.3.7.

Dependabot Updates

A number of deferred Dependabot-originated updates have been accepted. They all relate to (limited) automated testing and Docker image creation.

Version 4.3.7-dev-11-g7367d042

Automated Docker Build Fixes

Thanks to Charles Omer for fixes to the Github Action scripts for building and pushing Docker images.

Version 4.3.7-dev-3-g802058fe

Docker Enhancement

Add curl to the Docker images to facilitate automations. Thanks to ironcrafter54 for the suggestion.

Version 4.3.7-dev

This is effectively Version 4.3.6-dev-24-g015a5829, which is also effectively Version 4.3.6.

Version 4.3.6-dev-24-g015a5829

MQTT Documentation Addition

Show how to use MQTTThing with Homebridge to represent Shairport Sync’s active status. Thanks to keefar for the PR.

Version 4.3.6-dev-19-g39781ece

Documentation Fix

Fix a typo in the configuration file. Many thanks to Justin.

Version 4.3.6-dev-17-gce73230e

Documentation Fix

Correct and clarify the statistics documentation.

The descriptions of Net Sync PPM and All Sync PPM were partly swapped -- this has been corrected.
Generally clarify the language and harmonize the wording with the introduction.

Many thanks to willmo for the PR.

Version 4.3.6-dev-13-g00e595ce

Docker Build Optimistion

Ensure the /run/dbus directory, needed for dbus to start, is defined.

Version 4.3.6-dev-9-gf7401ec7

Docker Build Optimisation

Improve the Dockerfile build sequences as follows:

Build each dependency in a separate stage, facilitating parallel builds.
Define default value for ARGS, permitting easier local docker builds.
Clone the specified branch only, and to a depth of 1, thus getting relevant data faster.
Copy files in a one-off command, reducing the amount of Docker layers created.

Many thanks to David Girón for the PR.

Version 4.3.6-dev-3-ge4d3c6f7

Bug Fix

Fix a potential bug by checking that a buffer is not zero before attempting to deallocate it.

Version 4.3.6-dev-1-g409397d3

This is effectively the same as the release version 4.3.5.

Version 4.3.5-dev-56-g758648a5

Deprecation Note

The soundio backend is being deprecated and will be removed in a future update. It seems that nobody is using it, and as it stands it is very inflexible.

"If this be error and upon me proved," -- as Shakespeare wrote -- please let us know...

Version 4.3.5-dev-53-gaa3af3b3

Bug Fix

Fix a problem in the Jack Audio backend audio_jack.c. The problem was that if the system's jack server was running at anything other than 44,100 frames per second, the delay information being returned by the backend was incorrect. Thanks to lucianoiam for reporting the problem and for checking the proposed solution.

Version 4.3.5-dev-48-gfe743fdf

Docker Bug Fixes

Stop advertising the SFTP and SSH services on Bonjour. Thanks to https://github.com/jpbaril for bringing this to notice.

Bug Fix

Due to recent changes in the MQTT client, a compilation error occured when building for Classic Airplay only. Fixed.

Version 4.3.5-dev-44-ge4c2ce4a

Enhancements

Add Home Assistant MQTT Auto-Discovery and active/playing State Messages, thanks to aaronk6.
Send pvol metadata on mute, thanks to Tucker Kern.

Bug Fix

Check swr_init() and exit if error code found, thanks to Andrew May.

Version 4.3.5-dev-29-g17b134b0

PipeWire Enhancement

Initialise the PipeWire backend so that the PipeWire stream is initially inactive.

Version 4.3.5-dev-27-g8e6bd06c

PipeWire Enhancement

Until now, the stream in the PipeWire backend remained permanently active. This meant that external programs could not tell when audio was really playing or not. Now the stream will go inactive (i.e. "paused") when play is stopped and active when play resumes. Note that in AirPlay 2, play often stops momentarily between tracks, and so there will be momentary changes from active to inactive and back to active again in the PipeWire backend. This may change as the backend improves. Thanks to Nemo157 for the Idea: https://github.com/mikebrady/shairport-sync/discussions/1889.

Version 4.3.5-dev-23-g1687b2a4

Docker Enhancement

The AirPlay 2 Docker image now incorporates the PipeWire backend. Thanks to Maxim for the PR: https://github.com/mikebrady/shairport-sync/pull/1880.

Version 4.3.5-dev-6-g597aba0c

FreeBSD Bug Fix

Modify the sndio backend (native to OpenBSD, also used in FreeBSD) to deal with an intermittent bug. Specifically, use an explicit is_running flag to keep track of the playing status of the backend. Thanks to Jan Przybylak, Klemens Nanni and Amanda Stjerna for their help and persistence tracking down this problem. Resolves Issue: https://github.com/mikebrady/shairport-sync/issues/1765.

Configuration Comment Update

Update comments in the sndio section of the sample configuration file.

Version 4.3.5-dev-3-ge28c566a

Bug Fix

Fix a double-free fault introduced by replacing avcodec_close with avcodec_free_context. It seems as if the context is freed by a subsequent av_free anyway... Sigh.

Version 4.3.5-dev-1-g9909bc21

Bug Fix

Use (AVChannelLayout)AV_CHANNEL_LAYOUT_STEREO now in place of bit-mapped AV_CH_LAYOUT_STEREO when setting up the FFmpeg software resampler with swr_init(). It was possible to do this starting at FFmpeg 5.1, but is mandatory in FFmpeg 7. Also remove now-deprecated avcodec_close. Thanks to Deyan Dragov for the report: https://github.com/mikebrady/shairport-sync/issues/1876.

Version 4.3.4-dev-25-g15a7090a

Change

Revert the session_timeout to two minutes (120 seconds). In other words, if a player becomes disconnected for more than two minutes while playing, the session is terminated.

Bug Fixes

Enable the disconnected session timeout for AirPlay 2 operation -- it had been disabled by default.
Fix a bug that prevented a fatal error that occured while directly accessing the alsa output device from terminating the application cleanly.

Version 4.3.4-dev-21-g105299a7

Bug Fix

Fixed a bug that prevented Shairport Sync from recovering cleanly if a player disconnected without warning. The problem was that the player thread would not respond to cancel request. Fixed by moving a pthreadtestcancel() call to the innermost loop.

Associated with this, some obsolete watchdog code has been removed.

Also, the session_timeout default has been changed from 120 seconds to 60 seconds.

Thanks to Tobias Huttinger for the bug report -- Issue #1870.

Version 4.3.4-dev-13-gc064b8ba

Bug Fixes

Reorder some of the files to be included in shairport.c to fix compilation errors in old versions of Mac OS X.
Avoid using TCP_KEEPINTVL and TCP_KEEPCNT if they are not defined (they are not defined in older versions of Mac OS X). Thanks to Sergey Federov for raising these issues and pointing at a potential solution.
Fix a race condition with the metadata queues. The problem was that the queues were being initialised by threads launched by the main thread which, having started the threads, proceeded to use the queues. But if the threads were late in starting, the queues might not be initialised by the time the main thread tried to use them. Fixed by initialising the queues in the main thread.

Version 4.3.4-dev-10-gaade1b39

Docker Enhancement -- Continued

Move the ulimit -n ... command to set the maximum file limit from the 01-startup/script.sh (where it didn't seem to have any effect) to the 02-dbus/run. Thanks to rp86 for the feedback.

Version 4.3.4-dev-8-g111e247b

Docker Enhancement

Limit maximum open file handles in Docker images. Thanks to Florian Wallner for Issue #1756, iVolt1 for pointing to a fix and rp86 for the reminder!
Increase the level of optimisation while building the Shairport Sync application itself.

Version 4.3.4-dev-6-g5f64722a

Enhancement -- HDMI Ports

As a further enhancement for HDMI, enable access to mixers on a HDMI output device. The issue appears to be that a mixer can not be "attached" to a device whose name begins with hdmi:, so it must be attached to the same device, but with the hdmi: prefix replaced by hw:.

Version 4.3.4-dev-3-g238e4bbf

Enhancement -- HDMI Ports

If your device has HDMI ports, the Shairport Sync help command has previously listed them with a hw: prefix, e.g. hw:vc4hdmi0. Unfortunately, if you use a name like that as an output_device name for a HDMI device in Shairport Sync, the device may not be usable.

But if you use the hdmi: prefix, e.g. hdmi:vc4hdmi0, it may work: something capable of receiving audio must be connected to the HDMI port and it must be powered on when your device boots up.

The enhancement is to update the help text for the ALSA backend to denote HDMI devices using the hdmi: prefix rather than hw:. Now, for example, on a Raspberry Pi 4, the output is:
```
Settings and options for the audio backend "alsa":
  -d output-device    set the output device, default is "default".
  -c mixer-control    set the mixer control name, default is to use no mixer.
  -m mixer-device     set the mixer device, default is the output device.
  -i mixer-index      set the mixer index, default is 0.
  hardware output devices:
    "hdmi:vc4hdmi0"
    "hdmi:vc4hdmi1"
```
Previously it was:
```
Settings and options for the audio backend "alsa":
  -d output-device    set the output device, default is "default".
  -c mixer-control    set the mixer control name, default is to use no mixer.
  -m mixer-device     set the mixer device, default is the output device.
  -i mixer-index      set the mixer index, default is 0.
  hardware output devices:
    "hw:vc4hdmi0"
    "hw:vc4hdmi1"
```
...which is technically correct but unfortunately not very useful.

Get more information about the hardware output devices using sps-alsa-explore (also available as a Docker image).

Version 4.3.4-dev-1-gc945f3a9

This is effectively release version 4.3.3 -- the starting point for 4.3.4.

Version 4.3.3-dev-81-ge0b13829

Bug Fix

Undo the changes made in Version 4.3.3-dev-46. Unfortunately, the changes in PR 1831 make the Classic Airplay build of Shairport Sync invisible to iOS 17.5 and iPadOS 17.5. Thanks to poker335 for identifying the issue and suggesting the fix.

Version 4.3.3-dev-79-gf8e8550e

Enhancements

A number of minor documentation updates. Thanks to Ambrose Li for their PR.

Version 4.3.3-dev-73-g8d678c43

Enhancement

Add support for the mdebtls3 library. (Note: mdebtls3 is optional for Classic Airplay builds; it is not used in AirPlay 2 builds). Many thanks to orangepizza for the PR.

Version 4.3.3-dev-66-gb054c004

Enhancement

Simplify the macOS build check.
Add some extra CFLAG settings to configure.ac for libconfig, libpopt, openssl and libcrypto to enable compilation on macOS without extra flag settings.

Version 4.3.3-dev-61-gcc963bf0

Enhancement

Use macos-13 instead of macos-latest as the github runner for the Mac-compatible build check.

Version 4.3.3-dev-58-g85f8ea12

Enhancement

Use PKG_CHECK_MODULES, if it's available, to find the ao lib.

Version 4.3.3-dev-53-gc0f5112b

Bug Fix

Remove some almost-never-used and therefore untested code, and remove a potentially misleading comment from the ALSA backend.

Version 4.3.3-dev-49-gb5ea2b10

MQTT Documentation Updates

Thanks to Craig Lockwood for improvements to the MQTT document. The binary_sensor example has been updated and the rest of the document has been edited for clarity, length and consistency.

Version 4.3.3-dev-46-g6eba4fd8

Enhancement

This enhancement modifies the AirPlay attributes advertised by Shairport Sync to allow AirPlay clients to see only the player of the appropriate protocol -- Classic Airplay ("AirPlay 1") or AirPlay 2.

For example, if you run two instances of Shairport Sync, one built for Classic Airplay and the other for AirPlay 2, MacOS and iOS will recognize only the AirPlay 2 instance.

Without the enhancement, MacOS and iOS will detect both Classic AirPlay and AirPlay 2 devices at the same time. (TuneBlade recognised only the Classic Airplay device, since it is not compatible with AirPlay 2.)

Thanks to Oleh Kuzhylnyi for the PR.

Version 4.3.3-dev-43-g5922f9d1

Enhancement

If a network interface is specified in the configuration file, limit the addresses used for PTP to that network interface only. Thanks to Ryan Mounce for the PR.

Version 4.3.3-dev-41-g0f07107c

Enhancment

Look for DACP-ID and Active-Remote in the GET /info request, where it sometimes appears in an AirPlay 2 session originating from an Intel Mac.

Version 4.3.3-dev-40-g98627932

Enhancement

Add a configuration option --without-create-user-group to optionally disable the creation of the shairport-sync user and group during a make install. This makes packaging easier for some systems, e.g. Yocto. Thanks to hvilleneuve29 for the PR.

Version 4.3.3-dev-38-gab59f201

Docker Compose Enhancement

Set S6_KEEP_ENV = 1 to enable the passing of environment variables from the docker compose file into the image. Thanks to HNKNTA for the PR.

Version 4.3.3-dev-35-gd6ad6da1

Documentation Update

The introduction paragraph now more clearly mentions the hard facts/requirements with "as of v4.1 and newer" and the supported devices are displayed in bullet list format for better readabilty. Thanks to porg for the PR.

Version 4.3.3-dev-32-gcf10ff9d

Enhancement

Implements the idea in Issue 1808 to make Fedora package-building easier. Thanks to Bill Peck for the suggestion and continued support for Fedora.

Version 4.3.3-dev-30-g4aee4ec8

Enhancements

Start using the pledge(2) facilities in OpenBSD. In OpenBSD, limit the set of system calls Shairport Sync is allowed to make, most importantly, permit fork(2)/execve(2) if and only if user defined commands are run. PR 1803.

Bug Fixes

Do not print the password in debug logs. PR 1811.
If a string argument is a NULL in some debug messages, output the string (null). PR 1810.

Thanks again to Klemens Nanni for these PRs.

Version 4.3.3-dev-21-g926cd56e

Enhancements

Updates to documentation regarding OpenBSD -- PR 1797.

Bug Fixes

Fix an OpenBSD compilation warning -- PR 1797.
Terminate Shairport Sync if the configuration file exists but can not be opened -- PR 1798.

Thanks to Klemens Nanni for these PRs.

Version 4.3.3-dev-14-gf37d1b8e

Pesky Changes You Can't Ignore

The man entry for Shairport Sync has moved from Section 7 ("Miscellaneous information") to Section 1 ("General commands (tools and utilities)"). For this reason, you should delete the file /usr/local/share/man/man7/shairport-sync.7 if it exists. FYI, the man entry will now be placed at /usr/local/share/man/man1/shairport-sync.1 at the make install step. Thanks to Klemens Nanni for noticing this and for providing PR 1795 to deal with it.

Bug Fixes

A number of OpenBSD-specific issues have been discovered and fixed by Klemens Nanni. Thanks to them for PR 1794 and PR 1793.

Enhancement

Add a separate install-config-files Makefile target to selectively enable or disable the installation of configuration files at make install. Thanks to Zane van Iperen for PR 1782.

Version 4.3.3-dev-4-g7e741465

A slight change to CAR INSTALL, to add a two-second delay when accessing the WiFi device for the first time. It may be necessary in some cases, e.g. the Pi 3B.

Bug Fix

Use pthread_rwlock_wrlock instead of the incorrect use of pthread_rdlock_wrlock when tearing down a connection. (This didn't seem to cause any problems, but it was definitely a bug, now fixed.)

Version 4.3.3-dev-1-g9ab85989

Forgot to push tag 4.3.3-dev, so "back" to 4.3.3-dev-1. Apologies for the confusion. The commit hash is good.
Further updates to CAR INSTALL, hopefully to make updates a bit simpler.

Version 4.3.3-dev-7-ga7603893

Remove the a few compilation warnings during a Docker build -- the warnings were that some variables possibly being used uninitialised.

Version 4.3.3-dev-3-g2a5c49d3

Update CAR INSTALL for Bookworm, which uses NetworkManager and does not use dhcpcd.
Changes to the car installation setup may result in more stable WiFi operation.

Version 4.3.2-dev-58-gb70dd463

This became Release 4.3.2, approximately.

Investigation -- continued

Return 501 ("Not Implemented") instead of 200 ("OK") in response to a POST message with the argument /feedback on a Classic AirPlay connection.

Version 4.3.2-dev-56-g4cd3c1da

Investigation

Return 200 -- "OK" in response to a POST message with the argument /feedback on a Classic AirPlay connection. Continue to return 500 -- "Internal Server Error" for all other POST messages. This is part of an investigation into Issue #1745.

Version 4.3.2-dev-51-g98679bbb

Enhancement

Add a new pw (PipeWire) backend setting -- sink_target. Leave the setting commented out to use the sink target already selected by the PipeWire system.

Bug Fixes

Fix a bug in picking up the PipeWire node_name -- it was being sought in the pa stanza instead of the pw stanza of the configuration file.
Fix memory management bugs in the PipeWire backend -- settings strings were being deallocated twice on exit.
Fix memory management bugs in the PulseAudio backend -- settings strings were being deallocated twice on exit.

Version 4.3.2-dev-47-g288e5eb6

In the PipeWire backend, change the default for node_name from "shairport-sync" to "Shairport Sync".

Version 4.3.2-dev-45-g3763b321

Enhancement

Add two pw (PipeWire) backend settings -- application_name (default: "Shairport Sync") and node_name (default: "shairport-sync"). The application_name is used when referring to Shairport Sync in the GUI and the node_name is used in, for example, output from pw-link. Thanks to alexsarmiento for the suggestion.

Bug Fixes

Minor bug fixes to the PulseAudio backend.

Version 4.3.2-dev-41-gdc197ae7

Bug Fix

Fix underrun ("xrun") errors in the new PipeWire backend. These errors seem harmless, and the only place they were noticed was in the listing from pw-top on recent versions of PipeWire (e.g. PipeWire 0.3.80 in Fedora 38). Anyway, they are gone now.

Version 4.3.2-dev-38-gbde2bcc8

Enhancement

The PipeWire backend (pw) has been completely rewritten and now provides full sychronisation.

Bug Fixes

Stability improvements to the PulseAudio (pa) backend. some bugs with the use of mutexes and the treatment of a full FIFO buffer were identified and fixed.

Version 4.3.2-dev-30-gc36d322a

Bug Fix

If the volume control was at its absolute minimum (-144.0), audio would be muted even if ignore_volume_control was enabled in the configuration file. The fix was to mute only if ignore_volume_control is not enabled. Thanks to mc510 for reporting the issue.

Version 4.3.2-dev-27-g04e3f891

Bug Fixes

Fix bugs in the handling of an Avahi client disconnection event. Due to its rarity, Shairport Sync was not handling Avahi client disconnection events correctly. Specificially, it was not cleaning up before deleting the disconnected Avahi client and attempting to create a new one. This has now been fixed.

It is worth noting that these disconnection events are very rare and often indicate that there is something wrong with the computer as a whole.

Version 4.3.2-dev-25-gc0467468

Make the latency in the PipeWire backend 200,000 instead of 20,000. Should help with DAC underrun.

Version 4.3.2-dev-23-gc4975d5c

Fixed some debug messages that were missing arguments. In principle, these could cause crashes just when you need them to work properly, sigh. As far as is known, however, they did not cause problems. Many thanks to Nathan Gray for the report.

Version 4.3.2-dev-21-ga3f12d68

When a connection terminates abruptly while is it the principal_conn, make sure it sets the principal_conn to NULL and cleans up the Bonjour flags, if appropriate.

Version 4.3.2-dev-19-g91c0803d

Lock access to the principal_conn (i.e. the connection that may be playing) using a read-write lock rather than a mutex. Use read locking when checking that a connection is currently the principal connection before altering any system-wide values such as mDNS flags. This eliminates a number of data race conditions.
As soon as it has been decided that the current playing session (as specified in the principal conn) is to be preempted, demote it from principal_conn status before stopping play, closing the connection, etc.
Set the status flags correctly for a Classic Airplay session on an AirPlay 2 system.

Version 4.3.2-dev-4-g20a45def

Bump version information.

Version 4.3.1-dev-3-g2fb81ca9

Exploration

Add some slightly noisy diagnostics to try to locate a fault.

Version 4.3.1d-2-ge6a2a429

Bug Fix

Fix a recently-introduced bug that prevented Shairport Sync being added to Home.

Version 4.2.1d0-67-gef14cace

IMPORTANT Bug Fixes

A recent security audit has identified a number of issues with NQPTP that have been fixed in the latest update to NQPTP and in this corresponding update to Shairport Sync.
Please update to the latest development branch version of NQPTP before updating Shairport Sync. (Shairport Sync now requires the Shared Memory Interface version 10, i.e. smi10.)
When updating NQPTP on Linux, ensure you remove the old service file as directed in the README.
Having completed both updates and installations, remember to restart NQPTP first and then restart Shairport Sync.

Version 4.2.1d0-62-g556419e8

Bug Fix

Fix a bug introducted in the last development push, 4.2.1d0-60-g702e8285, whereby volume control changes would be ignored after a pause in playing of longer than about 8 minutes.

Version 4.2.1d0-60-g702e8285

Bug Fix

Fixes a bug that causes the Docker image to crash occasionally when OwnTone attempts to interrupt an existing iOS session. Thanks to aaronk6 for the report.

Version 4.2.1d0-56-ga9000de6

Bug Fixes

The active_end enhancement in 4.2.1d0-23 didn't work and has been rewritten here.
A crashing bug in NQPTP has been fixed in the development version -- please update. (The updated version will be incorporated automatically in the development version of the Docker image.)

Version 4.2.1d0-51-gbc2fda52

Enhancement

Modify the new dasl_tapered volume control profile to work better with mixers with a restricted attenuation range.

This volume control profile has the property that halving the AirPlay volume reduces the output level by 10 dB, which corresponds to roughly halving the perceived volume.

For example, if the AirPlay volume goes from 0.0 to -15.0, the output level will decrease by 10 dB. Halving the AirPlay volume again, from -15 to -22.5, will decrease output by another 10 dB. Halving the AirPlay volume once more, from -22.5 to -25.25, decreases the output by a further 10 dB, meaning that at AirPlay volume -25.25, the volume is decreased by 30 dB relative to the level at AirPlay volume 0.0.

Now, if the attenuation range of the mixer is only 30 dB, then changing the AirPlay volume in the range from -25.25 down to -30.0 would have no further effect on the output level, since it's already at the lowest possible level permitted by the attenuator. This "dead zone" is about one sixth of the full range of the AirPlay volume control.

To work around this, the "flat" output level is used if it gives a higher output dB value than the calculation described above. It means that changing the AirPlay volume, even at low levels, will always change the output level, while the original advantage of the dasl_tapered profile is retained at higher AirPlay volumes.

In practice, if the device's attenuation range is over about 50 dB, the flat output level will hardly be needed at all.

Version 4.2.1d0-46-g57061dfb

Enhancement

Add a new volume control profile called dasl-tapered. Shairport Sync already has two volume control profiles -- the standard profile -- which is the default -- and a flat profile. A feature of the dasl-tapered profile is that halving the volume control setting (e.g. moving the volume slider from full to half, or from half to a quarter) reduces the output level by 10dB, which roughly corresponds with a perceived halving of the audio volume level. Many thanks to David Leibovic, aka dasl-, for this. To activate the dasl-tapered profile, set the volume_control_profile to "dasl_tapered" in the configuration file and restart Shairport Sync. There may be some more minor adjustments to this profile for devices with a restricted attenuation range...

Version 4.2.1d0-40-g9ef4e351

Bug Fix

Fix a cross-compliation error caused by not looking for the correct version of the ar tool. The fix was to substitute the correct version during the autoreconf phase. Thanks to sternenseemann for raising the issue and the PR containing the fix.

Version 4.2.1d0-37-g9a8f1ba1

Bug Fix

Update the mDNS strings for the Classic AirPlay feature of AP2, so that it does not appear to provide MFi authentication. Addresses this discussion.

Version 4.2.1d0-35-g6acd73da

Update

Confirm the bug fix made in 4.2.1d0-26 to Classic Airplay Remote Control: always use a revision number of 1 when looking for status updates on the DACP remote control port.

Version 4.2.1d0-33-gd4e00380

Bug Fix

If an active_end signal is generated when the system is shutdown gracefully, ensure it is sent before shutting down the metadata transmission system, duh.

Version 4.2.1d0-31-gb0f2fb9a

Bug Fix

Fix a bug that could ocassionally cause a crash if allow_session_interruption is set to "yes" and a Classic AirPlay session is interrupted by a play session request from another device.

Version 4.2.1d0-28-g0ca5fd3c

Tiny Bug Fix

Fix a statistics bug (the minimum buffer size was incorrectly logged) and also tidy up the statistics logging interval logic for resetting min and max counters.

Version 4.2.1d0-26-g716aa051

Bug Fix

Classic Airplay Remote Control. Always use a revision number of 1 when looking for status updates on the DACP remote control port. This is ia quick-and-dirty change to try out a (good) suggestion in Issue #1658 -- if it works change will be made permanent. Thanks to ejurgensen, as ever, for the report and the suggested fix.

Version 4.2.1d0-23-g46a215b6

Enhancement

On graceful shutdown, an active_end signal should now be generated if the system was in the active state. Addresses issue #1647. Thanks to Tucker Kern for raising the issue.

Version 4.2.1d0-21-g2f52e699

Bug Fix

Add an important missing format string argument to a call in the Jack Audio backend. Many thanks to michieldwitte for their PR.

Version 4.2.1d0-17-g17414f57

Enhancements

Stop using a deprecated FFmpeg data structure reference.
Stop using deprecated OpenSSL calls. Thanks to yubiuser for their PR -- which did some of the updating -- and for their guidance.
Run workflow-based tests on PRs automatically. Thanks to yubiuser for their PR.

Version 4.2.1d0-5-gc3d99f96

Enhancement

Increase the level of detail in the debug log at verbosity level 2 (i.e. -vv).

Version 4.1-dev-922-gffeeacc4

This is (approximately) Version 4.2 release.

Enhancement

When built for AirPlay 2, include the Shared Memory Interface (SMI) version number in the version string, in the form: smi* where * is the version number, e.g. smi9. This must be same as the SMI version number of NQPTP, which can be listed by entering $ nqptp -V.

Version 4.1-dev-919-gbd068fb6

Enhancements

Allow compilation with libplist 2.3.0. Thanks to Markus Reiter for the update.
Updates to GitHub Action Workflows -- many thanks to yubiuser for this detailed work.
Include PulseAudio support in the Shairport Sync builds within the Docker images. Thanks to Ferdynand Naczynski and thanks also to Noel Hibbard for championing this idea for a long time.
Documentation Updates.

Version 4.1-dev-896-g03961830

Bug Fix

In some situations, the Device ID generated by Shairport Sync was all zeros, and so was invalid, causing connectivity problems. The cause of the problem was that get_device_id was not interpreting getaddrinfo information correctly. Thanks to Carl Johnson for reporting the issue, finding the (rather obscure) cause of the problem and for providing code to fix it.

Version 4.1-dev-886-ge74300d7

Updates and Enhancements

Merge Pull Request #1635 and Pull Request #1636 . The PRs update the MQTT documentation to correspond to updates in Home Assistant. Thanks to hunhejj for these.
Merge Pull Request #1624. The PR updates the Docker images to use Alpine 3.17 and ensure services such as Avahi and D-Bus start in the correct order. Thanks to yubiuser for their work on this.

Version 4.1-dev-876-g29ca3225

Bug Fix

Fix a bug reported in Issue #1633. The bug was that when a Realtime Audio stream (e.g. playing from Spotify on iOS or using Shairport Sync as the Sound Output on a Mac) was played, it was fine, but when a second stream was started, it could not be heard. The problem was that the PTP clock was not being correctly revalidated for second and subsequent Realtime Audio streams. The fix was to ensure that the PTP clock is revalidated on second and subsequent plays on the same connection. Thanks again to David Leibovic for finding the problem.

Version 4.1-dev-874-g551734b3

Bug Fix

Use TCP keepalive a little more generally -- treat it the same as a client closing the link rather than just an error.

Version 4.1-dev-872-g65c6975e

Bug Fix

Remove three potential race conditions between Shairport Sync opening a TCP connection and the client checking that the connections are open. The problem was that the connections were being opened in threads that were created just before the client was given the connection information. If the threads were delayed (e.g. on a slow or busy processor), the client could use the connection information to check the connections, but find that they were not (yet) open. This could cause the client to terminate the session immediately with a TEARDOWN. The fix was to open the connections before creating those threads and before sending the connection information back to the client. In this way, the connections are guaranteed to be open before the client has the information it needs to try to open them, even if the threads ared delayed in starting. This bug would manifest itself by allowing play to proceed but not play anything.

Version 4.1-dev-870-gc924387a

Bug Fix

When built for AirPlay 2, ensure the hexadecimal string that prefixes the AirPlay 1 Service Name in the Bonjour text strings matches the AirPlay 2 Device ID. For example, if the Service Name is Kitchen and the AirPlay 2 Device ID is b8:2f:eb:d7:85:df, the AirPlay 1 Service Name should be B82FEBD785DF@Kitchen. (When built for AirPlay 1, the hexadecimal prefix is simply a hash of the Service Name.)

Thanks to Casper for raising the issue and to ejurgensen for identifying the cause of the problem.

Version 4.1-dev-862-g6eb70eee

Pesky Changes You Can't Ignore

Important. Please update and re-start NQPTP. The Shared Memory Interface protocol that Shairport Sync and NQPTP use to communicate with one another has been updated to version 9 to reflect changes in NQPTP's operation.

Enhancements

A new "high volume check" attempts to prevent the unpleasant surprise of a new session playing at the same very high volume as the previous session if that previous session was some time, e.g. some hours, ago. How it works is that if a timeout period has elapsed since the last play session and the last play session was very loud, a lower volume will be suggested for new play sessions. Most iOS and iPadOS apps accept the suggestion as the new volume. However, Macs, HomePods and AppleTVs use the suggested volume only when connecting the first time. The timeout, loudness threshold and suggested volume are all settable in the configuration file. Please refer to the sample configuration file for more details. The feature is disabled by default.
The PulseAudio backend has been reworked to simplify the code and to remove a number of issues. Hopefully nothing has been broken.

Version 4.1-dev-846-gb5bb2fef

Improvements to the detection of a missing or non-existent output device. Look for ENODEV and ENOENT errors when opening or playing to an output device.

Version 4.1-dev-843-gae5910e2

Bug Fix

Stop endless error messages from the stdout backend.

Enhancements

Call the unfixable error handler if the output device can't be opened or generates errors while being used. If no program is attached to the run_this_if_an_unfixable_error_is_detected hook in the sessioncontrol section of the configuration file, the program will exit instead.
Shorten the amount of time to wait after a client disappears before terminating a play session.

Version 4.1-dev-824-g8e5393ec

Enhancements

Add man page and man utilities to the Docker images.
Enable the MQTT client to parse the phbt and phb0 Playing HeartBeaT metadata tokens.

Version 4.1-dev-818-gf15c3255

Enhancement

Add a configuration check for the xxd program when building for AirPlay 2. Cleans up an annoying problem mentioned in Issue #1341. Thanks to David Girón for the reminder.

Version 4.1-dev-815-gcb097034

Enhancement

Use TCP keepalive to close down a play session when the client disappears, e.g. when the player goes out of range of WiFi. A play session is now terminated after a break in connection lasting more than approximately one minute. Addresses the problem reported in Issue #1584. Thanks to JanLp for the report.

Version 4.1-dev-809-g8a69f5ea

Enhancements

Add another item of metadata with the code phb0 and the DBus property name FirstFramePosition. This is similar to the phbt and FramePosition metadata, except that it is updated for the first frame of a play session. It can be ignored, as a phbt token is also sent when the first frame is output.

Version 4.1-dev-805-g50738c36

Enhancements

Very provisional additions to the metadata -- add some functionality for Shairport Sync to send information about what frame of audio is being played at a particular time. It can be set up to periodically generate a phbt (a Playing HeartBeaT) item comprising the RTP frame number of the audio being played at a particular instant -- the computer's system time in nanoseconds. The two numbers are presented as a string, e.g. 595422363/4697675115573193. Set the interval in seconds with the new metadata setting progress_interval – 0.0 means no heartbeat is generated.
Equivalent additions have been made to the native DBus interface: the phbt information appears as a FramePosition property and the update interval can be set using the SetFramePositionUpdateInterval(Seconds) method.

Please note that this might all disappear or change radically.

Version 4.1-dev-798-g803eddbd

Docker

Within the Docker container, launch Shairport Sync as root user rather than as the user shairport-sync. This is experimental, to investigate possible device access issues.

Version 4.1-dev-795-g7f279efa

Bug Fix

Fix a bug if the ALSA device name isn't available. (Happens in Fedora 37 on Arm in VMWare Fusion on an Apple Silicon Mac.)

Version 4.1-dev-790-g03d291f4

Bug Fix -- Second Attempt!

Second attempt to fix a bug caused in the transition to version 4.1, where a change was made to how the 12-hex-digit prefix to the classic AirPlay service name was derived. Previously it was a hash of the service name, and in 4.1 this was changed to deriving it from one of the device's MAC addresses. This seems to cause problems with multiple instances of classic Shairport Sync running on the same system, as they would all get the same prefix. The fix was to generate the prefix from a hash of the service name and the device's MAC address, which should be unique for every instance. Addresses issue #1581. Thanks to Christoph Bloemer (?) for the report. The first attempt failed because not all the changes needed were done.

Version 4.1-dev-789-g75aa150e

Oops

Reverted the fix below. Something still to be done...

Version 4.1-dev-786-gfc117e73

Bug Fix

Fix a bug caused in the transition to version 4.1, where a change was made to how the 12-hex-digit prefix to the classic AirPlay service name was derived. Previously it was a hash of the service name, and in 4.1 this was changed to deriving it from one of the device's MAC addresses. This seems to cause problems with multiple instances of classic Shairport Sync running on the same system, as they would all get the same prefix. The fix was to generate the prefix from a hash of the service name and the device's MAC address, which should be unique for every instance. Addresses issue #1581. Thanks to Christoph Bloemer (?) for the report.

Version 4.1-dev-784-g60e913dd

Bug Fix

In the PulseAudio backend, Whenever a play or latency request is made, reopen the stream if it is closed. Addresses issue #1580. Thanks, as ever, to Noel Hibbard for the report.

Version 4.1-dev-781-g9af924dd

Metadata Enhancements

The following new metadata items have been added to the metadata pipe, MQTT and the native D-Bus interface.

core/asdk. This is glossed as daap.songdatakind. It seems to indicate whether the audio is timed or not, e.g. a track or album has the value 0, and a continuous untimed stream such as a radio station is 1, so it is potentially very useful for remote control displays, as it seems to indicate whether a progress bar, etc. could be used or not. The value is included, if available, in the native DBus interface in the metadata bundle with the tag sps:songdatakind.
ssnc/styp. This is the type of data stream currently being received by Shairport Sync. Values are Classic, Buffered or Realtime. Included in the native D-Bus interface as StreamType in the org.gnome.ShairportSync.RemoteControl interface.
ssnc/ofmt. This is the output format of audio going to the output device. Values are S32, S24 and so on. S=signed, U=unsigned, 32/24/16/8 is the bit depth, BE/LE is Big-Endian or Little-Endian. Note that S24 means signed 24 bits in a 32-bit space; S24_3LE means Signed 24 bits in a 3-byte little-endian form, etc. Each frame is always a stereo pair. Included in the native D-Bus interface as OutputFormat in the org.gnome.ShairportSync interface.
ssnc/ofps. This is the output rate in frames per second, usually 44100. Included in the native D-Bus interface as OutputRate in the org.gnome.ShairportSync interface.

Version 4.1-dev-776-g27754a62

Docker Enhancements

Place the configuration file and the sample configuration file in the Docker image at /etc/shairport-sync.conf and /etc/shairport-sync.conf.sample. Thanks to inDomus and tamasfodor1988 for the report, Issue #1575.

Version 4.1-dev-774-g3e4b67e9

Metadata Enhancements

Add the service name, e.g. "Den Speakers" as metadata. This has the code "svna" in the metadata pipe and the name "service_name" in the MQTT interface.
Add two properties to the D-Bus metadata interface:
1. ServiceName -- see above.
2. ClientName -- the name of the current client, e.g. "Joes's iPad".

Version 4.1-dev-772-g085bf128

Bug Fix

Fix a long-standing bug whereby the socket used for the RTSP connection wasn't closed when the connection was closed by the client, potentially exhausting the sockets available. Many thanks to Lars Strojny for the report: #1567.

Enhancements

Small documentation updates.
More use of GitHub actions to check standard builds.

Version 4.1-dev-756-g0a8b1231

Docker Updates

Move to using latest tags for the latest release and rolling for intermediate (non-release) updates on the master branch. Pushes to the development branch will result in Docker images with the development tag.

Enhancement

Tidy up --display_config output to skip empty configuration file stanzas and to note when there are no active settings whatever in the file.

Version 4.1-dev-747-ga4da36b4

Docker Updates

Extra command-line arguments passed when the Docker image is launched are passed to the shairport-sync instance as described on Docker Hub.
The shairport-sync instance runs as user and group shairport-sync, which has reduced privileges.
The "classic" docker image now uses the s6-overlay to manage processes, the same way as the standard (AirPlay 2) docker image. It does makes the image bigger, so takes a little longer to download.

Version 4.1-dev-745-gbb4e9078

Bug Fix

Fix a bug that caused new metadata not to be passed on immediately to the D-Bus, MPRIS and MQTT interfaces. Thanks to phelbas for finding the bug and the fix in Issue #1560.

Enhancement

Add two new metadata tokens for AirPlay 2 buffered audio streams only, which can be paused for a period of about five minutes before the session is ended. They are for Pause (paus) and Resume (pres).
Clean up the generation of MPRIS and D-Bus PlayerStatus values. Until now, Shairport Sync used extra information to try to determine the state a session was in -- Playing, Paused or Stopped. The extra information used what (1) when the first frame was played, (2) when a flush was requested and when (3) frame play was resumed. Unfortunately, these are noisy signals and are unreliable for this purpose, so they are now no longer used.

The situation now is that PlayerStatus becomes Playing when a play session begins and becomes Stopped when a play session ends, unless it is an AirPlay 2 buffered audio session.

In the case of a AirPlay 2 buffered audio session, a play session will be Paused when play stops (but the play session is not ended). If play resumes within a period determined by the client (about five minutes), PlayerStatus will return to Playing. Otherwise, the play session is ended by the client and PlayerStatus will transition to Stopped.

Version 4.1-dev-738-g9f7584eb

Enhancement

It seems that this missing session key issue discovered and discussed below is a transient problem: some client apps omit the session key occasionally but include it the rest of the time. So, to make the problem a bit less intrusive for users, the way a missing session key is dealt with has been changed. The new arrangement is that instead of dropping the AirPlay connection completely as noted below, the audio is simply skipped. From the user's perspective, the music simply won't play, but the AirPlay connection won't be dropped. When they start it again, the session key will hopefully be present and the audio will play. Let's hope that this will be less disruptive for users and that this issue goes away as clients are updated. Thanks again to Mike for his help with this in #1551.

Version 4.1-dev-735-g6a55774f

Bug Fix

Very occasionally, and for as-yet unknown reasons, an AirPlay 2 session may not include an important parameter called a "session key". This was causing Shairport Sync to crash. With this update, Shairport Sync will now simply drop the entire connection if a session doesn't include a "session key". Addresses the crashing issue reported in #1551. Big thanks to Mike for his huge assistance in tracking this down.

Version 4.1-dev-730-g63e0dfda

Minor Debugging Enhancements

Improve debugging of a Shairport Sync daemon process created with libdaemon.
List the command line when Shairport Sync starts with a verbosity of 1 or more.

Version 4.1-dev-726-g5e6e6344

Enhancement

Enhance --displayConfig to log information about the OS as well as about Shairport Sync itself, and use Shairport Sync's standard logging -- it's not stuck on STDERR anymore.

Version 4.1-dev-721-g93c1f1ae

Pesky Things You Can't Ignore

If you are updating from a previous version, after you have pulled the update, please redo the autoreconf -fi and the ./configure... steps (and the do a make clean for good measure) before makeing the executable -- there have been many changes to the build process.

Bug Fix

Correction to Makefile.am to make it work both on FreeBSD and Linux both in the source directory and in a subsidiary build directory.

Version 4.1-dev-717-g86539bc5

Pesky Things You Can't Ignore

Enhancements

A new command-line-only option is included: --displayConfig. This prints configuration information to STDERR and should be useful when debugging issues.
Help text is reordered and updated.
The man page is updated.
The man contents are no longer automatically built when Shairport Sync is built. This is okay because the contents are normally static. The man folder has a new Makefile.
The xmltoman application is not now needed when building Shairport Sync.
When updating the man page, xsltproc is now used instead of xmlmantohtml.

Version 4.1-dev-701-g65daef30

Bug Fix

Fix a bug in the generation of version information from git tags. The fix is to use lightweight tags as well as annotated tags. GitHub marks releases with lightweight tags, so this should make version and release information correspond better.

Enhancement

Add an new Advanced Topic -- Adjusting Sync explaining how to compensate for amplifier delays such as might be found on TVs or AVRs.

Version 4.1-dev-694-g234c00ad

Bug Fix

Fixed a memory allocation (malloc) bug caused by allocating on byte too few for a character string -- yep, the trailing NUL. Special thanks to ageorgios for their help in locating and fixing the bug! Thanks also to MTxx87 and Mike for reporting what seems to be the same bug.

Version 4.1-dev-688-g7dcad083

Bug Fixes

Fixed two memory leaks in Shairport Sync.
Reinstate the use of libcrypt again with the pair_ap library to avoid an apparent memory leak in libcrypto.
Quieten a noisy debug message in the dummy backend.

Version 4.1-dev-604-gf96fa2f7

Bug Fix

If the D-Bus interface was enabled, each change in volume control was calling the volume event hook twice. Fixed.

Version 4.1-dev-601-g98744211

Bug Fix

Recent versions of Shairport Sync have a "heartbeat" checker, to try to determine when the client has stopped running without warning -- typically when it has gone to sleep. Unfortunately, it interferes with some non-Apple clients, so it has been disabled in this update.

Version 4.1-dev-599-g2bc62c7d

Enhancements

Added some GitHub Actions to test different combinations of builds -- hopefully the result will be fewer bugs. Thanks to Charles Omer for the inspiration to try these in the first place.

Bug Fixes

Fixed a bug where the DAC was not closed after the active timeout when the alsa disable_standby_mode was set to "auto". Thanks to Tim Curtis for an exemplary bug report.
Fixed a couple of bugs (found with GitHub Actions) in the installers on both systemd and System V systems.

Version 4.1-dev-551-g30aaabc4

Update

Updated to the latest version of the pair_ap library. Thanks again to ejurgensen for this invaluable resource.

Enhancement

Removed the requirement for the libgcrypt library. OpenSSL is mandatory for other parts of Shairport Sync when operating in the AirPlay 2 mode and is now used in place of libgcrypt.

Version 4.1-dev-548-g7dc077e2

Removed the workaround for the apparent bug in AirPlay 2 Buffered Streams in iOS 16.0. A number of approaches were tried. The most aurally successful is left in the code but is disabled. Basically, it delays the timing of the frames following the 2,112 frame discontinuity by 2,112 frames. This eliminates the timing discontinuity but delays the AirPlay stream by 47.9 ms, and this can be heard in some situations. So it looks as if the bug -- if that's what it is -- can't easily be worked around. It has not been fixed by iOS 16.0.2, unfortunately.

Version 4.1-dev-543-g24f06b81

Enhancements

Add a workaround for an apparent bug in AirPlay 2 Buffered Streams in iOS 16.0. After playing exactly 22,528 frames of audio, iOS 16.0 sends 2,112 frames of audio with the same timestamps as the previous 2,112 frames. This makes the frames that follow 47.9 ms (2112/44100 seconds) late. The workaround is to drop these extra 2,112 frames.
If an AirPlay 2 Buffered Streams is being skipped or scrubbed, the audio that follows will generate an audible click due to an AAC decoding transient because preceding audio frames are missing. Shairport Sync now mutes the first 2,048 frames, down from 3,072 frames before.

Bug Fix

Give the RTSP idle checker a longer timeout -- 10 seconds -- and confine its operation to AirPlay 2 Runtime Streams and classic AirPlay only. This is to stop an occasional RTSP idle timeout silencing an AirPlay 2 Buffered Audio session.

Version 4.1-dev-532-g8dfebea2

Enhancements

Improve the response of Shairport Sync when a Mac is woken up from sleep and continues playing e.g. a YouTube video. Shairport Sync should resume play in most circumstances. (BTW, the HomePod mini does not resume in these circumstances.)

Bug Fix

Make the RTSP idle checker a bit more resilient -- wait for the full timeout even if interrupted by e.g. SIGINT. Also signal to NQPTP when to stop listening when a session goes idle or stops.

Version 4.1-dev-526-gfd880056

Pesky Changes You Can't Ignore

Important. Please update and re-enable NQPTP. The Shared Memory Interface protocol that Shairport Sync and NQPTP use to communicate with one another has been updated to reflect changes in NQPTP's operation.

Apart from moving to the new SMI interface for NQPTP, this update consists of many small enhancements and bug fixes. (Yeah, and the build number really did go backwards...)

Version 4.1-dev-535-gdafd1726

Bug Fix

Fix yet another bug in the Makefile.am. Thanks to Isioma Nnodum for finding and fixing it.

Version 4.1-dev-520-g1092a8c1

Enhancements

It is now possible to build Shairport Sync in a separate directory, thanks mainly to the work #1493 and #1500 of Lukas Rusak. A number of subsequent changes were necessary to make it work for FreeBSD.
Shairport Sync should build on piCore. Thanks to jackaroo for reporting and checking.

Version 4.1-dev-516-ga617e607

Updates and Enhancements

The Docker image has been enhanced. Thanks, as always, to Charles Omer. More changes are on the way here.

Bug Fixes

With Realtime Streams, if even one timing control packet was missing, Shairport Sync would work as if the sender had disappeared and cause a playback interruption. This has been modified so that it takes at least three missing control packets in a row to conclude that the sender was gone. Thanks to Devid Leibovic for a very thorough investigation of this issue.

Version 4.1-dev-494-gd34db2a4

The CAR INSTALL.md guide has been updated for AirPlay 2 and for Raspberry Pi OS (Bullseye).
A few noisy debug messages have been removed or quietened. Thanks to David Leibovic for the report.

Version 4.1-dev-468-gcb03d5c6

Updates and Enhancements

The development branch now builds again on macOS with brew. (Remember, though, that Shairport Sync will not function in AirPlay 2 mode on a Mac).
The libao backend has been updated to address an issue with the system becoming unavailable. The biggest change was to close the driver as soon as playing stops, reopening it when playing restarts.
The libao drivers are now listed in the help text. If available, it is suggested that the alsa driver be used in preference to the pulseaudio driver.

Bug Fixes

The classic AirPlay build now works properly again with tinysvcmdns and dns_sd.

Version 4.1-dev-466-g05dfcdfd

Enhancements

These are for advanced users.

Add a new Protocol property to the D-Bus interface. Values: AirPlay if built for AirPlay and AirPlay 2 if build for AirPlay 2.
Add a new Volume property to the D-Bus interface. This enables you to get and set the volume locally. Use this carefully: it means that you can set the volume of the player without changing it at the source (e.g. iTunes / Music). The source will not be informed of the change, so the volume it sets and and the actual volume may become different. It is preferable to use remote control (if available) to "ask" the player to change the volume.
Add a new DropSession method. This will immediately and forcibly terminate a playing session without informing the source. Use it carefully. It is preferable to use remote control (if available) to "ask" the player to stop playing.

Version 4.1-dev-454-ga774a6fc

Enhancement

Strip the trailing dot and everything after it in the hostname when using it as the basis for a service name. E.g. freebsd.local becomes freebsd.

Bug Fixes

Fix a few compilation bugs and portability issues, and turn off deprecation warnings when compiling for Mac OS.

Note: After this update, you'll need to run autoreconf -fi and the ./configure... steps again.

Version 4.1-dev-439-gb7a11cae

Documentation update. Comments, corrections and suggestions welcome.

Version 4.1-dev-429-g449e024c

Enhancement

With the ALSA backend, if the default device isn't available, Shairport Sync will now try to use "hw:0" instead. Background: the default ALSA device is sometimes a pseudo device provided by a sound server such as PipeWire or PulseAudio to play audio from ALSA-compatible programs. But it's not always available to all users, especially daemons like Shairport Sync. This simple change will try to use the first ALSA hardware device -- card 0 -- if the default output device is inaccessible with error code EHOSTDOWN. It allows Shairport Sync to work on default settings with Fedora 36.

Version 4.1-dev-424-g4729e325

Enhancements

Shairport Sync should no longer terminate if its ALSA output device is busy. This is useful when using ALSA devices in systems with sound servers such as PulseAudio or PipeWire. Shairport Sync now simply waits until the device becomes available. Shairport Sync retains exclusive access to the device (and so the sound server can not use it) until it is finished playing.
Wait up to ten seconds (was two seconds) for NQPTP to come online when starting up -- AirPlay 2 only.

Version 4.1-dev-420-g23d0502f

Bug Fix

This commit reverses the enhancement in Version 4.1-dev-418-g5011dc09 because it doesn't work properly. Specifically, some service files are not being renamed and installed correctly. Apologies for the inconvenience. Note After pulling this update, you should rerun the $ autotools -fi and $ ./configure... steps.

Version 4.1-dev-418-g5011dc09

Enhancement

The Makefile.am file has been updated to allow allow building and installing from a separate build directory. Thanks to Lukas Rusak for the contribution. Note After pulling this update, you should rerun the $ autotools -fi and $ ./configure... steps.

Version 4.1-dev-412-gf218a4d4

Note -- A bug has been fixed in NQPTP -- please update it.

Reversion

The change to the allowed settling time mentioned below has been reverted back to 5.0 seconds – the issue this was meant to address turned out to be a bug in NQPTP.

Version 4.1-dev-409-g6bfeb49f

Bug Fix

Shorten the settling time (from 5.0 seconds to 0.75 seconds) allowed when a new AirPlay 2 player, with its own clock, is added or removed from the devices currently playing. The problem was that if something else happens during the settling time, the changeover to the new clock may fail. This doesn't eliminate the issue, but hopefully it stops it being a problem for the user.

Version 4.1-dev-376-gca6e768f

Bug Fix

Fix a bug that permitted clipping to occur when the playback_mode as set to mono. Thanks to xStatts for the report and for checking the fix.

Version 4.1-dev-357-gf551274a

Explore remote control a bit more. No progress to report...

Version 4.1-dev-352-g4d608216

Bug Fix

Fix a bug in the activity monitor that could potentially allow the run_this_before_entering_active_state hook to be called more than once when the player was going active. It could also potentially allow the run_this_after_exiting_active_state hook to be called more than once when the player was leaving the idle state, but only if the active_state_timeout was set to 0. Thanks to Ben Willmore for the report.

Enhancement

Allow procedures hooked to run_this_before_entering_active_state and run_this_after_exiting_active_state to run without the activity_monitor_mutex in the locked state.

Version 4.1-dev-350-g82849e0d

Change

Return 501 instead of 404 for unimplemented GETs in AirPlay 2 mode.

Version 4.1-dev-347-g6556a79d

Bug Fix

If a speaker with its own master clock (e.g. a HomePod mini) was added and then removed from the group of output speakers in AirPlay 2 mode, Shairport Sync would stop working.

Note -- there is an important update to NQPTP out as well.

Version 4.1-dev-340-g4705be9b

Enhancement

Improve the AAC decoder check by iterating through all formats the AAC decoder supports.

Version 4.1-dev-332-g38c43f07

Bug Fixes

Fixed a bug where the AAC decoder check would not recognise the AAC decoder in ffmpeg version 3. Thanks to GXJ0102 for help with this.
Fixed a bug where, on a very fast CPU, "basic" interpolation would be chosen instead of "soxr" interpolation.

Enhancement

Relax the "fully-up-to-date" system requirement slighty -- Shairport Sync will build and run on Ubuntu 18.04 LTS.

Version 4.1-dev-317-g0dc34a46

Pesky Changes You Can't Ignore

A change has been made the shairport-syncservice/startup files, so before updating, please rerun the ./configure... step and (Linux only) remove the existing service file as follows:

$ ./configure ...  # whatever your preferred options are...
# rm /lib/systemd/system/shairport-sync.service # Linux only -- no need for this in FreeBSD

Enhancements

The AAC decoder check for AirPlay 2 operation was temporarily removed but has now been reinstated and is working again. If it is causing problems, please let us know. A section has been added to the TROUBLESHOOTING.md document.
Debugging and statistical information now outputs to STDERR by default, so the rather confusing -u command line option is no longer needed. This has the following implications:
- If Shairport Sync is run from a terminal window, then messages, warnings, debug and statistical information will appear on the terminal window.
- If Shairport Sync is run as a daemon, then STDERR will be redirected to the system log.
- If you wish to use syslog (e.g. you might wish to see the different levels of highlighting of different categories of information), there is a new command line option --log-to-syslog. (This is used by the modified startup scripts.)
The -u option is now redundant and is deprecated (see above).
A new command line option --log-to-syslog allows you to direct messages, warnings, debug and statistical information to syslog. For full effect, it should be the first argument in your list of command line arguments. It is really intended for when Shairport Sync is run as a daemon.

Version 4.1-dev-283-ga62e4b0b

Enhancements

FreeBSD compatibility. Shairport Sync (and NQPTP) can now work in AirPlay 2 mode on a FreeBSD system. Note that the build instructions and the configuration parameters have changed -- libdaemon is no longer needed and should not be included.
Certain Linux distributions -- notably Fedora 36 -- do not include a suitable AAC decoder for decoding AirPlay 2 Buffered Audio streams. Shairport Sync now includes a check to ensure that the AAC decoder can decode the stream, which seems to be encoded in Floating Point Linear Planar AAC ("fltp") format. (The AAC decoder is provided by the libavcodec library, part of the ffmpeg multimedia framework. For troubleshooting, the ffmpeg command line tool is very useful.)

Version-4.1-dev-266-g1d228870

Minor Changes

Cosmetic changes -- some debug and informational messages altered.

Version-4.1-dev-255-g8a2756b7

Bug Fix

Fix an audible interruption that could happen in certain circumstances when an output device was added or removed to a group of output devices. The "certain circumstances" are when the following two conditions are true:
1. An AirPlay 2 Realtime Stream is playing,
2. The new output device's clock takes or relinquishes control of output timing.

For example, (i) when playing Spotify on an iOS device (this currently uses an AirPlay 2 Realtime Stream) to a Shairport Sync device and (ii) adding or removing a HomePod mini as an output device (the HomePod mini's clock will take or relinquish control of output timing).

Enhancement

When a Shairport Sync device is added as an output device to a stream that is already playing, it now mutes for two seconds to improve synchronisation when it joins in and actually starts producing audio. The previous slight lack of synchronisation was inaudible, but would require some interpolation before settling down.

Version-4.1-dev-249-g38bbad6f

Bug Fix

Fix a bug in the systemd startup file. The bug was that even when Shairport Sync was built without Avahi support, Shairport Sync would not launch until the Avahi service was available. Thanks to klslz for reporting the problem in issue #1454.

Version-4.1-dev-247-ga295c2a2

Bug Fix

Fix a bug in the logic for suppressing clicks when the alsa disable_standby_mode is active.

Version-4.1-dev-245-gf34a69fa

Enhancement

AirPlay 2 only. Two new metadata messages have been added. They might be useful for amplifier switching, etc.

The conn message signifies "AirPlay 2 connect" and is sent when an AirPlay 2 device selects this player. It is sent before killing any current play session.

(Note: in AirPlay 2 operation, the existing clip message is identical, but it is sent after any existing play session has been terminated.)
The disc message signifies "AirPlay 2 disconnect".

Version-4.1-dev-242-g3877acc7

Bug Fix

Fix a crash that would occur after days of continuous play. The issue was that each time a cover art file was created (and previous cover art deleted) the coverart directory was opened with open(), but was not closed with close().

Version-4.1-dev-238-g1dc481c3

Enhancement

Add some extra diagnostic information when large sync errors occur: if available, add the total number of frames sent to the output device and also, if available, add th e current delay, in frames, in the output device.

Version-4.1-dev-234-ge8721889

Bug Fix

Fixed a bug using HomePod Software 15.4. The bug was that when a Shairport Sync device was added as a HomePod output device, visually it didn't appear to join the group of output devices and additionally its volume control could not be accessed. The bug was fixed by increasing the maximum permissible length of ID strings in Shairport Sync.

Version-4.1-dev-229-g08afa822

Enhancement

Add Minimum Buffer Size to statistcs information for a Buffered Audio stream (and remove the minimum and maximum number of decoded buffers -- they are not too interesting). The Minimum Buffer Size gives the smallest size, in bytes of kilibytes, of the buffer of audio that has yet to be decoded during the last statistics interval. The larger it is, the longer Shairport Sync can play while a network outage is occuring. It can legitimately be zero at the start of a track, and obviously it can reach zero at the end of a track, but if it is zero while a track is playing, it may indicate problems with the network.

Version-4.1-dev-224-g29d2155e

Pesky Change You Can't Ignore

A change has been made the shairport-sync systemd service file, so before updating, please remove the existing service file with the following command:

# rm /lib/systemd/system/shairport-sync.service

Bug Fixes

Interpret disable_standby_mode to determine if a flush should also close an alsa device as follows:
1. If disable_standby_mode is set to "no" (default) or "never", then a flush will immediately close the alsa device.
2. If disable_standby_mode is "auto", a flush will not close the alsa device. The device will be closed at the end of the active timeout.
3. If disable_standby_mode is "yes" or "always", a flush will not close the alsa device. The device will never be closed.
Remove the invalid Provides entry from the systemd service file. Thanks to David Crook for reporting Issue #1448.

Version-4.1-dev-214-gadf0845e

Enhancement

Check to see if the alsa_handle is NULL in precision_delay_and_status.

Version-4.1-dev-211-g9bac04e2

Bug Fix

Check for NULL pointers before dereferencing delay and state variable pointers in audio_alsa.c's delay and *-delay_and_status functions. Thanks to leirace for the report, Issue #1441.

Version-4.1-dev-209-gb4cd4fbc

Pesky Change You Can't Ignore

A change has been made the shairport-sync systemd service file, so before updating, please remove the existing service file with the following command:

# rm /lib/systemd/system/shairport-sync.service

Enhancements

Improve the timing service interface: Instead of opening and closing a Shared Memory Interface (SMI) whenever timing information was needed from NQPTP, the SMI is now opened only once, at startup. Overall, this reduces overhead at critical times and seems to improve the initial accuracy of synchronisation. It also requires the NQPTP service to be available and accessible at startup.
Improve alsa flush performance: Add new code to better handle a flush request in the alsa backend. This new code results in smoother operation and timing accuracy is improved when continuing after a flush.
Define the Shairport Sync service in the systemd service file.

Bug Fix

Fix a bug that caused a crash if an incorrect wait_for_completion option was chosen. Fixed a few similar bugs too. Thanks to HiFiBerry for reporting the issue at #1431.

Version-4.1-dev-193-g4848608d

Don't try to decode commands at debug level 2 -- leave it to level 3.

Version-4.1-dev-191-ge07c202b

Enhancement

This enhancement relates to MQTT with empty payloads. Many MQTT brokers and clients treat messages with empty payloads in a special way. For instance, MQTT Explorer hides messages with empty payloads and Node-RED seems to use them to release and garbage-collect data received previously. Many Shairport Sync messages contain no extra data and so would naturally have empty payloads. This is causing problems -- see #1425 and #1375. To avoid these problems, a short "dummy" payload consisting of the character string "--" is now added to MQTT messages that contain no extra data. This can be changed with a new MQTT option in the configuration file: empty_payload_substitute. Thanks to DOCaCola and UMB8998 for reporting on this.

Version-4.1-dev-188-gf135d857

Bugfixes

Ensure that when ignore_volume_control is true, the volume metadata has the current, max and min values of the [now ignored] attenuator set to 0.0. Thanks to Michael Daley for reporting in Issue #1417.
Add a fix for v3 of s6 overlay and other improvements to the Docker image. Thanks to Charles Omer for the fix and the improvements and thanks to rdrdog for reporting the issue.

Other Changes

Add code to check certain 32-bit and 64-bit conversions.

Version-4.1-dev-173-gdeb11654

Enhancements

Add some sanity checking of the latency offset and buffer size to check if they can be accommodated.
Discard non-sentinel UDP timing packets that are received just when a timing thread starts -- they may relate to a prior session.

Version-4.1-dev-171-g703717a5

Bugfix

Clear PTP clock information when a Realtime stream stops playing. This may address one of the issues reported in #1404.

Version-4.1-dev-169-g6ced6bc6

Enhancement

Add a new mixer_control_index setting to the alsa section of the configuration file. A mixer is fully identified by a name and index. The index defaults to zero, and, until now, it could only be set using the alsa command-line argument -i. Thanks to flipoidix for bringing this issue to notice.

Version-4.1-dev-164-gf79222f7

Bugfix

Fix a crashing bug in AirPlay 2 mode which occurs if no configuration file is found. This particularly affects the Docker image, as it contains no configuration file. Thanks to Charles Omer for reporting.

Version-4.1-dev-160-g9c2f9f7a

Bugfix

Fix a crashing bug in AirPlay 1 ("Classic") mode, whereby if a session was abruptly interrupted, e.g. by the sudden loss of a network, Shairport Sync would crash. The problem was that the interrupted session was not correctly terminated. Thanks to th0u for reporting issue #1398.

Version-4.1-dev-158-gb5860fc4

Enhancements

The following enhancements are mainly experimental, for advanced users only, and are intended to enable multiple instances of Shairport Sync (SPS) to run in one computer and provide multiple AirPlay 2 endpoints. At this point, multiple instances of SPS can indeed run on one machine and provide multiple AirPlay 2 endpoints, but unfortunately the presence of multiple services at the same address seems to confuse AirPlay 2 clients. So, it seems that while multiple instances of SPS can now run successfully on one device, they can't be used on the same network.

Use a uniquely-named named SMI interface to get dedicated access to NQPTP.
Simplify validation of the mDNS interface setting, if given.
Exit with a warning if the player is using a name that already exists.
Stop storing the timing peer list.
Generate an initial timing list during setup — don’t wait for the first timing peer list message. May gain around 50 ms.
Fix a bug and clean up generation of device's timing addresses.
Add some control to the generation of the Device ID:

Revise how the Device ID is generated from the device’s MAC addresses
Add a setting to add a fixed offset to the automatically-generated Device ID.
Add a setting to specify a complete Device ID, replacing the automatically-generated Device ID.

Be more careful to create default file names based on the name of the app.

Version-4.1-dev-146-g42e508b4

Enhancements

Extract several very useful extra pieces of client metadata for AP2. Many thanks to Cody Cutrer.
Enable a cleaner restart of the D-Bus daemon in a Docker image. Thanks again to Charles Omer.

Version-4.1-dev-138-g5617f40e

Minor Internal Changes

A small number of internal chages made.

Version-4.1-dev-127-g4d0460b9

Enhancement

Update the Docker workflow to automatically do Docker tagging and to use an s6-overlay implementation. Thanks to Charles Omer for all this work, and to Robert Casties for his s6-overlay Pull Request #1349 which formed the basis of the s6-overlay work.
Slight documentation update, thanks to michaeldeborst.

Version-4.1-dev-115-g8656149d

Simplify and improve timing when a play session from a new device is started.

Version-4.1-dev-106-ge98111fb

Enhancement

Try to improve the reliability of restarting a "silent clock" device.

Version-4.1-dev-104-g84dd2dc4

Begin to explore some more connection types.

Version-4.1-dev-102-g9bf45574

Enhancement

Make debug messages in the system log easier to see on macOS Terminal (!) by outputting them at LOG_INFO level rather than LOG_DEBUG level.

Version-4.1-dev-100-g8330f30b

Enhancement

Updated information on the statistics provided -- see MOREINFO.md. (Note: this has moved to STATISTICS.md.)

Version 4.1-dev-95-ga7a02083

Bug Fix

Fixed a compilation bug that occurs if metadata support is not included in the build configuration. The fix was to add the appropriate conditional code statements. Thanks to Daniel Gooß and winstonsetiawan for reporting.

Version 4.1-dev-92-g3ab16b5d

Enhancement

Thanks to Anton Lindqvist for updates and bug fixes to building for OpenBSD.

Other Updates

Thanks to tekdude for a documentation update.
Various documentation updates.

Version 4.1-dev-81-g24a5bbbe

This is a pretty big under-the-hood update.

Significant Changes

Change clock base to improve stability. You need to use the updated nqptp that has also been changed. If you forget, Shairport Sync will not work properly and will leave a message in the log.
Avoid skipping the first 100 milliseconds or so of a newly-selected track.
Clean up the output of statistics — shorter when log verbosity is zero.
Change behaviour after an unrecoverable error -- if not handled, exit Shairport Sync.
Add client and server ip metadata for AP2 Buffered Audio Stream.

Changes

Add client and server ip metadata for AP2. Remove timing peer list and DACP code only for a full AP2 teardown.
Fix a few memory leaks. Add bogus exits to allow SPS to quit at the end of a play session, to make it easier to use valgrind.
Stop checking that the timing peers are within the same subnet.
Look for at least 0.1 seconds of leadtime, ensure a master clock is at least 0.275 seconds old before use, quieten a few debug messages.
Add txtAirPlay data to the get info response.
Don't pause reception of long RTSP messages.
Don't ask for cover art if not asking for metadata too, duh.
Skip some types of invalid AAC packets.
Don't decode outdated frames.
Wait for timing information to be valid in AP2 Buffered Audio Streams processing.
Set the timing peer list as soon as a SETPEERS message is received -- don't wait until play is about to begin. Not sure if it works universally yet.
Tidy up the statistics printout table and stop outputting (non existent) nominal fps for AP2 Realtime Streams.
Use PKG_CHECK_MODULES to find libavcodec, to make it work with Fedora 35 (?)
Change behaviour after an unrecoverable error -- if not handled, exit Shairport Sync.
log statistics headers whenever verbosity goes on or off or whenever statistics are requested
Clean up statistics.
Stop watchdog timing out AP2 sessions.
Remove the commas in the statistics logs -- easier to get into a spreadsheet.
Don't overwrite service files if they already exist.
Try finding libplist as libplist-2.0 on Linux too.
Move to using CLOCK_MONOLITHIC_RAW to avoid NTP effects. Bump interface version.
Add code to check divisions and mods for a potential divide by zero problem. This may cause SPS to terminate but it will leave a log message.
Add a 'stats' function to the audio back ends to replace the 'rate_info' function. Zero all except the alsa back end.
Attempt to increase the precision of the FPS timing
Update to the latest version of ejurgensen's pair_ap library. With thanks.

Bug Fix

This fixes #1345 by checking for the libplist library both under the name libplist and libplist-2.0 using the fallback strategy as described in the autotools docs. Since we now try both names, we no longer need the FreeBSD/Linux check. Many thanks to FW for the bug report, the fix and this documentation!

Version 4.1-dev-21-g1032cad6

Enhancement

Update the pair_ap library to the latest version. Thanks again to ejurgensen. Addresses Issue #1334. Thanks to iChUdY for reporting the issue.

Version 4.1-dev-19-g3f6f0932

Bug fix

Fix a bug that would occasionally mute Shairport Sync when using it with AppleTV. Combined with the recent update of nqptp, this makes using Shairport Sync much more useful with an AppleTV 4K.

Version 4.1-dev-15-gf4115c45

Bug Fix

Fix the following buildroot build failure when the --with convolution flag is included. The issue is due to a change in the behaviour of automake 1.16.5 -- see https://git.savannah.gnu.org/cgit/automake.git/commit/?id=f4a3a70f69e1dbccb6578f39ef47835098a04624:

configure.ac:305: error: AM_INIT_AUTOMAKE expanded multiple times
/home/giuliobenetti/autobuild/run/instance-1/output-1/host/share/aclocal-1.16/init.m4:29: AM_INIT_AUTOMAKE is expanded from...
configure.ac:6: the top level
/home/giuliobenetti/autobuild/run/instance-1/output-1/host/share/aclocal-1.16/init.m4:29: AM_INIT_AUTOMAKE is expanded from...
configure.ac:305: the top level

Fixes: http://autobuild.buildroot.org/results/464148bdccb705d8992dc860262bfdeb01b7e2a1.

Thanks to Fabrice Fontaine for Pull Request #1314.

Version 4.1-dev-9-gd2e35fc0

Bug Fix

Fix an incompatibility with iOS 15.1 betas and release candidates. The problem was this: if an unknown RTSP command was received, Shairport Sync would return a HTTP error response code of 400 ("Bad Request") but the player would not continue. After some experimentation, it was discovered that a HTTP error response code of 501 ("Not Implemented") would allow the player to continue. Thanks to corrpel and bloomkd46 for reporting the issue.

Version 4.1-dev-4-g0fe21f3a

Bug Fixes

Fix a bug whereby the volume_range_db setting would be ignored if it was less than the range of the hardware mixer.
Fix a bug that prevented an AirPlay 2 build if metadata was not enabled, either directly or indirectly, at the ./configure... step.

Version 4.1-dev

Enhancement

Better Siri, HomePod mini and Home Integration An AirPlay 2 build of Shairport Sync now provides a visible volume control when used by a HomePod mini. This should work for other devices too -- reports welcome. You can use the Home app and Siri to set and adjust the volume when used to play from the HomePod mini.

Version 4.0-dev-308-g23da206

Bug Fixes

Restore logging to syslog.

Version 4.0-dev-303-g9074069

New Features

An initial PipeWire backend, with thanks to Lukas Rusak. Use the --with-pw configuration flag at the ./configure... stage to include support.

Bug Fixes

Fix a bug when using the tinysvcmdns mDNS implementation, with thanks to fesc2000.
When an unrecognised SETUP message is received, just ignore it and put a warning in the log. Remove a redundant client_setup_plist data item from the conn data structure.

Enhancements

Shairport Sync no longer needs to be in the same directory as NQPTP during compilation.
Add Docker automations -- thanks to Charles Omer.
Add Issue management automations -- thanks to Charles Omer.
Reconnect the DACP scanner for AirPlay 2. (It still isn't useful, unfortunately.)
Add initial support to allow dynamic modification of Rendezvous advertisements.
Simplify some UFW suggestions in the Troubleshooting Guide.
Merge some documentation changes from the master branch.
Add information to the Car Install Guide about improving boot times, thanks to vasilisvg

Version 4.0-dev-185-g0c02ee2

New Features

Home App Integration An AirPlay 2 build of Shairport Sync now offers limited integration with the Home app. Specifically, a Shairport Sync AirPlay 2 instance can now be added as a speaker to the Home app. Thanks to ckdo and ejurgensen for figuring this out and for coding it up. It means that some Siri interaction is possible.
Automated Docker Builds Thanks to the work of Charles Omer, Docker builds on the development branch should appear from time to time on the Docker Hub.

Bug Fixes

Crashing bug fix in nqptp -- thanks to ste94pz.
Honour the max_volume_db setting even when ignore_volume_control is true. Note that dithering is enabled if software attenuation is needed.

Other Changes

Spell out Shairport Sync instead of SPS in a few places.
Clang format some source files.

Version 4.0-dev-153-g9ccde50

Big Update

Version 4 brings limited AirPlay 2 functionality to Shairport Sync.

For information about AirPlay 2, including acknowledgements, please visit AIRPLAY2.md.

Known Issues

In the AirPlay 2 build, a crash can occur occasionally when the player is being selected. If you can get this to happen reliably, please let us know.

Warning

Big changes have been made to the codebase to enable it to be used to build either as the "classic" AirPlay 1 player or as a new AirPlay 2 player. These changes have probably introduced bugs into the classic AirPlay 1 build.
There is lots we don't know about AirPlay 2. This can result in incorrect behaviour. Watch out for very high volume levels, especially if you have a powerful audio system.
This is a development branch and is probably more buggy than usual. Normal support will not be provided -- instead, we will be interested in bug reports that help improve the program. You need to be adept with Linux or FreeBSD to get involved.

Version 3.3.8d7

Bug Fix

Fix a bug in the alsa back end. In the interval between checking to see if the alsa device handle was NULL and actually using it, the handle could be set to NULL. The interval between check and usage is now protected.

Version 3.3.8d6

Bug Fix

Fix a bug in the alsa precision timing code. Thanks to durwin99, Nicolas Da Mutten, mistakenideas, Ben Willmore and giggywithit for the report.

Version 3.3.8d5

Bug Fixes

Fix a fault in the configuration script configure.ac that caused the libdaemon library to be omitted even when requested. Thanks to aleszczynskig and xska2 for the report.

Version 3.3.8d4

Bug Fixes

Fix a fault in the configuration script configure.ac. The fault was that a --without-* configuration argument was being misunderstood and interpreted partly as a --with-* argument. Thanks to David Racine for the report.

Version 3.3.8d3

Enhancements

Documentation for the MQTT interface. Many thanks to minix1234!

Bug Fixes

Fix a bug that caused Shairport Sync to hang, but not actually crash, if an on-play or any on-*** script failed.
Fix a crash that occurred if metadata support is enabled during compilation but turned off in the configuration file. Thanks to Tim Curtis for the report.
Fix a crash that occurred playing from AirPower on Android. Thanks to Ircama for the report.

Version 3.3.8d2 -- 3.3.8d0

There are absent from the repository -- see 3.3.8rc0 and rc1 in the master branch.

Version 3.3.7d19

Bug Fix

Ensure the metadata pipe is created, if necessary, when the --with-metadata configuration option is chosen without the --with-dbus-interface, --with-mpris-interface or the --with-mqtt-client options. Super thanks to Philip Howard for finding this and for developing a possible solution.

Enhancements

Add a default name for the pipe backend. If you don't specify a name for the pipe backend's named pipe, it will be /tmp/shairport-sync-audio. Note that Shairport Sync will need to have write permission to /tmp to create the pipe.

Version 3.3.7d18

Bug Fix

Make the first output backend in the list of backends the default, and make its name the default output_name. Clang-format everything. Thanks again to kiwi-ed for bringing this issue to light.

Version 3.3.7d17

Bug Fix

Include the word jack in the version string if support for Jack Audio is included. Thanks to kiwi-ed for bringing this issue to light.

Version 3.3.7d16

Bug Fix

Fix potential inability to restore synchronisation quickly in certain situations.

Version 3.3.7d15

Enhancements

Changed permissions when creating the metadata pipe (and the audio pipe in the pipe backend) to rw-rw-rw- for compatibility with snapserver.

Version 3.3.7d14

Enhancements

Fixed a situation where a misleading error message was given if a configuration file cound not be located and get_coverart was selected as a command line option. Apart from a misleading message, get_coverart and enable_metadata should have been enabled automatically where metadata support is included in the build configuration. Thanks to Craig Fletcher for the bug report.

Version 3.3.7d13

This is 3.3.7rc1

Enhancements

Fixed another bug, related to the bug fixed in 3.3.7d4, where leading zeros were not removed from the DACP ID. Thanks again to julianc1969.

Version 3.3.7d12

This is 3.3.7rc0

Enhancements

Added the the string -alac to the the version string in '-V' if Apple ALAC decoder support is included.

Version 3.3.7d11

Bug Fixes

Fixed a number of bugs that prevented Shairport Sync from terminating cleanly in response to the MPRIS interface's Quit() command. Thanks to João Gabriel for reporting this issue.
Related to the above, the code used to terminate the application after a fatal error has been cleaned up. It now uses the correct exit() call rather than the rather hacky abort() call, returning the value of the constant EXIT_FAILURE (typically 1) to the caller .

Version 3.3.7d10

Bug Fix

Fixed a bug whereby the start and end of active mode tokens abeg and aend where not generated or published -- pend tokens were being generated instead. Thanks to minix1234 for the bug report and fix.

Enhancements

Cleaned up and simplified the code that handles FLUSH requests coming from the player. (Debug messages are still a little verbose.)

Version 3.3.7d9

Enhancements

Improved timing estimation. Shairport Sync has been using linear least-squares regression to estimate timing drift between the (remote) source clock and the local clock. This technique is now extended to provide an estimate of the remote-to-local clock difference itself. (The remote-to-local clock difference is used to remap the timing of audio frames from the remote device's clock to the local clock.)

Timing drift estimates are now saved when a sessions ends, keyed to the client IP number. When a new session starts from that IP number, the stored estimate is used until a new estimate can be generated from the new session.

In practice, the timing techniques in use up to now have been very accurate, but this should result in slightly smoother rates of correction.

Version 3.3.7d8

Enhancements

Tidied up the creation and initial opening of pipes. Suppress repeated pipe-opening error messages.
Tidied up warnings and fatal error messages when log verbosity is zero.
Cleaned up the code that provides a silent lead-in to play on a back end without synchronisation, e.g. a pipe or stdout.
Added in commented-out code to check the timeliness of the release of audio to a back end without synchronisation, e.g. a pipe or stdout. TL;DR – so long as the back end does not block, frames will be released to it not more than one packet (352 frames) late.

Version 3.3.7d7

Enhancements

Logs and statistics can now be directed to the system log (default), stdout, stderr or to a file or pipe of your choice using a new setting, log_output_to in the diagnostics section of the configuration file. This is very useful when the system log is disabled or diverted.
Audio data from the pipe back end and metadata from the metadata pipe are now written using standard blocking write commands rather than a slightly complex non-blocking write function. Pipes are now opened in non-blocking mode and changed to blocking mode when successfully opened.
Separate threads are now used for each metadata subsystem. Until now, all metadata was processed on a single thread. This included writing to the metadata pipe and the multicast stream and supplying metadata for the mqtt interface and for the dbus and MPRIS interfaces. Unfortunately, that meant that a problem with any one of these subsystems could propagate into the others. Now they all run on separate threads. If one thread blocks, it will not interfere with the other subsystems.

Version 3.3.7d6

Bug Fixes and Enhancements

Fixed a bug calculating the instantaneous synchronisation error. This bug could occasionally cause Shairport Sync to lose synchronisation and maybe even to mute for a few seconds before resynchronising. It was caused doing modulo arithmetic incorrectly and it's been there for a while.
Cleaned up and improved the code to synchronise the first frame of audio. This should result in more accurate and reliable initial synchronisation, usually to under a millisecond, and often to within 20 or 30 microseconds. Syncronisation should improve even when the silent lead-in time is as short as 0.3 seconds or when the audio_backend_latency_offset_in_seconds is as much as -1.7 seconds, i.e. when only 0.3 seconds of latency are left when the latency would normally be 2.0 seconds.
Removed a bug which would affect initial synchronisation if a FLUSH command was received from the player at an inopportune time.
Cleaned up some confused uses of modulo arithmetic.
Cleaned up the allocation of memory for gathering running statistics – the heap is now used instead of the stack.
Cleaned up the display of statistics for backends that do not implement active synchronisation, e.g. the pipe and STDOUT back ends.

Version 3.3.7d5

Bug Fixes and Enhancements

Added code to do calculations involving the audio_backend_latency_offset_in_seconds and audio_backend_silent_lead_in_time settings correctly. Many thanks to Tucker Kern for discovering a number of bugs associated with this and for proposing a solution. This prompted a closer investigation and a number of further improvements were made, and a few "hostages to fortune" removed.
Cleaned up the audio_backend_silent_lead_in_time setting by adding an "auto" setting.
Improved synchronisation accuracy with short silence lead-ins.

New Feature

For the PulseAudio backend pa, added a new server entry to the pa section of the configuration file, allowing you to specify a connection to a remote or a local system PulseAudio instance instead of letting PulseAudio choose. Thanks to Guillaume Revaillot for this new feature.

Version 3.3.7d4

Bug Fix

The DACP ID looks like a 64-bit number expressed in hexadecimal. It is normally quoted with leading zeroes removed, but in the _dacp._tcp service string, leading zeros are not removed from the DACP ID. The bug fix removes those leading zeroes. Thanks to julianc1969 for tracking down this bug so tenaciously!

Version 3.3.7d3

Enhancement

While a player is active, the DACP port number to which to send remote commands should be broadcast over ZEROCONF/Bonjour. However, if that information is not available, Shairport Sync will now check for it every two seconds.

Version 3.3.7d2

Pesky Changes

The underlying timing system has been moved from 64-bit fixed-point time representation (like NTP) to a 64-bit unsigned nanoseconds representation. This should make precisely no difference to the functionality of Shairport Sync but the transition might inadvertently have introduced bugs. Problem reports gratefully received.

Enhancement

The timing software in the sndio backend does some extra sanity checking on certain time estimates, it may help a little when running on virtual machines.

Version 3.3.7d1

This is 3.3.6 with some documentation updates.

Version 3.3.6d11 = Version 3.3.6

Bug Fix

Avoid using strndup as it seems older versions of OpenWrt do not recognise it.

Version 3.3.6d10

Bug Fix

Brown-bag fix -- do what 3.3.6d9 was supposed to do!

Version 3.3.6d9

Bug Fix

Fix a bug in the provision of metadata which would on occasion cause metadata from the previous track to be provided. Thanks to Tuomas Hämäläinen and HiFiBerry for reporting. This bugfix addresses issue #972.

Version 3.3.6d8

Bug Fixes

Tidy up compilation of the audio-dummy and audio-soundio back ends when the -fno-common flag is used.
Remove a superflous extra definition of a variable which would cause it to be used uninitialised.

Version 3.3.6d7

Bug Fix

Treat the mper (Persistent ID of a track) metadata attribute as the 64-bit item that it really is rather than a 32-bit item as hithereto. Output it as a hexadecimal number on the MPRIS and D-Bus interfaces to correspond with the format of the persistent id obtained from AppleScript. E.g:

tell application "Music"
	get the {persistent ID} of the current track
end tell

resulting in:

{"FD84B4B40FA33A85"}

The MPRIS trackid corresponding to this would be /org/gnome/ShairportSync/FD84B4B40FA33A85.

Thanks to to Scott Simon for finding a related bug in the shairport-sync-metadata-reader.

Other Changes

Include the -fno-common flag in the compilation options to detect incorrect definitions of global variables and multiple definitions of enum data types.

Version 3.3.6d7

Bug Fix

Make Shairport Sync compile in the forthcoming Fedora 32. Fedora 32 uses GCC-10 which defaults to -fno-common exposing a number of issues with Shairport Sync – multiple definitions of some enums and failure to define certain variables as extern.

Version 3.3.6d7 is an attempt to clear up all these errors. Many thanks to Bill Peck for his ongoing support, for bringing this issue to notice and for developing a workaround. Address issue #973.

Version 3.3.6d6

Bug Fix

Add a SIGCHLD handler to remove completed processes that were used to perform and program "hooks" without waiting for completion and thus prevent them from becoming zombie processes. Thanks to patrickjane for reporting the bug and for suggesting a solution. Addresses issue #968.

Version 3.3.6d5

Bug Fix

Fix an incompatibilty with Forked Daapd that was causing Forked Daapd to lock up. Thanks to @tomgadow and @ejurgensen for their help in finding and (hopefully) fixing this issue. Addresses issue #953 and Forked Daapd Issue #870.

Enhancements

Add some extra examples of using the RemoteControl interface's SetAirplayVolume feature to the shairport-sync-dbus-test-client source.

Pesky Changes You May Not Be Able To Ignore

Renamed the Server property in the D-Bus interface to Client. The rather strange language in use has it that a player like iTunes is a "client" of the AirPlay device like Shairport Sync, which is therefore considered the "server". The newly-renamed "Client" property is the IP number of the player.

Version 3.3.6d4

A fix for issue #953 that wouldn't work.

Version 3.3.6d3

New Features

Add SetAirplayVolume to the native D-Bus RemoteControl interface.
Add SetVolume to the MPRIS interface.

Bug Fixes

Hook up the Volume property in the MPRIS interface.

Enhancements

Modify RemoteCommand in the D-Bus interface to return the HTTP status and response in hex.
Add a few sample commands, including MPRIS commands, to the Sample D-Bus Commands document.

Version 3.3.6d2

New Features

Resampling has been added for the Jack Audio backend. This can be used to up-sample to 192kHz. Thanks to Pieter De Gendt for this addition.

Version 3.3.6d1

This is release version 3.3.5.

Version 3.3.5d1

Pesky Changes You May Not Be Able To Ignore

Renamed the LoudnessFilterActive property in the D-Bus interface to Loudness. Updated shairport-sync-dbus-test-client.c accordingly.

New Features

Added to the D-Bus interface the ability to turn on and off convolution, to set the convolution gain and to change the convolution impulse response files. See examples in sample dbus commands. Note: for these commands to make sense, Shairport Sync must be built with support for convolution and the native D-Bus interface (--with-convolution and --with-dbus-interface) and fully installed.

Bug Fix

Fixed a bug whereby if you enabled the Loudness filter via the D-Bus interface, the output disappeared until you changed the volume.

Version 3.3.5d0

Bug Fix

Fixed a crashing bug when output format "S24" was chosen. Fixes the issue reported by artenverho in #927.

Version 3.3.4

This version did not appear on the development branch -- it fixed a small compilation error.

Version 3.3.3d11

Bug Fix

Fixed a crashing bug -- if a plain HTTP packet (in fact, any packet that didn't have an RTSP-style header) was sent to the TCP session port (usually port 5000), Shairport Sync would crash! Thanks to @dubo-dubon-duponey for reporting. Fixes #921.

Pesky Change

The setting retain_cover_art is now part of the diagnostics group. Set it to "yes" to retain cover art cached by the D-Bus, MPRIS or mqtt interfaces. Your directory may fill up if you leave it set!

Version 3.3.3d9

Enhancements

Expose a metadata setting related to handling cover art:
- The setting cover_art_cache_directory allows you to specify where cover art files will be cached if Shairport Sync has been built with native D-Bus, MPRIS or MQTT support. The default is /tmp/shairport-sync/.cache/coverart. If you set it to an empty list: "", caching is disabled. This might be useful in, say, an embedded device, or wherever you want to minimise file writing.

Version 3.3.3d8

Bug Fix

Fix a bug in the resend request logic.

Enhancement

Expose the settings controlling the resend request logic. The new settings are in the general section:
- resend_control_first_check_time is the time allowed to elapse before a packet is considered missing, defaulting to 0.1 sec. UDP packets don't always arrive in order and they don't need to be re-requested just because they arrive out of sequence. Essentially, therefore, this parameter is to prevent needless resend requests for packets that are already in transit.
- resend_control_check_interval_time is the interval between repeated requests for a missing packet, defaulting to 0.25 seconds.
- resend_control_last_check_time is the time by which the last check should be done before the estimated time of a missing packet's transfer to the output buffer, defaulting to 0.1 seconds. In other words, if a packet is still missing 0.1 seconds before it is due to be transferred to the DAC's output buffer, don't bother asking for a resend.

Version 3.3.3d7

Duh

Versions 3.3.2d3 to 3.3.2d6 should have been labelled 3.3.3d<something>.

Enhancement

Rewrite the logic for identifying missing packets of audio and for asking for resends. It seems more robust -- there was a suspicion of the previous logic that resend requests were not made for some missing packets. In addition, requests for resends of continuous sequences of packets are rolled into one.

Version 3.3.2d6

Enhancements

Normalise the 'pvol' volume outputs so that when both the software and hardware attenuators are in use to extend the overall attenuation range, the maximum output level corresponds to the maximum output level of the hardware mixer.
Add the option of including the file and line number of each log entry's source. The option is on by default and is settable in the configuration file and in the dbus interface.

Bug Fixes

Fixes an error whereby the 'pvol'volume metadata was no longer sent if Shairport Sync was configured to ignore volume control information coming from the audio source. Addresses issue #903. Thanks to Jordan Bass for reporting the regression and for identifying the commit and code in which the regression occurred.
Fixes a compilation error if including the MQTT client -- thanks to exoqrtx for reporting.
Fixes a compilation error if including the MPRIS interface.
Ensure the hardware mixer of an alsa device is detected and initialised before responding to the first volume setting.

Version 3.3.2d5

Enhancement

Improves the detection of the remote services available when an audio source is playing. If the source is minimally compatible, e.g. iOS, Shairport Sync's org.gnome.ShairportSync.RemoteControl native dbus interface becomes "available". If the source is iTunes, then the org.gnome.ShairportSync.AdvancedRemoteControl interface also becomes available. Artwork, metadata, status and limited remote control facilities are accessible through these interfaces when they are in the available state. Follows on from issues raised in #890. Thanks again to exoqrtx for bringing these issues to light and for testing.

Bug Fix

Fixes an issue that occured in Ubuntu 14.04 – the shairport-sync daemon would silently die after a fairly long period. It typically happened just after a DHCP address was renewed. The problem seemed to be related to having more than one avahi threaded polling loop (though this isn't documented anywhere). The fix was to consolidate the avahi stuff down to one threaded polling loop. Addresses issue #895. Thanks to Hans (the) MCUdude for reporting and for initial troubleshooting.

Version 3.3.2d4

Bug Fixes and Enhancements

Fixes and enhancements to the MPRIS and native D-Bus interfaces. In particular, situations where artwork is absent are better handled, and the remote interface and advanced remote interface availability properties should be more resilient in the face of network problems. Addresses issue #890. Thanks to exoqrtx for bringing these issues to light and for testing.

Version 3.3.2d3

Bug Fix

Fixes a potential crash when an incomplete fmtp parameter set is sent by the requesting client. Thanks to Angus71 for the fault report and for the repair.

Enhancement

Instead of returning EXIT_FAILURE, return EXIT_WITH_SUCCESS on early exit with either "version" (–version or -V) or "help" (–help or -h) arguments. Thanks to Henrik Nilsson for the patch.

Version 3.3.2d2

Bug Fix

Fix a double-free memory bug. Thanks to Chris Boot for reporting this bug, which came through the Debian BTS: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=925577. The fix is different from the suggested patch.

Version 3.3.2d1

Enhancements

Allow disable_standby_mode to operate on any output device, not just real hardware devices. If there are too many underruns while outputting silence, the disable standby mode will be turned off.

The Inevitable Version 3.3.1rc1

Bug Fixes

Fix a bug in the MQTT documentation and add sanity checking for the port chosen -- thanks to David Crook.
Fix a bug that caused manual format and rate setting to be ignored -- thanks to Jörg Krause.
Add missing support for format settings S24_LE, S24_BE, S32_LE and S32_BE.
Fix a bug that caused dither to be too loud.
Fix error message for invalid disable_standby_mode choice -- thanks to Tim Curtis at Moode Audio.

Version 3.3rc8

Enhancements

Add a list of alsa hardware devices found to the alsa backend help section in the shairport-sync -h text. (Doesn't work for alsa on FreeBSD/OpenBSD.)
Always place D-Bus access policy documents in /etc/dbus-1/system.d in Linux, but adhere to the standard for FreeBSD/OpenBSD.

Version 3.3rc7

Enhancements

Improvements to the MQTT client -- extra diagnostic messages at run time and at configuration time.

Version 3.3rc6

Pesky Change You Can't Ignore

The while_active setting in the new disable_standby_mode has been renamed to auto.

Enhancements

Automatic bit-depth and speed selection for alsa output devices has been added and is the default. The greatest bit depth available is selected, and the lowest multiple of 44,100 frames per second is chosen.
Improve support for big-endian devices by adding support for S16_LE, S16_BE, S24_LE, S24_BE, S32_LE and S32_BE formats.

Version 3.3rc5

Had a bug, sorry -- please go to 3.3rc6 or later.

Version 3.3rc4

New Feature

Support is now included for the automatic selection of the interpolation method. If support for soxr interpolation is included at configuration time (using the --with-soxr at the ./configuration... step), then auto interpolation is made the default interpolation mode. During startup, the time it takes to do two soxr interpolations is calculated -- this, in milliseconds, becomes the soxr_delay_index. If the soxr_delay_index is less than or equal to a new general group setting called soxr_delay_threshold (default 30), then soxr interpolation will be chosen in auto mode; otherwise, basic interpolation will be chosen.

Version 3.3rc3

Minor Enhancement

Calculate the length of the first sequence of frames of silence preceding the audio at the start of a play session a little more carefully to make it somewhat longer. This should make output devices that operate with a fairly large buffer a little less likely to underrun at the start of a session.

Version 3.3rc2

New Feature

Shairport Sync can now accept AirPlay streams containing uncompressed PCM -- specifically, 16-bit network-endian interleaved stereo, 44,100 frames per second. There is a restricton -- the packets of audio must be 352 frames long.

Bug Fix

Compatibility has been restored with virtual ALSA devices. Sometimes, an ALSA output device isn't actually a real hardware device -- for example, if PulseAudio is installed in your system, the "default" ALSA output device may in fact a virtual device that provides a route into the PulseAudio sound server for audio from ALSA-compatible applications. Such virtual devices don't always provide the precise delay timing that Shairport Sync uses. The bug fix is to fall back to the standard calls when precise delay timing is not available.
If precise delay timing data is not available, the disable_standby_mode is turned off, as it relies on high precision timing.

Version 3.3rc1

New Feature

If support for soxr interpolation is included at configuration time, then soxr interpolation is made the default at run time. (This was later changed -- see 3.3rc4.)
If support for the Apple ALAC decoder is included at configuration time, then the Apple ALAC decoder is made the default at run time.
If support for metadata is included at configuration, then metadata and cover art are both enabled by default at run time. (Metadata is enabled if you configure support for metadata, the dbus interface, the MPRIS interface or the MQTT client.)

Enhancements

MQTT publishes active_start and active_end events when the active state is entered and exited.
Add correction to fix for tinysvcmdns CVE-2017-12130.
Partly update man pages.

Version 3.3rc0

Version 3.3rc0 is 3.3d56

Version 3.3d56 to Version 3.3d40

New Features

Two new external program/script hooks – run_this_before_entering_active_state and run_this_after_exiting_active_state are provided for when the system goes active or inactive. Background: Many users use the run_this_before_play_begins program hook to turn on an amplifier and the run_this_after_play_ends hook to turn it off. A big problem is when another play session starts immediately after a play session ends, causing the amplifier to be switched off and then on again very quickly. This happens, for example, when a YouTube clip ends and the next one begins. To get around this, the concept of an active state covering a sequence of play sessions is introduced. When a play session starts, the system goes active, i.e. it enters the active state. When the play session ends, the system remains active for a period determined by the active_state_timeout setting, 10 seconds by default. If another play session starts before the period elapses, the system stays active; otherwise the system goes inactive -- it leaves the active state. The two new hooks mentioned above can be used to execute programs/scripts when the system goes active or inactive.
A new alsa-only disable_standby_mode setting, for controlling the Disable Standby feature, can be set to always, while_active or never. The always setting is recommended for systems where the output device is dedicated to Shairport Sync. The "Disable Standby" state iself can be set or cleared via the D-Bus interface DisableStandby property.
A new command-line option, -u, directs logging to STDERR rather than the system log. Useful when you compile Shairport Sync without libdaemon using the --without-libdaemon configuration option.

Enhancements

Changes to the Jack Audio back end. The back end for Jack Audio, audio_jack.c, has been extensively rewritten by Jörn Nettingsmeier in a way that is more in keeping with the Jack Audio style. It uses native Jack Audio lockless buffers and offers autoconnect facilities that the previous version didn't have. Many thanks to him.
The volume-control software has been completely rewritten. From a user's point of view, the result should be a much smoother response to volume control changes, free from artefacts. It is now also possible to combine the hardware mixer and the software attenuator in two ways -- giving priority to the software mixer or giving priority to the hardware mixer. see the new volume_range_combined_hardware_priority setting in the general section opf the configuration file.
The muting/unmuting code has been rewritten to be simpler and more consistent.
In the alsa backend, new play() and delay() functions minimise the use of snd_pcm_recover() to prevent unnecessary resets of the output DACs.
In the alsa backend driver, hardware isn't accessed until the first time it is needed. That is, when Shairport Sync starts up, it no longer needs to access the device momentarily. Instead, it waits for the first use.
The libdaemon library is now an optional build. It is not necessary for systemd systems and can be omitted. Use the --without-libdaemon configuration option to leave it out.

Bug Fixes

The mdns-external method used to advertise the Shairport Sync AirPlay service on ZeroConf is now an optional build and is omitted by default. Previously it was included with --with-avahi and could not be included on its own.
A number of memory leaks associated with the use of OpenSSL have been fixed.
Use CLOCK_RUNTIME in place of CLOCK_MONOTONIC when doing synchronisation timing using the alsa library prior to 1.0.28. Necessary for compabibility with OpenWRT Barrier Breaker.

Version 3.3d39 to Version 3.3d38

New Feature

A new feature called Disable Standby keeps the output DAC in the play state all the time and helps to remove some annoying clicking / popping noises. It is really pretty impressive, especially combined with fixes to the dithering code described below. If you can enable 24- or 32-bit audio output to your output device, you can get even better results.

This is an ALSA-specific attempt to remove the annoying low-level clicking sounds that some output devices make just when they start processing audio and sometimes when they stop. Typically a faint click might be heard just before a play session starts or just before audio resumes after a pause. Similarly, a faint click can sometimes be heard just after a play session ends.

It is extremely difficult to remove these clicks completely from the hardware, so this new feature ensures that the output device avoids situations where these clicks might be generated by always playing audio. To accomplish this, if Shairport Sync isn't actually playing anything, audio frames consisting of silence are sent to the output device, keeping it playing. Apart from the initial startup transition, the output device never stops playing and thus never transitions to and from standby mode, avoiding the possibility of generating associated audio disturbances.

To enable this feature, a new alsa group setting with the name disable_standby_mode is available. (If you do a full $ sudo make install, a new sample configuration file with this setting in it is installed at /etc/shairport-sync.conf.sample or /usr/local/etc/shairport-sync.conf.sample.)

A downside to this feature is that the output device totally dedicated to Shairport Sync. For this reason, this new feature is disabled by default.

Note -- this setting is likely to change. It will probably be necessary to modify it somehow to enable it to be used in integrated systems. Your feedback would be welcome.

Enhancements and Bug Fixes

At present, Shairport Sync adds dither to the audio (a) if the built-in software-based volume control is used, (b) if the audio is mixed to mono or (3) if there is a reduction in sample size, say from 16- to 8-bit. The code for generating dither has been much improved. Due to a poor pseudo-random number arrangement, the dither noise didn't sound like white noise -- now it does. In addition, if dither is to be added, it is also added to the silence inserted just prior to the start of play, and is also added to the silent frames used to prevent the output device from going into standby mode, if selected.

Version 3.3d37 to Version 3.3d22

These updates are about stability.

Enhancements and Bug Fixes

With great help from gibman — see #772 for the gory details — a myriad of issues have been identified and fixed. In particular, gibman shared an automated way of stress-testing Shairport Sync, and this has resulted in the detection of many bugs.

And so, with apologies to Shakespeare, we have taken up arms against a sea of troubles, and by opposing we have ended them. It is hoped that the result is considerably more stable and can better withstand the, uh, slings and arrows of outrageous fortune.

Here is a flavour of some of the issues addressed:

Replace the existing watchdog, which only offered partial coverage, with a much more robust thread-based watchdog.
Allow a reported remote processing time of zero.
Fix a logical error that could cause an endless loop during a flush.
Ensure a player thread is correctly initialised before allowing it to be cancelled cleanly.
Ensure the player thread always has a cancellation point so that it should always be possible to ask it to terminate.
If a play session is interrupted, wait for it to terminate for up to three seconds.
If a play session is interrupted, ensure the new session uses a different set of UDP ports. This is to ensure that data from the interrupted session – which might be still in transit – doesn't enter the new session.
Make all ALSA command sequences un-cancellable. This is to ensure that ALSA subsystem will not be left in a partially-initialised state if Shairport Sync terminates abruptly.
When a connection is terminated abruptly, ensure that all the UDP ports is use are closed properly.
Impose timeouts on both reading and writing to the supervisory RTSP connection governing a session.
When closing the RTSP connection due to an error, close it immediately, without waiting for a full TCP handshake, because, if the other end has erred, the handshake may never come.
Fix a parameter initialisation error in a situation where there is no hardware mixer.
Fix an MQTT-related crash by ignoring unrecognised commands.
Fix a compilation error and a warning when using the --with-convolution configuration option.

New Feature

A new run_this_if_an_unfixable_error_is_detected (in the sessioncontrol group of settings) program hook is provided. At the moment, two conditions can trigger this. The first is if the watchdog is unable to terminate a play session. The second is if the output device stalls for a long period. Both conditions can be caused by malfunctioning DACs. The external program could, for example, reboot the device.

Version 3.3d21

Enhancements

Use /dev/urandom rather than /dev/random as a source of some kind of randomness for the cryptographic "nonce" used in AirPlay password exchange, as /dev/random blocks occasionally. Please see here for a discussion of the merits of both. The effect of /dev/random's blocking on Shairport Sync was to make the source of randomness somewhat less random. (By the way, you should never use an important password as an AirPlay password for Shairport Sync -- it is stored in Shairport Sync's configuration file in plain text.)

Version 3.3d20

Enhancements

The code that deals with packet loss resulting from network problems has been completely rewritten. The reason is that, while the old code worked quite well, it could be overwhelmed if the network problems were very serious. The new code is simpler and more robust in testing so far. This code interacts with the code for flushing audio before and after a play session, so it may have introduced regressions.
The build instructions have been changed to avoid compiler warnings coming from automatically-generated code produced for the D-Bus-based interfaces.
Warnings are now logged if the ALSA subsystem fails to recover properly after an error has been cleared.

Bug Fix

A compilation problem in OpenBSD has been fixed by changing the order of some include files.

Version 3.3d16

Enhancement

Extend the range of audio_backend_latency_offset_in_seconds to ± 1.75 seconds. Note that no sanity checking of any kind is done on this – if it is too large the program may simply crash.
Pay more attention to errors that may occur when asking for the DAC delay just before play starts. For diagnostic use.
Formatting of the settings file shairport-sync.conf has been fixed, thanks to the work of roblan.

Version 3.3d15

Enhancement

Adjust the latency calculation to accommodate changes in iOS 12 and AirPlay connections from macOS Mojave. Thanks to artenverho who first reported the issue.

Version 3.3d14

Bug Fix

Fix a problem when calling the program to be run when the volume control is changed. Thanks to shaven for the report.

Version 3.3d13

Reverted to 3.3d11 -- the modification in 3.3d12 was not needed and has been removed.

Version 3.3d11

Enhancement

Add a configuration option to specify the PulseAudio output sink. An extra option for the pa backend to allow the specification of the audio sink. Thanks to Maciej Wilczyński for his work on this.

Bug Fix

Remove unrecognised options from FreeBSD and OpenBSD compilation instructions.

Version 3.3d10

Modify the jack interface to ignore the latencies of any ports connected to the jack end. This is because it does not seem appropriate to try to compensate for the delays in the jack system. Not sure if this is the correct approach... Maybe it's better to allow the user to select no compensation, compensate for the lowest latency or compensate for the highest latency; it seems unnecessarily complex, not really the business of Shairport Sync.

Version 3.3d9

Many changes to compilation and linking flags. Stop using HAVE_* flags except where necessary, use CONFIG_* for optional stuff, use HAS_* for immediate definitions to be used during configuration, use USE_* for Automake definitions. Probably introduced bugs, sigh.

Version 3.3d8

Bug Fix

Ensure the compiler flag HAVE_LIBSOXR is defined if the --with-soxr configuration flag is used and pkg-config is in use.

Version 3.3d7

Remove the "rolling" requirement for Jack output to be sent.
Set the default buffer size for Jack to 0.5 seconds. This may be temporary!

Version 3.3d6

An improved Jack Audio backend. Testing notes:

At the ./configure step, include --with-jack. This should not require any extra packages or libraries when it is being compiled on an AVLinux machine. No need for any other backend to be included, so you can omit --with-alsa, etc.
Tested on the latest AVLinux only.
Jack Audio will not run correctly on a virtual machine; it will only work properly on a real device.
A new set of configuration options is present in the configuration file.
The Shairport Sync backend will attempt, every second, to open a client on the Jack server until it succeeds. This behaviour can be stopped or the interval extended with the jack auto_client_open_interval configuration option.
Once a Jack client has been opened by the Shairport Sync backend, it will remain open. This behaviour can be changed with the jack auto_client_disconnect configuration option.
Other Jack congfiguration options include the ability to change the name of the client – client_name – and the names of the channels – left_channel_name and right_channel_name.

Testing needed -- these arrangements may not conform to the norms of the Jack community, so all feedback gratefully received.

Some information, e.g. the true output rate, not implemented yet.

Version 3.3d5

Introducing a very rough implementation of a Jack Audio backend. The JACK Audio Connection Kit "provides a basic infrastructure for audio applications to communicate with each other and with audio hardware. Through JACK, users are enabled to build powerful systems for signal processing and music production."

Version 3.3d4

Sometimes libsoxr is built to rely on libavutil. With the present changes to configure.ac, if libavutil is present, link to it when linking to libsoxr, but if it's not present, don't link to it when linking to libsoxr.
Add pgk-config support to libsoxr selection.

Thanks to Jörg Krause for identifying these issues and proposing fixes.

Version 3.3d3

Modify the code that synchronises the Shairport Sync system's clock with the source clock to try to take account of the sources's nominal rate, which (oddly, e.g. iTunes on a Mac) might not be exactly 44,100 fps. There may be a 32-bit unsigned overflow error here somewhere!
Try to interpolate for the measured drift between the standard three-second timing snapshots. These changes make a very slight difference from time to time, of the order of microseconds, and it's not clear yet how reliable the drift interpolation is.
Add some extra fields to the statistics output, including nominal source rate, actual input rate, actual output rate, source clock drift, calculated correction needed in ppm. All these numbers agree to a high degree, but the generation of them is fragile and susceptible to errors when there are problems like underrun, and they are not actually running averages, which would be genuinely useful. But they show promise!

Bug Fixes

Fix a bug in the dbus native interface which would silently switch soxr interpolation to basic.
Fix a mutex lock bug in the metadata hub. No known effects.

Version 3.3d1

Internal changes are being made for version 3.3 to avoid using SIGUSR1 and pthread_kill to stop threads; the standard pthread_cancel and friends are being used instead. This should lead to more reliable and orderly cancellation of sessions and threads. However, it is quite a complex change, so bugs may have been introduced or reactivated. Lots of testing needed.

Bug Fix

Fix an arithmetic overflow in frame rate calculations that could occur after 2^32 frames – approximately 27 hours at 44,100 frames per second.

Version 3.3d0

New Features

Frame rates! Exact input and output frame rates are now included in the statistics output. The figures generated are averaged over the entire play session since the last pause/resume, if any, so they should settle down and become more accurate over a long play session, say a couple of hours. Timing is relative to CLOCK_MONOTONIC. When your system is connected for an appreciable period to network time, e.g. using an NTP client, CLOCK_MONOTONIC is adjusted ("conditioned") to keep time extremely accurately. The calculated output frame rate should be very accurate. The calculated input frame rate will vary considerably over short intervals due to network conditions, but over a long play session it should also become very accurate. Timing is done from the start of the play session, or from the resumption of play following a pause. Note that while some audio sources pause and resume between tracks, both iTunes on the Mac and the Music app on iOS play all the tracks on a playlist without pause (so long as the tracks are downloaded and present in the device in time).
Add the command quit to the MPRIS and the D-Bus interfaces. The main motivation for this is that it makes it easier to search for memory leaks.

Bug Fixes

A number of memory leaks have been identified and removed.
A bogus warning about using the deprecated general statistics options has been fixed.

Version 3.2d67

This is equivalent to 3.2.1.

Bug Fix

Fix a bug causing a crash when soxr interpolation was enabled and a play session was stopped. This bug overwrote incorrect memory locations, so depending on what it overwrote, may have been responsible for other inexplicable crashes. Thanks are due to hanaguro, FnasBas, priitohlo, David Krmpotić and artenverho.

Version 3.2.d66

This is equivalent to 3.2.

Version 3.2.d65

Modification

The algorithm for generating resend requests has been made somewhat more gentle -- a little less insistent.

Bug Chasing

Some very elementary bounds checking on the ANNOUNCE packet is performed: that it is 1024 bytes or less in size and that line lengths remaining after parsing do not turn negative when they should remain positive or be exactly zero.

Version 3.2.d64

Enhancement

An extra property has been added to the RemoteControl section of the native Shairport Sync D-Bus interface. It is the "progress" metadata emitted from time to time by the AirPlay source and consisting of RTP timestamps for the start of the current play sequence, the current play point and the end of the play sequence.

Bug Fix

Code to monitor the amount of time a mutex lock request took is improved.

Version 3.2.d63

Enhancement

An MQTT client interface is introduced, with support for metadata and for some remote control commands, thanks to the work of Till Zimmermann. MQTT is a fairly often used protocol in FOSS home-automation projects (as well as in commercial ones), and as Shairport Sync is often used in these setups, this adds client support for this protocol.

Version 3.2d62

Bug Fix

Restore compatibility with Synology AudioStation/5.2. Thanks to Jörg Krause for identifying both the issue itself and the likely location of the fix needed. It's not clear if the problem lies with Shairport Sync or Synology – the fix was to ensure that an RTSP reply was sent in one SEND call, which shouldn't be important.

Version 3.2d61

Bug Fix

Add a pthread_cancel cleanup routine to put_packet to unlock the player rw mutex when cancelled. Sincere thanks to David Krmpotić for help investigating this.

Version 3.2d57, 3.2d58, 3.2d59, 3.2d60

Bug Chasing

Debug messaging has been enhanced when a TEARDOWN message is received.
Check both timed and untimed mutex locks and give estimates of how long to wait. Generate debug messages when appropriate.
Unlock the ab_mutex when sending a resend request.

Version 3.2d56

Enhancement

The mute_using_playback_switch setting in the alsa group has been replaced by a use_hardware_mute_if_available, which defaults to "no". This new setting controls both the playback switch method and the magic volume level method for doing hardware-supported muting. If hardware muting is used, the output device will be muted when Shairport Sync releases it, potentially causing problems for other audio programs using the device. To avoid this, use_hardware_mute_if_available is disabled by default.

Bug Chasing

A debug message has been enhanced when a TEARDOWN message is received.

Version 3.2d55

Bug Fix

Flush requests that are received while the player is being initialised or deleted are now ignored. This should prevents two potential (but never seen) lock possibilities.

Version 3.2d54

Bug Fix

Prevent packets of audio being added when the play session has ended and the player is being deleted. They are now simply dropped.

Version 3.2d53

Bug Fix

Fix an incompatibility with Cygwin 64. It seems that the handling of signals in Cygwin is different to regular "native" Unix/Linux platforms. So, this is an attempt to use pthread_cancel calls where possible. In principle it should simplify thread management considerably, so let's see how it goes.
Fix an off-by-one error that was generating excessive resend requests.

Version 3.2d51

Fix a small bug locking and unlocking the read-write mutex. It might (and in principle, it could) cause a crash.

Version 3.2d50

Add a read-write mutex lock to the player thread so that it can't be accessed while it's being created and initialised or while it's being torn down and destroyed. Make external accessor functions acquire a read lock for access. It's "A Good Thing" and it might help the seg fault problem, which I'm afraid still can't reproduce...

Version 3.2d49

A few extra debugging messages to try to locate where a segfault is occurring.

Version 3.2d48

Bug Fix

A seg fault possibly caused by a dangling pointer has been addressed by making the UDP sockets blocking rather than non-blocking. A two millisecond limit has been put on the sendto calls.

Version 3.2d47

Bug Fix

A very subtle bug that would occasionally cause a loud 80 millisecond buzz when a new track was selected has been located and fixed. Thanks to mistipen and artenverho for help with this.

Version 3.2d46

Update TROUBLESHOOTING.md to correspond to 3.2RC6.

Version 3.2d45

Enhancement

Restore the old method for calculating latency for older AirPlay sources: an AirPlay source displaying an AirPlay User Agent string version of 353 or older -- corresponding to iOS 11.1.2 or older -- will add an extra 0.25 seconds to the latency requested. This seems to be right.

Version 3.2d44

Bug Fixes

When errors occur sending resend requests, back off for 0.5 seconds, rather than 10 seconds, and make the code actually work.
Make the configuration options for including the dbus interface and the mpris interface be --with-dbus-interface and --with-mpris-interface as expected, not --with-dbus and --with-mpris as they actually were.

Version 3.2d42

This version just brings some small changes made to the Release Candidates back into the development branch.

Version 3.2d41

Bug Fixes

Fixed a hitherto-silent bug that prevented Shairport Sync working properly with AirAudio. According to the unofficial standard, requests for resending missing packets come from the control port; however, up until now, Shairport Sync sent them on the audio port. All AirPlay sources responded to these improperly-delivered requests except AirAudio, which discards requests that do not come from the correct source. Fixed now, with many thanks to funtax and to Janusz Kowalczyk for bringing the issue to the fore.

Version 3.2d40

Bug Fixes

A number of serious and long-standing bugs have been identified and fixed in the threads that handle audio, control and timing packets. Specifically, if UDP reception or transmission errors occurred (a rare occurrence on a good network, but possible on noisy or congested networks), the threads would quit. In this way, an error on the reception of the first control packet could mute an entire play session.

Enhancements

The code used to request the retransmission of missing audio packets has been significantly improved.

Version 3.2d39

Enhancements

An extra diagnostic to artificially drop UDP packets to simulate a noisy network has been added. Set the proportion of packets to be dropped in the diagnostics section of the configuration file using the tag drop_this_fraction_of_audio_packets. The value should be between 0.0 and 1.0. E.g. a value of 0.001 would mean one packet in a thousand would be dropped, on average. Look in the sample configuration file /etc/shairport-sync.conf.sample for the added entry.
Minimal compatibility with AirAudio has been added / restored. There remains a question about error correction for handling UDP packet loss. Thanks to Janusz Kowalczyk for reporting the issues.

Version 3.2d35

Enhancements

More cleaning up of the D-Bus and MPRIS interface messages -- they are quieter now.

Bug Fix

Thanks are due to yejun for noticing and proposing a fix for the bug that dithering is left on when the volume control is ignored. Audio samples should pass through without alteration. (The fix was already in the development branch though.)

Version 3.2d34

Enhancements

Better compatibility with TuneBlade -- Shairport Sync honours the latency settings properly now.
Big cleanup of D-Bus and MPRIS interface messages -- it's a lot less noisy. More to be done here.
The brokey YouTube iOS app, which generates a great deal of invalid metadata (do they even know?), is handled a bit better. If valid metadata is there, Shairport Sync can process it.
clip and svip messages are now only emitted for a play connection, not for all connections (e.g. connections that just enquire if the service is present).
pfls and prsm messages are less frequent, especially when a play session starts.

Other Developments

Shairport Sync now uses about an extra half megabyte of RAM for compatibility with TuneBlade's option to have a very long latency -- up to five seconds.

Version 3.2d33

A new metadata token -- 'pffr' -- is emitted when the First Frame of a play session has been Received. Not sure we'll keep it...

Version 3.2d30

Enhancements

A "native" D-Bus Remote Control permits remote control of the current AirPlay or iTunes client. It includes status information about whether the remote control connection is viable or not, i.e. whether it can still be used to control the client. A remote control connection to the audio client becomes valid when the client starts AirPlaying to Shairport Sync. The connections remains valid until the audio source deselects Shairport Sync for AirPlay, or until the client disappears, or until another client starts AirPlaying to Shairport Sync. It is likely that a time limit will be put on this, so that after, say, 30 minutes of inactivity, the remote control connection will be dropped.

Version 3.2d29

Enhancements

CAR INSTALL and OPENBSD notes added.
A barebones "native" D-Bus interface for Shairport Sync permitting control of some diagnostic settings. To be expanded...
A partly implemented MPRIS control interface including play/pause/next/previous/volume and some metadata.
Remote control of an iTunes source including play/pause/next/previous/volume.
Remote control of an AirPlay source including play/pause/next/previous.

Version 3.2d28

Continuing the experiments with D-Bus and related DACP support. In this revision, an attempt is made to control the amount of scanning the system does to maintain up-to-date information about a DACP source. As before, please note that the implementation is likely to change greatly or be removed at any time.

Enhancements

Barebones support added for OpenBSD compilation.
Only ask for missing packets to be resent once, and if any error occurs making the request, stop for 10 seconds.
Include the -pthread flag -- including the pthread library with -lpthread isn't always enough.

Version 3.2d26

Enhancements

Improvements in the documentation relating to scripts -- thanks to Niklas Janz.
Add optional timing annotations to debug messages -- see the new settings in the diagnostic stanza of the configuration file.

Bug Fixes

Ensure the TEARDOWN of a play session is not delayed by a long sleep timer.
Allow more than one ANNOUNCE packet for the same play session. Honour the settings in the most recent one.
Move the creation and calling of a player thread from the SETUP handler to the RECORD handler.
When closing an ALSA sound device, don't wait for any remaining audio to be output with snd_pcm_drain; instead, just drop all remaining frame using snd_pcm_drop.
TEARDOWN should complete in less than 50 ms.

Version 3.2d25

Enhancement

Better handling of missing timing packets.
Improved resnchronisation logic should improve performance with slow-to-download YouTube videos.
Shairport Sync will now log an unexpectedy dropped or faulty RTSP connection. This might be useful on noisy networks.

Version 3.2d24

New Feature

A new general option volume_control_profile, for advanced use only, with two options: "standard" which uses the standard volume control profile -- this has a higher transfer profile at low volumes and a lower transfer profile at high volumes -- or "flat" which uses a uniform transfer profile to linearly scale the output mixer's dB according to the AirPlay volume.

Version 3.2d23

Continuing the experiments with D-Bus and related DACP support.

Enhancement

Some DACs have a feature that the lowest permissible "attenuation" value that the built-in hardware mixer can be set to is not an attenuation value at all – it is in fact a command to mute the output completely. Shairport Sync has always checked for this feature, basically in order to ignore it when getting the true range of attenuation values offered by the mixer. However, with this enhancement, Shairport Sync can actually use this feature to mute the output where appropriate.

Version 3.2d22

Continuing the experiments with D-Bus and related DACP support.

Bug Fix

Fix timing error when using Airfoil as a source.

Version 3.2d21

Continuing the experiments with D-Bus and related DACP support. In this revision, tinyhttp is now used for sending and retrieving DACP information. Many thanks to Matthew Endsley for this work on tinyhttp. As before, please note that the implementation is likely to change greatly or be removed at any time.

Version 3.2d20

Bug Fix

Fix silly seg-fault bug in 3.2d19, activated when a DACP record was withdrawn.

Version 3.2d19

Enhancement

Add compatibility with Swinsian, a Mac music player.

Version 3.2d18

Bug Fix

In recent versions of iOS (11.2) and mac OS (10.13.2), when play is resumed after a pause, the volume level is not always restored, and, if software volume control is being used, Shairport Sync plays at full volume. This issue has been addressed by storing the last airplay volume setting when a play session ends and using it as a default when a new play session begins. (This is a more generalised solution than in 3.2d16.)
Better AirPlay synchronisation. Older versions of Shairport Sync added an 11,025 frame (0.25 seconds) offset to all the latencies agreed with the sender. This seems now only to be correct for iTunes and ForkedDaapd sources, but incorrect for AirPlay sources. Accordingly, the offset is only added for iTunes and ForkedDaapd. The result is better sync with videos, e.g, YouTube, etc. while iTunes and ForkedDaapd synchronisation is unaffected.

Version 3.2d16

Bug Fix

In recent versions of iOS (11.2) and mac OS (10.13.2), when play is resumed after a pause, the volume level is not always restored, and, if software volume control is being used, Shairport Sync plays at full volume. This issue has been addressed by storing the last software volume setting when a play session ends and using it as a default when a new play session begins.

Version 3.2d15

Bug Fix, kind of...

Shairport Sync crashes on Arch Linux with with pulseaudio backend enabled. The cause appears to be a pulseaudio configuration issue, but of course, Shairport Sync shouldn't crash. For the present, the bug fix merely adds an error message before terminating Shairport Sync.

Enhancements

Still lots of changes and experiments with D-Bus and DACP. As before, please note that the implementation is likely to change greatly or to be removed at any time.

Version 3.2d13

Security Update

The version of tinysvcmdns bundled in Shairport Sync has a buffer overflow bug: "An exploitable heap overflow vulnerability exists in the tinysvcmdns library version 2016-07-18. A specially crafted packet can make the library overwrite an arbitrary amount of data on the heap with attacker controlled values. An attacker needs send a dns packet to trigger this vulnerability." The vulnerability is addressed by additional checking on packet sizes. See also CVE-2017-12087 and Vulnerability in tinysvcmdns. Thanks and Chris Boot for fixing this bug.

Version 3.2d12

Experimenting with an MPRIS-compatible D-Bus interface. A very small number of features have a tentative implementation. As with the Shairport Sync D-Bus interface, please note that the implementation is likely to change greatly or be removed at any time.

Continuing the experiments with D-Bus support, Shairport Sync can now be compiled to have a D-Bus presence on the D-Bus system bus. It presents a small number of properties and can execute a method call which sends a command string to the audio source's DACP port. As before, please note that the implementation is likely to change greatly or be removed at any time.

Enhancement

The metadata output stream can include a dapo message carrying the DACP port number to be used when communicating with the DACP remote control. This might be useful because the port number is actually pretty hard to find and requires the use of asynchronous mdns operations. You must be using the Avahi mdns back end.

Bug Fix

A bug in the hardware volume control affects output devices that have hardware mixers but that do not allow the volume to be set in dB. One example is the Softvol plugin in ALSA. Shairport Sync fails silently when presented with such a device when hardware volume control is enabled: the volume events have no effect. The bug has been fixed by adding two missing lines of code to the init() function in audio_alsa.c. Thanks to Jakub Nabaglo for finding and fixing the bug.
A number of bug fixes due to belboj. Many thanks for these!
Enhancements to the handling of quit requests by threads, thanks(again) to belboj!

Other Stuff

The directory structure has been rearranged somewhat. Probably will change again...
Typo fix! Thanks to corbinsantin.

Version 3.2d8

Bug Fix

Fixed a bug that prevented Shairport Sync from starting automatically on systems using the System V startup system (e.g. Ubuntu 14.04). The problem was that the directory to be used – /var/run/shairport-sync/ – was deleted on power down and needed to be recreated on startup. In it's absence, Shairport Sync would not start and would report a mysterious daemon error #2.

Version 3.2d7

This introduces a very experimental D-Bus interface to Shairport Sync. At present, in a very ad-hoc trial arrangement, Shairport Sync provides a system bus D-Bus service enabling a program to get and set Volume, to enable and disable the Loundness Filter and to get and set the Loundness Filter threshold (remember, BTW, the Loudness filter only works with software-based volume control). The implementation is likely to change greatly or be removed at any time. Tested on Ubuntu 16.04 and on Raspbian Stretch. Two extra configuration options are provided: --with-dbus and --with-dbus-test-client. (BTW, the test client is never installed, merely compiled.)

Version 3.1.2

Shairport Sync is more stable playing audio from YouTube and SoundCloud on the Mac.

Pesky Changes You Should Not Ignore

When you update from a previous version of Shairport Sync, your output device may have been left in a muted state. You should use a command line tool like alsamixer or amixer to unmute the output device before further use.

Change of Default

The default value for the alsa setting mute_using_playback_switch has been changed to "no" for compatibility with other audio players on the same machine. The reason is that when this setting is set to "yes", the output device will be muted when Shairport Sync releases it. Unfortunately, other audio players using the output device expect it to be unmuted, causing problems. Thanks to Tim Curtis at Moode Audio and Peter Pablo for clarifying the issue.

Bug Fixes

Fixed bugs that made Shairport Sync drop out or become unavailable when playing YouTube videos, SoundCloud streams etc. from the Mac. Background: there has been a persistent problem with Shairport Sync becoming unavailable after playing, say, a YouTube clip in a browser on the Mac. Shairport Sync 3.1.2 incorporates a change to how certain AirPlay messages are handled. Introduced in nascent form in 3.1.1, further follow-on changes have improved the handling of player lock and have simplified and improved the handling of unexpected loss of connection. Shairport Sync also now works properly with SoundCloud clips played in a browser on the Mac.
Using infer, a number of silent issues have been detected, such as not checking some calls to malloc to ensure the response is not NULL. Most of these have been addressed by additional checks.

Version 3.1.1

Bug Fixes

A bug in the sndio backend has been fixed that caused problems on some versions of Linux.
A change has been made to how Shairport Sync responds to a TEARDOWN request, which should make it respond better to sequences of rapid termination and restarting of play sessions. This can happen, for example, playing YouTube videos in Safari or Chrome on a Mac.
Choosing soxr interpolation in the configuration file will now cause Shairport Sync to terminate with a message if Shairport Sync has not been compiled with SoX support.
Other small changes.

Version 3.1

Version 3.1 brings two new backends, optional loudness and convolution filters, improvements in non-synchronised backends, enhancements, stability improvements and bug fixes.

New Features

A sndio backend gives Shairport Sync native fully synchronised output on OpenBSD and FreeBSD, thanks to the work of Tobias Kortkamp (t6).
A pa backend now allows Shairport Sync to provide synchronised output on PulseAudio-equipped systems -- many desktop Linuxes use PulseAudio as their sound manager.
Optional loudness and convolution filters can be incorporated in the audio processing chain, thanks to the fantastic work of yannpom.
A volume-change program hook run_this_when_volume_is_set has been added to the general settings stanza to execute an application whenever the volume is changed.

Pesky Changes You Should Know About

The audio_backend_buffer_desired_length_in_seconds and audio_backend_latency_offset_in_seconds settings have been moved from individual backend stanzas to the general stanza. They now have an effect on every type of backend.
If you are using a System V (aka systemv) installation, please note that the default location for PID file has moved -- it is now stored at /var/run/shairport-sync/shairport-sync.pid. This change is needed to improve security a little and to improve compatibility across platforms. If you're not doing anything strange, this should make no difference.

Enhancements

Resynchronisation, which happens when the synchronisation is incorrect by more than 50 ms by default, should be a lot less intrusive when it occurs – it should now either insert silence or skip frames, as appropriate.
The Linux installer has been improved and simplified and a FreeBSD installer introduced.
A new setting, audio_backend_silent_lead_in_time, allows you to set the duration of the period of silence played (the "silent lead-in") before a play session starts.
A new command-line option, --logOutputLevel, allows you to output the volume levels to the log whenever they are changed. This may be useful during setup.
Improvements have been made to the handling of large items of metadata over UDP.
A new command line option, -j, demonizes Shairport Sync without creating a PID file.
A new alsa-only setting, mute_using_playback_switch, is available for advanced use.
Other minor enhancements.

Bug Fixes

Stability improvements. More care has been taken (!) to make code thread-safe, resulting in improved stability.
Conversion from stereo to mono has been fixed to avoid clipping while preserving full resolution. Thanks to Robert Jones (RobDeBagel) for bringing this to notice.
Short intrusions of audio at the start of a new session from the end of the previous session have been eliminated.
Many (many!) miscellaneous bugs fixed.

Version 3.0.2

Bug Fixes

Fixed bugs in the ao, pulseaudio and sndio back ends. Basically they were expecting default sample rate and depth information, and were terminating when they saw explicit rate and depth data.

Version 3.0.1

This update fixes one alarming and potentially very noisy bug and restores the identification of Shairport Sync as "ShairportSync" so that TuneBlade recognises it as an open source application.

Bug Fixes

Fixed a bug that was causing Shairport Sync to possibly make a very loud and alarming noise whenever an audio frame was missing.
In 2.8.6, a change was made to the way Shairport Sync identified itself, so that it could be recognised by TuneBlade as an open source application and treated preferentially. That change was inadventently lost in the transition from 2.8.6 to 3.0. Now it's restored.

Version 3.0

Big Update

Version 3 brings in support for 24-bit and 32-bit (and 8 bit!) DACs and for DACs running at multiples of 44,100 samples per second.

The most obvious audible change is if you are using software volume control and can take advantage of 32- or 24-bit DACs. Dithering can now occur on a 32-bit or 24-bit sample rather than on a 16-bit sample, making the noise floor very much lower. This is the case, for example, with a Pimoroni PHAT DAC.

Here is the list of new features:

New Features

8-bit, 16-bit, 24-bit, 24-bit three-byte (S24_3LE and S24_3BE) and 32-bit output to ALSA devices.
44,100, 88,200, 176,400 and 352,800 sample per second output. This is done using simple upsampling. It's only worth doing if 44,100 samples per second output is not available.
Internal processing including software volume control and interpolation is done after sample size and rate conversion.
Apple ALAC decoder support. This needs the libalac library, available at ALAC, to be installed. Add the flag --with-apple-alac to the ./configure arguments. Then you can choose the Apple ALAC decoder in the configuration file.
Support for mbed TLS has been added and the use of PolarSSL is deprecated, as mbed TLS is a development of PolarSSL and PolarSSL itself is not being developed further.
Choose Network Interface. Add a new setting, for advanced users only, in the general section. Use the interface setting to allow you to specify the interface on which to provide the AirPlay service. Omit the setting to get the default, which is to choose the interfaces automatically.
Set Max Volume. Add a new setting, for advanced users only, in the general section. Use the volume_max_db setting to allow you to specify the maximum level to set on the hardware mixer (if chosen) or the built-in software mixer otherwise. The software mixer's range is 0.0 dB to -96.1 dB. The setting must be a number with a decimal point, e.g. 21.3.
An experimental new back end for libsoundio, a C library for cross-platform real-time audio input and output. Many thanks to Serg Podtynnyi. Please see https://github.com/mikebrady/shairport-sync/pull/433 for more details.