Forgot updates on line.

Merge branch 'development' of https://github.com/mikebrady/shairport-sync into development

FREEBSD.md

@@ -1,7 +1,13 @@
+Introduction
+----
 This is a very quick initial note about installing Shairport Sync on FreeBSD. Some manual installation is required.
 
-The build instrctions here install back ends of `sndio` (native to OpenBSD) and ALSA. ALSA is, or course, the Advanced Linux Sound Architecture, so it is not "native" to FreeBSD. It has, however, been ported, so it should work pretty well.
+Please see important notes at the end about using the `sndio` back end -- some workarounds are needed for the present.
 
+The build instructions here install back ends for `sndio` (native to OpenBSD) and ALSA. ALSA is, or course, the Advanced Linux Sound Architecture, so it is not "native" to FreeBSD. It has, however, been ported, so it should work pretty well.
+
+General
+----
 This build was done on a default build of `FreeBSD 11.0-RELEASE-p9`.
 
 First, update everything:
@@ -16,6 +22,8 @@ Next, install the `pkg` package manager and update its lists:
 # pkg update
 ```
 
+Subsystems
+----
 Now, install the ALSA and Avahi subsystems. Note: `avahi-app` is chosen because it doesn’t require X11 and `nss_mdns` allows FreeBSD
 to resolve mDNS-originated addresses. Thanks to [reidransom](https://gist.github.com/reidransom/6033227) for this:
 
@@ -33,6 +41,9 @@ hosts: files dns mdns
 ```
 Reboot for these changes to take effect.
 
+Building
+----
+
 Next, install the packages that are needed for Shairport Sync to be downloaded and build successfully:
 ```
 # pkg install git autotools pkgconf popt libconfig openssl sndio
@@ -52,14 +63,29 @@ $ CPPFLAGS="-I/usr/local/include" ./configure  --with-alsa --with-avahi --with-s
 $ make
 ```
 
+Manual Installation
+----
 After this, you're on your own – the `$ sudo make install` step does not work for FreeBSD. Maybe some day...
 
 To continue, you should create a configuration file at `/usr/local/etc/shairport-sync.conf`. Please see the sample configuration file for more details.
 
+Using the `sndio` backend
+----
+
+The `sndio` back end does synchronisation, thanks to the work of [t6](https://github.com/t6), using information from the `sndio` subsystem. The format of the information is not the same as that coming from the ALSA subsystem, so Shairport Sync cannot yet use it properly. As a workaround, please use the following settings:
+
+In the `general` stanza of the configuration file at `/usr/local/etc/shairport-sync.conf`, make the following settings:
+```
+drift_tolerance_in_seconds = 0.005; // allow some more tolerance before attempting to correct
+resync_threshold_in_seconds = 0.0; // ignore a large error in the initial estimation of synchronisation time...
+```
+Note that there are workarounds -- it is hoped that they won't be necessary for too long.
+
+Setting Overall  Volume
+----
 Note, the `mixer` command is useful for setting the output device's overall volume settings. With the default settings for the `sndio` back end, the `pcm` mixer controls its maximum output:
 
 ```
 $ mixer vol 100 # sets overall volume
 $ mixer pcm 100 # sets maximum volume level for the default sndio device used by Shairport Sync
 ```
-