Mike Brady
60143518c2
- 48,000 frames per second operation, - 48k lossless stereo, 5.1 and 7.1 surround sound - Multichannel and multi rate operation on ALSA, PipeWire, PulseAudio, FreeBSD, stdout and unix pipe output backends. Automatic, flexible and controllable output format (rate, sample format and channel count) selection. Full FFmpeg integration to support transcoding, resampling, and new audio formats. Better operation on lower powered devices down to e.g. Raspberry Pi B. Reduced Docker image sizes with a slimmed-down FFmpeg library. Enhanced timestamp handling for better synchronization. Improved the sync error calculation. A new "vernier" resampling and interpolation method for low-power CPUs. Bug fixes and minor enhancements. Note -- there are many breaking changes from previous versions of Shairport Sync!
85 lines
3.6 KiB
C
85 lines
3.6 KiB
C
/*
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* dummy output driver. This file is part of Shairport.
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* Copyright (c) James Laird 2013
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* All rights reserved.
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*
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* Modifications for audio synchronisation
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* and related work, copyright (c) Mike Brady 2014--2025
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* All rights reserved.
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*
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* Permission is hereby granted, free of charge, to any person
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* obtaining a copy of this software and associated documentation
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* files (the "Software"), to deal in the Software without
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* restriction, including without limitation the rights to use,
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* copy, modify, merge, publish, distribute, sublicense, and/or
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* sell copies of the Software, and to permit persons to whom the
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* Software is furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be
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* included in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
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* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
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* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
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* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
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* OTHER DEALINGS IN THE SOFTWARE.
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*/
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#include "audio.h"
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#include "common.h"
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#include <inttypes.h> // for PRId64 and friends
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#include <stdio.h>
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#include <sys/time.h>
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#include <unistd.h>
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static int init(__attribute__((unused)) int argc, __attribute__((unused)) char **argv) { return 0; }
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static void deinit(void) {}
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static void start(int sample_rate, __attribute__((unused)) int sample_format) {
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debug(1, "dummy audio output started at %d frames per second.", sample_rate);
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}
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// clang-format off
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// Here is a brief explanation of the parameters:
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// sample_type is 'play_samples_are_untimed' or 'play_samples_are_timed' defined in audio.h.
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// untimed samples are typically silence used by Shairport Sync itself to set up synchronisation or to fill for missing packets of audio -- the timestamp and playtime are zero.
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// timed samples come from the client.
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// timestamp is the RTP timestamp given to the first frame by the client
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// playtime is when the first frame should to be played. It is given in "local time".
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// local time is CLOCK_MONOTONIC_RAW if available, or CLOCK_MONOTONIC otherwise, expressed in nanoseconds as an unsigned 64-bit integer (See get_absolute_time_in_ns() in common.c)
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// clang-format on
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static int play(__attribute__((unused)) void *buf, __attribute__((unused)) int samples,
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int sample_type, uint32_t timestamp, uint64_t playtime) {
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// sample code using some of the extra information
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if (sample_type == play_samples_are_timed) {
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int64_t lead_time = playtime - get_absolute_time_in_ns();
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debug(2, "leadtime for frame %u is %" PRId64 " nanoseconds, i.e. %f seconds.", timestamp,
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lead_time, 0.000000001 * lead_time);
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}
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return 0;
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}
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static void stop(void) { debug(1, "dummy audio stopped\n"); }
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audio_output audio_dummy = {.name = "dummy",
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.help = NULL,
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.init = &init,
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.deinit = &deinit,
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.configure = NULL,
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.start = &start,
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.stop = &stop,
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.is_running = NULL,
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.flush = NULL,
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.delay = NULL,
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.stats = NULL,
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.play = &play,
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.volume = NULL,
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.parameters = NULL,
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.mute = NULL};
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