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!
109 lines
4.3 KiB
C
109 lines
4.3 KiB
C
/*
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* stdout output driver. This file is part of Shairport Sync.
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* Copyright (c) Mike Brady 2015--2025
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*
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* Based on pipe output driver
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* Copyright (c) James Laird 2013
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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 <errno.h>
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#include <fcntl.h>
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#include <memory.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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static int fd = STDOUT_FILENO;
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static int warned = 0;
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static unsigned int bytes_per_frame = 0;
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static int play(void *buf, int samples, __attribute__((unused)) int sample_type,
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__attribute__((unused)) uint32_t timestamp,
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__attribute__((unused)) uint64_t playtime) {
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char errorstring[1024];
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if (bytes_per_frame == 0)
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debug(1, "stdout: bytes per frame not initialised before play()!");
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int rc = write(fd, buf, samples * bytes_per_frame);
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if ((rc < 0) && (warned == 0)) {
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strerror_r(errno, (char *)errorstring, 1024);
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warn("error %d writing to stdout (fd: %d): \"%s\".", errno, fd, errorstring);
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warned = 1;
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}
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return rc;
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}
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static int init(__attribute__((unused)) int argc, __attribute__((unused)) char **argv) {
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// set up default values first
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config.audio_backend_buffer_desired_length = 1.0;
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config.audio_backend_latency_offset = 0;
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// get settings from settings file, passing in defaults for format_set, rate_set and channel_set
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// Note, these options may be in the "general" stanza or the named stanza
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#ifdef CONFIG_AIRPLAY_2
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parse_audio_options("stdout", (1 << SPS_FORMAT_S32_LE), (1 << SPS_RATE_48000), (1 << 2));
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#else
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parse_audio_options("stdout", (1 << SPS_FORMAT_S16_LE), (1 << SPS_RATE_44100), (1 << 2));
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#endif
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return 0;
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}
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static int32_t get_configuration(unsigned int channels, unsigned int rate, unsigned int format) {
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// use the standard format/rate/channel search to get a suitable configuration. No
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// check_configuration() method needs to be passed to search_for_suitable_configuration() because
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// it will always return a valid choice based on any settings and the defaults
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return search_for_suitable_configuration(channels, rate, format, NULL);
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}
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static int configure(int32_t requested_encoded_format, __attribute__((unused)) char **channel_map) {
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int response = 0;
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unsigned int bytes_per_sample =
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sps_format_sample_size(FORMAT_FROM_ENCODED_FORMAT(requested_encoded_format));
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if (bytes_per_sample == 0) {
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debug(1, "stdout: unknown output format.");
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bytes_per_sample = 4; // emergency hack
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response = EINVAL;
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}
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bytes_per_frame = bytes_per_sample * CHANNELS_FROM_ENCODED_FORMAT(requested_encoded_format);
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return response;
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}
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audio_output audio_stdout = {.name = "stdout",
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.help = NULL,
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.init = &init,
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.deinit = NULL,
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.get_configuration = &get_configuration,
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.configure = &configure,
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.start = NULL,
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.stop = NULL,
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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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