433 lines
16 KiB
C
433 lines
16 KiB
C
/*
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* Asynchronous PulseAudio Backend. This file is part of Shairport Sync.
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* Copyright (c) Mike Brady 2017-2023
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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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// Based (distantly, with thanks) on
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// http://stackoverflow.com/questions/29977651/how-can-the-pulseaudio-asynchronous-library-be-used-to-play-raw-pcm-data
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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 <pthread.h>
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#include <pulse/pulseaudio.h>
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#include <stdio.h>
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#include <string.h>
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#include <unistd.h>
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// note -- these are hacked and hardwired into this code.
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#define FORMAT PA_SAMPLE_S16NE
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#define RATE 44100
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// Four seconds buffer -- should be plenty
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#define buffer_allocation 44100 * 4 * 2 * 2
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static pthread_mutex_t buffer_mutex = PTHREAD_MUTEX_INITIALIZER;
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pa_threaded_mainloop *mainloop;
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pa_mainloop_api *mainloop_api;
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pa_context *context;
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pa_stream *stream;
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static char *audio_lmb, *audio_umb, *audio_toq, *audio_eoq;
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static size_t audio_size = buffer_allocation;
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static size_t audio_occupancy;
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void context_state_cb(pa_context *context, void *mainloop);
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void stream_state_cb(pa_stream *s, void *mainloop);
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void stream_success_cb(pa_stream *stream, int success, void *userdata);
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void stream_write_cb(pa_stream *stream, size_t requested_bytes, void *userdata);
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int status_error_notifications = 0;
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static void check_pa_stream_status(pa_stream *p, const char *message) {
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if (status_error_notifications < 10) {
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if (p == NULL) {
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warn("%s No pulseaudio stream!", message);
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status_error_notifications++;
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} else {
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status_error_notifications++; // assume an error
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switch (pa_stream_get_state(p)) {
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case PA_STREAM_UNCONNECTED:
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warn("%s Pulseaudio stream unconnected!", message);
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break;
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case PA_STREAM_CREATING:
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warn("%s Pulseaudio stream being created!", message);
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break;
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case PA_STREAM_READY:
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status_error_notifications--; // no error
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break;
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case PA_STREAM_FAILED:
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warn("%s Pulseaudio stream failed!", message);
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break;
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case PA_STREAM_TERMINATED:
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warn("%s Pulseaudio stream unexpectedly terminated!", message);
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break;
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default:
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warn("%s Pulseaudio stream in unexpected state %d!", message, pa_stream_get_state(p));
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break;
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}
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}
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}
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}
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static void connect_stream() {
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// debug(1, "connect_stream");
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uint32_t buffer_size_in_bytes = (uint32_t)2 * 2 * RATE * 0.1; // hard wired in here
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// debug(1, "pa_buffer size is %u bytes.", buffer_size_in_bytes);
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pa_threaded_mainloop_lock(mainloop);
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// Create a playback stream
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pa_sample_spec sample_specifications;
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sample_specifications.format = FORMAT;
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sample_specifications.rate = RATE;
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sample_specifications.channels = 2;
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pa_channel_map map;
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pa_channel_map_init_stereo(&map);
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stream = pa_stream_new(context, "Playback", &sample_specifications, &map);
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pa_stream_set_state_callback(stream, stream_state_cb, mainloop);
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pa_stream_set_write_callback(stream, stream_write_cb, mainloop);
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// pa_stream_set_latency_update_callback(stream, stream_latency_cb, mainloop);
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// recommended settings, i.e. server uses sensible values
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pa_buffer_attr buffer_attr;
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buffer_attr.maxlength = (uint32_t)-1;
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buffer_attr.tlength = buffer_size_in_bytes;
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buffer_attr.prebuf = (uint32_t)0;
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buffer_attr.minreq = (uint32_t)-1;
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pa_stream_flags_t stream_flags;
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stream_flags = PA_STREAM_START_CORKED | PA_STREAM_INTERPOLATE_TIMING | PA_STREAM_NOT_MONOTONIC |
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PA_STREAM_AUTO_TIMING_UPDATE | PA_STREAM_ADJUST_LATENCY;
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int connect_result;
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if (config.pa_sink) {
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// Connect stream to the sink specified in the config
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connect_result =
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pa_stream_connect_playback(stream, config.pa_sink, &buffer_attr, stream_flags, NULL, NULL);
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} else {
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// Connect stream to the default audio output sink
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connect_result =
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pa_stream_connect_playback(stream, NULL, &buffer_attr, stream_flags, NULL, NULL);
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}
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if (connect_result != 0)
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die("could not connect to the pulseaudio playback stream -- the error message is \"%s\".",
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pa_strerror(pa_context_errno(context)));
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// Wait for the stream to be ready
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for (;;) {
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pa_stream_state_t stream_state = pa_stream_get_state(stream);
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if (!PA_STREAM_IS_GOOD(stream_state))
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die("stream state is no longer good while waiting for stream to become ready -- the error "
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"message is \"%s\".",
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pa_strerror(pa_context_errno(context)));
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if (stream_state == PA_STREAM_READY)
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break;
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pa_threaded_mainloop_wait(mainloop);
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}
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pa_threaded_mainloop_unlock(mainloop);
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}
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static int init(__attribute__((unused)) int argc, __attribute__((unused)) char **argv) {
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// debug(1, "pa_init");
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// set up default values first
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config.audio_backend_buffer_desired_length = 0.35;
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config.audio_backend_buffer_interpolation_threshold_in_seconds =
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0.02; // below this, soxr interpolation will not occur -- it'll be basic interpolation
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// instead.
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config.audio_backend_latency_offset = 0;
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// get settings from settings file
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// do the "general" audio options. Note, these options are in the "general" stanza!
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parse_general_audio_options();
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// now the specific options
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if (config.cfg != NULL) {
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const char *str;
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/* Get the PulseAudio server name. */
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if (config_lookup_string(config.cfg, "pa.server", &str)) {
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config.pa_server = (char *)str;
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}
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/* Get the Application Name. */
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if (config_lookup_string(config.cfg, "pa.application_name", &str)) {
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config.pa_application_name = (char *)str;
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}
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/* Get the PulseAudio sink name. */
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if (config_lookup_string(config.cfg, "pa.sink", &str)) {
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config.pa_sink = (char *)str;
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}
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}
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// finish collecting settings
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// allocate space for the audio buffer
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audio_lmb = malloc(audio_size);
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if (audio_lmb == NULL)
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die("Can't allocate %d bytes for pulseaudio buffer.", audio_size);
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audio_toq = audio_eoq = audio_lmb;
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audio_umb = audio_lmb + audio_size;
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audio_occupancy = 0;
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// Get a mainloop and its context
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mainloop = pa_threaded_mainloop_new();
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if (mainloop == NULL)
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die("could not create a pa_threaded_mainloop.");
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mainloop_api = pa_threaded_mainloop_get_api(mainloop);
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if (config.pa_application_name)
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context = pa_context_new(mainloop_api, config.pa_application_name);
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else
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context = pa_context_new(mainloop_api, "Shairport Sync");
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if (context == NULL)
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die("could not create a new context for pulseaudio.");
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// Set a callback so we can wait for the context to be ready
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pa_context_set_state_callback(context, &context_state_cb, mainloop);
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// Lock the mainloop so that it does not run and crash before the context is ready
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pa_threaded_mainloop_lock(mainloop);
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// Start the mainloop
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if (pa_threaded_mainloop_start(mainloop) != 0)
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die("could not start the pulseaudio threaded mainloop");
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if (pa_context_connect(context, config.pa_server, 0, NULL) != 0)
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die("failed to connect to the pulseaudio context -- the error message is \"%s\".",
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pa_strerror(pa_context_errno(context)));
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// Wait for the context to be ready
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for (;;) {
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pa_context_state_t context_state = pa_context_get_state(context);
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if (!PA_CONTEXT_IS_GOOD(context_state))
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die("pa context is not good -- the error message \"%s\".",
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pa_strerror(pa_context_errno(context)));
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if (context_state == PA_CONTEXT_READY)
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break;
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pa_threaded_mainloop_wait(mainloop);
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}
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pa_threaded_mainloop_unlock(mainloop);
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connect_stream();
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check_pa_stream_status(stream, "audio_pa initialisation.");
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return 0;
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}
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static void deinit(void) {
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check_pa_stream_status(stream, "audio_pa deinitialisation.");
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pa_stream_disconnect(stream);
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pa_threaded_mainloop_stop(mainloop);
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pa_threaded_mainloop_free(mainloop);
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// debug(1, "pa deinit done");
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}
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static void start(__attribute__((unused)) int sample_rate,
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__attribute__((unused)) int sample_format) {
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check_pa_stream_status(stream, "audio_pa start.");
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}
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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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// debug(1,"pa_play of %d samples.",samples);
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// copy the samples into the queue
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check_pa_stream_status(stream, "audio_pa play.");
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size_t bytes_to_transfer = samples * 2 * 2;
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pthread_mutex_lock(&buffer_mutex);
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size_t bytes_available = audio_size - audio_occupancy;
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if (bytes_available < bytes_to_transfer)
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bytes_to_transfer = bytes_available;
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if (bytes_to_transfer > 0) {
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size_t space_to_end_of_buffer = audio_umb - audio_eoq;
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if (space_to_end_of_buffer >= bytes_to_transfer) {
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memcpy(audio_eoq, buf, bytes_to_transfer);
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audio_eoq += bytes_to_transfer;
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} else {
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memcpy(audio_eoq, buf, space_to_end_of_buffer);
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buf += space_to_end_of_buffer;
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memcpy(audio_lmb, buf, bytes_to_transfer - space_to_end_of_buffer);
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audio_eoq = audio_lmb + bytes_to_transfer - space_to_end_of_buffer;
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}
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audio_occupancy += bytes_to_transfer;
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}
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if ((audio_occupancy >= 11025 * 2 * 2) && (pa_stream_is_corked(stream))) {
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// debug(1,"Uncorked");
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pthread_mutex_unlock(&buffer_mutex);
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pa_threaded_mainloop_lock(mainloop);
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pa_stream_cork(stream, 0, stream_success_cb, mainloop);
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pa_threaded_mainloop_unlock(mainloop);
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} else {
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pthread_mutex_unlock(&buffer_mutex);
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}
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return 0;
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}
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int pa_delay(long *the_delay) {
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check_pa_stream_status(stream, "audio_pa delay.");
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// debug(1,"pa_delay");
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long result = 0;
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int reply = 0;
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pa_usec_t latency;
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int negative;
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pa_threaded_mainloop_lock(mainloop);
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int gl = pa_stream_get_latency(stream, &latency, &negative);
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pa_threaded_mainloop_unlock(mainloop);
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if (gl == PA_ERR_NODATA) {
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// debug(1, "No latency data yet.");
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reply = -ENODEV;
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} else if (gl != 0) {
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// debug(1,"Error %d getting latency.",gl);
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reply = -EIO;
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} else {
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result = (audio_occupancy / (2 * 2)) + (latency * 44100) / 1000000;
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reply = 0;
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}
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*the_delay = result;
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return reply;
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}
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static void flush(void) {
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check_pa_stream_status(stream, "audio_pa flush.");
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pa_threaded_mainloop_lock(mainloop);
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if (pa_stream_is_corked(stream) == 0) {
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// debug(1,"Flush and cork for flush.");
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pa_stream_flush(stream, stream_success_cb, NULL);
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pa_stream_cork(stream, 1, stream_success_cb, mainloop);
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}
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pa_threaded_mainloop_unlock(mainloop);
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pthread_mutex_lock(&buffer_mutex);
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audio_toq = audio_eoq = audio_lmb;
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audio_umb = audio_lmb + audio_size;
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audio_occupancy = 0;
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pthread_mutex_unlock(&buffer_mutex);
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}
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static void stop(void) {
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check_pa_stream_status(stream, "audio_pa stop.");
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// Cork the stream so it will stop playing
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pa_threaded_mainloop_lock(mainloop);
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if (pa_stream_is_corked(stream) == 0) {
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// debug(1,"Flush and cork for stop.");
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pa_stream_flush(stream, stream_success_cb, NULL);
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pa_stream_cork(stream, 1, stream_success_cb, mainloop);
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}
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pa_threaded_mainloop_unlock(mainloop);
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pthread_mutex_lock(&buffer_mutex);
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audio_toq = audio_eoq = audio_lmb;
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audio_umb = audio_lmb + audio_size;
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audio_occupancy = 0;
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pthread_mutex_unlock(&buffer_mutex);
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}
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audio_output audio_pa = {.name = "pa",
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.help = NULL,
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.init = &init,
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.deinit = &deinit,
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.prepare = 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 = &flush,
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.delay = &pa_delay,
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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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void context_state_cb(__attribute__((unused)) pa_context *context, void *mainloop) {
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// debug(1,"context_state_cb called.");
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pa_threaded_mainloop_signal(mainloop, 0);
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}
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void stream_state_cb(__attribute__((unused)) pa_stream *s, void *mainloop) {
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// debug(1,"stream_state_cb called.");
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pa_threaded_mainloop_signal(mainloop, 0);
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}
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void stream_write_cb(pa_stream *stream, size_t requested_bytes,
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__attribute__((unused)) void *userdata) {
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check_pa_stream_status(stream, "audio_pa stream_write_cb.");
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int bytes_to_transfer = requested_bytes;
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int bytes_transferred = 0;
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uint8_t *buffer = NULL;
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int ret = 0;
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pthread_mutex_lock(&buffer_mutex);
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pthread_cleanup_push(mutex_unlock, (void *)&buffer_mutex);
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while ((bytes_to_transfer > 0) && (audio_occupancy > 0) && (ret == 0)) {
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if (pa_stream_is_suspended(stream))
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debug(1, "stream is suspended");
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size_t bytes_we_can_transfer = bytes_to_transfer;
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if (audio_occupancy < bytes_we_can_transfer) {
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// debug(1, "Underflow? We have %d bytes but we are asked for %d bytes", audio_occupancy,
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// bytes_we_can_transfer);
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pa_stream_cork(stream, 1, stream_success_cb, mainloop);
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// debug(1, "Corked");
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bytes_we_can_transfer = audio_occupancy;
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}
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// bytes we can transfer will never be greater than the bytes available
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ret = pa_stream_begin_write(stream, (void **)&buffer, &bytes_we_can_transfer);
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if ((ret == 0) && (buffer != NULL)) {
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if (bytes_we_can_transfer <= (size_t)(audio_umb - audio_toq)) {
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// the bytes are all in a row in the audo buffer
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memcpy(buffer, audio_toq, bytes_we_can_transfer);
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audio_toq += bytes_we_can_transfer;
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ret = pa_stream_write(stream, buffer, bytes_we_can_transfer, NULL, 0LL, PA_SEEK_RELATIVE);
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} else {
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// the bytes are in two places in the audio buffer
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size_t first_portion_to_write = audio_umb - audio_toq;
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if (first_portion_to_write != 0)
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memcpy(buffer, audio_toq, first_portion_to_write);
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uint8_t *new_buffer = buffer + first_portion_to_write;
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memcpy(new_buffer, audio_lmb, bytes_we_can_transfer - first_portion_to_write);
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ret = pa_stream_write(stream, buffer, bytes_we_can_transfer, NULL, 0LL, PA_SEEK_RELATIVE);
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audio_toq = audio_lmb + bytes_we_can_transfer - first_portion_to_write;
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}
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bytes_transferred += bytes_we_can_transfer;
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audio_occupancy -= bytes_we_can_transfer;
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bytes_to_transfer -= bytes_we_can_transfer;
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}
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}
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pthread_cleanup_pop(1); // release the mutex
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if (ret != 0)
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debug(1, "error writing to pa buffer");
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// debug(1,"<<<Frames requested %d, written to pa: %d, corked status:
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// %d.",requested_bytes/4,bytes_transferred/4,pa_stream_is_corked(stream));
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}
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void stream_success_cb(__attribute__((unused)) pa_stream *stream,
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__attribute__((unused)) int success,
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__attribute__((unused)) void *userdata) {
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return;
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}
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