audio_pulse.c

/*
 * PulseAudio output driver. This file is part of Shairport.
 * Copyright (c) Paul Lietar 2013
 * All rights reserved.
  *
 * Modifications for audio synchronisation
 * and related work, copyright (c) Mike Brady 2014
 * All rights reserved.
 *
 * Permission is hereby granted, free of charge, to any person
 * obtaining a copy of this software and associated documentation
 * files (the "Software"), to deal in the Software without
 * restriction, including without limitation the rights to use,
 * copy, modify, merge, publish, distribute, sublicense, and/or
 * sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 */

#include <stdio.h>
#include <unistd.h>
#include <memory.h>
#include <pulse/simple.h>
#include <pulse/error.h>
#include <pulse/def.h>
#include "common.h"
#include "audio.h"

static pa_simple *pa_dev = NULL;

static struct {
  char *server;
  char *sink;
  char *apname;
} pulse_options = {.server = NULL, .sink = NULL, .apname = NULL};

static int pa_error;

static void pulse_connect(void);

static void help(void) {
  printf("    -a server           set the server name\n"
         "    -s sink             set the output sink\n"
         "    -n name             set the application name, as seen by PulseAudio\n"
         "                            defaults to the access point name\n");
}

static int init(int argc, char **argv) {

  pulse_options.apname = config.apname;

  config.audio_backend_buffer_desired_length = 44100; // one second.
  config.audio_backend_latency_offset = 0;

  optind = 1; // optind=0 is equivalent to optind=1 plus special behaviour
  argv--;     // so we shift the arguments to satisfy getopt()
  argc++;

  // some platforms apparently require optreset = 1; - which?
  int opt;
  while ((opt = getopt(argc, argv, "a:s:n:")) > 0) {
    switch (opt) {
    case 'a':
      pulse_options.server = optarg;
      break;
    case 's':
      pulse_options.sink = optarg;
      break;
    case 'n':
      pulse_options.apname = optarg;
      break;
    default:
      help();
      die("Invalid audio option -%c specified", opt);
    }
  }

  if (optind < argc)
    die("Invalid audio argument: %s", argv[optind]);

  pulse_connect();

  return 0;
}

static void pulse_connect(void) {
  static const pa_sample_spec ss = {.format = PA_SAMPLE_S16LE, .rate = 44100, .channels = 2};

  pa_dev = pa_simple_new(pulse_options.server, pulse_options.apname, PA_STREAM_PLAYBACK,
                         pulse_options.sink, "Shairport Stream", &ss, NULL, NULL, &pa_error);

  if (!pa_dev)
    die("Could not connect to pulseaudio server: %s", pa_strerror(pa_error));
}

static void deinit(void) {
  if (pa_dev)
    pa_simple_free(pa_dev);
  pa_dev = NULL;
}

static void start(int sample_rate) {
  if (sample_rate != 44100)
    die("unexpected sample rate!");
}

static void play(short buf[], int samples) {
  if (pa_simple_write(pa_dev, (char *)buf, (size_t)samples * 4, &pa_error) < 0) {
    fprintf(stderr, __FILE__ ": pa_simple_write() failed: %s\n", pa_strerror(pa_error));
    if (pa_error == PA_ERR_CONNECTIONTERMINATED) {
      fprintf(stderr, __FILE__ ": reconnecting.");
      deinit();
      pulse_connect();
    }
  }
}

static void stop(void) {
  if (pa_simple_drain(pa_dev, &pa_error) < 0)
    fprintf(stderr, __FILE__ ": pa_simple_drain() failed: %s\n", pa_strerror(pa_error));
}

audio_output audio_pulse = {.name = "pulse",
                            .help = &help,
                            .init = &init,
                            .deinit = &deinit,
                            .start = &start,
                            .stop = &stop,
                            .flush = NULL,
                            .delay = NULL,
                            .play = &play,
                            .volume = NULL,
                            .parameters = NULL,
                            .mute = NULL};