-#endif
-
-static void play_rtp(void) {
- pthread_t ltid;
-
- /* We receive and convert audio data in a background thread */
- pthread_create(<id, 0, listen_thread, 0);
-#if API_ALSA
- {
- snd_pcm_t *pcm;
- snd_pcm_hw_params_t *hwparams;
- snd_pcm_sw_params_t *swparams;
- /* Only support one format for now */
- const int sample_format = SND_PCM_FORMAT_S16_BE;
- unsigned rate = 44100;
- const int channels = 2;
- const int samplesize = channels * sizeof(uint16_t);
- snd_pcm_uframes_t pcm_bufsize = MAXSAMPLES * samplesize * 3;
- /* If we can write more than this many samples we'll get a wakeup */
- const int avail_min = 256;
- snd_pcm_sframes_t frames_written;
- size_t samples_written;
- int prepared = 1;
- int err;
-
- /* Open ALSA */
- if((err = snd_pcm_open(&pcm,
- device ? device : "default",
- SND_PCM_STREAM_PLAYBACK,
- SND_PCM_NONBLOCK)))
- fatal(0, "error from snd_pcm_open: %d", err);
- /* Set up 'hardware' parameters */
- snd_pcm_hw_params_alloca(&hwparams);
- if((err = snd_pcm_hw_params_any(pcm, hwparams)) < 0)
- fatal(0, "error from snd_pcm_hw_params_any: %d", err);
- if((err = snd_pcm_hw_params_set_access(pcm, hwparams,
- SND_PCM_ACCESS_RW_INTERLEAVED)) < 0)
- fatal(0, "error from snd_pcm_hw_params_set_access: %d", err);
- if((err = snd_pcm_hw_params_set_format(pcm, hwparams,
- sample_format)) < 0)
- fatal(0, "error from snd_pcm_hw_params_set_format (%d): %d",
- sample_format, err);
- if((err = snd_pcm_hw_params_set_rate_near(pcm, hwparams, &rate, 0)) < 0)
- fatal(0, "error from snd_pcm_hw_params_set_rate (%d): %d",
- rate, err);
- if((err = snd_pcm_hw_params_set_channels(pcm, hwparams,
- channels)) < 0)
- fatal(0, "error from snd_pcm_hw_params_set_channels (%d): %d",
- channels, err);
- if((err = snd_pcm_hw_params_set_buffer_size_near(pcm, hwparams,
- &pcm_bufsize)) < 0)
- fatal(0, "error from snd_pcm_hw_params_set_buffer_size (%d): %d",
- MAXSAMPLES * samplesize * 3, err);
- if((err = snd_pcm_hw_params(pcm, hwparams)) < 0)
- fatal(0, "error calling snd_pcm_hw_params: %d", err);
- /* Set up 'software' parameters */
- snd_pcm_sw_params_alloca(&swparams);
- if((err = snd_pcm_sw_params_current(pcm, swparams)) < 0)
- fatal(0, "error calling snd_pcm_sw_params_current: %d", err);
- if((err = snd_pcm_sw_params_set_avail_min(pcm, swparams, avail_min)) < 0)
- fatal(0, "error calling snd_pcm_sw_params_set_avail_min %d: %d",
- avail_min, err);
- if((err = snd_pcm_sw_params(pcm, swparams)) < 0)
- fatal(0, "error calling snd_pcm_sw_params: %d", err);
-
- /* Ready to go */
-
- pthread_mutex_lock(&lock);
- for(;;) {
- /* Wait for the buffer to fill up a bit */
- while(nsamples < READAHEAD)
- pthread_cond_wait(&cond, &lock);
- if(!prepared) {
- if((err = snd_pcm_prepare(pcm)))
- fatal(0, "error calling snd_pcm_prepare: %d", err);
- prepared = 1;
- }
- /* Wait until the buffer empties out */
- while(nsamples >= MINBUFFER) {
- /* Wait for ALSA to ask us for more data */
- pthread_mutex_unlock(&lock);
- snd_pcm_wait(pcm, -1);
- pthread_mutex_lock(&lock);
- /* ALSA wants more data */
- if(packets && packets->timestamp + packets->nused == next_timestamp) {
- /* Hooray, we have a packet we can play */
- const size_t samples_available = packets->nsamples - packets->nused;
- const size_t frames_available = samples_available / 2;
-
- frames_written = snd_pcm_writei(pcm,
- packets->samples_raw + packets->nused,
- frames_available);
- if(frames_written < 0)
- fatal(0, "error calling snd_pcm_writei: %d", err);
- samples_written = frames_written * 2;
- packets->nused += samples_written;
- next_timestamp += samples_written;
- if(packets->nused == packets->nsamples) {
- struct packet *f = packets;
-
- packets = f->next;
- nsamples -= f->nsamples;
- free(f);
- pthread_cond_broadcast(&cond);
- }
- } else {
- /* We don't have anything to play! We'd better play some 0s. */
- static const uint16_t zeros[1024];
- size_t samples_available = 1024, frames_available;
- if(packets && next_timestamp + samples_available > packets->timestamp)
- samples_available = packets->timestamp - next_timestamp;
- frames_available = samples_available / 2;
- frames_written = snd_pcm_writei(pcm,
- zeros,
- frames_available);
- if(frames_written < 0)
- fatal(0, "error calling snd_pcm_writei: %d", err);
- next_timestamp += samples_written;
- }
- }
- /* We stop playing for a bit until the buffer re-fills */
- pthread_mutex_unlock(&lock);
- if((err = snd_pcm_drain(pcm)))
- fatal(0, "error calling snd_pcm_drain: %d", err);
- prepared = 0;
- pthread_mutex_lock(&lock);
- }