-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;
- int infilling = 0, escape = 0;
- time_t logged, now;
- uint32_t packet_start, packet_end;
-
- /* 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 */
-
- time(&logged);
- pthread_mutex_lock(&lock);
- for(;;) {
- /* Wait for the buffer to fill up a bit */
- logged = now;
- info("%lu samples in buffer (%lus)", nsamples,
- nsamples / (44100 * 2));
- info("Buffering...");
- 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;
- }
- /* Start at the first available packet */
- next_timestamp = packets->timestamp;
- active = 1;
- infilling = 0;
- escape = 0;
- logged = now;
- info("%lu samples in buffer (%lus)", nsamples,
- nsamples / (44100 * 2));
- info("Playing...");
- /* Wait until the buffer empties out */
- while(nsamples >= minbuffer && !escape) {
- time(&now);
- if(now > logged + 10) {
- logged = now;
- info("%lu samples in buffer (%lus)", nsamples,
- nsamples / (44100 * 2));
- }
- if(packets
- && ge(next_timestamp, packets->timestamp + packets->nsamples)) {
- info("dropping buffered past packet %"PRIx32" < %"PRIx32,
- packets->timestamp, next_timestamp);
- drop_first_packet();
- continue;
- }
- /* Wait for ALSA to ask us for more data */
- pthread_mutex_unlock(&lock);
- write(2, ".", 1); /* TODO remove me sometime */
- switch(err = snd_pcm_wait(pcm, -1)) {
- case 0:
- info("snd_pcm_wait timed out");
- break;
- case 1:
- break;
- default:
- fatal(0, "snd_pcm_wait returned %d", err);
- }
- pthread_mutex_lock(&lock);
- /* ALSA is ready for more data */
- packet_start = packets->timestamp;
- packet_end = packets->timestamp + packets->nsamples;
- if(ge(next_timestamp, packet_start)
- && lt(next_timestamp, packet_end)) {
- /* The target timestamp is somewhere in this packet */
- const uint32_t offset = next_timestamp - packets->timestamp;
- const uint32_t samples_available = (packets->timestamp + packets->nsamples) - next_timestamp;
- const size_t frames_available = samples_available / 2;
-
- frames_written = snd_pcm_writei(pcm,
- packets->samples_raw + offset,
- frames_available);
- if(frames_written < 0) {
- switch(frames_written) {
- case -EAGAIN:
- info("snd_pcm_wait() returned but we got -EAGAIN!");
- break;
- case -EPIPE:
- error(0, "error calling snd_pcm_writei: %ld",
- (long)frames_written);
- escape = 1;
- break;
- default:
- fatal(0, "error calling snd_pcm_writei: %ld",
- (long)frames_written);
- }
- } else {
- samples_written = frames_written * 2;
- next_timestamp += samples_written;
- if(ge(next_timestamp, packet_end))
- drop_first_packet();
- infilling = 0;
- }
- } else {
- /* We don't have anything to play! We'd better play some 0s. */
- static const uint16_t zeros[INFILL_SAMPLES];
- size_t samples_available = INFILL_SAMPLES, frames_available;
-
- /* If the maximum infill would take us past the start of the next
- * packet then we truncate the infill to the right amount. */
- if(lt(packets->timestamp,
- next_timestamp + samples_available))
- samples_available = packets->timestamp - next_timestamp;
- if((int)samples_available < 0) {
- info("packets->timestamp: %"PRIx32" next_timestamp: %"PRIx32" next+max: %"PRIx32" available: %"PRIx32,
- packets->timestamp, next_timestamp,
- next_timestamp + INFILL_SAMPLES, samples_available);
- }
- frames_available = samples_available / 2;
- if(!infilling) {
- info("Infilling %d samples, next=%"PRIx32" packet=[%"PRIx32",%"PRIx32"]",
- samples_available, next_timestamp,
- packets->timestamp, packets->timestamp + packets->nsamples);
- //infilling++;
- }
- frames_written = snd_pcm_writei(pcm,
- zeros,
- frames_available);
- if(frames_written < 0) {
- switch(frames_written) {
- case -EAGAIN:
- info("snd_pcm_wait() returned but we got -EAGAIN!");
- break;
- case -EPIPE:
- error(0, "error calling snd_pcm_writei: %ld",
- (long)frames_written);
- escape = 1;
- break;
- default:
- fatal(0, "error calling snd_pcm_writei: %ld",
- (long)frames_written);
- }
- } else {
- samples_written = frames_written * 2;
- next_timestamp += samples_written;
- }
- }
- }
- active = 0;
- /* We stop playing for a bit until the buffer re-fills */
- pthread_mutex_unlock(&lock);
- if((err = snd_pcm_nonblock(pcm, 0)))
- fatal(0, "error calling snd_pcm_nonblock: %d", err);
- if(escape) {
- if((err = snd_pcm_drop(pcm)))
- fatal(0, "error calling snd_pcm_drop: %d", err);
- escape = 0;
- } else
- if((err = snd_pcm_drain(pcm)))
- fatal(0, "error calling snd_pcm_drain: %d", err);
- if((err = snd_pcm_nonblock(pcm, 1)))
- fatal(0, "error calling snd_pcm_nonblock: %d", err);
- prepared = 0;
- pthread_mutex_lock(&lock);
- }
-