} // namespace
ALSAOutput::ALSAOutput(int sample_rate, int num_channels)
- : num_channels(num_channels)
+ : sample_rate(sample_rate), num_channels(num_channels)
{
die_on_error("snd_pcm_open()", snd_pcm_open(&pcm_handle, "default", SND_PCM_STREAM_PLAYBACK, 0));
die_on_error("snd_pcm_hw_params_set_channels", snd_pcm_hw_params_set_channels(pcm_handle, hw_params, num_channels));
// Fragment size of 512 samples. (A frame at 60 fps/48 kHz is 800 samples.)
- // We ask for four such periods.
- unsigned int num_periods = 4;
+ // We ask for 16 such periods (~170 ms buffer).
+ unsigned int num_periods = 16;
int dir = 0;
- die_on_error("snd_pcm_hw_params_set_periods_near", snd_pcm_hw_params_set_periods_near(pcm_handle, hw_params, &num_periods, &dir));
+ die_on_error("snd_pcm_hw_params_set_periods_near()", snd_pcm_hw_params_set_periods_near(pcm_handle, hw_params, &num_periods, &dir));
period_size = 512;
dir = 0;
- die_on_error("snd_pcm_hw_params_set_period_size_near", snd_pcm_hw_params_set_period_size_near(pcm_handle, hw_params, &period_size, &dir));
- die_on_error("snd_pcm_hw_params", snd_pcm_hw_params(pcm_handle, hw_params));
+ die_on_error("snd_pcm_hw_params_set_period_size_near()", snd_pcm_hw_params_set_period_size_near(pcm_handle, hw_params, &period_size, &dir));
+ die_on_error("snd_pcm_hw_params()", snd_pcm_hw_params(pcm_handle, hw_params));
//snd_pcm_hw_params_free(hw_params);
+ snd_pcm_sw_params_t *sw_params;
+ snd_pcm_sw_params_alloca(&sw_params);
+ die_on_error("snd_pcm_sw_params_current()", snd_pcm_sw_params_current(pcm_handle, sw_params));
+ die_on_error("snd_pcm_sw_params_set_start_threshold", snd_pcm_sw_params_set_start_threshold(pcm_handle, sw_params, num_periods * period_size / 2));
+ die_on_error("snd_pcm_sw_params()", snd_pcm_sw_params(pcm_handle, sw_params));
+
die_on_error("snd_pcm_nonblock", snd_pcm_nonblock(pcm_handle, 1));
+ die_on_error("snd_pcm_prepare()", snd_pcm_prepare(pcm_handle));
}
void ALSAOutput::write(const vector<float> &samples)
if (ret == 0) {
if (buffer.size() >= period_size * num_channels * 8) {
// OK, almost 100 ms. Giving up.
- fprintf(stderr, "warning: ALSA overrun, dropping some audio\n");
+ fprintf(stderr, "warning: ALSA overrun, dropping some audio (%d ms)\n",
+ int(buffer.size() * 1000 / (num_channels * sample_rate)));
buffer.clear();
}
} else if (ret > 0) {