diff options
| -rw-r--r-- | dxr3audio-alsa.c | 53 |
1 files changed, 43 insertions, 10 deletions
diff --git a/dxr3audio-alsa.c b/dxr3audio-alsa.c index 6463028..a946d2f 100644 --- a/dxr3audio-alsa.c +++ b/dxr3audio-alsa.c @@ -117,11 +117,31 @@ void cAudioAlsa::setup(int channels, int samplerate) esyslog("[dxr3-audio-alsa] Unable to set samplerate %d: %s", samplerate, snd_strerror(err)); } - if (snd_pcm_state(handle) == SND_PCM_STATE_RUNNING) { - if ((err = snd_pcm_drain(handle)) < 0) { - esyslog("[dxr3-audio-alsa] Cannot drain (%s); will try to set parameters anyway\n", snd_strerror(err)); - } + static unsigned int buffer_time = 500000; // ring buffer length in us + static unsigned int period_time = 100000; // period time in us + snd_pcm_uframes_t size; + + // set the buffer time + err = snd_pcm_hw_params_set_buffer_time_near(handle, alsa_hwparams, &buffer_time, NULL); + if (err < 0) { + esyslog("[dxr3-audio-alsa] Unable to set buffer time %i for playback: %s\n", buffer_time, snd_strerror(err)); + } + err = snd_pcm_hw_params_get_buffer_size(alsa_hwparams, &size); + if (err < 0) { + esyslog("[dxr3-audio-alsa] Unable to get buffer size for playback: %s\n", snd_strerror(err)); + } + snd_pcm_sframes_t buffer_size = size; + + // set the period time + err = snd_pcm_hw_params_set_period_time_near(handle, alsa_hwparams, &period_time, NULL); + if (err < 0) { + esyslog("[dxr3-audio-alsa] Unable to set period time %i for playback: %s\n", period_time, snd_strerror(err)); + } + err = snd_pcm_hw_params_get_period_size(alsa_hwparams, &size, NULL); + if (err < 0) { + esyslog("[dxr3-audio-alsa] Unable to get period size for playback: %s\n", snd_strerror(err)); } + snd_pcm_sframes_t period_size = size; // set hardware pararmeters err = snd_pcm_hw_params(handle, alsa_hwparams); @@ -137,18 +157,23 @@ void cAudioAlsa::setup(int channels, int samplerate) // // set software settings - err = snd_pcm_sw_params_current(handle, alsa_swparams); if (err < 0) { esyslog("[dxr3-audio-alsa] Cannot get current sw params: %s", snd_strerror(err)); } - static snd_pcm_uframes_t chunk_size = 1024; + // start the transfer when the buffer is almost full: */ + // (buffer_size / avail_min) * avail_min */ + err = snd_pcm_sw_params_set_start_threshold(handle, alsa_swparams, (buffer_size / period_size) * period_size); + if (err < 0) { + esyslog("[dxr3-audio-alsa] Unable to set start threshold mode for playback: %s\n", snd_strerror(err)); + } - // start playing when one period has been written - err = snd_pcm_sw_params_set_start_threshold(handle, alsa_swparams, chunk_size); + // allow the transfer when at least period_size samples can be processed */ + // or disable this mechanism when period event is enabled (aka interrupt like style processing) */ + err = snd_pcm_sw_params_set_avail_min(handle, alsa_swparams, buffer_size); if (err < 0) { - esyslog("[dxr3-audio-alsa] Failed to set chunk_size: %s", snd_strerror(err)); + esyslog("[dxr3-audio-alsa] Unable to set avail min for playback: %s\n", snd_strerror(err)); } snd_pcm_uframes_t boundary; @@ -229,7 +254,15 @@ void cAudioAlsa::write(uchar* data, size_t size) void cAudioAlsa::flush() { - snd_pcm_drop(handle); + int err = snd_pcm_drop(handle); + if (err < 0) { + esyslog("[dxr3-audio-alsa] failed to pcm_drop: %s", snd_strerror(err)); + } + + err = snd_pcm_prepare(handle); + if (err < 0) { + esyslog("[dxr3-audio-alsa] failed to pcm_prepare: %s", snd_strerror(err)); + } } void cAudioAlsa::Xrun() |