GstCaps *
gst_alsa_probe_supported_formats (GstObject * obj, gchar * device,
snd_pcm_t * handle, const GstCaps * template_caps)
{
snd_pcm_hw_params_t *hw_params;
snd_pcm_stream_t stream_type;
GstCaps *caps;
gint err;
snd_pcm_hw_params_malloc (&hw_params);
if ((err = snd_pcm_hw_params_any (handle, hw_params)) < 0)
goto error;
stream_type = snd_pcm_stream (handle);
caps = gst_caps_copy (template_caps);
if (!(caps = gst_alsa_detect_formats (obj, hw_params, caps)))
goto subroutine_error;
if (!(caps = gst_alsa_detect_rates (obj, hw_params, caps)))
goto subroutine_error;
if (!(caps = gst_alsa_detect_channels (obj, hw_params, caps)))
goto subroutine_error;
/* Try opening IEC958 device to see if we can support that format (playback
* only for now but we could add SPDIF capture later) */
if (stream_type == SND_PCM_STREAM_PLAYBACK) {
snd_pcm_t *pcm = gst_alsa_open_iec958_pcm (obj, device);
if (G_LIKELY (pcm)) {
gst_caps_append (caps, gst_caps_from_string (PASSTHROUGH_CAPS));
snd_pcm_close (pcm);
}
}
snd_pcm_hw_params_free (hw_params);
return caps;
/* ERRORS */
error:
{
GST_ERROR_OBJECT (obj, "failed to query formats: %s", snd_strerror (err));
snd_pcm_hw_params_free (hw_params);
return NULL;
}
subroutine_error:
{
GST_ERROR_OBJECT (obj, "failed to query formats");
snd_pcm_hw_params_free (hw_params);
return NULL;
}
}
/**************************************************************************
* wine_snd_pcm_recover [internal]
*
* Code slightly modified from alsa-lib v1.0.23 snd_pcm_recover implementation.
* used to recover from XRUN errors (buffer underflow/overflow)
*/
int wine_snd_pcm_recover(snd_pcm_t *pcm, int err, int silent)
{
if (err > 0)
err = -err;
if (err == -EINTR) /* nothing to do, continue */
return 0;
if (err == -EPIPE) {
const char *s;
if (snd_pcm_stream(pcm) == SND_PCM_STREAM_PLAYBACK)
s = "underrun";
else
s = "overrun";
if (!silent)
ERR("%s occurred\n", s);
err = snd_pcm_prepare(pcm);
if (err < 0) {
ERR("cannot recover from %s, prepare failed: %s\n", s, snd_strerror(err));
return err;
}
return 0;
}
if (err == -ESTRPIPE) {
while ((err = snd_pcm_resume(pcm)) == -EAGAIN)
/* wait until suspend flag is released */
poll(NULL, 0, 1000);
if (err < 0) {
err = snd_pcm_prepare(pcm);
if (err < 0) {
ERR("cannot recover from suspend, prepare failed: %s\n", snd_strerror(err));
return err;
}
}
return 0;
}
return err;
}
bool AlsaLayer::alsa_set_params(snd_pcm_t *pcm_handle)
{
#define TRY(call, error) do { \
if (ALSA_CALL(call, error) < 0) \
return false; \
} while(0)
snd_pcm_hw_params_t *hwparams;
snd_pcm_hw_params_alloca(&hwparams);
const unsigned SFL_ALSA_PERIOD_SIZE = 160;
const unsigned SFL_ALSA_NB_PERIOD = 8;
const unsigned SFL_ALSA_BUFFER_SIZE = SFL_ALSA_PERIOD_SIZE * SFL_ALSA_NB_PERIOD;
snd_pcm_uframes_t period_size = SFL_ALSA_PERIOD_SIZE;
snd_pcm_uframes_t buffer_size = SFL_ALSA_BUFFER_SIZE;
unsigned int periods = SFL_ALSA_NB_PERIOD;
snd_pcm_uframes_t period_size_min = 0;
snd_pcm_uframes_t period_size_max = 0;
snd_pcm_uframes_t buffer_size_min = 0;
snd_pcm_uframes_t buffer_size_max = 0;
#define HW pcm_handle, hwparams /* hardware parameters */
TRY(snd_pcm_hw_params_any(HW), "hwparams init");
TRY(snd_pcm_hw_params_set_access(HW, SND_PCM_ACCESS_RW_INTERLEAVED), "access type");
TRY(snd_pcm_hw_params_set_format(HW, SND_PCM_FORMAT_S16_LE), "sample format");
TRY(snd_pcm_hw_params_set_rate_resample(HW, 0), "hardware sample rate"); /* prevent software resampling */
TRY(snd_pcm_hw_params_set_rate_near(HW, &audioFormat_.sample_rate, nullptr), "sample rate");
// TODO: use snd_pcm_query_chmaps or similar to get hardware channel num
audioFormat_.nb_channels = 2;
TRY(snd_pcm_hw_params_set_channels_near(HW, &audioFormat_.nb_channels), "channel count");
snd_pcm_hw_params_get_buffer_size_min(hwparams, &buffer_size_min);
snd_pcm_hw_params_get_buffer_size_max(hwparams, &buffer_size_max);
snd_pcm_hw_params_get_period_size_min(hwparams, &period_size_min, nullptr);
snd_pcm_hw_params_get_period_size_max(hwparams, &period_size_max, nullptr);
DEBUG("Buffer size range from %lu to %lu", buffer_size_min, buffer_size_max);
DEBUG("Period size range from %lu to %lu", period_size_min, period_size_max);
buffer_size = buffer_size > buffer_size_max ? buffer_size_max : buffer_size;
buffer_size = buffer_size < buffer_size_min ? buffer_size_min : buffer_size;
period_size = period_size > period_size_max ? period_size_max : period_size;
period_size = period_size < period_size_min ? period_size_min : period_size;
TRY(snd_pcm_hw_params_set_buffer_size_near(HW, &buffer_size), "Unable to set buffer size for playback");
TRY(snd_pcm_hw_params_set_period_size_near(HW, &period_size, nullptr), "Unable to set period size for playback");
TRY(snd_pcm_hw_params_set_periods_near(HW, &periods, nullptr), "Unable to set number of periods for playback");
TRY(snd_pcm_hw_params(HW), "hwparams");
snd_pcm_hw_params_get_buffer_size(hwparams, &buffer_size);
snd_pcm_hw_params_get_period_size(hwparams, &period_size, nullptr);
snd_pcm_hw_params_get_rate(hwparams, &audioFormat_.sample_rate, nullptr);
snd_pcm_hw_params_get_channels(hwparams, &audioFormat_.nb_channels);
DEBUG("Was set period_size = %lu", period_size);
DEBUG("Was set buffer_size = %lu", buffer_size);
if (2 * period_size > buffer_size) {
ERROR("buffer to small, could not use");
return false;
}
#undef HW
DEBUG("%s using format %s",
(snd_pcm_stream(pcm_handle) == SND_PCM_STREAM_PLAYBACK) ? "playback" : "capture",
audioFormat_.toString().c_str() );
snd_pcm_sw_params_t *swparams = NULL;
snd_pcm_sw_params_alloca(&swparams);
#define SW pcm_handle, swparams /* software parameters */
snd_pcm_sw_params_current(SW);
TRY(snd_pcm_sw_params_set_start_threshold(SW, period_size * 2), "start threshold");
TRY(snd_pcm_sw_params(SW), "sw parameters");
#undef SW
return true;
#undef TRY
}
