2010/8/31 Stephen Warren swarren@nvidia.com
Takashi Iwai wrote:
Unfortunately, it doesn't look like it's possible for applications to
query
this information from ALSA, since a hw_params_t exposes just a min/max channel count rather than a mask.
It can be also masked.
Are you saying the APIs already support a mask for channel count, and I just didn't find it, or that the APIUs should be updated to report a mask?
Thanks.
you can find the examples in intel8x0.c
static unsigned int channels2and8[] = { 2, 8, };
static struct snd_pcm_hw_constraint_list hw_constraints_channels2and8 = { .count = ARRAY_SIZE(channels2and8), .list = channels8, .mask = 0, };
runtime->hw.channels_max = 8; snd_pcm_hw_constraint_list(runtime, 0, SNDRV_PCM_HW_PARAM_CHANNELS, &hw_constraints_channels2and8);
The ALSA application need to snd_pcm_hw_params_test_channels() to find the supported channel one by one