[alsa-devel] PCM extra attributes

[Jaroslav Kysela]

Date 24.7.2013 19:09, Vinod Koul wrote:
> Hey Takashi,
> 
> We were looking to find the substream index in the userspace for the device
> opened (in case we support multiple substreams and mix them). Since we also
> wanted to have some specific alsa controls for each substream the problem of not
> knowing substream in usermode make stuff interesting!

The substream/subdevice index is in the snd_pcm_info field, so you can
correlate the PCM with the controls from the control API.

snd_pcm_info_get_subdevice()

					Jaroslav

-- 
Jaroslav Kysela <perex at perex.cz>
Linux Kernel Sound Maintainer
ALSA Project; Red Hat, Inc.