[pulseaudio-discuss] alsa: split up 6-channel streams into 3 stereo pairs?

[David Henningsson]

On 11/16/2011 12:19 PM, Daniel Mack wrote:
> On 11/14/2011 08:27 PM, Tanu Kaskinen wrote:
>> On Sat, 2011-11-12 at 17:14 +0100, Daniel Mack wrote:
>>> A 6-channel audio device I wrote support announces a single ALSA
>>> subdevice that has to be opened as a whole in order to access all six
>>> channels. However, I would like to offer the channels as three pairs of
>>> stereo (for both directions), so stereo clients can be routed to each of
>>> them individually.
>>>
>>>  From what I saw in the alsa-mixer module code, there is no way to
>>> specify such things of settings in the profile-sets, right? Are there
>>> any plans to support these kind of setups?
>>
>> So even if the card would be used as three stereo pairs, Pulseaudio
>> would still have to open the device with six channels, right?
>
> Exactly. All other attempts to open the pcm will fail.

For the record, ICE1712 cards have the same problem (can only open with 
10 output channels and 12 input channels), so PulseAudio in general 
failed to open them. I resolved that with this alsa-lib patch:

http://git.alsa-project.org/?p=alsa-lib.git;a=commitdiff;h=d3906a93072171e5b5f4000d4a228af4eb8fa253

-- 
David Henningsson, Canonical Ltd.
http://launchpad.net/~diwic