[pulseaudio-discuss] [PATCH] alsa: Remove four channel input profile

[David Henningsson]

On 2014-08-07 13:18, Tanu Kaskinen wrote:
> On Fri, 2014-08-01 at 18:13 +0200, David Henningsson wrote:
>> With the new multichannel profile, we can remove this one and
>> handle the four channel input as a generic multichannel fallback.
>
> I believe the generic fallback initializes the channel map to a surround
> channel map that doesn't really make sense. Maybe we should modify the
> fallback channel map logic so that if it's an input device, use stereo
> map if the device is a stereo device, but otherwise use an aux-only
> channel map.

I think a surround channel map makes a lot more sense than an aux-only 
channel map. Most apps do a simple stereo recording, and AFAIK they will 
just record silence instead of recording the first two channels, if the 
channel map is aux-only.

So this patch is improving the OOTB experience for those devices.

If that didn't convince you, consider the fact that an app calling e g 
pa_simple_new() without specifying a channel map, will get a surround 
mapping by default, regardless of direction. I e, anything else than a 
surround mapping on the device level causes a mismatch.

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