[pulseaudio-discuss] [PATCH] alsa-mixer: Take channel mask of volume element into account when finding a subset path

[Tanu Kaskinen]

On Mon, 2011-10-24 at 22:29 +0300, Tanu Kaskinen wrote:
> On Wed, 2011-10-19 at 20:47 +0200, Maarten Bosmans wrote:
> > The patch looks simple, but I'm not entirely sure the concept is
> > sound. Please review.
> > 
> > The problem I'm trying to solve is that analog-output-mono is (in my
> > view incorrectly) seen as a subset of analog-output-lfe-on-mono.
> 
> The patch might very well be correct, but I'm having hard time proving
> it to myself.
> 
> There might be another bug in the alsa mixer system, and fixing that
> probably would solve the particular issue that you are seeing. For the
> lfe-on-mono path to make any sense, it looks to me like the sink should
> have at least one channel dedicated for lfe. Otherwise the Master Mono
> element will always have its volume set to the maximum of all of the
> sink channels, and I think this is equivalent to having override-map.1 =
> all, and I believe that defeats the purpose of the lfe-on-mono path.
> 
> So, maybe it should be possible to say in the path configuration that
> "this path requires the sink to have lfe in its channel map". If the
> condition isn't met, the path will not be available.

Actually, if my reasoning above makes sense, there's no need to
implement anything. Just remove the lfe-on-mono path from the mappings
in profile-sets/default.conf that don't have lfe in their channel map.

Can someone say why lfe-on-mono would be needed on mappings without
separate lfe channel?

-- 
Tanu