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

[Tanu Kaskinen]

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.

-- 
Tanu