[alsa-devel] Only one element for multichannel mixer controls please!

Takashi Iwai tiwai at suse.de
Mon Oct 27 09:19:56 CET 2008

At Sat, 25 Oct 2008 01:49:33 +0200,
Lennart Poettering wrote:
> Heya!
> It seems that quite a few ALSA drivers for multichannel sound cards
> export three seperate stereo mixer controls to control front, rear and
> center/lfe independantly. That sucks because a client (such as
> PulseAudio) cannot make use of this. Instead they should export a
> single 6ch mixer control!

Depends.  For casual users, left/right and rear left/right grouping
is more natural way than all separated mixer controls.

> The "amixer scontents" output looks very strange for these drivers
> since it lists a "Rear" control that as a "Front Left" and a "Front
> Right" channel. So, what is it now: front or rear?
> Is there any reason for this current driver behaviour? I mean, the
> mixer knows channel ids like SND_MIXER_SCHN_REAR_LEFT perfectly
> well. Or is it that those devices have some devices joined and this
> cannot be expressd with a single boolean "joined" for each
> control?

All these are about the channel abstrcation.
And, the current smixer abstraction sucks.  Really.


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