[alsa-devel] Should we get rid of {surround21/surround41/surround50}.conf from alsa-lib?

[Tom Yan]

By the way,

[tom at localhost ~]$ diff <(grep surround41.conf
/usr/share/alsa/cards/*.conf | cut -d ":" -f 1) <(grep surround50.conf
/usr/share/alsa/cards/*.conf | cut -d ":" -f 1)
[tom at localhost ~]$ diff <(grep surround41.conf
/usr/share/alsa/cards/*.conf | cut -d ":" -f 1) <(grep surround21.conf
/usr/share/alsa/cards/*.conf | cut -d ":" -f 1)
12d11
< /usr/share/alsa/cards/Echo_Echo3G.conf
[tom at localhost ~]$

On 16 January 2016 at 22:09, Tom Yan <tom.ty89 at gmail.com> wrote:
> What I mean is, should we really by default set up PCMs that provide a
> SUBSET of POSSIBLE channel configurations that IS BUILT and RELYS ON
> ttable?
>
> [tom at localhost ~]$ grep ttable /usr/share/alsa/pcm/surround*
> /usr/share/alsa/pcm/surround21.conf:    ttable.0.FL 1
> /usr/share/alsa/pcm/surround21.conf:    ttable.1.FR 1
> /usr/share/alsa/pcm/surround21.conf:    ttable.2.LFE 1
> /usr/share/alsa/pcm/surround41.conf:    ttable.0.FL 1
> /usr/share/alsa/pcm/surround41.conf:    ttable.1.FR 1
> /usr/share/alsa/pcm/surround41.conf:    ttable.2.RL 1
> /usr/share/alsa/pcm/surround41.conf:    ttable.3.RR 1
> /usr/share/alsa/pcm/surround41.conf:    ttable.4.LFE 1
> /usr/share/alsa/pcm/surround50.conf:    ttable.0.FL 1
> /usr/share/alsa/pcm/surround50.conf:    ttable.1.FR 1
> /usr/share/alsa/pcm/surround50.conf:    ttable.2.RL 1
> /usr/share/alsa/pcm/surround50.conf:    ttable.3.RR 1
> /usr/share/alsa/pcm/surround50.conf:    ttable.4.FC 1
>
> If we are really gonna provide them, why only these 3? What about:
> surround30 (surround51 - RL - RR - LFE)
> surround31 (surround51 - RL - RR)
> surround60 (surround71 - FC - LFE, corresponds to surround40)
> surround61 (surround71 - FC, corresponds to surround41)
> surround70 (surround71 - LFE, corresponds to surround 50)
>
> surround30 more or less corresponds to surround50 as well, and
> surround31 doesn't even have the weirdness of using only either one
> channel in the C/Sub port like the others.