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

[Tom Yan]

I have to admit that the surround60/surround61
[FL+FR+RL+RR(+LFE)+SL+SR] I mentioned probably never existed. And it
SEEMS that surround21 is particularly needed by some laptops with LFE
speaker.

On 16 January 2016 at 22:24, Tom Yan <tom.ty89 at gmail.com> wrote:
> 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.