[alsa-devel] Fwd: Front speakers doesn't work in multichannel output, regression in ALC888

[Anssi Hannula]

14.05.2015, 09:26, Raymond Yau kirjoitti:
>>>> I started MS Windows and without externals speakers plugged in I
>>>
>>> could test
>>>  > 5.1 configuration and it seemed that sound was coming from
>>> different directions.
>>>
>>>  >
>>>  > What I managed to determine:
>>>  > I've got 3 stacks:
>>>  > 1 ST: Headphone, Line-out (FL and FR), SPDIF
>>>  > 2 ST: Microphone, Line-out (CLFE)
>>>  > 3 ST: Line-in, Line-out (RL and RR)
>>>  >
>>>  > I've got 5 responsive output pins
>>>  > PIN 0x14: Internal FL FR
>>>  > PIN 0x15: External FL FR
>>>  > PIN 0x17: Internal LFE
>>>  > PIN 0x18: External CLFE
>>>  > PIN 0x1a: External RL RR
>>>  >
>>>  > How can we make it work with these information?
> 
> speaker-test -Dhw:0,0 -c6 -t wav
>  
>>>
>>>
>>>
> https://git.kernel.org/cgit/linux/kernel/git/tiwai/sound.git/plain/Documentation/sound/alsa/Channel-Mapping-API.txt
>>> [1]
>>>
>>> seem chnmap type _FIXED , _VAR and _PAIRED does not fit when LFE and
>>> FC can be swapped for internal speaker and external speaker
>>
>>
>> Right, you can't do it with a single map of one of those types.
> 
> http://git.alsa-project.org/?p=alsa-utils.git&a=search&h=HEAD&st=commit&s=chmap
> 
> do chmap of internal speakers need {FL FR RL RR LFE NA} ?

>From above it looks like there are 3 internal speakers, so I guess e.g.
{FL FR LFE NA} might be in order (or just {FL FR LFE} if 3-channel
playback is supported).

> http://git.alsa-project.org/?p=alsa-lib.git&a=search&h=HEAD&st=commit&s=chmap
> 
> as set_chmap() still not yet implemented in pcm_route.c
> 
> do speaker-test need to specify channel map when using those odd number
> channels ?
> 
> speaker-test -D surround21  -c3 -t wav
> speaker-test -D surround41  -c5 -t wav -mFL,FR,RL,RR,LFE
> speaker-test -D surround50  -c5 -t wav

Well, the driver should provide the correct chmap.

> http://git.alsa-project.org/?p=alsa-utils.git;a=commitdiff;h=7b14c00b56784f69ecc954a2de36e0a058fc8849;hp=000bf230cfb3b0abe88d27701dd77982675126ec
> 
> this example seem not working
> 
> speaker-test -c2 -t wav -Dplug:front -mFR,FL

You are getting an error?
If so, that is expected if the underlying device does not support the
wanted channel map.

>>
>>
>>>
> https://git.kernel.org/cgit/linux/kernel/git/tiwai/sound.git/commit/sound/pci/hda?id=0fb87bb474f978446786263deff6263284e6e011
>>> [2]
>>>
>>> How do the driver implement channel map when codec has  swap
>>> center/lfe switch ?
>>>
>>> Do chmap contain both {FL FR RL RR FC LFE} and {FL FR RL RR LFE FC} ?
>>
>>
>> If you want to provide support for userspace doing it both ways, then
> yes, you need those two _FIXED maps.
> 
> Can chmap contain two _FIXED maps of same number of channels ?

Sure.

-- 
Anssi Hannula