[alsa-devel] wrong decibel data?

Colin Guthrie gmane at colin.guthr.ie
Wed Jun 23 11:12:00 CEST 2010

'Twas brillig, and Raymond Yau at 23/06/10 02:15 did gyre and gimble:
> why PA server still insist to open front device for capturing ?

Couldn't tell you. Perhaps Lennart is unaware that it is considered
invalid? I'll ask him.

> http://thread.gmane.org/gmane.linux.alsa.devel/67912/focus=68248
> As Takashi had already mention that
> "I agree that the capture from "front" PCM isn't considered as valid.
> The "front", "rear", "center_lfe" definitions are rather for multi-channel
> playbacks. The capture on these channels aren't useful in most cases."
> you can perform an experiement
> pcm.test {
>     type softvol
>     slave.pcm "hw:0,0"
>     control {
>         name "PA Playback Volume"
>         card 0
>     }
> arecord -D test -f CD -d 10 -v test.wav
> you will find "PA Playback Volume" in playback screen of alsamixer
> I am not sure the softvol control created when PA open front device
> for playback and capture is used for playback or capture
> BTW , PA still using "front" to open CTL device too

You'll have to ask Lennart directly about that bit.

I can't speak for him with regards to the full setup of the mixer path
probing stuff, so perhaps "front" should be edited out of this for
paths. It would likely be a fairly trivial change to configuration files
rather than any code changes.



Colin Guthrie

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