Re: [Alsa-devel] Re: ALSA / emu10k1 / SPDIF / surround?

[Lee Revell <rlrevell@joe-job.com>]

On Wed, 2005-08-31 at 02:04 +0200, Thomas Zehetbauer wrote:
> On Mon, 2005-08-29 at 19:08 -0400, Lee Revell wrote:
> > I guess you already looked at Documentation/SB-Live-mixer.txt?
> 
> Sure I have, but I don't think this documentation is correct:
> 
> "Wave (Surround|Center|LFE) Playback Volume" apparently do some kind of
> stereo upmixing. I guess that is why I have seen these controls going to
> zero when using 6 channel output.

Actually the docs are correct:

name='Wave Playback Volume',index=0

This control is used to attenuate samples for left and right PCM FX-bus
accumulators. ALSA uses accumulators 0 and 1 for left and right PCM samples.
The result samples are forwarded to the front DAC PCM slots of the AC97 codec.

name='Wave Surround Playback Volume',index=0

This control is used to attenuate samples for left and right PCM FX-bus
accumulators. ALSA uses accumulators 0 and 1 for left and right PCM samples.
The result samples are forwarded to the rear I2S DACs. These DACs operates
separately (they are not inside the AC97 codec). 

name='Wave Center Playback Volume',index=0

This control is used to attenuate samples for left and right PCM FX-bus
accumulators. ALSA uses accumulators 0 and 1 for left and right PCM samples.
The result is mixed to mono signal (single channel) and forwarded to
the ??rear?? right DAC PCM slot of the AC97 codec.

name='Wave LFE Playback Volume',index=0

This control is used to attenuate samples for left and right PCM FX-bus
accumulators. ALSA uses accumulators 0 and 1 for left and right PCM.
The result is mixed to mono signal (single channel) and forwarded to
the ??rear?? left DAC PCM slot of the AC97 codec.

Lee



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