Re: [Alsa-devel] Re: [Alsa-user] ALSA / emu10k1 / SPDIF / surround?
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From: Lee R. <rlr...@jo...> - 2005-08-31 00:26:28
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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 |