[alsa-devel] capture line-out

Rene Herman rene.herman at gmail.com
Tue Mar 27 12:06:48 CEST 2007

On 03/27/2007 03:18 AM, Tomas Carnecky wrote:

> If I understood you correctly, you suggest to 'hook' functions and
> intercept the sound data before it's sent to the hardware, correct?

I must say I wasn't suggesting much of anything really. Was just 
wondering, a little, what Windows was doing...

The output mixer (that which the "Mix" capture source grabs the output 
of) is about mixing analog inputs (mic, line in, aux in, ...) in with 
the output from the chip's DAC and those analog inputs aren't "sent to 
the hardware" so hooking the API wouldn't be of help with those.

If you'd be satisfied with only the "PCM source" then yes, you could 
hook the API for that and let the mixer just capture the mic. Would get 
you better quality. The Mix capture source for PCM will go:

Software -> Chip -> DAC -> Output Mixer -> Input Mixer -> ADC -> Chip -> 

which sort of has one scratch one's head when no mixing in of analog 
sources is desired.

In the absence of hardware support for multiple capture sources, I don't 
have any bright ideas about grabbing both "that which the user hears" 
and the microphine idependently...


> A better solution would be to temporarily switch the capture device to
> 'Mic' before the user enables capturing in TeamSpeak (usually using a
> hotkey) and starts speaking and set it back to 'Mix' after he finishes.

If that works for you, great :)


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