[linux-audio-user] Disabling Playthrough

[Christoph Eckert]

> My confusion turned out to be with what exactly alsamixer
> does.  I was getting playthrough because the "Mic" device
> was unmuted in the mixer. So alsa was doing the playthrough
> directly.

Well, because alsamixer is a tool which tries to match to all 
cards supported by ALSA, it is sometimes a bit confusing.

But we do not have a better solution; ask your manufacturer to 
write a GPL'ed UI-Mixer for that certain device.

> I somehow had the impression that one used alsa 
> mixer to set the input levels of various devices that were
> available to be opened by software talking to alsa.

What does various devices mean in this case?

> But by 
> experimenting with audacity, I see that with Mic muted in
> alsamixer, audacity is able to get input from the Mic
> device via alsa. Does this imply that ALL input devices
> should be muted in alsamixer and apps are responsible for
> reading from the input?  For example, it seems to not
> matter whether I've muted the CD or not.. AlsaPlayer can
> still play a CD.

I guess that alsaplayer reads the CD and puts it out to PCM. 
The CD channel is if you have a CD inserted and you've 
pressed the play button on the drive. In this case, it 
behaves like a CD player. If it is connected via an extra 
cable to the mainboard, the drive will output the sound 
directly to the soundcard and then adjusting the CD channel 
would make sense.


 Best regards


    ce