[linux-audio-user] mono to stereo input in ALSA

Florian Schmidt mista.tapas at gmx.net
Sun Mar 19 10:25:51 EST 2006

On Sun, 19 Mar 2006 09:15:47 -0500
Ken Schutte <kschutte at csail.mit.edu> wrote:

> I've used qjackctl, but I thought there might be a way to do it at a 
> lower level.  Because, in qjackctl Connections, if I have no connections 
> set, I still hear the mono line-in coming directly out the left output. 
>   If I then connect alsa_pcm:capture_1 to alsa_pcm:playback_1 and 
> playback_2, this seems to add extra connections, and sounds like it's a 
> bit like a chorus effect.
> Or maybe there is a way to turn off the "automatic throughput", so only 
> the connections I see in qjackctl are actually made?

Pretty much any soundcard has an analog mixer on board. In your case,
the line in is routed to the line out by way of this analog mixer. In
alsamixer, on the playback page, pull down line in. The volume on the
record page (toggle with F3/F4) determines how much signal is going to
the ADC.


Palimm Palimm!

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