[alsa-devel] Record stereo from one input on the soundcard

[Tomas Nordin]

Pavel Hofman <pavel.hofman at ivitera.com> writes:

> Hi Tomas,
>
> Dne 25. 01. 19 v 21:44 Tomas Nordin napsal(a):
>>>
>>> The following command lets me record audio from the card,
>>>
>>> $ arecord -c 2 -d 60 -f S24_3LE -r 48000 -D hw:1,0 s3.wav
>>>
>>> The resulting wav file has all hearable audio in the left speaker when
>>> listening.
>
> If you really feed stereo signal into your soundcard stereo input jack 
> and the card is not somehow configured to merge the input channels, the 
> above command does record stereo signal.

Ok, thanks. I have been a bit confused about the relation between the -c
option argument and the number of inputs on a card. If I understand
correctly, the -c option does not say anything about what inputs to
record from, it is saying what kind of audiofile to produce?

> Available controls of the card are listed by command
>
> amixer -c 1 contents

Here is the output of that:

$ amixer -c 1 contents
numid=2,iface=PCM,name='Capture Channel Map'
  ; type=INTEGER,access=r----R--,values=2,min=0,max=36,step=0
  : values=0,0
  | container
    | chmap-fixed=FL,FR

numid=1,iface=PCM,name='Playback Channel Map'
  ; type=INTEGER,access=r----R--,values=2,min=0,max=36,step=0
  : values=0,0
  | container
    | chmap-fixed=FL,FR

And I didn't mention that in my original post but, alsamixer has been
informing me that "This soundcard does not have any controls." when I
select the AudioBox via F6.

Is this giving any more hints on what I can do?

Best regards
--
Tomas