[MPlayer-users] help with channel manipulation

[Jaume Ferrete]

After writing this email I came up with a solution that I do not truly
understand...

to play file only on left channel I can do:

mplayer file.wav -af channels=2:2:0:0:0:0

...and only on right channel:

mplayer testone.wav -af channels=2:2:0:1:0:1

It is as if the output canNOT be 1 channel? And why two movements
necessarily?

Thanks for helping me understand.

On Mon, Sep 14, 2015 at 10:10 PM Jaume Ferrete <jaume.ferrete at gmail.com>
wrote:

> Hello,
>
> I would like to use mplayer to play mono audio files through selected
> audio output channels.
>
> I.e. on a stereo output device, play a .wav file ONLY through left
> channel, while right channel remains silent; or the other way around.
>
> Ultimately I would like to do this with a 4 channel device (i.e. focusrite
> usb audio interface), selecting which particular channel to output every
> time i play a file.
>
> I've tried to understand channel manipulation from docs, and assumed that
> I could do something like:
>
> mplayer file.wav -af channels=1:1:0:1
>
> ...understanding it as 1 output channel, 1 movement, left channel to right
> channel; and thus getting audio output only from right channel. I am
> attempting to do this with a mono audio file.
>
> the result goes like:
>
> --
> (...)
> [channels] Invalid routing in pair nr. 0. [libaf] Reinitialization did not
> work, audio filter 'channels' returned error code -2 Error at audio filter
> chain pre-init! Exiting... (Fatal error)
> --
>
> Could somebody help me understand, please?
>
> Thank you very much
>
>