Re: Multichannel audio playback
On Wed, Apr 28, 2021 at 06:21:27PM +0000, Rodolfo Medina wrote:
> Joel Roth <joelz@pobox.com> writes:
>
> > I don't think there is a problem with ecasound.
> > For comparison, you can try
> >
> > aplay -D <devicename> test.wav
> >
> > You get the device name from aplay -L.
> > Please also show the output from
> >
> > cat /proc/asound/cards
> >
> > With your ecasound examples, the -a argument is not necessary, and
> > selecting channels is not its purpose.
>
>
> Now it works:
>
>
> $ ecasound -a:1,2,3 -i:sndfile,3canali.wav -o alsaplugin,2,0
> **************************************************************************
> * ecasound v2.9.1 (C) 1997-2014 Kai Vehmanen and others
> **************************************************************************
> (eca-chainsetup) Chainsetup "untitled-chainsetup"
> (eca-chainsetup) NOTE: Real-time configuration, but insufficient privileges
> ... to utilize real-time scheduling (SCHED_FIFO). With small buffersizes,
> ... this may cause audible glitches during processing.
> (eca-chainsetup) "rt" buffering mode selected.
> (audioio_sndfile) Using libsndfile to open file "3canali.wav" for reading.
> (eca-chainsetup) NOTE: using existing audio parameters -f:s16_le,3,48000
> ... for object 'sndfile' (tried to open with -f:s16_le,2,44100).
> (eca-chainsetup) Opened input "sndfile", mode "read". Format: s16_le,
> ... channels 3, srate 48000, interleaved (locked params).
> (eca-chainsetup) Opened output "alsaplugin", mode "write". Format: s16_le,
> ... channels 2, srate 48000, interleaved.
> - [ Connected chainsetup: "untitled-chainsetup" ] ------------------------
> - [ Controller/Starting batch processing ] -------------------------------
> - [ Engine - Driver start ] ----------------------------------------------
>
> - [ Engine - Processing finished ] ---------------------------------------
> - [ Controller/Batch processing finished (0) ] ---------------------------
> - [ Controller/Processing stopped (cond) ] -------------------------------
> - [ Engine exiting ] -----------------------------------------------------
> (eca-control-objects) Disconnecting chainsetup: "untitled-chainsetup".
>
>
> So we could consider problem 1) solved.
>
> Let's try to go to problem 2). The above command properly sends channel 1 to
> loudspeaker 1 and channel 2 to loudspeaker 2, but it doesn't manage to send
> channel 3 into loudspeaker 3. Actually, the Behringer seems to behave in
> stereo mode. But the strange thing is that outputs `B' (i.e. 3 and 4) do not
> work at all and seems to be dead. So please help: how can I - if ever possible
> - send channel 3 to loudspeaker 3? And, more in general: is it possible, even
> with some other device, to achive what I want?
The soundcard capabilities that linux sees are documented
in the /proc/asound filesystem. That's worth investigating.
Here's one reference to what you can find there:
https://www.ti.com/lit/an/sprac10/sprac10.pdf
Another helpful source for guidance would be the Linux Audio
Users mailing list, with many knowledgeable and helpful
members.
cheers
> Thanks,
>
> Rodolfo
>
--
Joel Roth
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