Re: Multichannel audio listening (was: Live recording)

[Joel Roth <joelz@pobox.com>]

On Mon, Mar 05, 2018 at 10:39:19AM +0100, Rodolfo Medina wrote:
> Hi all.
> 
> After learning, some months ago, thanks to listers' help, how to live record
> into a multi channel audio file, I was wondering about the reverse problem: now
> I have my multi channel audio file, e.g. composed by three different channels.
> Is it possibile (I guess it is), and how?, to send each of the three outputs
> into a different loud speaker and so listen to the song...?
> 

Hi Rodolfo,

Ecasound is pretty convenient for routing audio.

If you connect three powered speakers to the first three
channels of a (sufficiently capable) soundcard and you're
using ALSA (the default low-level linux audio API), it's
pretty simple:

For example,

ecasound -i:3ch.wav -f:16,3,44100 -o:alsa,default
 
If you need to fool around with the routing, you can do
almost anything. For example, assuming  you have an
8-channel soundcard and want to route ch1 to ch5, ch2 to ch6
and ch3 to ch7:

ecasound -i:3ch.wav \
-f:16,8,44100  \
-chmove:1,5 \
-chmove:2,6 \
-chmove:3,7 \
-o:alsa,default

Maybe you need to add separate effects (e.g. volume control) to each channel:

ecasound \
-a:in -i:3ch.wav -o:loop,3ch \
-a:ch1,ch2,ch3 -i:loop,3ch \
-a:ch1 -chmove:1,5 -ea:80 \
-a:ch2 -chmove:2,6 -ea:70 \
-a:ch3 -chmove:3,7 -ea:60 \
-a:ch1,ch2,ch3 -f:16,8,44100 -o:alsa,default

There's a lot more you can do with ecasound, and there are
various front ends that provide a higher level of
abstraction.

Hope this helps,

> I hope I was clear enough...

> Thanks for any help.
> 
> Rodolfo
> 

-- 
Joel Roth