Subject: Re: [ecasound] Ecasound multitrack recording
From: Kai Vehmanen (k_AT_eca.cx)
Date: Tue Mar 04 2003 - 22:30:37 EET
On Sun, 2 Mar 2003, Julien Patrick Claassen wrote:
> I'm using a m-audio delta 1010lt soundcard and would like to do a
> multitrackrecording. Consider the foloowing idea:
> I wanna record guitar and keyboard at the same time. But I want to store the
> results of those instruments in different files, so I can postprocess them
There are basicly two ways to solve this:
1. Route the channels to multiple chains
Route the 12 channels coming from the delta1010lt to multiple
ecasound chains, and use the -erc and -eac operators
to copy the channels so that the channel you are interested
will be the first channel and others are muted. This is usable
for <4ch setups, not so nice for otherwise (with hammerfall
or delta66/delta1010).
ecasound -a:1,2 -f:16,4,44100 -i alsa,default \
-a:1 -f:12,2,44100 -o foo.wav -erc:3,1 -erc:4,2 \
-a:2 -f:12,2,44100 -o bar.wav
... what happens it that both chains '1' and '2' get data from all the
four input channels. As both 'foo.wav' and 'bar.wav' are stereo file, only
the first two channels will be written to them. So to achieve the wanted
result, we need to copy channels 3&4 to 1&2 in one of the chains. In this
case we added the -erc operators to chain '1'. This works, but obviously
doesn't scale well to +4ch scenarios.
2. Use JACK
This is much more flexible and scale even to very high channel counts.
A simple example
ecasound -a:1 -f:32,2,44100 -i jack \
-a:2 -f:32,8,44100 -i jack \
-a:3 -f:32,1,44100 -i jack \
-a:4 -f:32,1,44100 -i jack \
-a:1,2,3,4 -o null -c
When you connect this, ecasound will register 12 JACK input ports
(ecasound:in_1 -> ecasound:in_12). First two will be routed to chain '1',
the next four to '2' and the last two to mono chains '3' and '4'. In other
words you can group the channels and chains in any way you want without
any performance penalty.
(3. ALSA PCM plugins)
I'm not 100% sure of this, but you should be able to access individual
channels (or stereo-pairs) of multichannel cards using the ALSA share
PCM-plugin. I haven't used this myself, so I can't give better
instructions.
-- http://www.eca.cx Audio software for Linux!
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