Re: [ecasound] 'circular' use of loop devices?

From: Kai Vehmanen <kvehmanen@email-addr-hidden>
Date: Sat Apr 14 2012 - 16:52:27 EEST


On Sat, 14 Apr 2012, James Mckernon wrote:

> I'm trying to experiment with some experimental effects paths within
> ecasound - in particular, ones that involve 'circular' chains, whose
> input and output are the same loop device. I'm thinking something along
> the lines of the following:
> ecasound -a:1 -i:input.mp3 -o:loop,1 -a:2 -i:loop,1 -o:alsa -a:3 -i:loop,1 [some_effects_here] -o:loop,1

When ecasound processes this, when it reaches "-a:3 -i:loop,1", it
connects "loop,1" only to chain 3 and not anymore to 1, and this causes
the error messages below (no input for chain 1).

So when you want to connect an input/output to multiple chains, you have
to do it like this:

  ecasound -a:1 -i input.mp3 -a:1,3 -o:loop,1 -a:2,3 -i:loop,1 -a:2 -o:alsa -a:3 [some_effects_here]

But this is probably not quite what you are looking for, as each hop from
a loop output to its input, causes an additional delay of one engine
iteration (equivalent to -b:size, e.g. -b:1024@email-addr-hidden -> delay of
~23.2ms). You can modify the delay by setting -b:xxx to different values,
but this is a bit clumsy and may have side-effects to e.g. overall
performance (low buffersize values increase engine overhead).

> Funnily enough, the closely related setup,
> ecasound -a:1 -i:input.mp3 -o:loop,1 -a:2 -i:loop,1 -o:alsa -a:3 -i:loop,2 [some_effects_here] -o:loop,2
> seems to instantiate without any problems.

Yep, so here "loop,1" and "loop,2" are considered separate objects, so the
above error doesn't happen (each chain has an input and an output defined

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Received on Sat Apr 14 20:15:01 2012

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