Re: [ecasound] problems with the loop device and changing formats

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Subject: Re: [ecasound] problems with the loop device and changing formats
From: Kai Vehmanen (k_AT_eca.cx)
Date: Wed Oct 31 2001 - 01:44:03 EET


On Tue, 30 Oct 2001, Jeremy Hall wrote:

> I tried the following chain setup file
[...]
> # chain operators and controllers
> -a:1 -^erc$:1.00,2.00
> -a:2 -^epp$:0.00
> -a:3 -^erc$:1.00,2.00 -^epp$:100.00
> -a:4 -el:freeverb3,0.00,0.90,0.80,0.08,0.50,1.00 -^ea$:55.00
> -a:5 -el:freeverb3,0.00,0.80,0.25,0.17,1.00,1.00

Btw; this bug (regexp-strings were saved to chainsetup files) is now fixed
in CVS.

> now when I start this, it produces noise! I have determined it is the
> freeverb's that is doing the noise. I first have to start ecasound
> rolling, THEN add them. When I start ecasound rolling, I get a burst of
> noise, probably because the loop devices aren't initialized properly, then
> I get recognizable sound...but only out of the left channel.

There's so many things happening here that it's difficult to say what is
causing trouble. I managed to get the above chainsetup working on my
machine. I did get the additional noise you mention. This is now fixed in
CVS. Freeverb didn't make the problems worse for me.

Can you possibly trigger these problems with smaller setups. At least
the following params make debugging difficult:
- with / without effects
- non-standard / standard srate
- loop-devices in setup
- only mono / only n-channels / mixed setup
- ... and so on

If you can isolate the problem with the above criteria (ie. enabling
effect x triggers the problem), finding the cause gets much, much easier.

> if I put all that crap on the command line and output to alsa,dsp1, all is
> lovely (minus the freeverb of course) and then if I try to write to a wav
> file, not only does the wav file run off the end of the session, but it
> sounds quite dithered or processed, as if the wrong sample rate was used
> internally somewhere.

The first problem - setups with loop-devices never end - is a known
one. I'll try to take a look at it later today. As for the dithering,
after the chainsetup is loaded, check 'aio-status' and verify that all
files and devices have the correct sample-rate (48000 in this case).

-- 
 http://www.eca.cx
 Audio software for Linux!

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