Re: [ecasound] reverbs

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Subject: Re: [ecasound] reverbs
From: Kai Vehmanen (
Date: Wed Sep 15 1999 - 11:17:04 EEST

On Sat, 11 Sep 1999, Jeremy Hall wrote:

> -efh and -efl: they may not be doing the right thing
> -efh:1000 -efl:1000 does not produce silence. It should, or in the least
> should produce an extremely narrow frequency set on 1000hz. --efh:1000

Well, they actually do the right thing (filter low and high
frequencies) but not with enough precision. It would be interesting
to test all ecasound's filters to see just how accurate they are.
Of course, accurarate filters need more computational power, so
although new filters might be added, -efh and efl are still useful.

> -efi: appears to do something interesting if one plays with the numbers,
> but the effect is not quantifyable, meaning, it is difficult to predict
> what setting the value is going to do, mainly because I do not fully
> understand the effect.

Yep, you have to understand the theory behind this. A good example
of values is "-efi:8,0.999". This divides the whole frequency
range into 8 subsections. Frequencies "in the middle" of the
subsections are passed through untouched while frequencies
near subsection bounds are more or less filtered out. Oh well,
not a very good explanation...

> -gc: works fine
> -ge: I could not get this to work, it complained of argument problems.

Tested with 1.5.12r6 and both worked fine.

> -kos: OH WIERD!
> ecasound -i /tmp/in.raw -ef3:800,1.5,0.9 -c -kos:1,400,4200,0.2,0
> -kos:2,0.1,1.5,0.15,0
> Clearly this wants more explanation so the full potential is realized. (I
> realize documentation isn't everybody's favourite task)

Currently the most important piece of documentation is the "Examples"
page (

Kai Vehmanen <> -------- CS, University of Turku, Finland
 . - linux audio processing
 . - ambient-idm-rock-... mp3/ra/wav

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