Subject: Re: [ecasound] the -ev option in ecasound
From: Kai Vehmanen (kaiv@wakkanet.fi)
Date: Fri Feb 25 2000 - 15:15:40 EET
On Thu, 24 Feb 2000, Christopher Taylor wrote:
> -ev Analyze sample data to find out how much the signal
> can be amplified without clipping. The resulting
> percent value can be used as a parameter to -ea and
[...]
> Well, I've spent a couple of hours looking at examples and trying things
> and I don't see how I can use the -ev option to use the resulting percent
> value as a parameter to -eas. How would that be done?
Ok...: "ecasound -i input -o input -ev" ... and when the processing
ends, you get following:
--cut--
...
(audiofx) -- End of statistics (counters reseted)--
(audiofx) Max amplitude 0.94858; signal can be amplified by 105.42097%.
--cut--
105.42097%, is the percent value you need. You can also get this in
interactive mode with the "cop-status" command. The problem is that
you can't do normalization in one phase (--> ecatools_normalize is
just for this).
> My solution: pipe everything through compression and normalization filters.
> Is this the correct approach? Any help on this process and how it can be
> accomplished with ecasound is greatly appreciated. I noticed that there the
> ecatools_normalize tool exists for normalization, but it seems to me that a
> simple normalization step isn't going to assure consistent levels. I
> believe a compression step is necessary to acomplish consistent levels...
Yes, this is the right approach. Unfortunately ecasound doesn't yet offer
an easy way to do it. I've been thinking about coding another ecatools
program for doing combined compression+normalizion (I really need this
myself, too), but so far I haven't had the time. Anyway, the
"-eca" compressor is rather good, so it's a good starting point. You
should find a good set of -eca parameters (see ecasound(1) man page) and
use a combination "ecasound -eca:blaa,baaa .." + ecatools_normalize
(peak normalization) in your batches. I'm interested in hearing how this
works.
-- Kai Vehmanen <kaiv@wakkanet.fi> -------- CS, University of Turku, Finland . http://www.wakkanet.fi/ecasound/ - linux multitrack audio processing . http://www.wakkanet.fi/sculpscape/ - ambient-idm-rock-... mp3/ra/wav
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