[ecasound] Re: frequency equalisation (fwd)

[Kai V. <kve...@ec...>]

I thought that this might of general interest:

---------- Forwarded message ----------
Date: Thu, 23 Dec 2004 12:08:02 +0200 (EET)
From: Kai Vehmanen <kve...@ec...>
To: Anonymous Ecasound-User 

Hi,

On Thu, 23 Dec 2004, Anonymous Ecasound-User wrote:
> Can I use ecasound to apply some frequency equalisation
> to either wav or mp3 files.

yes, no problem.

> I've had a look at the ecasound documentation. Say I wanted to
> do a low freq boost, Can I do something like:

Look at the effect_presets file in Ecasound distribution. It contains a 
few examples on how to do bass boosts and multiband eq'ing. 

> feed input to 2 chains,
> pass one unaltered,
> apply -efb and -ea to the other chain
> add the two back together.

That's the basic idea. There are also numerous LADSPA plugins
available that provide more advanced filtering:

http://www.ladspa.org
http://www.linux-sound.org/plugins.html
http://plugin.org.uk/ (a well-known plugin set from Steve W. Harris)

For example SWH plugin 1203 provides a simple parametric eq. To use
to it give a 6dB boost at 200Hz:

ecasound -i foo.wav -o foo-bassboost.mp3 -el:singlePara,6,200,2

Note that it's not recommended to process mp3 (or any lossy-coded) files
multiple times. You lose some quality at each decode-encode stage.

Btw, you can also play with the parameters in real-time:
ecasound -i foo.wav -o /dev/dsp -el:singlePara,6,200,2 -c

And then use the interactive mode to change the params:
ecasound> start
# decrease boost to 3dB
ecasound> cop-set 1,1,3
# modify center frequency to 400Hz
ecasound> cop-set 1,2,200
# check current values
ecasound> cop-status

You'll find more info from the manpages ecasound(1) and ecasound-iam(1).

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

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