[linux-audio-dev] anyone interested to develop a new apps ?

Mario Lang mlang at delysid.org
Sun Oct 24 18:23:08 UTC 2004

dubphil at free.fr writes:

> I want to setup a sound system with linux. For this, I need an app that
> could split an audio file in four tracks in order to add them separately
> some effects.


> it should be compatible with Jack and could just get a stereo channel
> for input and provides 4 stereo channels. The 4 stereo channels would be
> the result off a crossover spliting by frequency ranges of the input
> stereo channel. 
> we could give a default preset like this :
> 1st stereo channel : low
> 2nd stereo channel : low-mid
> 3rd stereo channel : high-mid
> 4th stereo channel : high 
> of course thoose ranges should also be set manually.

ecasound -a:1,2,3,4 -i Jimi-Hendrix---The-Ultimate-Experience---11---Castles-Made-of-Sand.mp3 \
-a:1 -efl:300 -o jack -a:2 -efb:500,400 -o jack -a:3 -efb:1000,600 -o jack \
-a:4 -efh:1300 -o jack

Now, use this as a starting point.  In interactive mode (-C) you can change
the filter parameters at runtime, or you just use the ECI API
to build some simple app on top of this using ecasound.  As the author of
ecasound.el I have to say that this probably takes about 30 lines of Emacs Lisp
code to make it controllable from within emacs :)

> each channel could have the gain controlled and could have assigned 4
> effects with LADSPA plug-ins.

Well, you can add a -ei operator to do the gain per chain, and in ecasound you
could add the ladspa effects you want to use directly, or you use
something like jack-rack and mix the stuff back together somehow else.
> each slider or knob should be midi controlled (I know that Jack Rack
> already does this).
You can make the ecasound filter args midi controlled, however that would mean
you have to control center/width for the bandpass filters separately.

> Does this kind of apps should take a long time to be developped ?
No, with ecasound, that would be very simple to do.

> I'm not skilled to undergo this kind of project alone as I'm a poor PHP/Perl
> and little Python developper.
ECI bindings are available for Python.


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