Re: [ecasound] ladspa control outputs

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Subject: Re: [ecasound] ladspa control outputs
From: Kai Vehmanen (
Date: Wed Nov 28 2001 - 22:22:19 EET

On Tue, 27 Nov 2001, Jesse Chappell wrote:

> I would really like to use the control output ports from LADSPA
> plugins within the ecasound framework. Simply mapping a control port
> output to an ecasound output file (non-audio) would suffice.

Unfortunately ecasound has no support for non-audio files, so there's no
standard way to store control output data.

> While searching this list's archive I found some mention of this
> by Kai in Dec 2000, but I can't seem to find the feature
> in the documentation. If this is not yet available I am willing
> to implement it, as it is vital for my continued use of ecasound.

What ladspa plugins are you using (ie. what type of control output data)?

> Additionally, using a ladspa control output to feed an ecasound
> chainop parameter (like the -k options) would really facilitate
> some good effect construction (eg. envelope controlled filters).

Ecasound has a similar mechanism where an audio stamp (-eS:id) is used to
route audio data to controller objects (currenly only -ksv), which again
can control other chain operators. This makes it for instance possible to
control effects attached to chain 'x' based on amplitude of chain 'y'. In
other words we are converting from audio data (of chain 'x') to control
data (fed to chainops of chain 'y').

> A side note for people using pyecasound and having problems
> using alsa i/o (or other internal plugins): When Python loads
> dynamic libraries (like and hence
> it does NOT use the RTLD_GLOBAL flag with dlopen(), the result being
> that future dlopens in the libecasound for the internal plugins
> (like alsa, etc) fail because they cannot resolve symbols they
> need from libecasound. You can get around this by patching the

Hmm, very interesting. Thanks for this note!

 Audio software for Linux!

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