Subject: Re: [ecasound] eci / ecamonitor / -ev
From: Kai Vehmanen (k_AT_eca.cx)
Date: Wed Nov 06 2002 - 17:22:59 EET
On 6 Nov 2002, Adam Linson wrote:
> is it possible to "harvest" the values from "-ev" for use in an ECI
> implementation?
It is possibly, although -ev is not the optimal solution for this.
The basic trick is to use analysis operators (ecasound native
effects or LADSPA plugins) that have output parameters. For instance
-ev takes two parameters: -ev:cumulative-mode,result-max-multiplier
The first one sets the analysis mode, but the second one is an output
parameter and is updated in real-time. You can use the 'copp-get' (get
chainop parameter value) ECI command to query its current value.
Better suited operator for this is:
-evp:peak-amplitude-ch1,...,peak-amplitude-chN
... it calculates the peak amplitude for each processed channel.
The peak is resetted to zero whenever the value is read. I've
used this to implement a VU-meter using ECI => ecasignalview.
Mario has done the same in Lisp (see the latest ecasound.el).
If you want different kind of data, you can write a new analysis effect to
ecasound or extend the old ones. It's also possible to use LADSPA plugins
(they, too, can have output parameters).
> my guess is that it's a bit tricky, since the normal EIAM "-ev" waits
> for the sample to finish ("wait_for_stop ok"), and only with ecamonitor
The "-ev screen" is printed in reaction to the "cop-status" command. This
is automatically issued when processing is finished. But as "cop-status"
returns all the information in one big string, it's a bit difficult to
parse and inefficient.
-- http://www.eca.cx Audio software for Linux!
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