Re: [ecasound] My presentation + error in the OSC documentation

From: Kai Vehmanen <kvehmanen@email-addr-hidden>
Date: Mon Apr 09 2012 - 13:11:20 EEST


btw, welcome to the list!

On Tue, 7 Feb 2012, ORL wrote:

>> /ecasound/chain/NAME/op/OPID/param/ID
>> /ecasound/chain/CHAINID/op/OPID/param/ID
> Ahem, auto-reply, just to announce I didn't had understood that -a:
> could be followed by a string, and that this string was called
> "chainname". So it's working perfectly, and there's no error in the doc.

Yup, that's correct. But it's indeed a bit confusing as all the examples
and docs (a habit of mine that dates to earliest versions) use numerical
chain names, while in practise they could be anything.

> I've checked the code a bit, but didn't find any easy way to get op
> giving their name to the OSC path, directly. It's annoying, as if you,
> for example, choose to use another op before the others, all your OSC
> controls upon that chain will be false.... In my particular case, it
> obliged me to make 2 chains for each "strip", the second beginning with
> -eadb, so that I'm sure I will act on the attenuation by sending an osc
> message at the 1st op.

This is a valid problem, but there's no easy way to fix this with the
current API (both ECI and OSC). The root of the problem is that chain op
instances do not have unique names. If you'd have two amplify-ops (-eadb)
in the same chain, there's no way to separate the two (both instances have
the same name and description). And as ordering matters (one must be able
to address the first, second and Nth amplify in a chain), this would need
a new abstraction (assigning/exposing a unique string to all op

As a practical workaround (in ECI apps), you can use introspection to
track chainops. E.g. "cop-iselect 1 ; cop-describe" tells you what is the
current first chainop in the chain. If this is shown in the UI, one will
never accidentally control the wrong chain op.

But hmm, I can now see the problem with OSC apps, as there's no
'cop-describe' equivalent in the OSC interface at the moment.

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Received on Mon Apr 9 16:15:02 2012

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