Re: [LAD] LV2 Oscilloscope

From: Lars Luthman <mail@email-addr-hidden>
Date: Thu Oct 10 2013 - 21:37:46 EEST

On Thu, 2013-10-10 at 18:29 +0100, Aurélien Leblond wrote:
> My plan was to use the ll-scope gtk widget, add it to a LV2 plugin and
> start from there.
>
> The problem I'm at the moment facing is this:
> - ll-scope widget requires the sample rate as a constructor but I
> can't find an easy way for an LV2 plugin to pass the sample rate.
> - what is the cleanest way to access input port data from the GUI? GUI
> and plugin are very well separated in LV2, I can't figure out what's
> the proper way to do this.

I would just bypass the LV2 host altogether and use shared memory to get
the audio data to the GUI. This is what the DSSI plugin does. This means
that it will not work if the plugin and the GUI are running on separate
machines, but that seems to be pretty rare.

One problem is that there is no obvious way of finding out which plugin
instance a GUI is controlling in order to know which SHM file to read if
there are multiple instances of the plugin running. In the DSSI GUI this
is solved by sending a configure() message with a unique string, but
there is no corresponding call in LV2 without adding more extensions.
You might be able to do it with an atom input port or, if you prefer
avoiding additional extensions, with a control output port that you
write your unique value to in the plugin.

--ll

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Received on Fri Oct 11 08:15:03 2013

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