Subject: Re: [linux-audio-dev] ladspa GUI round 2
From: Steve Harris (S.W.Harris_AT_ecs.soton.ac.uk)
Date: Thu Mar 29 2001 - 16:10:26 EEST
On Wed, Mar 28, 2001 at 01:36:23PM -0500, Paul Davis wrote:
> it took me less than 10 minutes to add some code to ardour that could
> handle the IPC via a FIFO (using the LADSPA_Parameter_Change struct I
> included in my last message).
>
> all we need to settle on is the struct used to send port value change
> requests (and its name!) and the IPC method (which i think should
> clearly be a pipe). the requests themselves don't need timestamps or
> anything complex, just a way for the host to identify the plugin, the
> port ID and the new value.
Uniquly identifying plugins is the only thing that would seem difficult,
maybe the host should pass a token to the plugin when its instantiated?
I'm not sure what routing you images, but I would like to see:
---------- ----------
| | | |
| Host |--->| Plugin |
| | | |
---------- ----------
^ ^
| |
| |
---------- |
| GUI |<-------/
----------
Obviously the GUI needs to be linked to the plugin in some way, but I
would like it if the parameters changed by the gui were sent to the plugin
in the normal port float write way whereever possible. Hopefully this
should make host automation more equivalent to manual parameter
alteration and preserve the block approach of plugins.
I suppose its reasonable that parameters that can't be expressed in LADSPA
can't be automated, and on the whole they are going to be the sort of
thing that can't be usefully automated anyway.
I was imagining that the plugin would only invoke the gui if/when the host
requested it, or mauybe the plugin should just broive the host with a
method or data required to open the custom interface.
> which requests are sent (it may even choose not to have such a pipe at
> all). i suppose the host should pass the name of the FIFO
> (e.g. /tmp/ardour_ladspa_gui_pipe), or a null pointer, so that a
> plugin can tell if and where to send GUI requests (and thus whether or
> not to bother with a GUI at all).
>
> i still that a plugin should indicate if it has its own GUI, so that
> hosts like ardour, sweep and many others can build their own simple
> GUI for those that choose not to provide one.
>
> what do you all think ? we could have this done in a few days!
That sounds fantastic, I've been away for the last few days, and havn't
been able to really think about the implications if this, but I'm
returning this evening. I could nock up something quickly to test this
approach give an api. Its sounding more and more like the right thing.
- Steve
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