[linux-audio-dev] XAP spec - early scribbles

[David Olofson]

On Saturday 01 March 2003 17.07, torbenh at gmx.de wrote:
[...]
> > If we do this on the right level, we can have both. We definitely
> > should have a standard graph description (and preset) file format
> > anyway, and all we need is a way for plugin authors to provide
> > useful subgraphs with their plugins.
>
> did you specify a serialization method on the plugins ?

Well, plugins should be scheduled in "flow order" - that's all there 
is to it. (Oh, and this feedback loop issue, of course.) What do you 
mean, exactly?


> how will this be handled ?

Subgraphs are just high level descriptions of how to connect any few 
plugins into something that you can throw into a net. This could be a 
desription of how to set up a mixer using the parts in a plugin pack, 
or it could be a user defined "patch", constructed from just any 
plugins. Physically, it would most probably be XML based.

Just a file format, that is - although the host SDK might contain code 
to helt hosts support it.


> > As to user interfaces, this is where many->one and one->many
> > (DSP->GUI) gets in. You might want to have a single "panel" for a
> > mixer, even if it's constructed from multiple DSP plugins.
>
> This is already implemented in galan and i find it very
> nice...
>
> I have been talking with a friend about the gui issue...
> and he said that an interface which lets the plugin return
> a bitmap would do the trick to make it toolkit independent...

Sure. It would also be insanely slow - especially if you run the 
plugin remotely. It would also be totally incapable of taking 
advantage of any kind of h/w accelerated rendering, such as X and GDI 
2D acceleration, Direct3D, OpenGL and whatnot.

GUIs are not to be part of the DSP plugin binary, period.


> we could add some sort of slider interface also but
> this was not the issue...

Well, I think the current "hinted control" solution (very similar to 
LADSPA) will work fine for that. Add grouping hints or XML, and hosts 
can construct real nice (G)UIs for most plugins.

This is (almost) completely irrelevant for plugins that can't really 
be used without custom GUIs, though.


//David Olofson - Programmer, Composer, Open Source Advocate

.- The Return of Audiality! --------------------------------.
| Free/Open Source Audio Engine for use in Games or Studio. |
| RT and off-line synth. Scripting. Sample accurate timing. |
`-----------------------------------> http://audiality.org -'
   --- http://olofson.net --- http://www.reologica.se ---