[linux-audio-dev] processing plugin standard wrapper

[David García Garzón]

On Monday 12 February 2007 21:34:08 Stefano D'Angelo wrote:
> > Well, that's our intent in CLAM[1]. The goal is that CLAM should be able
> > to run a given processing algorithm transparently under several backends.
> > Currently we support, to some extend, PortAudio, Jack, Alsa, and VST. The
> > first three backends can be used with a Qt Designer interface. We still
> > have to face several fronts: Unifying the interface to fit all the
> > backends, incorporating more backends (some work on Ladspa has been
> > done), and enabling Qt GUI's to more backends (notably VST).
>
> Well, I think I've not understood what you mean: Jack, Alsa and
> PortAudio are not sound processing plugin formats... can you explain
> it easier please? (I'm sorry, I'm not a native English speaker)

They are not plugin systems, you're right, but if you have a processing 
algorithm encapsulated in a way that it describes itself (number of ports, 
controls... then you can build wrappers (what we call backends) that maps 
this algorithm to a given plugin system (ladspa, vst...) but also to a given 
underlaying audio system api (portaudio, alsa, directx..)

For example, if i want my algorithm to be a Laspa plugin, i could use a Ladspa 
backend, that compiles as library, that maps connection topology of the 
processing algorithm to a Ladspa descriptor and when it is called, it just 
feeds data to and from the ports and executes the algorithm. A Jack backend 
should be very similar but it compiles as an application and publishes the 
ports as Jack ports to the server. And so on. Of course, there is a lot of 
work on handling each backend singularities such as JACK server availability, 
api/device enumeration in portaudio...

In short, the intended result is that the developer designs the algoritm once 
and then it can be used as any kind of plugin (what you asked for, didn't 
you?), and not just plugins but also standalone application.

We also provide a way of relating a qt interface to certain parts of the 
algorithm. This is already available for standalone applications backends[1] 
(JAck, PA, Alsa..) but we want to provide that also for plugin systems such 
as VST.

[1] http://iua-share.upf.es/wikis/clam/index.php/Network_Editor_tutorial

I hope to have explained myself better, but feel free to ask me more 
information if you are interested in.

David.