[linux-audio-dev] Creating the conditions for VST-like plugins on Linux.

[Juan Linietsky]

Hi ! I'm writing this mail because at this point I'm seeing that the 
Linux Audio Development community is still going aimlessly on how to 
develop powerful audio applications.  As we know, one of the key factors 
missing nowadays is audio plugins and synth plugins. Some audio plugin 
needs can be covered by LADSPA, but in other cases you need a lot more 
complex interfaces than just a few sliders.. (like is compressor with 
curves, graphical equalizers with band feedback, parametrics, multiband 
compressors, voice autotunning, surround spatial repositioning.. and 
everything available of course, that would become more intuitive and 
useful with more feedback)

Also there is the need for instrument plugins, single or multi timbral 
(so you dont have to load all the instances at once). DSSI provides this 
(except the multitimbral) but you have to write the interface separated 
than the core, which not only is more difficult to program, but also 
very limiting because in many cases you cant show with much detail what 
is going inside the synth, like editing a sample, draw freeform 
envelopes, edit the oscilator generator, etc. And better not talk about 
effects, which need spectrums, vus, and other kind of complex feedback.

So, I'm sure that many of you have asked yourselves, why cant we have a 
VST-like plugin architecture for Linux?

The following are excuses:

-Because we need core and interface separation, this way we warranty a 
clean design and network transparency
-Because it would force both interface and core to be memory locked, as 
a result of being a jack clients, forcing more physical memory to be used
-Because separating interface and core makes for a clear design.

And I say, ALL THIS IS LIES. Every single of such reasons are of no 
concern to musicans. If I just want to make music, I would not care 
about any of such reasons. I'd just fire up an application and make 
music. All that seems to me more like academia-speech than real reasons. 
You can believe them or not, but it's PROVEN that none of these are 
needed to make music.

However, there is a one and single reason of why we dont have VST-Like 
plugins in Linux:

-It is impossible to make a plugin in a widget toolkit that will be 
hosted by another widget toolkit.  (say, gtk on qt, or fltk on fox).

Why is this? The answer is simple.. X11.  An X client connects to the 
Xserver (via unix socket/tcp/wathever) then stays blocked in that 
connection until it receives events (keypress/mouse/etc), which are sent 
to the event loop. It is then the toolkit  (gtk/qt/etc) the one 
responsible for handling the events. This way, even if you load many 
toolkits at the same time, and even each opens a connection... one of 
them has to stay blocked in the event loop.

This is the REAL reason why we cant make a VST-Like plugin API in Linux, 
or EVEN port opensource VST plugins and use them here.
Up to now, nobody has really bothered in solving this problem, instead 
most just attempt finding a workaround. 

So what I am proposing is to SOLVE this problem.. how?

-Designing a library that will act as intermediate between the toolkits 
and the X Connection, handling the event loops for all of them, so they 
can run together.
-Placing this library in freedesktop.org
-Encouraging toolkit makers to support this library, and porting them to it

As you see, this is not a simple task, and much less something I can do 
alone, so I will need help!! I am very sure that at some point we will 
get support from other groups which will also benefit from this.

So before anything, I'd like to know who is interested in this, and who 
would like to help, offer experience, etc.

Well, hope I get any feedback

Cheers!

Juan