[CM] audio plugins in grace working

[Heinrich Taube]

apologies for the longish report, if you are interested in generating  
real-time audio using AU, VST, ASIO plugins in Grace, read on!
--
You can now load 'plugin graphs' and send midi/audio streams to them  
to generate real-time audio output. Plugin graphs are user defined  
collections of nodes (plugins and other audio processors) with  
connections that route audio/midi signals between them. To create a  
plugin graph right now use JUCE's "Audio Plugin Host" app (shipped in  
its extras/ folder). Plugin Host will find all the plugins on your  
machine, let you add and connect plugins together to forms graphs,  
test graphs out using the app's midi keyboard panel, and save plugin  
graphs as .filtergraph files (XML graph description).

To load a plugin graph in Grace type COMMAND-P or use the Audio >  
Plugin Graphs > Load Plugin Graph... menu item . You can then route  
midi to it by just closing (unchecking) all  midi output ports: if no  
midi output ports are open then Grace will automatically send whatever  
midi you generate straight to any plugin graph. To route midi input to  
a plugin graph, open the input port and select Audio > Midi In > Send  
To Plugin. In addition, any audio input Grace receives will  
automatically be routed to the audio inputs of your plugin graph.

You can also open any plugin's GUI editor iand tweek its parameters  
while it is generating audio!  To open a gui editor select it from   
Audio > Plugin Graphs> Plugin Editors menu.  This may take a few  
second to open if its a huge plugin lilke Kontakt ...

I will add more features as time goes on, for example being able to  
add connectins and send plugin parameter data from Scheme. (Im less  
inclined to provide a gui graph editor because Plugin Host already  
does this very well)

Obviously to use plugins you have to have plugin support working on  
your machine... Getting it working ranges from easy to impossible. On  
Mac its easy and ive saved a new alpha built with AU plugin support. I  
also have a  version of Juce's Plugin Host app that you can use to  
create AU plugin graphs:

Mac:

Grace with AU support:
	http://camil.music.uiuc.edu/software/grace/Grace-3.8.0-alpha4-osx.zip

Plugin Host with AU support:
	http://camil.music.uiuc.edu/software/grace/PluginHostAU-osx.zip

Plugin graph replacement for SimpleSynth:
	http://camil.music.uiuc.edu/software/grace/dls.filtergraph


All other types of plugins (VST/ASIO ) on Windows, Linux or Mac will  
require you to enter into an agreement with Steinberg and build "Audio  
Plugin Host" and Grace from sources .  I was able to build the  "Audio  
Plugin Host"  with VST on windows. I tried for several days to build  
it on linux but gave up. ( If you manage to build it and get it to  
make a sound then please let me know)  Assuming you have VST plugins  
working in the Plugin Host, then to build grace with VST support   
enabled all you do is add the new --vst option to premake:
   premake  ...  --vst /path/to/VST_3  ...