[gmpi] Re: Reqs 3.8 Events - gesture start/end

  • From: David Olofson <david@xxxxxxxxxxx>
  • To: gmpi@xxxxxxxxxxxxx
  • Date: Wed, 24 Dec 2003 02:11:32 +0100

On Wednesday 24 December 2003 01.52, Tim Hockin wrote:
> On Tue, Dec 23, 2003 at 05:31:40PM -0700, Mike Berry wrote:
> >     I believe that all we need to do is require that GMPI define and
> > support gesture start and end events. Everything else from there
> > becomes an implementation detail (i.e. how you create these
> > events, how you handle them, etc...).
>
> Who sends them to whom?  Does the host send them to a plugin?  What
> is a pluging going to do with them?  Does the the plugin send them
> to the host?

        * Anyone who outputs control data and has some notion
          of active and passive states, or gestures in some form,
          may send gesture events.

        * Anyone that is interested in detecting gestures, for
          detection of status (active/passive), grouping of
          events or other reasons, may receive gesture events.

The "detection of status" part is probably the most interesting bit. 
The most common setup would probably be something like this:

        .---------.   .-----------.   .----------------.
        | Foo GUI |-->| Sequencer |-->| Foo DSP Plugin |
        | Plugin  |<--|           |   `----------------'
        `---------'   `-----------'


Normally, the sequencer would just monitor the events from the GUI 
plugin, while sending recorded eventns to the DSP plugin. If the user 
starts messing with a knob on the GUI, the GUI plugin would use the 
gesture feature to tell the sequencer that "priority" data is 
available. The sequencer might decide to send the live data instead 
of the recorded data, whenever a gesture is in progress.

The GUI plugin might look at the gesture data from the sequencer to 
decide whether to track the automation data, or accept user input. 
(Doesn't really make sense to allow manipulation of the GUI if the 
sequencer refuses passing any data on to the DSP plugin, does it?)


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

.- Audiality -----------------------------------------------.
|  Free/Open Source audio engine for games and multimedia.  |
| MIDI, modular synthesis, real time effects, scripting,... |
`-----------------------------------> http://audiality.org -'
   --- http://olofson.net --- http://www.reologica.se ---


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