[gmpi] Re: Reqs 3.9. Time - opening arguments.1

  • From: "David Viens" <davidv@xxxxxxxxxx>
  • To: gmpi@xxxxxxxxxxxxx
  • Date: Thu, 05 Feb 2004 13:06:49 -0500


>Paul Kellett:
>I'm just thinking out loud here so this might be a stupid idea, but
>if it's like VST, the plug-in just reads some "musical time info" 
>at the start of each audio buffer and doesn't really care where 
>that info has come from.  So how about having an array of tempo maps,
>one of which (or more, or none) are the host's responsibility, but a
>plug-in can also register itself as a tempo map provider.  Each 
>plug-in gets read-only access to the tempo maps upstream from it.
>Usually it will read the first one and ignore the rest.

we approve this 100%

>I'd like to drill down into the idea that a GMPI plugin can generate tempo
>changes.  Basically, I'm unclear how a host app which contains a "project
>file", would track tempo changes initiated by a plugin.  
>- If the host has an undo system, is it expected that the plugin's changes
>are undoable?
>- If the plugin changes tempi while the transport isn't rolling. does that
>count as (possibly undoable) edit?

Its clear that we also should not confuse concepts.

A) Plugins can read or generate streamed info chunks representing a moment 
in a TempoMap (VstTimeInfo-like) 
->This is allready included in VST 2.0.<-

  Ex1: a plugin can be a fully contained audio/midi sequencer and
  export streaming timeinfo, recording input MIDI and audio.

  Ex2: a plugin can transform incoming TimeInfo and generate a "half-time"
  version of it, or do funky things 
  like transforming three input 4/4 bars into four 3/4 bars.

B) Plugins can have random read OR write access to another tempoMap
(coming from a plugin or NOT, like say the host's main sequencer)
->This is in VST module Architecture 1.0.<-

This to me is an OFFLINE matter. and something that very few hosts will allow
for obvious reasons.

For me A and B are two VERY different things and should be different GMPI 

David Viens, Plogue Art et Technologie Inc. 
Montreal. http://www.plogue.com

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