[gmpi] Re: 3.9 Time Formats

  • From: "Michael Stauffer" <michael@xxxxxxxxxxxxxxxxxx>
  • To: <gmpi@xxxxxxxxxxxxx>
  • Date: Mon, 16 Feb 2004 21:01:33 -0500

Jeff wrote:

>> Fair enough.  So the question is, does a plugin need access
>to the hosts
>> full tempo map, or only information  from the host about
>tempo/meter for
>the
>> current set of samples/events ?
>
>Thinking out loud....
>
>What if we don't give the plugin direct access to the tempo
>map?, An offline
>plugin could still get it.  It would perform an pre-pass of the
>entire song,
>recording any tempo/meter changes internally  to construct a
>complete tempo
>map.
>  It seems to me that any offline plugin could use this
>technique to build a
>complete tempo map, regardless of host support for such things.
>
>I figure that supports our aim of keeping GMPI simple, while still
>supporting the oddball plugins. Importantly, we don't force all hosts to
>support any particular tempo map format.

For my admitedly oddball tempo-analysis offline plug-in, I could use a
generic tempo "marker" set/get routine, that could be format independent
(I think!). I'm imagining passing an event/command to the host to update
its tempo map. It would need:

- sample count (& sample rate if somehow variable)
- msr, beat, tick
- tempo
- time sig

The host could do what it wants (even ignore) with this event/command,
updating its internally tempo map, as is the user manually added a tempo
event at particular spot using the host's GUI.

Getting the map from the host could be similar, get a list of such
events, or query one at a time.

BTW, querying the host's tempo map would be useful for 'look ahead'
capabilities for delay plugs, et al, as long as the map is being used for
tempo during performance, since it won't change. If the host is setup for
external sync (clocks, ReWire, or GMPI plug-in) then it wouldn't be any
use.

I thought of another possible use for a plug to set the host's offline
tempo map, although this is largely speculative. I think I recently saw a
VST (?) plug-in for adding video playback capabilities to a VST host (I
think). If such a plug allowed the user to indicate hit points in the
video, it would be useful for the plug then to set the host's tempo map
to sync playback with the hit points. Or is that way off?

Cheers,
Michael


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