[gmpi] Re: 3.15 MIDI
- From: "Jeff McClintock" <jeffmcc@xxxxxxxxxx>
- To: <gmpi@xxxxxxxxxxxxx>
- Date: Thu, 17 Jun 2004 14:27:13 +1200
> What about MIDI sync? Do we want the GMPI graph to be able to chase to
> external beat boxes?
We sure do.
Every MIDI message (except sysex) is a parameter change. In this case "Song
Position"
This is a "Well Known Control", expose a parameter called "Song Posistion"
(or whatever), and for each MIDI clock, your plugin receives an timestamped
event containing the new timecode value.
> I'm not convinced this is achievable. For example, let's consider the
> conversion of MIDI volume controller to GMPI. MIDI volume doesn't have a
> standard mapping from 0-127 to gain values. So how does this value get
> converted within GMPI? How the does the converted value survive the round
> trip through a processor that does:
> MIDI -> GMPI - > [Event Processing] -> GMPI -> MIDI.
All 7 bit controllers get converted like so....
float gmpi_value = (float) midi_cc / 127.0;
.. and converted back like so...
int midi_cc = (int) (gmpi_value * 127.0 + 0.5);
( as usual, i've probley made some terrible coding error, like forgot a
semicolon, or rounded down instead of up, but I hope you get the gist)
Don't assume the conversion to GMPI is some over-complicated thing, we're
not going to convert everything to Angstroms or anything. It's just a
converion to floating point.
The intention isn't to reinvent the whole thing, only to give controllers
more resolution by converting to floating point.
Jeff
----- Original Message -----
From: "Ron Kuper" <ronkuper@xxxxxxxxxxx>
To: <gmpi@xxxxxxxxxxxxx>
Sent: Thursday, June 17, 2004 2:08 PM
Subject: [gmpi] Re: 3.15 MIDI
> > Keep the GMPI graph pure and lovely, like the driven snow.....
>
> And then only Eskimos will want to play in our graphs. :-P
>
> What about MIDI sync? Do we want the GMPI graph to be able to chase to
> external beat boxes?
>
> What about MIDI machine control? Do we want the GMPI graph to play when
the
> user presses [Play] on their ADAT machine?
>
> > What matters are not byte-level correspondence, but semantic
> > correspondence, and this is easily achievable.
>
> I'm not convinced this is achievable. For example, let's consider the
> conversion of MIDI volume controller to GMPI. MIDI volume doesn't have a
> standard mapping from 0-127 to gain values. So how does this value get
> converted within GMPI? How the does the converted value survive the round
> trip through a processor that does:
> MIDI -> GMPI - > [Event Processing] -> GMPI -> MIDI.
>
> The problem with MIDI, or rather, with assuming we can cleanly convert
MIDI
> messages to another control format, is that in many cases the semantics of
a
> MIDI message are opaque.
>
>
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