[gmpi] Re: MIDI: Common event coding

  • From: Chris Grigg <gmpi-public@xxxxxxxxxxxxxx>
  • To: gmpi@xxxxxxxxxxxxx
  • Date: Wed, 23 Jun 2004 11:29:14 -0700

Paul said:

Chris said:
2.1.1. Whole-Unit Addressing - Many messages implicitly address the
receiver as a whole unit:
- System Real Time group (Timing Clock, Start, Continue, Stop, Active
Sensing, System Reset)
- System Common group (MTC QuarterFrame, Song Position Pointer, Song
Select, Tune Request, End of SysEx
- Manufacturer SysEx (may be internally addressed further, but in the
general case contents are opaque)

In GMPI, the 'whole unit' is probably the plug itself. These can be
represented by the path "/", which could be required in all parameter
maps, or could be inferred as a general GMPI rule.

A minor nitpick perhaps, but this lept out at me.


Its not clear to me that the "whole unit" is the plugin. I would have
thought it was the host.

This is a detail, but can be handled in the path syntax. Earlier I suggested something like //host/graph/plugsSpecificPathInGraph/parameter. These both work together, e.g. initial single / means current plug.



It would seem very odd to me to deliver a
Start message to a plugin while the host transport system remained
stopped.

Why should certain messages be stopped before reaching plugs? Use cases: sequencer plug-ins in dumb hosts, MIDI studio routing. I suppose the graph itself, and/or the host app, could expose a proxy plug within the graph so you can do state and configuration from GMPI, but that should be thought about carefully.



You also need to consider non-manufacturer sysex, such as MTC full
frame and MMC, but I think this is easily dispensed with by leaving it
at the host level.

These are all there in the common coding, and should not be reserved for particular targets for the same reasons.


-- Chris G.

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