[sdiy] MIDI state machine for arpeggiator

[ASSI]

On Samstag, 28. Februar 2009, Matthew Smith wrote:
> At the end of this message there is a little fragment of C (if I
> remember to paste it!) - I would appreciate any comments on the
> finite state machine that I'm using to filter the incoming MIDI
> stream. Thought I should get this in now when people are still
> thinking arpeggiators from this morning.

I don't know where you expect to get the MIDI data from and if you can 
make certain assumptions, but if it's from a master keyboard or 
sequencer you really need to implement running status (you get just 
one status byte and then many note/velocity pairs) and recognize that 
a NoteOn with Velocity=0 really is a NoteOff.

All the realtime messages are sidechannel data, which means they can 
come anywhere inbetween any other messages and don't break running 
status.  Otherwise running status is ended when another command comes 
in.  Your state machine is not robust in the sense that when a byte 
goes missing it doesn't synchronize at the next command byte (it would 
swallow it when waiting for velocity for instance).


Achim.
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