[sdiy] Bunching of MIDI clock messages

[Olivier Gillet]

> In this case, it's necessary to process Real-Time MIDI messages a.s.a.p.,
> which means they must be handled in the interrupt - at least the critical
> parts.

There are situations in which whatever you ought to do to react to the
MIDI message (for example, clock tick -> move to the next beat ->
trigger a drum sample) will have to wait anyway, because, for example,
you fill your audio output buffer by 1 ms chunks ; or refresh your
trigger outputs at a fixed sample rate. In this case, I think, it
makes sense to defer the processing of the realtime message out of the
ISR.