Midi Merge Technique?

theinmans at mindspring.com theinmans at mindspring.com
Mon Jan 7 07:24:07 CET 1980

> Is it legal for a system realtime message (F8, FA, FB, FC) to occur *during*
> another message ?
> For example, can midi clock occur inside a note on ? ie  90,3C,F8,7F...

This information often doesn't appear in Internet postings of the 
Midi Spec, but it is mentioned in Craig Anderton's Midi for Musicians
(see Appendix A, page 100).  "The System Real Time messages can be sent
at any time.  Any messages which consist of two or more bytes may be
split to insert Real Time messages."  From page 95:  "In such cases
the Real-Time message is either ignored or acted upon, after which 
the receiving process resumes under the previous status."

Penfold's Advanced Midi USer's Guide says (p. 35):  "... can be sent at
any time, even in the middle of other messages."

Oddly, Buick and Lennard's Music Technology Reference Book says only
RT messages may be ""interleaved with System Exclusive messages." (p. 1)
They don't seem to mention other messages.

Most places, this fact isn't mentioned at all.

That's the bad news.  The good news is that, unless I am mistaken, such
messages are the only ones that begin 11111xxx, with bits 7-3 set high 
(low current), so it would be easy to weed these out.


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