[linux-audio-dev] MIDI interface latency

David Olofson david at olofson.net
Thu Feb 12 19:38:51 EST 2004

On Friday 13 February 2004 00.53, Tim Goetze wrote:
> David Olofson wrote:
> >Depends on the wire. For standard 31250 bps MIDI cables, the
> > minimum latency for a NoteOn message (status, pitch, velocity -
> > three bytes) is 0.96 ms. (It is one start bit and one stop bit,
> > right...?)
> yes, but you forgot there's only two bytes for the message in
> running status.

Good point - but running status (by definition) only works when you 
happen to deal with multiple events with the same status. (That is, 
same event type and same channel.) In real life, that means you get 3 
bytes for the first note in a chord, and (if you're lucky), 2 bytes 
for each of the following notes. Though this can save bandwidth and 
reduce latency slightly at times, you can't really rely on it in any 
truly useful way in this context.

//David Olofson - Programmer, Composer, Open Source Advocate

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|  Free/Open Source audio engine for games and multimedia.  |
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