[LAD] "Open midi-keyboard"

Ralf Mardorf ralf.mardorf at alice-dsl.net
Sat Sep 26 21:09:38 UTC 2009

> Jens M Andreasen wrote:
>> On Sat, 2009-09-26 at 14:03 +0200, Ralf Mardorf wrote:
>>> When using several MIDI ports even a lot of SysEx can be sent 
>>> real-time, but using only one MIDI port even aftertouch can cause 
>>> timing problems.     
>> A stream of channel-aftertouch is single bytes, and can at any point be
>> interrupted by more important data (note-on) with at most 0.3
>> miliseconds delay ...
> When interrupted it's 2 bytes, one byte only when running status can 
> take effect. To be honest, I don't know if aftertouch will be 
> interrupted by applications and devices by default. Is this MIDI 
> standard? And to be honest, much more data is produced by the pitch 
> wheel, because of the low and high byte. I never had any timing issues 
> because of aftertouch and pitch bend, but I noticed that they produce 
> much more traffic than real-time SysEx for filters. IIRC I had 4 MIDI 
> outputs for the Atari ST, I guess using just one MIDI output can cause 
> trouble for pure MIDI music.
> Ralf

Yes, the Midex had 4 MIDI outs.

Have you tested heavy traffic with just one MIDI port?

I can't speak for aftertouch, but SysEx can become problematic. Okay, 
SysEx always needs to be transmitted from $F0 to $F7, while aftertouch 
can be interrupted, anyway, aftertouch can cause really a lot of data, 
much more than SysEx for filters.

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