[sdiy] Processing Midi - Dropping Notes

[phillip m gallo]

Theo,
 
The issuance of a Note On message should preclude the need for an Active
Sense  message.   I have no doubt that folks violate the intent of
Active Sensing by tying it to some blind timer based routine, but Active
Sensing is intended to occur when there is no other traffic that would
indicate the MIDI link is "in service".
 
regards,
p
 
-----Original Message-----
From: owner-synth-diy at dropmix.xs4all.nl
[mailto:owner-synth-diy at dropmix.xs4all.nl] On Behalf Of Theo
Sent: Friday, July 16, 2004 1:22 PM
To: synth-diy at dropmix.xs4all.nl; David Brown
Subject: Re: [sdiy] Processing Midi - Dropping Notes


Hi David,
 
Yes real-time messages can replace expected data just like the example
you gave.
Yes the real time message is guaranteed to be one byte only, but more
than one real-time message is possible.
 
Like:
Note on
Note value
Real-time active sensing 
Real-time timing clock
Note velocity
 
Or:
Note on
Real-time active sensing 
Note value
Real-time timing clock
Note velocity
 
The real time messages are:
$F8 - Timing clock
$F9 - undefined
$FA - start
$FB - continue
$FC - stop
$FD - undefined
$FE - active sensing
$FF - system reset
 
The other one byte messages ($F1...$F7) are not real-time and not
allowed to go in-between the data of other messages.
However I like to pars them as if they where real-time messages, part
for easy of coding.
But also because of timing.
"Midi time code quarter frame" ($F1) is one of them, you don't like that
one waiting in a FIFO too long.
And having "Song select"($F3) or "Song position pointer"($F2) waiting in
the FIFO while $FA "start" is received and executed in is also a bit
sloppy.
 
Best use a method that takes care of these things automatically.
Like the one I described in the other message.
 
Cheers,
Theo
 
 
 

----- Original Message ----- 
From: David  <mailto:davebr at earthlink.net> Brown 
To: synth-diy at dropmix.xs4all.nl 
Sent: Friday, July 16, 2004 6:14 PM
Subject: Re: [sdiy] Processing Midi - Dropping Notes

At 09:34 PM 7/13/2004, you wrote:


For even more fun there is also "real time messages" that can come
in-between the bytes of other messages.
 
The real time messages are one byte only.
So just check if a message is real time, then do something with it, like
nothing at all.


Can you clarify the real time messages?  I'm writing my own MIDI parser
and I don't know if I have handled it correctly.  Specifically, can a
real time message replace the expected data in a message?  For example
...

Note on command
Note value
Real time message
Note velocity

In this case, is the real time message always guaranteed to be one byte?

Thanks. - Dave 

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