Re: It cannot be done under OS X !!
Re: It cannot be done under OS X !!
- Subject: Re: It cannot be done under OS X !!
- From: "John Lazzaro" <email@hidden>
- Date: Sat, 27 Mar 2004 10:04:44 -0800
Kurt Revis <email@hidden>
It sounds like they are saying that the Mac puts longer or shorter
pauses between individual bytes of sysex, in a different way than the
PC does. This is certainly possible -- I haven't sat down with an
oscilloscope to look at it. But as far as I know, the MIDI spec does
not specify absolute timing for individual sysex bytes.
Standard MIDI Files (SMF) let you code a SysEx command with an
individual timestamp for every data byte, via the segmentation
feature. This characteristic lets you accurately record and
play back MIDI sources that encode information in the relative
timing of each data octet in a SysEx command. According to:
From: http://www.borg.com/~jglatt/tech/midifile/evts.htm
Really oddball midi units send a system exclusive message as a
series of small "packets" (with a time delay inbetween transmission
of each packet). The first packet begins with an F0, but it doesn't end
with an F7. The subsequent packets don't start with an F0 nor end with
F7. The last packet doesn't start with an F0, but does end with the F7.
So, between the first packet's opening F0 and the last packet's
closing F7,
there's 1 SYSEX message there. [... see URL above for more info ...]
SMF segmentation works the way it does in order to record streams
from the old hardware that used this feature ... which is why the RTP
MIDI design also lets you transcode this idiom accurately.
However, I think its safe to say encoding information in the
timing of octets of a SysEx command is not recommended
for new MIDI designs.
---
John Lazzaro
http://www.cs.berkeley.edu/~lazzaro
lazzaro [at] cs [dot] berkeley [dot] edu
---
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