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I generally agree with Brian's statements.
... and sequencers certainly shouldn't preserve (slow) MIDI timings when
playing back on higher resolution interfaces such as USB.
I agree in principle with this, too. If I can shove 20 notes into a single
1ms USB Frame because they were intended to all play on the downbeat of the
bar, then I should do so.
If those notes are being sent to a synth with built in USB interface, then
the synth will receive them all at the same time and should play them all as
quickly as possible (ideally all at the same time). Hopefully the synth's
ability to parse and play the notes is better then the speed of classic
If those same 20 notes were being sent to a USB interface with a classic
MIDI output, then the interface will have to send them all as quickly as
possible within the classic MIDI speed (recognizing that the classic MIDI
limitation will be a bottleneck).
System Exclusive is an exception (as it often is). I'm not saying we
shouldn't speed up delivery of Sys.Ex.; I love the idea of quickly sending a
large Sys.Ex. message over a high speed bus. But it can cause problems in
some cases (my experience is on USB):
1. There are some devices that expect to receive Sys.Ex. with particular
timing. Speeding up the delivery of the data can cause the communication to
fail if particular timing is expected.
2. High speed interfaces like USB can transfer enough to data to quickly
fill the input buffers of a device with built in USB interface. MIDI devices
have never had to be able to receive and parse data at anywhere near the
rate of USB. This is a challenge to device manufacturers, larger buffers and
faster processors are required to truly take advantage of USB speed. Sys.Ex.
is a worst case scenario with largest packet sizes and often with complex
parsing/processing required. The buffers and processing speed necessary to
handle high speed Sys.Ex. might tend to be unreasonable overkill for
handling all other MIDI data 99% of the time. So such devices might tend to
NAK high speed Sys.Ex. transactions on a regular basis.
|>Re: Questions on data in MIDIPackets (From: RolandCorp R&D <email@hidden>)|
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