Paul,
My understanding is that its not a case of bandwidth (MIDI only needs
31.25KBits/s)...its a case of the underlying protocol used to deliver the
data. Both Serial and Parallel interfaces have handshake protocols
(implemented in hardware). This means if you try to overrun the receiving
device it can hold off further transmission until its ready.
Many USB MIDI devices appear to operate on a 'fire and forget' scheme...they
expect the receiver always to be in a state where it is ready to accept
data. However, in the case of USB MIDI there is a step transition of
bandwidth. ie. at some point you have to go from the 100Mbps of USB, to the
31.25KBits/s of MIDI. Unless the interface designers have done some clever
stuff, this can cause big problems.
Typically I have found most USB devices work fine for simple MIDI
playback/record. However when you start putting heavy demands on
them...particularly involving large amounts of sysex....then problems occur.
The net result is often that data is lost due to receiver overrun (or other
glitches).
The An1x uses big sysex packets for transferring patch data and is very
sensitive to the packet timing. Consequently it tends to show up problems in
USB interfaces:-(
Perhaps if people with working USB interfaces (that can reliably bulk dump
AN1x data to/form the computer) would care to post a message...then we could
weed out the good ones from the bad.
Regards
Gary
Email:
gary@... http://www.yme.co.uk/yme-----Original Message-----
From:
dkblade@... [mailto:
dkblade@...]
Sent: 15 February 2001 10:18
To:
AN1x-list@yahoogroups.comSubject: [AN1x-list] Re: MIDI Interfaces - avoid USB?
Hey there,
I really don't see how the interface between the PC and the MIDI port
could make a difference. USB supports over 100Mbps transfer rate,
compared to 112Kbps of serial and 5Mbps of parallel. Er...greater
bandwith = higher timing resolutions possible = more accurate. But
it's besides the point. The timing is determined by either your
sequencing software or your master midi clock, not by interface.
The only reason not to get USB midi port is possible
incompatibilities with software, but mine works great :)
Cheers,
Paul Kabzinski