The Yamaha AN1x Synthesizer mailing list

For those who are interested in further reading - there was a good 
article titled 'A Musician's Guide to USB' by Scott Wilkinson in the 
"Desktop Music Production Guide 2000" published by Electronic Musician 
about a year ago. If you can find a copy of this article you'll be able 
to read about the differing methods USB can use to transmit data and 
see why Gary's explanation is accurate - and parallesl so many of our 
experiences.

You might also have noticed Win users appear to have much better luck 
with USB + SysEx then Mac users - I have no scientific proof this is 
only my general impression. If time permits, I create some more SysEx 
dumps via USB - I still some old ones from the MIDIMAN 2x2 too.

Jon

--- In AN1x-list@y..., "Gary Gregson" <gary@y...> wrote:
> 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@y...
>      http://www.yme.co.uk/yme
> 
> -----Original Message-----
> From: dkblade@b... [mailto:dkblade@b...]
> Sent: 15 February 2001 10:18
> To: AN1x-list@y...
> Subject: [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