I'm sure you are correct about the advantages and disadvantages of the
different protocols, but using USB with MOTU's MTP AV interface (along with
FreeMIDI and Digital Performer) allows me to take advantage of the "midi
time stamping" technology that MOTU has developed, and the reduction in midi
slop is audible. I have a Mac (beige G3/466 with Orange Micro USB/Firewire
PCI card and mostly use SoundDiver 3.02 to access all of my synths and sound
modules. I have no problem with 2-way communication with the AN1X using SD -
just AN1XEdit doesn't allow me to receive data from the synth. I would
prefer to use AN1XEdit because the interface is better, but I can't unless I
switch to serial comms, which I don't want to do. Please don't take this as
a criticism - I have the highest respect for software gurus such as
yourself, and I know it isn't easy to address every combination of hardware
out there. Best regards --- Jim Weisbin
----------------------------
Jim Weisbin
jim@...http://www.savagetranscendental.com"Gary Gregson" <
gary@...> wrote:
> 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.