As part of a summer research internship in computer music, I'm planning to do some latency and jitter testing on computer<->MIDI interfaces under Linux, Mac OS X, and MS Windows. In order to get a useful test, I'd like to cover the range of stuff that's actually being used out there, so if you use a computer<->MIDI interface for anything at all, it'd be helpful if you could give me some information on what it is. USB, PCI, serial port, anything that's actually being used (and that I can get my hands on) is of interest.

In case anyone's interested, the method I'll be using to test latency is described in:
James Wright, Eli Brandt. "System-Level MIDI Performance Testing." Proceedings of the International Computer Music Conference, 2001. Online: http://www.cs.cmu.edu/~eli/papers/icmc01-midiwave.pdf

See the paper for details, but a short summary: It's a hardware-based method, because it's considered more accurate than using software timers. The hardware device sends MIDI data to the interface into the computer, which routes it using a software MIDI-thru back out to the MIDI interface and to the hardware device again. The data is then recorded as an audio signal and compared to a reference stream in order to calculate latency and jitter.

I plan to basically follow that method without modification, except to extend it to cover more interfaces and operating systems (they only tested three interfaces, and only under Windows). There's a lot of questions in the computer music community about "what MIDI interface should I use for my system" but since they're mostly music-type-people rather than computer systems people, nobody seems to have bothered to spend much effort on answering that question thoroughly, so there's a lot of hearsay like "oh I hear the [blah blah] works well." So hopefully I can get a paper published (I don't have a PhD, but I'm working with a prof. who does, which helps in getting these things through peer-review I hear).

Hi Delirium, I'm not sure I get what it is exactly you're going to
test here. I have a computer that I use for MIDI and, (of course),
a MIDI device or two that I control with it. The MIDI "interface"
is nothing more than a cable that adapts the game port, to the
MIDI din connector. Is that what you mean? I can't imagine there'ld
be much difference between one and another.

Dex

Yeah that's what I mean, and that's actually really interesting 'cause I've never heard of a gameport one. The one we currently use is an external box with the din connectors on it that hooks up to the computer through the USB port. I've also heard of MIDI PCI cards and serial port <-> MIDI connectors.

As for differences between them, the paper I linked showed some pretty big differences between the USB and the PCI card interface. Well, big differences are relative, but on the order of 5-7ms is important for some people, especially if you're trying to do realtime.

Many of the Creative SoundBlaster series use the gameport on the card for MIDI also. They then sell a separate cable that has the classic PC joystick plug on end, and MIDI In and Out Din plugs on the other end.

My SB16, AWE32 and Live Value all work this way. I used ot dabble on the AWE32 quite a lot with a Roland Midi Keyboard (can't remember the model number) but I haven't dabbled on the Live at all, although I understand it works the same way.

Den.

My game theatre XP has standard Midi in/out ports on the external box sitting inbetween to my main monitors, but I have never had reason to use them yet.

I have a Roland SCC-1 which is an ISA 8 bit card with Midi In/out and an SC-55 built in synth. I can only use it with old hardware (any motherboard with ISA slots). Last time i tried, Linux was unable to use it properly (eats notes, etc). Only true DOS or Windows seems to handle it properly (using any regular MPU-401 driver).

I know there was also a "parallel port" device for midi connections. I suppose nowdays only PCI or USB should do.