ORIGINAL: dstrenz

Interesting thread. Midi feels a little sluggish to me too nowadays. My Roland Fantom has a 16 track midi sequencer (I think it's only 192ppq), and it feels more accurate than PC recording.

BTW, there was something of a standard in Roland's MPU-401's 'Smart Mode', which would receive, buffer and time stamp midi input events in the hardware, and trigger interrupts to notify the PC sequencer that there is data available. Maybe the new MIDI 2.0 standard can borrow some from the ideas Smart Mode midi input handler in the MPU-401.

ORIGINAL: dewdman42
Getting a little technical, in Windows there is a timer that has historically been used, called a Multimedia timer. It is supposed to have 1ms accuracy. However, experiments with this timer have shown that it jitters all over the place in real world situations. Some tests even showed it like +-15ms...yikes! That was a few years back though before XP. In addition, if the software using it is not careful, then GUI use and such can make things even worse.

ORIGINAL: dstrenz

I actually had the Voyetra mpu clone too. As I recall, it only cost about $300 which was significantly less than Roland's. I too wrote a little 8-track sequencer (using smart mode) in Turbo Pascal, and asm for the interrupt handler. That was convenient because it only handled 8 tracks natively. It worked fine. Then I added some brain-damaged brute-force algorithm in a feeble attempt to generate music. I've got an old recording of it playing through an FB-01 but am too embarassed to post a link. What a terrible waste of time.

ORIGINAL: dewdman42
Regarding the older MPU-401. My understanding is that it did not actually timestamp midi events in the hardware. The timestamping of midi events happened in the card's driver software. However, those older midi cards were interrupt driven. So when a midi event came in, the driver would usually trump anything else that was running on the cpu to immediately timestamp the event in the driver. Personally I had terrible midi performance with an MPU-401 and early versions of cubase, so I can't say it was any better, but I know the driver is where most midi interfaces timestamp the events.

The difference with the MOTU interfaces is that they timestamp the midi event in hardware the instant it is received on the midi port, then the driver will eventually kick in and use the timestamp that was already created by the hardware. You still want the driver to react as quickly as possible because if you are playing a VSTi or something in realtime, you want low-latency. But the accuracy of the timestamp in that situation is based on an earlier timestamp that did not have to wait for the OS to give the driver time to do it. The only dependency is whether the MOTU driver passes the hardware timestamp along to the host DAW, which MOTU told me once that it does. So as long as the host software is using the timestamp created or recognized by the MOTU driver...then it should be the hardware one. If Sonar makes its own timestamp(which would be dumb), then jitter times would be much much worse and hardware timestaming would be moot.

Playback, however is another story.

ORIGINAL: evzevz

Dewdman - I don't mean latency, I mean playing back midi parts with correct feel and timing - really choppy and inconsistant timing... almost a stuttering, but always varied somewhat - in other words, loop over the same measure and it messes up differently every time thru.

ORIGINAL: RTGraham

I would say that this is due to the fact that some softsynths can't handle such high buffer sizes... at extremely high latencies, some softsynths just start getting choppy, like what you're describing. However, the fact that it was happening when sending MIDI out to you Roland hardware unit (as you mention in another post) makes me wonder what else could be going on.