jeamsler
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RE: MIDI "Jitter" - It Does Exist
2008/09/15 12:26:32
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ORIGINAL: Jim Wright
Hi Jon,
What kinds of MIDI interfaces are you testing?
USB 1.0 protocols uses a 1 millisecond 'frame rate', so under best-case circumstances, events will be quantized to a 1-millisecond window. USB 2.x supports micro-frames (0.125 millisecond rate), so in theory quantizing effects could be smaller.
If you're testing MIDI I/O on a Mac, using a non-timestamping USB MIDI interface, I would expect the lower jitter bound to be around 1 millisecond, more or less. That doesn't mean you'll get such tight timing in practice - that's just the best you could expect if the rest of the software was working with very close tolerances..
Of course, under Windows, many apps probably still use the 'Windows multimedia timer' (MMT) - which has a nominal accuracy of 1-millisecond, but is not very precise (ticks can be delayed for lots of reasons, and then 'delayed' ticks can be sent in a clump - speaking imprecisely here). An app that uses the MMT for timing and USB MIDI for MIDI I/O will generally exhibit worse jitter than an app that uses the MMT and a PCI-based card for MIDI I/O. (Reason: jitter effects are cumulative).
- Jim
Hi Jim I have used many interfaces over the years but the best ones and quickest have been the Lynx One and an ensoniq Audiopci(which is much like a SB). Both are very quick and stable. Yes usb stinks though you can get respectable interfaces sometimes but usually not. Yes with timestamping you can get things better but that to me is a work around for os issues and you have to get specific hardware and use specific software. I'm measuring the midi data itself coming out of the interface so again it is not exactly as it might appear. The sequencer is trying to keep the data in tempo so it has to overcompensate to do it. If the an event was delayed say 1ms then at some point that has to be made up by pushing an event 2ms. Things would actually be better if after the 1ms delay the sequencer simply played in tempo from then on rather than accelerating to make up the difference. At least that is what I'm seeing in the raw data coming out of the interface. It is very consistent and correlates well if you simultaneously record it into another sequencer and compare. Here is another good example of timing tests that deal with the raw midi data. http://www.cs.hmc.edu/~bthom/publications/NIME_04.pdf Good stuff and somewhat similar to what I'm doing though I'm focusing on the sequencer playback itself. Jon
post edited by jeamsler - 2008/09/16 10:00:19
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Tom F
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RE: MIDI "Jitter" - It Does Exist
2008/09/15 12:51:45
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ORIGINAL: Jim Wright
>> transfer of Note On/Off command takes from 0,64 to 0,96 ms via MIDI and from 0,64 to 2,464 ms via DCB....
DCB ?
- Jim
thats an old propietary standard similar to midi that was used by roland in the days of the juno/jupiter era... actually it didnt make it against midi... cheers
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Jim Wright
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RE: MIDI "Jitter" - It Does Exist
2008/09/15 14:33:32
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ORIGINAL: info@tomflair.com
ORIGINAL: Jim Wright
>> transfer of Note On/Off command takes from 0,64 to 0,96 ms via MIDI and from 0,64 to 2,464 ms via DCB....
DCB ?
- Jim
thats an old propietary standard similar to midi that was used by roland in the days of the juno/jupiter era...
actually it didnt make it against midi...
cheers Oh yes, I'd forgotten about that one. There was also an "Oberheim System" interface (pre-MIDI) that used parallel rather than serial data transfer. The Oberheim interface was much faster than MIDI DIN (I don't have numbers handy), but had several drawbacks: - It was not ground isolated (MIDI DIN uses opto isolators). In practice, it was easy to blow out the interface electronics at a gig, if electrical grounds were at all funky. Roland DCB seems likely to have the same problem, based on the connector pinout I just Googled.
- The parallel interface circuitry cost a lot more than a MIDI DIN interface. Since MIDI was intended for use in products with street pricing as low as $200 or less (1982 dollars), the cost of the parallel interface was prohibitive.
A couple of points about MIDI DIN and Note On/Off messages. - The times given (0,64 to 0,96 ms) are correct for sending a 2-byte (Running status) or 3-byte message over MIDI DIN.
- Those times don't include overhead for MIDI processing in a typical computer. Add at least another 1-2 milliseconds for 'modern' workstations / operating systems.
- Dedicated hardware boxes can certainly do better. I built hardware in the late 80's that could process MIDI with no more than 0.4 milliseconds added latency (for smart MIDI filtering, etc), using an 8 bit micro and no Windows or OS X overhead. The Akai MPC products have pretty low-jitter MIDI capture/playback, AFAIK (some of the Roland Microcomposers may also be good; I'm not sure).
- USB MIDI (in 2000, when I tested it), had latencies in the range (5,15 ms to 12,65 ms) under typical load conditions. Current USB MIDI is better (according to tests by Martin Walker/Sound On Sound), but still not as good as good PCI-based MIDI interfaces.
- Jim
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Tom F
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RE: MIDI "Jitter" - It Does Exist
2008/09/15 14:53:27
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ORIGINAL: Jim Wright
ORIGINAL: info@tomflair.com
ORIGINAL: Jim Wright
>> transfer of Note On/Off command takes from 0,64 to 0,96 ms via MIDI and from 0,64 to 2,464 ms via DCB....
DCB ?
- Jim
thats an old propietary standard similar to midi that was used by roland in the days of the juno/jupiter era...
actually it didnt make it against midi...
cheers
Oh yes, I'd forgotten about that one.
There was also an "Oberheim System" interface (pre-MIDI) that used parallel rather than serial data transfer.
The Oberheim interface was much faster than MIDI DIN (I don't have numbers handy), but had several drawbacks:- It was not ground isolated (MIDI DIN uses opto isolators). In practice, it was easy to blow out the interface electronics at a gig, if electrical grounds were at all funky. Roland DCB seems likely to have the same problem, based on the connector pinout I just Googled.
- The parallel interface circuitry cost a lot more than a MIDI DIN interface. Since MIDI was intended for use in products with street pricing as low as $200 or less (1982 dollars), the cost of the parallel interface was prohibitive.
A couple of points about MIDI DIN and Note On/Off messages.- The times given (0,64 to 0,96 ms) are correct for sending a 2-byte (Running status) or 3-byte message over MIDI DIN.
- Those times don't include overhead for MIDI processing in a typical computer. Add at least another 1-2 milliseconds for 'modern' workstations / operating systems.
- Dedicated hardware boxes can certainly do better. I built hardware in the late 80's that could process MIDI with no more than 0.4 milliseconds added latency (for smart MIDI filtering, etc), using an 8 bit micro and no Windows or OS X overhead. The Akai MPC products have pretty low-jitter MIDI capture/playback, AFAIK (some of the Roland Microcomposers may also be good; I'm not sure).
- USB MIDI (in 2000, when I tested it), had latencies in the range (5,15 ms to 12,65 ms) under typical load conditions. Current USB MIDI is better (according to tests by Martin Walker/Sound On Sound), but still not as good as good PCI-based MIDI interfaces.
- Jim
thanks for the additional facts - usb ..to 12ms...wow that scares me ! but i wouldnt ever use a usb midinterface anyway....maybe i should bring my atari st520 back from the garage :-) anyway i just got a yamaha rx7 and i will use it to sync (via midi2cv&roland sync) my old synths and the 808 ....i am really looking forward to jam with 4-5 synced units without having even to powwr up my pc ... hahaha !!!
post edited by info@tomflair.com - 2008/09/15 14:54:32
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Jim Wright
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RE: MIDI "Jitter" - It Does Exist
2008/09/15 16:56:10
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>> thanks for the additional facts - usb ..to 12ms...wow that scares me !
It's the jitter (7.5 ms peak) that was really bad, more than the latency (around 8 ms average).
However, these measurements are for first-generation USB interfaces (circa 2000).
Recent USB interfaces (Edirol UM-550, Emu 0404-USB) are a fair bit better.
For example, Martin Walker measured the MIDI latency of the Emu 0404-USB as 1.7 ms. He didn't report jitter; I'd guess jitter is in the 1-3 ms range.
Still not as good as a PCI-based interface (e.g. my Emu 1820M), but probably usable.
Also, these numbers do not incude any jitter contributions from OS timers (used to timestamp captured MIDI, and play it back).
For example, assume the MIDI interface has inherent jitter of 2 ms. Now, use OS timers with 1 ms accuracy to capture and playback MIDI.
Jitter for MIDI Capture will be 2 ms (interface) +1 ms (OS timer) == 3 milliseconds (total jitter on "live" MIDI data recorded by your sequence).
Now, play back the MIDI data. Additional jitter will be 1 ms (OS timer) + 2 ms (MIDI interface) == 3 milliseconds total additional jitter for playback.
However - the actual total jitter imposed on the original live performance will be 6 milliseconds in this case, because capture ('recording') and playback jitter are additive (3 ms capture + 3 ms playback = 6 ms total peak jitter).
6 ms jitter is quite audible if you have good ears, especially against something like a complex percussive background.
All of these numbers assume your system is tuned, drivers are up to date, and nothing (network drivers, anti-virus, etc) is messing up the basic timing accuracy of your system.
All of this is true for any DAW (sequencer) software running on a Mac or Windows PC. The numbers may vary a bit, but the principles are the same.
Since MIDI capture and playback go through MIDI interfaces (that add some amount of jitter) and MIDI events are timestamped using OS timers (that also exhibit some amount of jitter), you end up with less-than-perfect playback of a live performance. Since the live performance is played back through a similar process (using OS timer and MIDI interface) - more jitter is added during playback. I have no particular reason to think that Sonar is any worse (or any better) than any other Windows sequencer. Mac sequencers might provide better timing accuracy (Core Audio has some nice sequencer-timing support, and some MOTU interfaces claim to provide 0.3 ms timestamping accuracy), but I haven't tested them.
This is why (IMHO) the performance of each individual piece in the chain has to be really good, in order to produce an end result that is musically adequate.
- Jim
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Dan_E10
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Re: RE: MIDI "Jitter" - It Does Exist
2015/04/14 15:55:44
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I have been researching some midi latency issues I'm having and came across this excellent old thread. Anyone have any idea where things are with regards to midi jitter and latency in 2015 running under Windows 7? Directsound is mentioned in this thread as having the ability to timestamp midi events. This doesn't seem to be applicable, at least for Win 7 64bit which I'm using. Do most modern audio interfaces perform time stamping of the midi events now? Does Sonar X3 recognize these time stamps? The Emu 1820M is mentioned in this thread at least a couple of times by Jim Wright as having good jitter and latency performance. I'm still using this interface, but it doesn't have anything other than beta drivers for Win 7. I wonder if its performance is still high in Win 7...
Dan
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brundlefly
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Re: RE: MIDI "Jitter" - It Does Exist
2015/04/14 17:29:09
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I was running an E-MU 1820m at the time of this thread as well. It did have excellent MIDI performance, but the x64 beta driver proved very unstable for me, and a hardware fault eventually forced me to dump it. I'm now back to using my MOTU MIDI Express XT USB which is much slower, but jitter continues to be a non-issue for me now as it was at the time.
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Earwax
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Re: RE: MIDI "Jitter" - It Does Exist
2015/04/15 20:59:37
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Dan_E10
I have been researching some midi latency issues I'm having and came across this excellent old thread. Anyone have any idea where things are with regards to midi jitter and latency in 2015 running under Windows 7? Directsound is mentioned in this thread as having the ability to timestamp midi events. This doesn't seem to be applicable, at least for Win 7 64bit which I'm using. Do most modern audio interfaces perform time stamping of the midi events now? Does Sonar X3 recognize these time stamps? The Emu 1820M is mentioned in this thread at least a couple of times by Jim Wright as having good jitter and latency performance. I'm still using this interface, but it doesn't have anything other than beta drivers for Win 7. I wonder if its performance is still high in Win 7...
Dan
I use an Emu 1616m PCMCIA laptop system to play BFD2 "live" on a Windows 7 64-bit laptop. It is imminently playable, with no jitter issues to speak of. Very gratifying and quite fun to play. Sounds fantastic, too.
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konradh
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Re: RE: MIDI "Jitter" - It Does Exist
2015/04/15 23:39:46
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There is a well-documented jitter bug in Sonar.
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Doktor Avalanche 
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Re: RE: MIDI "Jitter" - It Does Exist
2015/04/15 23:41:01
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Documented well where? :)
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konradh
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Re: RE: MIDI "Jitter" - It Does Exist
2015/04/15 23:54:45
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It was a joke: jitterbug. Well, I should say, it was *meant* to be a joke. 
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Doktor Avalanche
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Re: RE: MIDI "Jitter" - It Does Exist
2015/04/15 23:56:35
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Darn I had the elbow grease on standby..
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RobertB
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Re: RE: MIDI "Jitter" - It Does Exist
2015/04/16 00:16:13
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konradh
There is a well-documented jitter bug in Sonar.
Well played, Konrad.  Made me laugh.
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lfm
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Re: RE: MIDI "Jitter" - It Does Exist
2015/04/16 02:31:48
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Easy to test the core of midi like this:
Make a loopback cable from midi out to midi in(on whatever ports you've got.
Play back one midi clip - and record to another track.
#1.Compare what you've got if they line up - this is roundtrip latency.
#2. then nudge recorded clip till they line up - and compare of all notes are in the same spot on each clip
Any deviance is what we might call "jitter" or part of limitations in midi as such.
To my surprise I found the RME internal midi port as out was slower than my EMI Xmidi 2x2 on usb.
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tenfoot
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Re: RE: MIDI "Jitter" - It Does Exist
2015/04/16 07:09:29
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This is a very old thread. I remember many problems years ago, but surely midi timing issues are a thing of the past?
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Jon Bryson
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Re: RE: MIDI "Jitter" - It Does Exist
2015/04/16 17:45:39
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Well, I found this thread also recently and wonder if it's an issue I experience with an Akai lpk25 keyboard. The timing when I play it back is atrocious so quit using that particular keyboard.
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Dan_E10
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Re: RE: MIDI "Jitter" - It Does Exist
2015/04/17 08:57:13
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tenfoot
This is a very old thread. I remember many problems years ago, but surely midi timing issues are a thing of the past?
That's what I'm wondering. At the time of this thread, PCI and Firewire seemed to offer better performance than USB. However, I was this thread before the advent of USB2 audio interfaces? I don't remember when those became more common. Has anything changed on the OS side to improve midi performance? I'm guessing not as midi for games is even less common now than it was in 2007. Maybe developers such as Cakewalk have developed kernel level api's for midi? Maybe the 1-2ms jitter level has just been acceptable with consumers and things haven't really changed since 2007? Dan
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brundlefly
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Re: RE: MIDI "Jitter" - It Does Exist
2015/04/17 10:28:28
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I found jitter with the 1820m to be sub-millisecond at the time for discrete events. I bigger issue is the delay of messages that are intended to be sent simultaneously in due to serial transmission which has not changed for hardware though soft synths rendered from existing MIDI tracks may not be subject to that. I'd have to check.
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Cactus Music
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Re: RE: MIDI "Jitter" - It Does Exist
2015/04/17 11:01:58
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Even though this is an old thread sadly enough the issues are still the same. It's still all about the hardware/ connection /drivers/ software. That remains a variable as there is thousands of combinations of the four.
I think that most of us do not notice the tiny amount that may be present even on a top notch set up. And because we tend to quantize the crap out of midi it not an issue at all. It's more an issue for people playing soft synths live.
Generally when someone is having issues with MIDI Latency it's because they have a plug in like the LP 64 EQ or Multiband running.
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brundlefly
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Re: RE: MIDI "Jitter" - It Does Exist
2015/04/17 11:36:19
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Cactus Music
And because we tend to quantize the crap out of midi it not an issue at all.
I look at this other way around; because I tend not to quantize the crap out of MIDI, typical levels of jitter/delay in the system are masked by the natural variations of a live performance. Based on my own long experience of recording and analyzing my own performances and some performances of others, I'm fairly confident that the vast majority of users who believe that SONAR does not capture and/or playback their performances with sufficient precision are deluded about the precision of their playing. Or their environment has issues that are not typical. If you have a keyboard synth, you can easily check this precision by recording simultaneous audio and MIDI from a hardware synth under Local Control and then re-recording audio from the synth being driven by MIDI playback. Audio timing can't be variable (clicks, pops and distortion would result), so if the MIDI timing matches the original audio track, and the two audio tracks match each other (after compensating for MIDI and audio latency), it's all good. Of course, this test assumes that the response of the keyboard synth itself is fast and consistent in both directions - not always a good bet - but you don't need to worry about that unless you find problems.
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AT
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Re: RE: MIDI "Jitter" - It Does Exist
2015/04/17 12:21:27
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If you are talking milliseconds then my playing is way too slow (or just plain bad) to notice any problems.
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Jeff Evans
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Re: RE: MIDI "Jitter" - It Does Exist
2015/04/17 18:16:56
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brundlefly
I was running an E-MU 1820m at the time of this thread as well. It did have excellent MIDI performance, but the x64 beta driver proved very unstable for me, and a hardware fault eventually forced me to dump it. I'm now back to using my MOTU MIDI Express XT USB which is much slower, but jitter continues to be a non-issue for me now as it was at the time.
What do you mean by slower. Slower what? It either works or not I suspect. The reason I ask is I have just built a new machine and I am needing a new midi interface as I am running Win 7 64 bit. There are not many drivers out there for an 8 IN/ 8 OUT interface except for the MOTU. So for me this is one of the most obvious choices.
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Cactus Music
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Re: RE: MIDI "Jitter" - It Does Exist
2015/04/17 20:41:04
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Hey Dave , yes that's the part I guess I meant buy playing soft synths live, in other words real keyboard people. I'm talking about us guitar players who DO have to use quantizing or you'd certainly not be able to use my tracks :) This is say, a simple organ or string part. If I play piano parts they never get beyond 4 notes at a time, nothing faster than a 16th note. I've recorded and edited the midi from real piano players and I would not even attempt to quantize that! I will manually correct the odd clunker in those cases. So I totally follow what real keyboard players would be dealing with. When I record ( real) bass I have to use headphones or stick my head close to the monitors because I can't stand the delay it takes the sound to travel 3 feet!!! Just kiding, but it sort of true if your a timing freak. And I've stopped quantizing my drum parts since I got my Yamaha DTX kit. I only quantize the Kick now. I find my snare and hi hats are just a hair ahead of the beat and that seems to be where they belong to my ears. I'm finding my midi set up is now as good as it was on my Atari so I'm happy again.
post edited by Cactus Music - 2015/04/17 20:52:54
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tlw
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Re: RE: MIDI "Jitter" - It Does Exist
2015/04/17 22:01:01
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Human keyboard players (or any other musicians) aren't entirely accurate in the first place, nor do they repeat the same note pattern with exactly the same timing every time.
A few years ago I saw a documentary that was primarily looking at reaction times, "muscle memory" and transmission of commands via our nervous system.
One of the things they did was high-speed video concert pianists playing the same music multiple times. When the video was slowed down it turned up a couple of relevant things. Taking a five-finger arpeggio as an example, once the thumb hit the first note then the timing of the other four fingers hitting the top of the keys in turn was consistently within a 3-5 millisecond bracket. Which the researchers thought an amazing level of repetitive accuracy. That first note of the arpeggio however varied in its timing placement by as much as 15ms.
The conclusion was that once a well-learned muscle movement pattern starts it can have very tight and consistent timing within the pattern, but outside such patterns things get sloppier. Which is why I guess we practice, to make as many muscle patterns "automatic" and cut down the "what do I do next" bit to as short as possible.
In other words, sweating about a few milliseconds of MIDI jitter when playing live is probably pointless because the human part of the equation isn't that accurate in the first place. After all, how many guitarists can play in time when five feet from their speaker cab but find their timing goes to pieces once they get eight feet away?
Sonar Platinum 64bit, Windows 8.1 Pro 64bit, I7 3770K Ivybridge, 16GB Ram, Gigabyte Z77-D3H m/board, ATI 7750 graphics+ 1GB RAM, 2xIntel 520 series 220GB SSDs, 1 TB Samsung F3 + 1 TB WD HDDs, Seasonic fanless 460W psu, RME Fireface UFX, Focusrite Octopre. Assorted real synths, guitars, mandolins, diatonic accordions, percussion, fx and other stuff.
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Jeff Evans
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Re: RE: MIDI "Jitter" - It Does Exist
2015/04/18 16:11:04
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Midi jitter is only one aspect of midi performance. And on its own with just one instrument involved it may be insignificant and not affect the performance unduly.
But there are other aspects of midi especially when a larger number of external devices are involved and you are creating sequences where say 8 to 16 things are playing at once. As a composer coming from background as a drummer I am rather over sensitive to timing issues so for me it has always been about all these things coming together very well in groove and time and feel.
If you have a midi interface with 8 OUT ports then you should be good to run at least one instrument per port to minimise and midi latency due to multiple channels being on one port. With this setup only one synth is on a port so it should take 1 mS to send a note on from the midi interface to the hardware.
Some parts in your sequence may be quantised but others may be completely live against the click. The DAW has to record and playback the live performances perfectly and accurately and to multiple sound generators and keep all that timing intact too.
So there is the issue then of how well the whole midi system performs driven by a computer that has also got many audio tracks under its control and a CPU that may be working hard doing it all while managing many plugins. The timing between the midi and audio should be strong and relentless and not vary in any capacity. That is the heavy stuff the total system has to keep under its control.
Some DAW's do this better than others and also some hardware configurations also work better I believe. For a long time I had audio being controlled over the PCI port and the midi over the serial port. That had been a brilliant combination and timing is rock solid especially when the audio side of the machine is working ultra hard.
But a new build for me involving Win 7 and 64 bit has left many of these midi interfaces out in the cold. So that is why I am keen on the MOTU Midi Express XT in order to make my newer setup work. It is the main option for me now. Currently I am using a nice RME PCI sound card now but the midi will be over USB instead. I am hoping that is going to work.
I have found Logic and Studio One to be strong in keeping midi timing not effected by heavy audio CPU usage. (but that was midi over the serial port so not sure yet about midi over USB) They also seem to record and playback midi performances accurately too. That is a critical factor I feel in the whole process too. I still feel it is better to keep audio and midi on separate ports too. It makes sense, just less for each port to do. Means better performance.
Midi on virtual instrument tracks driving VST's poses other issues. The fact the audio side of your DAW has to be allocated to making the sounds is one of them. VST latency can affected more on what the rest of the audio system is doing too compared to external midi devices running off its own port. Live input I mean in this sense. Fast computers really help in this area while audio processing can be done using external DSP such as the UAD system backing up your own main system.
Specs i5-2500K 3.5 Ghz - 8 Gb RAM - Win 7 64 bit - ATI Radeon HD6900 Series - RME PCI HDSP9632 - Steinberg Midex 8 Midi interface - Faderport 8- Studio One V4 - iMac 2.5Ghz Core i5 - Sierra 10.12.6 - Focusrite Clarett thunderbolt interface Poor minds talk about people, average minds talk about events, great minds talk about ideas -Eleanor Roosevelt
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Dan_E10
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Re: RE: MIDI "Jitter" - It Does Exist
2015/04/20 10:43:17
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Jim Wright
There needs to be a MIDI 2, but I don't think there would be enough interest now.
Oh, there's definitely interest. The standards folks are still working on "HD MIDI" (Google it) -- these things just take time to percolate. If HD MIDI doesn't happen, something else will come along eventually. Don't give up! (Not that this helps any musician struggling with a DAW today, unfortunately....)
- Jim
I just got to to this post by Jim so I googled HD Midi. It looks like it's still alive: http://www.midi.org/aboutus/news/hd.phpI wonder when or if we're going to see anything that supports it. I also wonder about the performance of Thunderbolt audio/midi interfaces. In this thread it seems like the concensus was that the old parallel port and PCI interfaces offered the best performance in terms of latency and jitter followed by firewire. USB was the worst but still able to get under 1 msec of jitter if everything was right. I wonder how Thunderbolt stacks up. Is it just a faster USB or does it allow some kind of synchronization like firewire does to help line up midi and audio? Dan
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mettelus
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Re: RE: MIDI "Jitter" - It Does Exist
2015/04/20 11:00:54
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brundlefly
[...] I'm fairly confident that the vast majority of users who believe that SONAR does not capture and/or playback their performances with sufficient precision are deluded about the precision of their playing. [...]
I am blinded by such a beacon of truth, but it is still far simpler to blame my computer rather than accept my own flaws!!!
ASUS ROG Maximus X Hero (Wi-Fi AC), i7-8700k, 16GB RAM, GTX-1070Ti, Win 10 Pro, Saffire PRO 24 DSP, A-300 PRO, plus numerous gadgets and gizmos that make or manipulate sound in some way.
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