MIDI "Jitter" - It Does Exist

Nick:

I agree about the WIPINWIG (What I Play Is Not What I Get) sometimes - I haven't thought about MIDI jitter as much as I have considered velocity issues between my old Ensoniq SD-1 that I use as a controller and the soft synth I am controlling. So you are saying you hear timing errors - is there a way to sync a controller to launch midi notes at specific times locked to Sonar and see if the triggered not drifts? There should be a way to do that eh?

-D

ORIGINAL: Nick P
I've had some heated arguments around here about the accuracy with which Sonar records un-quantized MIDI. To me, I don't think it's all that accurate - what I play in is not what I hear back.

So evidently, at least in that program, people were discerning MIDI timing error or "jitter". I definitely discern it in Sonar. Any comments on this?

Is your midi set at 960 ticks per quarter note? Otherwise you could be getting a whole lot of changes due to quantization error. 960 ticks should give you around 1 millisecond timing accuracy or less depending on your project tempo.

Midi devices I've owned that mentioned anything about Midi latency said that it's in the nanosecond range (meaning unnoticeable...)

You should be able to test if everything is the same by recording both your midi instrument as real-time audio and as midi. Then playback the recorded audio along with the re-triggered synth audio simultaneously. They will either be the same or they will be different. You may have to re-align clips and levels to get everything to playback in sync.

It is not just a Sonar issue. Look to your MIDI interface as well. Not all MIDI interfaces are as accurate in timing as we may think.

ORIGINAL: Nick P

I've had some heated arguments around here about the accuracy with which Sonar records un-quantized MIDI. To me, I don't think it's all that accurate - what I play in is not what I hear back.

Just as a point of reference, I notice one of the features of the latest Ableton "Live" software is:

" Improved MIDI Timing
The MIDI engine has been reworked and we were able to significantly reduce timing error (jitter) of recorded MIDI."

So evidently, at least in that program, people were discerning MIDI timing error or "jitter". I definitely discern it in Sonar. Any comments on this?

If you are using USB MIDI interfaces instead of Firewire MIDI Interfaces or PCI MIDI interfaces then you very well could be seeing jitter and timing errors. A lot depends upon the speed of the USB interface, the drivers for the USB device, and what else may be sharing the USB bandwidth if there are multiple devices on the same root hub with the MIDI device. This would be seen in any application, not just SONAR. There has been some very interesting discussion about this in the past on this SONAR forum. I believe Jim Wright had some extensive things to say about it and had done a lot of testing a few years ago.

MIDI timing is only a problem if you have an underpowered computer.

Nope. Sorry. Wrong, wrong, wrong, wrong, wrong. But thanks for playing 5ster.

Jim Wright is infinitely more knowledgeable in this area than I am, but it seems like we should have MIDI 2.0 available by now. When my mouse is transmitting data at a higher bandwidth than a MIDI connection, it's time to rethink the whole concept. The fact that you can't really play a large chord and have all the notes sent down the MIDI cable at the exact same time (MIDI is a serial protocol) tells you how limited it can be for real-time performances. As a keyboard-centric musician, I long for the day when the response is truly as snappy as my hardware keyboards.

BTW, my live setup is MIDI free and I've never been happier.

Great answers, all. I've been using MIDI almost since its inception circa 1982 (close to 25 years). I've been sequencing with all manner of hardware sequencers since 1986, and more recently software sequencing w/ 4 versions of Sonar. I definitely notice various sequencers being more or less accurate at recording and playing back un-quantized MIDI performances.

A couple of comments:

1) I am using 960PPQ. However I have recorded into MPCs w/ 1/10th that resolution (96PPQ) and gotten results which to my ears sound more accurate than what I hear with Sonar (maybe more accurately stated: with software-based MIDI recording solutions, since I've not tried other software products such as Logic, DP, Cubase, etc.). So from my perspective, clock resolution is not as important as marketers would have you believe. For example set a metronome at 120BPM. Listen to each beat and try to conceptualize it being divided into 96 parts. Now 960 parts. What's the difference. If MIDI were being recorded with perfect accuracy, 96PPQ would be completely sufficient.

2) As I understand it, MIDI is a relatively (being that it's now 2007) slow protocol, as well as being a serial interface. Since it seems that I was getting equal or better results 20 years ago, I must assume that Firewire vs. USB would not make a difference in terms of causing a MIDI bottleneck. Certainly it's a concern w/ audio, but I don't think so with MIDI. People have been sequencing with software-based solutions for at least 20 years, when computers were much, much less powerful than even today's budget models.

3) LOL, Dave, my PC's a little more modern than that.

My theory (completely unscientific), is that as these software DAW applications have gotten more and more bloated, they put less and less emphasis on tight MIDI timing in the rush to "gold-plate" the application. This combined with how a computer's OS deals with incoming and outgoing data (handling multiple housekeeping chores at once, but still in the final analysis, one at a time, such as mouse moves, screen repaints, etc...) just begs for MIDI timing to be less than 100% accurate. And why should a manufacturer put emphasis on it? Many Sonar users in this forum seem to be guitarists or bassists who are just thrilled to have audio recording available outside of an expensive commercial recording studio. Many users have no idea what MIDI is, how long it's been around, or how it differs from audio recording (get Scott Garrigus' book).

All I know is that my ears hear the difference when MIDI is recorded and played back accurately, versus sloppily, and I am very happy to see that at least one software manufacturer has acknowledged this issue, and has apparently done something about it.

I wish Cakewalk would put aside their rush to audio nirvana for a minute and do some serious MIDI recording and playback tests - i.e. have a seasoned professional keyboardist record MIDI data in real time into Sonar and at the same time record the audio into Pro Tools or something similar. Now record the output of Sonar's MIDI playback from the sound source again into Pro Tools. Compare the timing of the 2 tracks at a high level of magnification. I think a difference would be easily perceptible.

(Edited for grammar/spelling)

Wow! I thought I was an old man! You have approximately two years more seniority than me with MIDI. I think I remember a conversation with Susan and John where we were discussing some of the possible reasons why MIDI has lagged behind in innovation. It's still my theory that as long as it was the dominant medium there was no pressure to change. Then with the advent of Pro Tools and similar audio based mediums the focus had to change just so platforms like Sonar could keep up. That along with the fact that more and more platforms are geared toward the home studio. Now it seems they've noticed that there are in fact more people still using MIDI than was realized. The problem now is how to update MIDI without rendering all the MIDI products before obsolete. There are still the physical constraints to contend with. By the way, you're so old I'm sure you remember a company called SoftPacific that used to make some of the first software sequencers like Sonus for Apple and Commodore computers on 5 1/4" diskettes don't you? 2mb of storage space! I thought that was awesome!
-Rajay

For what it's worth, I was just doing some routing testing to check between the midi I'm recording, the audio that that midi is producing, and the sound of me actually whacking a drum pad. I set up a midi track and two audio tracks. I record the midi note being triggered, the audio from the drum brain, and the audio from a mic picking up my stick hitting the head of the drum.

I do these sorts of tests every so often to make sure that I understand what is being recorded and tell how close it is to what I'm playing.

I was impressed with how close they all were, actually, having experienced some midi to audio issues on my previous system.

I'm using a Layla 3G and a TD-20 drum brain. when zooming in as far as I can, and changing the ruler bar to display samples, I can measure the space between the three diferent recordings and it is REALLY tight. It's a little hard to measure the exact differences, but it seems like it's somewhere around 23 samples total diffefrence between the three hits - this is about 1/2 millisecond based on my calculations at 44.1khz.

I don't know how much it adds to this particular discussion, but I thought I'd throw it out here anyway.

There is also a switch in the ttsseq.ini file that allows you to adjust the "ignore midi in timestamps". In some cases, switching it ON (1) makes the midi tighter because the timestamp of the midi interface is ignored and instead stamped with the time Sonar got it.

A few points

1 - You will get MORE jitter if you use 960 PPQ. (huh?). Its true. If you want more reliable timing accuracy, then go with 480, or if you can, go even lower than that. The only downfall of lower PPQ is that you are introducing a very subtle form of quantizing to whatever you record. However, let's do the math:

at 120 BPM, that is 2 quarter notes per sec. That is 1920 ticks per sec, which is sub millisecond.

So right off the bat, changing to 480 PPQ will give you theoretically around 1ms tick timing.

However, what you need to know is that the Windows OS is not even capable of reliably providing timing even that low. Many tests and studies have been done about this. As soon as you try to get down to 1ms timing, or even somewhat higher...the error rate goes up...which is what gives you real jitter. This is particular true while recording your midi track from a midi keyboard. USB adds even more latency and jitter to the mix.

If you could, for example, live with say 5ms ticks, then the jitter is a lot less, because the OS timers can keep up with it more or less error free.

200 ticks per second = 5ms ticks. At 120 BPM that is only 100 PPQ.

Moral of the story, lower PPQ values will give you more reliable and error free, reproducible playback. It will play back more exactly what you see on your PRV. As you raise the PPQ, more and more jitter will be present. The downside is that if you want to nudge notes forward or backward by 1ms or whatever...then you need the higher PPQ and just have to live with the jitter. One situation where you might care about that is if you're doing film scoring or something where you need to line up beats on frames, etc.. Having more PPQ allows you to calculate tempos that are more accurate for those hit points. In that case, you're not using a midi keyboard to record, so the Windows OS crappy timers are not relevant. Also, once the midi track is recorded, if its playing back through a VSTi, then when the track is frozen or a mixdown is done, in theory there should be no jitter. If it has to play back through external midi gear or even using a virtual midi cable inside the PC...then the jitter can be bad and there is not much Cakewalk can do about it.

2 - Cubase is notoriously worse

timing problems exist on the Mac also, don't kid yourself. If you want more accuracy, use hardware. In the old days a lot of people using macs used to let their MOTU midi timepiece act as the master midi timer and have the mac slave to it. This was more reliable as somehow the interrupt received by the mac, from the hardware somehow forced a less jittery performance.

But also don't get down about it. The timing these days is remarkably good on both OSX and XP and as I said, if you're using soft instruments, then they should all be mixing down without jitter. The biggest issue today IMHO is the timing havoc created by using USB midi controllers. For this reason I use a parallel interface midi interface on my PC. If you're the kind of person that does not rely on real time performance timing too much and tends to quantize or program most of your notes to where you want them....most of this is a moot point.

I don't think I'm kidding myself but it certainly seems a lot tighter to me. i never have the sense that what's recorded is different than what i played like I sometimes get in windows - not picking on any particular app- they all seem the same in that regard and things like quantizing in Reason feel like I'm playing hardware, it makes me play tighter, seems to move me while I'm playing, while in windows apps I never really feel it when I play but only hear it upon playback. Purely subjective, but that's how it seems to me.

Ok, I stand corrected, I'm kiddin' myself, mac's midi blows, whatever. I only know what happens for me and that's as I've described. I'm not really interested in trying to establish some "objective truth" of the matter.
Good luck.

I hear ya there on all counts. That is definitely one reason people use MPC's. I have thought about getting one just for that reason. I also thought about picking up an older used thing like a Roland hardware sequencer or something like this. But in the end I decided that the timing on Sonar is perfectly adequate enough for what I am doing. All things considered, I think Sonar's midi timing is about as good as its gonna get on Windows due the OS limitations.

Depending on your situation and what you're trying to accomplish, you might be able to tighten things up in your studio through other means. What are you trying to accomplish? Describe your sequencing method and exactly when and how you experience the jitter.

Here are random suggestions

1 - Get a parallel or serial port based midi interface for your midi keyboard, do *NOT* use USB. This will help capture your realtime performance a lot lot lot more accurately.

2 - If you can't use the above, try PCI based midi

3 - lastly try firewire midi

4 - Try setting the PPQ lower as I suggested earlier.

5 - make sure you're playing back all midi tracks through VSTi's in sonar, nothing external to Sonar

6 - Freeze midi tracks into audio as soon as possible.