MIDI and timing

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jdbakker

Well-known member
Joined
Nov 24, 2005
Messages
1,431
Location
Amsterdam, The Netherlands
I've a bit of a problem.

A good friend of mine has composed some songs, and she's asked me to help her record them. While she intends to use 'real' instruments for the final recordings (somewhere this summer), she wants to create demo versions ASAP using her MIDI synthesizer (a Roland JV-30).

Some parts of her songs are beyond the capabilities of the JV-30 (dropped/truncated notes etc). I have suggested her to record a separate track for each instrument group, which would also allow us to gradually move the mix from synthesized to real instruments (should those fit better in the mix).

Here's where the fun starts.

This afternoon we've started tracking the first song. After recording all instrument groups it became obvious that the timing for pretty much all tracks was way off. I'd aligned the beginning of the tracks, and five minutes into the song some instruments would be a second or so early/late. In an attempt to find the cause I recorded the same drum track three times in succession. All three would audibly shift back and forth compared to the other two, creating doppler/flanger-like effects. Nice, but not quite what I was looking for.

Now I mostly record live performances, so I've never had to deal with MIDI, and all my MIDI-knowledge comes from a fruitless three-hour Googling session. Does any of you know whether (a) this is normal for MIDI, (b) how to fix it or (c) whether I'm using the wrong tool for the job altogether? FYI, we're using an old PIII with XP, running a decade-old 16-bit copy of Score Perfect through an Edirol UM-1 into the aforementioned JV-30. I'm not quite sure which device, if any, provides clocking. None of the recorded tracks sound obviously wrong when auditioned by themselves; no tempo changes, no dropped notes, no hiccups.

Any ideas?

Thanks,

JDB.
[my current plan of attack is to record each song into a different sequencer over MIDI, and hope&pray that that fixes it. I've tried generating MIDI files directly from Score Perfect, but for some reason those lack note volume information when played through Windows Media Player to the JV-30]
 
Programs like Sonar and Cubase these days have a feature that comes up on start up, something to the effect of Wave Profiler that runs and assesses any inherent latency within your hardware and software and corrects for this.
 
[quote author="dshay"]Programs like Sonar and Cubase these days have a feature that comes up on start up, something to the effect of Wave Profiler that runs and assesses any inherent latency within your hardware and software and corrects for this.[/quote]
Latency I don't mind, I can correct for that. What I'm seeing is effectively jitter and/or time compression/expansion.

Plus, those tend to be for (sampled) audio paths, not MIDI, as far as I can tell.

JDB.
 
Sounds like it might be application specific. Cubase has this issue with native versus emulated midi ports. If you don't set up your midi ports and midi time stamping options correctly, you will experience problems similar to what you described, where the midi seems to wander around out of sync. It might be related to the standard windows midi driver. Maybe checking the cubase FAQ's at steinberg.net might help point you in the right direction.

-Chris
 
...Are these two sequencers free-running? -Or is one slaved to the other?

If there's no slaving involved, it's like asking if you can make a 4-track by hitting "play" on two 2-tracks at the same time...

Keith
 
[quote author="SSLtech"]...Are these two sequencers free-running? -Or is one slaved to the other?[/quote]
In the normal mode of operation only one sequencer, Score Perfect, is active. The hack I had in mind would have the second (recording) sequencer slave off MIDI, and then be re-wired to be the sole master on playback. I don't much mind some timing jitter, as long as neither her nor I can hear it; I just want the same jitter across all instruments.

At the moment I'm not sure whether MIDI clock is generated by the PC or by the JV-30. We're recording at her place, and she's left for the evening to see her parents, so I have no access to the setup until morning.

JDB.
[and when I was still there, I didn't know enough about MIDI yet to check who's the clock master. MIDI doesn't appear to be that difficult, but debugging is a bit involved when you can't run tests on the target system. So right now I'm downloading tools and doing research to get the procedure working as fast as possible once I get there]
 
If you're getting "a second" of timing errors, there can't be any functioning slaving... and I don't see any way top get stuff from one sequencer to the other any other way...

So unless I'm misunderstanding something, it soulds like your'e just set up wrongly... -It doesn't matter WHICH is master, so long as they;re marching in step. -If you do that, they'll NEVER go out of time.

It's nothing to do with latency, it sounds like there's no sync being followed.

Keith
 
Update:

Neither the sequencer (Score Perfect v3.1) nor the Edirol UM-1 MIDI interface driver have any options related to clocking or sync. I get the impression that Score Perfect is mostly a music notation program with MIDI recording/playback bolted on as an afterthought. In the end I replaced her setup with my P4M/1.8GHz laptop running the latest version of Score Perfect (v5) with a battered M-Audio Quattro USB for MIDI. I have not tested which of those substitutions produced the greatest improvement, but I have seen nor heard any more timing discrepancies between tracks.

I do not claim that this fixes the problem, just that the symptoms have now become benign enough to be unnoticeable.

JDB.
 

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