MIDI/audio sync problem. HELP!

[Wurlitzer]

If anyone can lend a hand with this, I'll be mighty grateful. Its doing my head in.

I have a project consisting first of all of a number of MIDI tracks. Some of these are triggering plugin synths within Sonar, some are triggering a JV1080, and some are triggering Gigastudio running on a separate PC, via MIDIoverLAN, which are routed back to the main PC via TDIF.

I bounce the plugin tracks to audio using Sonar's internal facility for this. The resulting audio is in perfect sync with the MIDI.

I record the other tracks to audio by bringing them all in to my Mixtreme soundcard, and recording from there to new audio tracks in Sonar.

When I play these back, they are ever so slightly stretched, so they drift out of time with the MIDI tracks and the plugin-derived audio tracks. I say "ever so slightly" because for the first minute or so they sound fine, then they start to sound a bit funny, and by the end of the song (about five minutes) they are about a beat behind!

Its definitely the plugin-derived tracks that are correct - the audio hits line up with the MIDI beats they came from. I can actually see on the screen that the other, recorded audio tracks are about a beat too long.

Some more details & thoughts:

1. All the recorded audio tracks are perfectly in time WITH EACH OTHER. Thus it wouldn't seem to be a problem with the JV1080, the second PC or MIDIoverLAN, because if one of these were at fault I would hear it out of sync with the other one. No, everything is gathered together perfectly by the Mixtreme in the main PC, but its like its then given a different timecode or something that is slightly slower than the original timing.

2. It wouldn't seem to be a latency issue, because if it were then the audio would be a consistent amount late all the way through (wouldn't it?). But its not, its fine at the beginning then gradually gets worse. So its like every beat is turned into 1.001 beats, and the effect is cumulative.

3. I have Sonar set to audio clock, in accordance with the instructions in the manual for using MIDI and audio together.

4. I tried using FIT TO TIME to shrink the recorded audio but it wouldn't do it by such a small amount. At any rate, I know this is not a viable long-term solution.

HELP!

[moskus]

Just a thought, why are you you recording from one PC to another (if I understood you correctly)?

[James Argo]

Wurlitzer...

It is latency... (or "faded latency"). I bet you use "gamers" soundcard, right ? And your problem is common. There are different way of process to "Bounce to track" (like you did with internal MIDI synth to audio) and to record from "out side". I dunno exactly how they work, but to solve his problem, you need better card (or driver) or record 'em in the same way (route your internal synth audio out back to line in). They will sync, but they will still "out of ticks" ofter certain amount of time. Get ASIO supported card, and you'll notice this problem reduced alot till you can't hear the delay between them.


Jaymz

[BluesMeister]

I may be getting out of my depth here, so please correct me if I'm wrong.

If the "gamer" card has fixed sampling rate of 48kHz and you are recording at 44kHz, the internal on-the-fly resampling in the "gamer" card causes the timing drift.

I believe that the only way to prevent this is to record everything at the "gamer" card sampling rate, then resample down to 44kHz on final mixdown. It doesn't help with music you've already recorded, but it will prevent future occurences of this irritation.

I'm sure I've read about his phenomenon many times, but I don't really absorb the information because it isn't an issue for me with my audio card.

If I'm way off-beam here, I'll just go back to sleep...

--
BluesMeister

[Wurlitzer]

I just found the answer, thanks to the very helpful FAQ at Cakewalk.com:

Options - Audio - Advanced - Timing offset.

Made for soundcards that don't report their timing information accurately to Sonar. It gives increments of one thousandth of a millisecond, and I was dreading the thought of having to get it right by painstaking trial and error.

But as it turned out, I tried it on -1 ms and it synced perfectly. Just recorded the bass part and it plays back in perfect time with the MIDI source. Trying some others now.

That the card is offset by exactly 1ms would seem an extraordinary co-incidence, unless its due to something perversly deliberate on the part of the manufacturers.

But just for the record, the Mixtreme is anything but a "gamer's" soundcard. Its a high-end 16 channel digital jobbie, which has worked fantastically for me until this little hiccup. The Cakewalk FAQ gives a list of cards known to have this problem - the Mixtreme isn't on there, but several other well-respected cards from M-Audio, Echo etc are.

In the course of trying to solve this, I did a search and found a LOT of posts from people with similar problems (including, I think, James, one from you - might have been from a long time ago). So if you have this problem, do have a look at this setting - its completely separate from the ordinary audio latency slider.

Ah, now back to work . . .

[Wurlitzer]

I run two PCs in order to run Gigastudio alone on one of them. This is a quite common - possibly even the normal - way to run Gigastudio, since it is very hungry for resources and also very prone to conflicts with other software. This way it has a whole machine to itself and works much better.

Sounds like a lot of trouble to go to, but its worth it for the incredible Giga sounds. I built both my PCs so they weren't that expensive, and the second one only needs a minimal spec.

I have it working very transparently now and it feels more or less like using one PC. Only its more powerful and more stable.

[James Argo]

Ah... it's not the first time I made a mistake . Please accept my appologies... And thanks for corecting me, Wurlitzer


Jaymz

[moskus]

We know, we know... :P