Synchronizing music recorded on two DVXs?

S

SantaCruzMichael

Well-known member
Hey folks,
Last night our audio recordist failed to show up for a live recording of a Hammond organ trio. (note: I wasn't responsible for hiring the no-show....)
We were expecting to slate two DVXs and a multitrack audio recorder, so I had to devise a quick fix.

We recorded two of the instruments into a tripod mounted DVX. The handheld cam had a wireless receiver getting the third instrument. All were close mic-ed to avoid audience noise.
Then a stereo flash recorder was used to get an overall sound seperate from the cameras. But I'm not counting on that little device for good sound.

So I will have two video tracks, with three relevant audio tracks. We should be able to sync the video using the visual of the slate (several very pretty ladies competed for the honor of slating each song....)
However, I doubt the sound of the slate will be audible on the instrument mics recorded to the camera.

Is there any hope of getting the three tracks sync-d up? My suspicion is, if they are off at all, it's going to sound like the whole thing was plugged into a cheap guitar "Chorus" pedal.

Suggestions?

Thanks,
Michael
 
The trick, of course, is to get the third mic synced with the stereo track. Likewise the handheld if you want to use it. The bad news is it's gonna be tough. Very tough. I could do it, with considerable effort, but I'm in NYC and I'm not cheap! I assume by your name you're on the left coast...

It has to be done by ear - no way around that. The 3rd track/audience mics have to be painstakingly listened to and examined on a DAW, then *precisely* slid into place (within a millisecond or two) then re-examined and re-slid at intervals to keep them in sync given the inevitable drift, while artfully crossfading the segments to keep it seamless. Otherwise it will, as you fear, sound like it's "chorused" - or worse.

It's expert level work, and not many people have taken the time to specialize in this sort of thing. I was fortunate enough to have been trained in it early in my analog recording days by a famous recording engineer I assisted who was particularly good at it. We used two tape machines and a varispeed control to do it then. But that's a longer story...

Unfortunately, music-to-music synchronization, especially if there is some of the same material in each element, is *vastly* more critical than audio to picture. Many people wouldn't notice audio to video sync mismatches of a frame or two, even more in some cases (like on many PBS news segments), but a tiny fraction of that amount will spoil music-to-music sync.
 
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Thanks, Ted
That confirms my suscpicions. I am going to listen to all five or six tracks tonight and see if I can find a solution that doesn't require music-to-music sync.

If I had it to do over again, I would have just put two condensers over the whole band....but we didn't have a matched pair....darn that audio guy for not showing up.
 
Ted, if you're still listening, here's a detail that might make the sync more possible.

You mentioned that it would be a harder sync if there's some of the same material in each track...
Well, the third track was a guitarist with a loud amp, mic-ed close with a Shure SM57. On headphones during the show, that track sounded very clean.

However, the Hammond organ mic might have picked up a trace of the guitar, since the AKG condenser on that had to be placed a foot or two from the leslie rotary speaker.

-Michael
 
To the extent that the guitar is isolated within its own track, and there's relatively little of it in the other tracks, you should be able to mix the two together much more easily. Electric guitar is an instrument on which a little "chorusiness" is usually tolerable, sometimes even desirable. If only a "trace" of it's in the other tracks you might get away with the whole shebang just fine.

Then it's a matter of finding common material in the two recordings, most likely between guitar phrases, and matching those spots up. You will still probably need to do this in several sections though, due to drift betweeen the cameras. Again, if the guitar is largely isolated, sync can be a tiny bit off and not ruin it.

Guitar is an instrument whose rhythmic specificity is somewhat less than let's say drums or percussion, which even in the absence of chorusing artifacts, will feel wrong even if they're only slightly off. Less so with guitar, especially electric, to the extent that it's distorted. Distortion takes away some "resolution" if you will, and makes it less rhythmically hyper-critical.

It sounds to me like you may be able to salvage the recording with some time and patience. Best of luck to you.
 
Michael,

there are many programs out there that will show you a precise audio wave form. My experience has been that there's always something available in the audio to use as a visual sync point. You just need to spot it. Sometimes it's an ambient sound between selections, whistling in the crowd or, a percussive downbeat that all performers hit together. You can do it in FCP if you expand the audio tracks enough but if not, I've had great success doing that sort of thing in Sony Acid. Any audio editor would probably do... Find your common "mark/pattern" in the waveform and simply note the movement in time necessary to match everything up and apply it when you get back into your NLE.
 
Holy moly!
Last night I sync-ed up the first song as a test and it sounds great. I might be able to get it a little tighter with Soundtrack Pro, but the guitar track is really clean and drops right on top of the drum mix and Hammond recorded on the other DVX.
Sounds a little more lush too, with the clean guitar track mirrored by a faint bleed in the drum condensors that's probably SLIGHTLY off time.

Yowsers!
Now I have four usable tracks to mix:
Track 1 - Condensor on Hammond organ rotary speaker
Track 2 - Drum mix
Track 3 - Close mic-ed guitar cabinet
Track 4 - On camera mic for a tiny bit of ambience (there's nearly zero audience noise in the main mix...) This is also fun to fade in a little between songs to get some audience reaction and musician chatter.

I had concerns, but now I'm really glad we tried this approach, instead of a pair of overheads or something.

Will post a link this evening once I put the footage on my server.

Thanks for the feedback guys!
Michael
 
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