matching audio with video

DV wave files

I have a 24 bit audio recording of an opera from Protools with separate R/L channels sampled 24 bits, and I want to edit it into a camcorder video that is DV format, NTSC, 29.97 FPS drop frame time coding. I resampled to 32KHz already, and I know how to mix into one stereo file, and how to insert the wave file into the video.

My problem is this. In the past, when I line up the audio and video, it’s OK at the start, but then the audio gets out of line with the video as the time extends. How do I synch these?

Mike Richmond

Its sounds like a frame rate issue. Im really not sure. Im not sure that audio even has something equilalent to a video frame rate but if it was different from the video then they would become more and more out of snyc as the video progressed. Im not sure how you could fix this. Sorry.

When you make a multiple-system recording you need to have known time standards for each recorder (audio, video). Some devices all accept a common external clock (eg video sync) to keep them locked. You didn’t mention what sync or clocking arrangements were used, so i’m guessing maybe none were, in which case your lock or lack thereof is dependent on a couple different crystals.

Anyway, that’s all history. The easiest way to fix your issue is to load the project into a PC video editing system, leave the audio alone and cut and re-sync the video to the audio as often as needed to look synced - eg every 3 minutes. This should take a half-day tops.

You’d need a good enough video I/O card and a video/audio editing program. Here’s a simple one: Multiquence

[edit] OK on review I’ve maybe underemphasised the complexity of video editing, but this still would be the 100% fix, provided you have access to good editing systems. (eg Avid)

You can try doing the math to figure out the mismatch (how much it goes out, divided by low long it took to go that far out of sync), and calculate a factor to expand/contract the sound to correct for that and try again… but it will take forever and may sound like crap when you’re finished.

I guess the chosen solution depends on how important the project is and your budget.