View Full Version : Audio/Video out of sync?

01-11-2004, 11:42 PM
I've got a Beige G3 with a Targa 2000 card, OS 9.1. Final Cut Pro 1.2.5 goes out of sync, more and more, during the record phase. I play back the file, the beginning is fine, 20 minutes into the film, it's so out of sync I can't tell which is leading, the audio or the video. Does this sound familiar to anyone?

Chip Tredo


02-21-2004, 03:50 AM
When you say twenty minutes in, do you mean into an edited sequence, or into a contiguous video clip?

If you mean the latter; have you checked to make sure the capture settings match the recorded material? If the video was shot in LP Mode, for instance, the audio would be 32KHz, rather than the default for DV capture, which is 48KHz. If the settings are wrong, there's slightly more video than audio duration-wise, and it gradually goes out of sync.

02-24-2004, 04:12 AM
It depends on the kind of camera you used for filming. If it was a consumer model camera the problem lies there.
next time when you shoot your material use/rent a professional camera (mini DV) or if you can't do that try to shoot short clips with the consumer camera (5 minutes max) , the longer you shoot without a start/stop break on a consumer camera the more likely you are to get this problem.
The out of sync you are experiancing now (correct me if I am wrong) is exponentially , so the only solution without re-shooting your material is to cut up your footage into small pieces and manually sync the audio for every piece.?
Hope this helps.


02-24-2004, 01:53 PM
Perhaps not relavant, but my brother is a teacher that has lots of Jr. High students doing video projects with imovie and low end consumer cams, and he has commented about sync problems there too.

His solution:

Have a scratch volume that is used for a piece of a project; once done don't just delete the footage, but erase the volume. Cleared up sync problems for them completey.

Sounds kinda like voodoo, but if it works, an easy fix.


Charlie Don't Surf!

02-26-2004, 10:16 PM

I don't agree with your premise that a 'professional' camera is needed to deal with this problem. Mini-DV ranges from the entry level camcorder to higher end models, like the Canon XL series. That aside, I've gotten very long clips to import without sync problems, having only used a consumer level Canon ZR series.

Would the original poster please go into more detail about the situation? What kind of camera, media, etc.?

02-27-2004, 01:42 PM

yes you are right , when i shoot 5 tapes (not looking at the lenght of the "scenes") and then import them there's usually one tape that shows this problem.
Recently I found out that the big difference between consumer and pro cams is that a consumer cam will only "attach" the audio track at the beginning and the end of the shot.
Wich leaves the audio hanging between those two points and since audio and video in this case use slightly different means of counting (?) it can go out of sync.
Pro cams on the other hand "attaches" the audio every other second (as I understood it) for wich a pro cam has more hardware wich makes it even more expensive (apart from the pro chip and lens of course).

this is what I know if anyone can tell me more please do

02-27-2004, 10:13 PM
I've never heard of "attaching" anything. If that were the case, wouldn't batch capturing based on arbitrary in/out points be impossible due to sync issues?

As far as I know, when a clip is imported all frames are counted/captured, whereas audio is sampled at a specified rate. If the rate of capture doesn't match the rate at which the original audio was recorded, a sync issue will occur.

This has been my experience when dealing with audio that was recorded at 32KHz, while the default capture in Final Cut Pro is 48KHz for DV. A long clip captured under these incorrect settings would result in a shorter audio than video track.

02-28-2004, 05:16 AM
To extend upon what unclemac mentioned, ideally (or possibly necessarily), you don't want to be capturing to the boot drive. Even more ideally, you have a drive set up internally on either a fast ATA or SCSI bus, and is used exclusively for video projects. Why? To reduce chances for the drive to become fragmented, and keeping it off the system/app drive reduces the possibility of corruption, and allows it to be driven independent of the boot drive, so it will be that much faster. Speed is your friend because it will reduce the possibility of dropped frames, which is another cause of sync issues.

These are better-than-general-populous setups, and I've seen people do OK with a fast enough internal drive, or even a FireWire drive under some circumstances. Just some things to consider.

03-05-2004, 02:07 PM
mechanicalman is absolutely right (assuming the footage is DV. Analog footage can do the same thing, but that's off topic.) Almost all DV cameras have their default audio setting to 12bit(32KHz) so if you capture that footage into a computer with the standard capture setting of 16bit(48KHz) the audio will always drift. Capture 12bit audio at 32KHz, and 16bit audio at 48KHz and you will never have a problem.

Duh...ok, I just saw you are using a Targa card which is analog, so disregard what I said above since that only applies to capturing video over firewire. So then, even if you have a relatively fast processor (450+MHz) and a separate A/V capture drive, audio sync can still drift. FCP (even version 1.2) has the fix built-in. In the preferences, there is an AutoSyncCompensator option, set it to 3 mins. The raw captured footage will still be out of sync, but when you insert it into the timeline or canvas, FCP will fix it. It assigns audio blocks to specific frames during capture. I had that problem for years at about 50mins using the built-in a/v from a 7500, an XclaimVR 128, and an Aurora Fuse, all had success after changing the preferences.

[This message was edited by despaxas on Fri March 05, 2004 PT at 13:53.]

03-05-2004, 09:16 PM
Heh. My bad.

What is this ah-nuh-log you speak of?

03-13-2004, 06:08 PM
I haven't been getting the e-mail motifications on new posts for this topic. But the last post seems to address the situation better. I am not using digital I/O. I've got a Targa Truevision 2000 card. Just dumpling old VHS footage into the Mac to conversion to DVD.

We'll see how it goes... stay tuned. ;-)