Movies lose audio/video sync as they progress

I didn't read every post on this thread, but I skimmed through most of it. I have a couple ideas, though I can't guarantee either. (This post is too long and gets clipped, so I'll post the suggestions one at a time.)

1. The problem may or may not be partially Apple's fault with iMovie. However, I think some of the cheaper DV/analog bridges ("video grabbers") -- and maybe some cameras, too -- may see problems due to not having any embedded audio sync. The way I understand it (which may or may not be right), some players (usually cheaper ones) just play back the audio and video as a data stream and leave it to the software (iMovie) to keep it together. Some of the more advanced models actually include some sort of flags in the data stream to tell the software exactly where the audio and video sync. (Someone please correct me if my understanding is wrong.)

I use the Canopus ADVC-300, which features the "locked audio and video synchronization". I only upgraded to iLife '05 last night, so I haven't tried a long project yet, but it sounds like some people even had problems with iMovie 4, and I didn't, at least with 45-minute projects. You might look into getting a video grabber (or camera) that has the av sync.

I like my Canopus, but I got the 300 because of the video correction options. As I feared, these don't really work as advertised; they tend to either have no visible effect or actually make things worse. If you get the ADVC-110 or 100, you can get all the main stuff that the 300 has (including av sync) but without the video correction stuff, and the 100 or 110 is a lot cheaper. Apple has the 110 for $319, but you can get it on eBay for $235 (buy-it-now), or you might be able to find them even cheaper (especially if they're already used). The 300 is around $435 on eBay. Yes, Canopus is more expensive, but you get what you pay for -- they seem to be really good. (If anybody is really really concerned and considering buying one, I could try a 2hr project sometime soon and let you know.)

Canopus ADVC series:
http://www.canopus.us/US/products/ADVCselection_guide/pm_advcselection.asp

2. Requires QuickTime Pro. Export the video as a .mov, full quality DV (or find the reference .mov -- I can help you if you can't find it). Open that with QuickTime Player. Go to Extract Tracks (or similar -- I think in the Edit menu). First extract one track (audio or video), then do it again for the other. You'll get each track in a separate new movie window. Go to the audio track you extracted. Check the length and see if it matches the video one. If not, good (for this instance). If so, you may have to find where the audio actually ends, select the rest, and hit [delete] or cut (command-x) or something to get rid of the empty stuff. (That could be difficult if the end is quiet.) Select all (command-a), copy (command-c). Go to the plain video track you extracted. Select all (command-a). Now do a scaled add -- I think it's command-option-shift-v, but maybe just command-option-v. Hold down the modifier keys, then click in the Edit menu and look for something like "Add Scaled". If it isn't there, try different modifier keys. (Again, you need QT Pro.) This pastes the clipboard piece (your audio) scaled across to match the total length of what you have selected (the entire video).

I have not tried this method under the exact circumstances here; i.e., av sync error from iMovie or the video source. However, I have used it to match CD audio to music videos and things that were slightly off, and when stretching or shrinking the audio, it works very well. If you are a true audio professional, I think it will technically change the pitch and lose slight perfection, but seriously, especially without the original playing simultaneously, I don't think any human will ever notice a difference. (And technically, the audio was probably the part that got smooshed and wasn't perfect in the first place.) A few seconds over the course of even a few minutes becomes unnoticeable. And QT is good; you shouldn't get any hiccups in either track.

After verifying everything is synced the way you want it, save that version of the .mov (originally your video extraction, but now with audio). If you need to do further editing, you may have to export it to DV before iMovie will re-import it. But I think you can drop the reference movie (not the full-size original file) on iDVD (or certainly Compressor, if you have DVD Studio Pro), and it should work.

Obviously, this would be very annoying to have to do every time. And it may take several attempts to get the sync right if you don't know exactly where the end of the real audio is.

Other notes related to some posts in this thread:

Wow, everybody's planning on doing Star Wars conversions, eh? I also have the LDs -- The Definitive Collection -- and plan to eventually grab those and the LD Special-Ed and DVD versions and piece together the best of each. (Han shot first!) I figured out "stories" (as opposed to plain tracks) in DVD Studio Pro and plan to use the same video and let the user choose among several variations and combinations, like whether to include the Jabba scene in SW4 or not. But I need to finish up some other projects before I have time... And of course they still won't be the quality of the commercial DVDs.

Also, since iMovie 2, I have always made a backup copy of iMovie BEFORE upgrading. I got screwed the first time I upgraded to iMovie 3, because I originally had a Formac Studio for grabbing video, and iMovie 3 screwed up the audio from that. So I was using iMovie 2.1.2 until my Formac Studio got sick and I got the ADVC-300 for video grabbing. Seeing some of the problems with the new iMovie, I may stick with my backup copy of iMovie 4 for the near future. Anyway, I highly recommend keeping a backup copy of each major version of iMovie before upgrading. There is just too much history of problems in the new versions.

Brand new G5, and this is happening to me too at around the hour mark. iMovie 5, OSX 10.3.9. Things look fine in iMovie, but in the Quicktime and DV exports the audio is way out of sync by the end.

I called support and they gave me the same "should have captured in 16-bit" line, and sent me a support article on it. I'm editing 7+ hours of DV video, and I'm hesitant to recapture at 16-bit if people are still reporting problems.

This is a real drag.

MT

as far as the "locked audio" touted by Canopus, it doesn't really have any effect with this problem; it refers to the firewire protocol during capture and it's really a meaningless "feature" designed to make you think you should buy their product over someone else's.

Locked audio is DVCam, which locks the audio frame by frame.
Unlocked audio (which is DV) resets itself every second (30 frames), though typically it's only out by a frame or two.

The problem most people have with the audio going out of sync usually has to do with capturing with 12bit and/or using Canon cameras.

How many clips (approximately) are in your movie?

I've never had the audio go out of sync, but my projects usually have under 25 clips.

I'm going to create a 1 hour iMovie 5 project made up of 3 minute clips and I'll see what happens.

I have both iDVD5 and Toast.

I also have FCE and FCP, so I can compare.

So, you don't edit them very much/or at all, just drop whole big clips into the iMovie timeline?
You're not applying a bunch of transitions or titles either?
And, you've watched the iMovie from start to finish (not start and stop at points) to see that it does in fact play out continuously in iMovie without dropping out of sync?

(just trying to nail down all the variables)

What file do you use to import into iDVD?
(what steps do you take to go from finished iMovie project to opening/importing movies into iDVD?

can you email me?

I have some thoughts about where/why this is happening.

click on my name to see my emai address.

regards,

bt

'can you email me?'

PLEASE NO! Please keep the discussion in the forum !

Many of us are following this, it seems many have this problem, we need to get all the info and see if/how/when it gets resolved. Taking things off-line will hinder that. There are apparently a lot of variables - some people with problems, others without. Little rhyme/reason that I can see.

I'm about to undertake some big projects, and I want to avoid this problem if possible. I've subscribed to this list to stay on top of it.

Thanks, - ken