TMPGEnc DVD Author 3 gradually loses audio sync

[timmus]

I am having a annoying problem with TMPGEnc DVD Author 3 producing DVDs that have good audio sync at the beginning but drift toward the end of the program, reaching up to about 1-2 seconds of sync error. The sync errors start to become noticeable about 70 minutes in, and by 100 minutes are quite obvious.

The source file is a 122-minute AVI/DV Type 1 with PCM uncompressed audio, captured via WinDV over Firewire. I viewed this file it in VirtualDub and the sync is perfect at all points in the video file, so the problem is NOT the source.

The only issue I can think of is that the DVD track is 122 minutes long (equalling the length of the source video) but a lot of regular movies have 122 minute tracks with no problem. There has to be some other issue I should be looking at.

Tim

[tomlee59]

The cause still might be dropped frames during capture. The AVI container has metadata that can often mask that problem during playback. But when converting to MPEG2, the underlying problem can (re)appear. If the error is such that the sound is ahead of the video, the likelihood of this being the problem goes up. But regardless of the source of the error, you can fix the problem.

Often, the sync drift is well approximated as having a constant rate. In that case, using Audacity's "Tempo change" function can fix things nicely. In other cases, there is an abrupt change in sync error. Again, you can fix that with Audacity (this time, either add a silence or delete a small segment, as necessary). And of course, combinations of offset and delay can be fixed with a combination of these strategies.