Audio slowly de-synchs from beginning to end of movie

[steptoe]

I know this has been briefly covered, but can somebody explain, technically if necessary exactly why this happens :

Playing the Cube (DivX) plays perfectly, checking various stages, audio and video are in synch

Convert to separate streams (audio and video), and encode using TMPGenc Plus, or any other MPEG encoder for that fact, just encoding the video, then using BeSweet to encode the WAV from VirtaulDun into an MP2

Check the output before encoding, using edit in TMPGenc DVD Author, or even after burning the result :

The audio in perfectly in synch to start with, but checking various parts again, especially near to the end of the movie, the audio is way off synch, guessing at about 1-2 seconds behind, so its unwatchable

Why the gradual de-synch of the audio ???

Technical advice or suggestions, even in-depth explanation would be grateful so I can try and figure a way around this annoying fact

Not all conversions do it, some are bearable, or perfect, so are terrible, its not as if its a constant factor, but the source DivX always plays in-synch right through ????

Thanks

[bugster]

Thie first thing that springs to mind from your description is framerate. Make sure the format/framerate you select in Tmpgenc matches that of the source file. If not then gradual sync loss as you describe is the result.

[Hardcoreruss]

Once you have extracted the audio, use it tmpgenc without running it through besweet.

[trojanrabbit]

What's happening is somewhere the video is remaining at 29.97fps, while the audio is getting changed to 30fps, so you get the gradual loss of sync. Since I don't know how the programs you have work I can't offer any advice other than check your program options to make sure it doesn't think you're working with 30fps files.

[Tommyknocker]

Click here.

[trojanrabbit]

Interesting.

Would that explain sync problems with DV files though?

[TheGr8Steve]

Don't know how long the video piece you're working with is. See if one is encoded with 48,000Hz or 44,100Hz and then being re-encoded with the other (which ever it's not). If it's a short video test, that could be the cause.