Audio Sync Problem

[briesm]

Okay, I took a DivX file and used Virtual Dub to extract audio. It gives me a message saying there's an improper VBR audio encoding in the source AVI file. It then says there may be some skew as a result. I decide to go through the burn anyway. I use TMPGENC and then MOVIEFACTORY 2.0 and burn. It starts out well but near the end audio is pretty far off by a couple of seconds.

VDUb mentioned decompressing the wav but I'm wondering if this movie file is basically a problem and the audio will be out of sync or if I just need to decompress or something to fix the problem.
Thanks

[kees1952]

Did you extract the audio in the correct way ? Or in the same way most people do: load AVI into VDub, hit File, Save Wav... and that's it. The audio tab will show "direct stream copy" and you'll end up with a .wav file wich is really an MP3.
The correct way: load AVI into VDub, set audio to "full processing mode", convert to 44.1 kHz if necessary, no compression and save as .wav file.
Load this wav file as audio in TMPGenc, correct the (constant) audio sync in the source selection part, and encode.
It worked for me and it's woth the try.

Regards, Kees Janssen.

[mats.hogberg]

load AVI into VDub, hit File, Save Wav... and that's it

No, that's not it - there's one more step before it's complete. You'll now have a .wav file that is not a wav file, but an MP3 (or AC3 or whatever it was encoded as before interleaved with the video). To complete this, you convert this non-wav wav to wav with your trusted AC3/MP3/whatever to WAV converter. Now you have a real wav, that you feed your encoder.

The correct way: load AVI into VDub, set audio to "full processing mode", convert to 44.1 kHz if necessary, no compression and save as .wav file.

My opinion (not fact, I'm only guessing here!) is that, since VDub complains about the VBR audio in the first place, and says it can't handle it properly, it will still have this problem when you use full processing mode. By decoding to wav outside of VDub, you work around its shortcomings. Using VDub to decode something it says it's got problems decoding does not. Maybe VDub handles VBR mp3 better when it doesn't have to deal with video at the same time, but to be safe, I always extract direct stream, then convert to wav with something else (CDEX for MP3).

/Mats

[kees1952]

@Mats
Reading my reply and the first part of yours it seems to me that we are talking about the same thing, distracting an audio part to a real .wav format. As the English language is not my native language I have to apologize for not using the right words or phrases to express myself. I just wanted to help by describing a methode that solved the same problem I've had.
In the second part of your reply you've got a point. Using VDub for something it complains about in an earlier stage is strange. But it works this way and you'll end up with a .wav part that gives you no (sync) problems after encoding. Perhaps other readers have some experience in using other tools for converting.

Regards, Kees Janssen.