Audio Sync OK in DivX, then out of synch converting to MPG

[fiiido]

Hi all,
I have a DivX movie that is fine with regards to audio synch. I then use virtualDub to separate oout and create a .wav file. I then use TMPGEnc to combine the original .avi and the new .wav file. The resultant mpg has a ausio sync problem that gets worse towards the end. It starts of fine though.

Is there a way to stretch the .wav file to the same length as the video file?

Thanks in advance.
Mandeep

[ZippyP.]

Is there a way to stretch the .wav file to the same length as the video file?

Yes, in Goldwave it's called "Time Warp," and you can extract the wav file with Goldwave as well.

You'll have to calculate the video duration first, here's how:

Check the file information using Virtualdub then,

#of frames / frames per second = # of seconds for video

Convert that to H:MM:SS.sss

Plug your H:MM:SS.sss into Goldwave and do the Time Warp!

[cumminc]

be careful, i just spent weeks with synch problems. yes Goldwave, sound forge, etc etc can stretch audio, and offset audio , but it can only correct it if the video is a good source.

Any dropped frames, frozen frames etc then it will never be correct. believe me most problems i have see or encountered i bet my bottom dollar most are because the source is poor or faulty.

If your source is good and you still have constant or progressive synch probs there are plenty of good guides on how to correct it using Goldwave for progressive and my preference is BBMPG for constant synch (Where you only need to0 delay one or the other) because BBMPG seems good at maintaining and correcting synch when muxing.

[ZippyP.]

Any dropped frames, frozen frames etc then it will never be correct. believe me most problems i have see or encountered i bet my bottom dollar most are because the source is poor or faulty.

Agreed, scan and remove any bad frames first!

[Landtank]

load the avi file into virtualdub and watch for an error that the audio is of a variable bit rate. If it is you'll need to save it uncompressed and then re-encode it so the bit rate is constant, or at least that is what I do.

Rick

[ZippyP.]

load the avi file into virtualdub and watch for an error that the audio is of a variable bit rate. If it is you'll need to save it uncompressed and then re-encode it so the bit rate is constant, or at least that is what I do.

Extract it with Goldwave, less hassle.

[Anders_H]

But what if you don't get an error while opening the (divx)avi file in VirtualDub ??
I made a Dvd, converted with TMPGEnc and authored and burned with Dvd moviefactory 2.
Good sync all the way until about 40 minutes into the movie, now it's about 2 secs out of sync.

I've made a bunch of movies this way, they all worked fine except for this one.

[ZippyP.]

Find the spot where it goes out of sync and you'll probably find a glitch in the video, edit the glitch out of the avi manually using Vdub. Sometimes Vdub misses a bad frame when scanning, it happened to me.

[mats.hogberg]

Anders, there's some bad frames in the AVI where the audio/video goes out of sync, I'm pretty sure.
First, use VDub and scan for bad frames, then save out a new copy using direct stream copy for both audio & video. From now on, just use you new copy.
Extract the audio as WAV using either VDub (Direct stream copy) + convert to WAV with external app, or load the AVI in GoldWave and save the audio as WAV.
Use the AVI as video source and you WAV as audio source in your mpeg encoder.
And always stick to the same frame rate as the original AVI.
If you've downloaded the AVI specially over some P2P network, there's almost always bad frames in the AVI, and you have to scan for bad frames before doing any further processing.

/Mats

[AngusMacGyver]

Some words more:
In VirtualDub you have to convert that WAV to 16bits/44kHz/Stereo.

[mats.hogberg]

In VirtualDub you have to convert that WAV to 16bits/44kHz/Stereo.

Have to disagree - VDub is a great tool, but the best sound converter it aint. Better to get the audio stream using direct stream copy, then do all conversions with a (several?) dedicated sound tool. I don't trust VDub for audio tasks, that's why to extract the audio in the first place, innit?

/Mats

[AngusMacGyver]

OK. I meant to advice to remember that conversion.
By personal experience, I noticed when I didn't convert, "out of syncs" were created.
Another thing. It's not necessary having bad frames to have loss of sync when converting from Divx. Even perfect divx files may create sync problems in TMPGEnc.

Thank you for your experience share, Mats.

[mats.hogberg]

Well, the DivX's we (or is it just me? :P ) mostly come across, are dl'ed from some P2P network, and to my experience, a majority has some problems, that may or may not be detected by VDub, but are sure to create all kinds of trouble on their way to (S)VCD, sync problems most frequent. If it's not of a movie that's out of print, it's usually not worth the trouble trying to create a (S)VCD backup from a downloaded DivX of your scrathed DVD.

/Mats

[MaximumIce]

Hey,

In all honesty, it isn't worth the hassle trying to figure this out. I spent weeks trying with the same issue. There are just too many variables.
It could be frameserved incorrectly when the DVD is ripped,
It could be the Variable Bit Rate settings are off when ripped/converted
It could be that if the source file was out of sync, the person who ripped it may have resampled it to a different frequency to correct the issue or stretched it or displaced it in an audio editing program - in which case you would fiddle for days trying to figure it out....There are just too many variables,

My advice is....if the audio is messed, it's most likely the source file you are using. Try downloading another copy off the net, or try ripping it yourself from an original. It isn't worth the hassle man. I was trying this on Kiss of the Dragon for weeks. I finally gave up...but I learned a lot.

Good luck

Ice