sound and video do not match in virtualdub

[Umen Pich]

Please, help ! I spent 3 days, about 16 hours a day, working on a movie, and now I have this problem.

The story: I downloaded about an hour from my DV camera, (about 300 pieces (scenes). Then I marked which pieces to use, which pieces remain with the original sound and where the original sound should be changed with music.
Coding to divX, replacing the sound and merging was done with virtualdub. The sound is 32khz, 96kbps mp3 (by lame3).
Finaly I got 30 bigger pieces, each of them is ok and consists either of original sound or replaced sound.
When I merge these 30 pieces into one, which is supposed to be the final clip, the sound is totally displaced, e.g. a new scene starts, while the sound from the previous one still continues. Especially annoying is this when a person speaks to the camera in a close distance.

Any useful advice would be greatly appreciated, just don't tell me to throw virtualdub and start from the beginning with some other software. I would rather kill myself.

I guess the problem comes from the fact that the music which I put instead of the original sound was not EXACTLY the same length as the corresponding video. It was precise within for example 0.2-0.3 secs. And maybe during the merger, virtualdub merges the videoparts and the audioparts separately ??? Thus if you have (3s video + 2.5 s audio) + (2 s video + 2 s audio) you get ==> 5s video + 4.5s audio, but the audio of the second scene will start during the first one. Is that the situation ?? This is only a guess. I am not sure.
At the moment the theory is not that important, I need to solve the problem practically.

thank you very much!

[manono]

Is that the situation ??

Yep, that's about it. When merged, all those little audio pieces "slide" up against each other, and all those little 0.2-0.3 second differences add up to more and more of an audio asynch as the video goes along.

What to do? Well, you didn't want to be told to start from the beginning , so I won't tell you that.

There's an AviSynth solution, but since I don't mess with audio in this way, I've never had to use it. I think it's a combination of SegmentedAVISource and Aligned Splice:

http://www.avisynth.org/SegmentedAviSource
http://www.avisynth.org/Splice

If you don't get any better answers here, you might try over at Doom9 in the AviSynth forum.

[guns1inger]

That's why I do my editing in a real, timeline based editor. I love virtualdub, but I never use it for editing.

[redwudz]

If I read your post right, you converted to Divx, then merged the files? Unfortunately, you should have done all the editing and splicing in DV format, then merged, then converted to Divx. Divx is not a good format to be editing in.

The audio does have to be precise. .1 or .2 seconds doesn't sound like much, but it will cause sync problems if these errors start to add up. You may be able to put the sound into a audio editor and fix it. Audacity is freeware and will accept MP3 or WAV audio. But any way you do it, it will be a lot of work.

[Umen Pich]

guys,
I work on laptop (even without a mouse). the hard disk is only 60gb and I have about 20 gigs for this task. So editing in DV is just impossible. More over, I dont edit anything which is already in divx, I only merge.
Unfortunately avisynth cannot solve the problem in this case.
So I changed the times of all the sounds (uncompressed wav) to the exact values of the video lengths. Then I encode them in virtualdub and merge (video-->directcopy). What was my surprise to find that after that there again will be some difference between the audio and the video. This comes obviously from the mp3 encoding. At the end this difference is about 2 seconds.
I am desperate.

[Megahurts]

You might get lucky with AVI Joiner. Seven day Tiralware with a 2gig avi file limit located in tools section.

Chas

[Umen Pich]

manono,
thank you very much for the great idea to use avisynth !!!
I chained eveything with double pluses, then opened the avs file in vdub, then I set up the audio to full uncompressed and the video to some very small size, like 120x80 pixels. "Save to avi" and
then after 20 minutes I had this new file in which the important part was the audio. Then I "Save WAV" and got the correct sound I needed. Direct saving of the big wav from the avs input was impossible. Then the easy part -- merge my ready video with this sound by coding it to mp3 in the same time. Again in VirtualDub.

thank you !

[ZippyP.]

Suggestion: large external hard drive in a USB box.

[manono]

I'm glad you got it done. When you said originally that it couldn't be done in AviSynth, I knew you were wrong, but since I've never had to do anything like that, I was in no position to contradict you, or explain exactly how to do it. But you used the idea and modified it to get the job done. Good going. It may help me and others when I and they have similar projects with similar problems.

[Umen Pich]

Suggestion: large external hard drive in a USB box.

The suggestion is accepted with high confidence
I see the price is about 80USD for 250gigs + about 20USD for the box.