Audio Sync Problem Joining 2 AVI's Together from a 2 DVD Set

[boofer]

Hello,

I am fairly new to video editing. I finally decided to get some of our DVD's transfered on to my laptop for viewing on long trips. I have been using DVDDecrypter and AutoGK. The movies turn out great.

I recently transfered Lord of the Rings which is a 2 DVD set. Each individual movie turned out great. So, I got curious. I decided to see if I could join the 2 movies together. I tried using VDub, but the audio that goes with the second movie is out of sync. It leads the video by about 2-3 seconds. I am not using VBR audio which I have learned can cause trouble. Each movie plays fine by itself. It is only when I try to join them that I have the sync issue. I use the same settings in DVDDecrypter and AutoGK for both disks.

Any help would be greatly appreciated. I have spent the last 8 hours reading and searching before I decided to post my question.

[guns1inger]

I would try AVI Demux, which has worked well for me on the occasions that I have had to join clips. I have noticed on a few joins that the video slows down for a second or two, but soon gets back to normal sync remains true. Anyway, you lose nothing by giving it a try.

[manono]

Hi-

Movies which are spread over 2 DVDs sometimes have the audio of the first half shorter than the video length. When you join the second half, the audio "slides up" against the first half's audio, and it throws the second half off. In your case, there's probably a bunch of black frames, or some "Put in the 2nd DVD" type message, which doesn't have any audio in it at the end of the first half. You could have avoided the problem when decrypting by leaving out the chapter or cell at the end that didn't have any audio. But if you don't want to do the whole thing over again, here's what you do:

Open the first part in VDubMod and go File->File Information. Write down the lengths of both the video and the audio. There should be that 2-3 second difference you mentioned. Figure the difference exactly. What you want to do is to delay the audio in the 2nd half by that amount. Then when you play the second half by itself, the audio will then trail the video, but when joined with the first half of the movie, it'll be back in synch.

So, now open the 2nd half in VDubMod and set the Video for Direct Stream Copy. Go Streams->Streams List->right-click the audio->Interleaving->Audio Skew Correction, and Delay Audio Track by the right amount (1 second=1000 ms). Save it under a different name. Play it and the audio should now be playing after the video. Now join it with the first half, and if you did everything right, it should all be in synch when done.

I am not using VBR audio which I have learned can cause trouble.

It's nothing to do with VBR audio.

[boofer]

Thanks for the help.

manono, using your procedure worked. Although, I need to remember to remove the offset prior to saving the finished movie, lol. I am very pleased with the result. I was able to use VDub in lieu of VDubMod.

I am going to attempt to do your first suggestion. The first AVI does have a few seconds of black at the end. When I use DVDDecrypter I select the IFO mode and check "Include PGC Number" and "Include Angle Number." All other options I leave at defaults. Are these correct settings? And, in the list of chapters displayed by DVDDecrypter, would it be somewhat fair to say that the last chapter is the source of the black frames?

Once again, I appreciate your assistance and I will let you now how things turn out.

guns1inger, I have read many of your posts throughout the forum. I will keep your suggestion in my hip pocket. I am doubtful that one solution will be a cure-all for every situation. Thanks!

[boofer]

Just an update. I tried decrypting the first DVD minus the last chapter. It did not get rid of the black frames at the end of the first DVD. The last chapter (that was non-selected) showed to be only 10ms. Not really sure what is going on there.

But, I did get curious about the two good AVI files that I had and how I might be able to "work" them in VDub. I selected the first AVI. I set the marker at the beginning and then set the end marker only a few frames into the black frames. When I saved the file (direct stream copy w/ no audio offset), the result was an AVI that had matching audio and video duration. So, I loaded the new AVI and appended it with the second AVI and the final product was a completely in sync movie from start to finish. The scene change from the end of the first AVI to the second AVI is a little abrupt, but I can tweak the first AVI to allow a little more time in the "black."

It is interesting that the "shortened" first AVI is larger than the original with respect to file size. Any ideas why?

What would be really nice is to append the second AVI with a second or two of overlap on to the first AVI. Thus, create a sort of fade into the next scene.

But, I am happy with what I have managed to produce. I sometimes have to sit back and remember exactly why I am doing what I am doing; keeping it simple.

Thanks for all of your help!

[manono]

The last chapter (that was non-selected) showed to be only 10ms.

That's common. That's so you can go to the end of the movie and it'll then go back to the menu. You should have checked for a cell or chapter just before that lasting the 2-3 seconds you mentioned, and deselected that as well. I'm not positive there is one, but there often is.

It is interesting that the "shortened" first AVI is larger than the original with respect to file size. Any ideas why?

The audio in your second version wasn't muxed the same as it was in the original. The Preload and/or Interleaving is different. You might be able to find the settings by opening the AVI(s) in GSpot. If the audio is AC3, I like to use 96ms for both (not frames), rather than the default 500ms/1 frame, which is better for MP3 audio, and which, I think, makes for a larger file size if the audio is AC3.

Although, I need to remember to remove the offset prior to saving the finished movie, lol.

Hehe, so you initially wound up with a movie out of synch the whole way? I'll bet you threw a few well chosen curses my way. Good for you that you soon found out what went wrong and corrected it.

[boofer]

Actually, I knew exactly what I had done as soon as it happened.

I am going to give your advice on the chapter removal technique another shot. I have the luxury of using my desktop for the video stuff while using my laptop for other stuff. So, I am not really hampered by the time it takes to do the ripping and converting.

The trouble that I have is that I get the hang of something then I want to tweak it to perfection.