Sound out of synch

[RichieP]

Please help. This is driving me mad!

I have downloaded a film that is divx AVI. It plays fine on my PC but I have tried using DIKO, AVI2SVCD and Nero to convert it to DVD, but the sound always comes out about 3 seconds out of synch. I've also tried another program (the name escapes me now) to check the whole file for bad frames and it says there are none.

What is going wrong with this?

Is there any way I can move the synch on the converted DVD files?

Help much appreciated.

[mats.hogberg]

Extract audio to wav. Add/subtract 3 secs at the start (depending on if the audio is ahead or behind video - I bet it's ahead!).
Use AVI as video source, edited wav as audio source when encoding.

/Mats

[RichieP]

Extract the audio with what? Do you mean from the finished DVD files? There are about 4 files in the Video_TS folder. How do I extract from these and make it all work together? I'm a relative novice at this so it's got to be a fairly simple solution.

[mats.hogberg]

No, this is done on the source AVI file. There's not much that can be done to an already authored DVD.
Use VirtualDub to extract audio.

/Mats

[RichieP]

Thansk for your replies so far. I don't think I explained it well enough. The synch is perfect on the AVI file. It's out when I convert it to DVD. That's why it's so frustrating. Virtualdub is the program I used to check for bad frames and it says all OK.

[Hardcoreruss]

Extract the audio in virtualdub.

When you convert in tmpgenc use the new file as the source for the audio and the original avi for the video.

[mats.hogberg]

Thansk for your replies so far. I don't think I explained it well enough. The synch is perfect on the AVI file. It's out when I convert it to DVD. That's why it's so frustrating. Virtualdub is the program I used to check for bad frames and it says all OK.

It's actually very simple. When an AVI is interleaved, the audio doesn't have to "align" with the video.

Red=Video, Blue=Audio

No matter how you make it from AVI to mpg, somewhere audio and video in the AVI has to be separated into two entities. Video is encoded and audio is encoded, and these two are again put together (multiplexed). The "misalignment" in the AVI is lost in the process, hence the mpg will play out of sync, even if the AVI is fine!

/Mats

[RichieP]

Right. I'm getting there now. Once I've extracted the audio and put it into the encoder as the audio file and the AVI as the video, how do I add 3 seconds at the start (yes, the audio is ahead)? Or will it work it all out by itself?

[mats.hogberg]

No, you got to load the audio into an audio editor before encoding - Goldwave is good at this. Then add 3 sec silence at beginning and save.

/Mats

[Stacman]

No, you got to load the audio into an audio editor before encoding - Goldwave is good at this. Then add 3 sec silence at beginning and save.

/Mats

Kind of jumping in mid-topic on this as I was reading different threads. Aren't there 1-2 encoding apps that have an audio delay/adjustment that can be set prior to the process? I thought I remembered seeing in Pegasys TMPGEnc 3.0 XPress where there was a setting.

Sorry, I don't have the app on this machine at the moment so I can't verify it myself.

Thanks!

[mats.hogberg]

Yes, I think you're right. But this process works regardless of tools used to encode/author.

/Mats

[RichieP]

Thanks for help so far. I extracted the audio using Virtualdub and removed some of the audio using Audacity, as I already have that on my machine and it's free. I encoded using TPMGEnc and it's still a bit out but I just need to play around with it a bit to get it right.

One more question. I tried to use DIKO as it's much quicker but there doesn't seem to be an option to load video and audio seperately. Anyone know otherwise or another tool to use?

Cheers.