gradual sync gain! plz help!

[savior118]

Hi,
I have been having a 'gradual sync gain' problem. I have recently converted an AVI file to a MPEG using virtualdub to split the video and audio and then encoded it with TMPGenc. When the video starts it is out of sync, the audio comes before the video (I hear someone speak before I see them say it) then after about 4mins30secs of playing it is in sync and stays in sync throughout the rest of the video.

I have found out the legnth of the video and legnth of the audio shown below:

In Virtual dub it says that its legnth is 0:25:33.635

I GoldWave it says that its legnth is 0:25:33.257

Therefore the difference is 0.378 seconds

I have also checked for bad frames in VirtualDub, it sais there were no bad frames at all.

Any help you can give is highly appreciated
Thanks a lot
Savior118

[Tommyknocker]

When you play the video, how far out of synch does it sound? Not the .378 value you mentioned, but how does it sound to you?

[savior118]

I have looked at it and I’m guessing it is around half a second out of sync, but I cannot be sure, it is extremely hard for me to tell. I can say that it is very easy to tell that it is out of sync, so the value cannot be too small.

Thanks again
Savior118

[Melkor]

Don't have a rock solid answer for you but based on my observations.....

It seems that people always run into synch problems when they let the encoder mux the audio/video streams together. Sometimes it does just fine and then you se a post about it not working. I don't know what the answer is but I do know that I have had absolutely no synch problems. Maybe due to the fact that I let the encoder do what it's best at... encode the video to an elementary stream (.m2v), then let the authoring software mux the .m2v & ac3 together.

If all else fails, try it this way and see if it doesn't solve the problem.

Good luck!

[Soapm]

When you play the video, how far out of synch does it sound? Not the .378 value you mentioned, but how does it sound to you?

You could try and decompress the audio to see if that fixes it. Careful, it will be over a GIG when you decompress it. Also, did you get that error when you opened it in Vdub saying it had an improper header? If so then it skews it a bit also. You can also try running it through besweet or Beslice to see if they can fix the audio.

[Tommyknocker]

Hi,
I have been having a 'gradual sync gain' problem. I have recently converted an AVI file to a MPEG using virtualdub to split the video and audio and then encoded it with TMPGenc. When the video starts it is out of sync, the audio comes before the video (I hear someone speak before I see them say it) then after about 4mins30secs of playing it is in sync and stays in sync throughout the rest of the video.

I have found out the legnth of the video and legnth of the audio shown below:

In Virtual dub it says that its legnth is 0:25:33.635

I GoldWave it says that its legnth is 0:25:33.257

Therefore the difference is 0.378 seconds

I have also checked for bad frames in VirtualDub, it sais there were no bad frames at all.

Any help you can give is highly appreciated
Thanks a lot
Savior118

It does sound like the classical drift symptom. Use Gold wave Effects-->Time Warp to make the audio match the video.