Gradual loss of audio sync converting AVI to SVCD

[captnemo]

I am having several issues converting old VHS tapes to SVCD. Here is the process I am using:

I use the pass-through capability of a Sony camcorder to convert the VHS analog to a DV which I send to the computer via firewire and save to an AVI file with WinDV. This process works flawlessly with the exception that the resultant video does not seem to have the same level of brightness as the original video.

Next I run it through virtualdub freeze to look for broken frames - but have never had any.

Next I open the AVI in virtualdub (using panasonic DV codec) and cut out unwanted scenes, process it through the brightness filter to lighten it up if needed, then save as AVI. I then open it in virtualdub again and check it. At this point video and audio have always been in sync. I close out virtualdub.

Next I open TMPGenc, and using one of the guides referenced on this forum, convert to SVCD mpeg2. When I review the resultant mpg file, I notice that the sound gradually gets out of sync towards the end of the file. It is okay until about 80% through 50 minutes of video and then becomes noticably out of sync.

I went back and double-checked the avi file and it is definitely okay. I have also used virtualdub to save the audio as a wav and then recombine with the avi during the convert in TMPGenc. This helps but there is still a subtle lack of sync towards the end of the resultant mpg file.

Any suggestions?

Also is the loss of brightness normal?

[ZippyP.]

I suggest that when you do your brightness filtering that you frameserve the video to TMPGEnc directly instead of saving it. When you save it you are re-compressing, resulting in a quality loss. Frameserving allows you to feed the audio and video direct while setting the output to uncompressed. Look here.

I'm not sure if it will fix the sync problem but it's worth a try.

[captnemo]

Thanks for the suggestion, but the filtering is not the problem. I converted the same avi without any filtering and I still get the gradual loss of sync. Also the AVI after filtering still plays fine with no sync problem.

Is the Panasonic DV codec used in the conversion process? Could there be a problem with it?