Out-of-sync after mp4 demux

[windranger]

Hi,

I'm trying to convert a mp4 file (H264 codec) to avi (mpeg2 or divx).

I demux the sound and it's OK; the sound is in syncro with the original.

When I demux the video with Vdub via Avisynth frameserving, it's not syncronized at all with the original. It gives errors of up to 1 minute delay so when I mux it with the sound it's a mess.
The interesting thing is that the video has the same timelength as the original and the soundtrack, so I dont figure out how the delay comes out.

I did the same with other files like mkv, ogm, etc and I had no problem so I wonder why this time it doesn't work properly.

Any advice is welcome.

[redwudz]

Maybe variable bitrate audio or video? That can cause those type of sync problems at times. I usually use ConvertXToDVD for MKV/MPEG4 conversions to DVD. I'm not clear on your demuxing method. I usually demux those type of files with tsMuxeR. But normally, I just convert them as is with no demuxing.

I've used Any Video Converter for those type of conversions also if I don't need a DVD file.

You might drop the original and outputted files into MediaInfo and see what differences they have. Should be a clue there somewhere. Usually audio is where the sync problems come from. If the video is the sync problem, that's more often because of a damaged file.