How to sync WAV with MPEG

[AlanHK]

I've encoded an AVI to MPEG2 video. The audio was MP3, I saved that out as WAV from VDUB and converted it to MP2, then muxed them in MPEG2VCR. The sound gradually gets out of sync, to about 1 second at the end. (I.E., it's not a fixed delay.)

MPEG2VCR doesn't seem to have any tools for adjusting sync (if it does, can someone point out where).

Is there an easy way to sync the sound -- where I can adjust it and see/hear it immediately? (Something that's free, not a $1000 video suite).

I tried Hypercube, but that crashes every time I try to open the wave, so no luck there.

I've got Audacity, and the "Tempo" adjustment seems the tool to use, but saving, convert to MP2, remux to check... so every time I try takes about 20 minutes.

[Soopafresh]

Just out of curiosity, did you encode with 3:2 pulldown in HC ? That might be a factor.


Try muxing with ffmpeg, which has a "sync" switch

ffmpeg -i audio.mp2 -i video.m2v -acodec copy -vcodec copy -vsync -y TARGET.MPG


Do a remux of the original AVI and determine if the resulting file is in sync


ffmpeg -i SOURCE.AVI -vcodec copy -an -y v1deo.avi
ffmpeg -i SOURCE.AVI -vn -y audio.wav
ffmpeg -i audio.wav -ab 384 -ac 2 -vn -y audio.mp3
ffmpeg -i audio.mp3 -i v1deo.avi -acodec copy -vcodec copy -y TARGET.AVI

[AlanHK]

Just out of curiosity, did you encode with 3:2 pulldown in HC ? That might be a factor.

Yes, but playing the original AVI in VLC is not perfectly synced either, though not as bad as the MPEG. (Though 1 second isn't really bad, but enough to be annoying.)

I'll try reapplying pulldown with DGpulldown and give that a try.

And if my first attempts with Audacity don't work I'll try ffmpeg.

[jman98]

MPEG2VCR does have a way to adjust audio sync during muxing. I'm working from memory here as I don't have access to the program as I write this, but in the muxer option, at the bottom (I think) is a tab for audio. If you click on that there is an option to change the offset positively or negatively in the mux.

[AlanHK]

MPEG2VCR does have a way to adjust audio sync during muxing. I'm working from memory here as I don't have access to the program as I write this, but in the muxer option, at the bottom (I think) is a tab for audio. If you click on that there is an option to change the offset positively or negatively in the mux.

Yes, there's an offset, but I wanted something interactive, that I could slide while playing. Also I don't need an offset but a creep, a slight change in speed, as the sync is correct near the beginning and gets out more to the end.

Anyway, I finally did it the slow way by marking a point near the end when a sharp sound and visual cue and used Audacity to find that bump in the soundrack, and then changed the "tempo", as it's called here, to stretch the soundtrack by 0.7 sec over 2 hours. Just looked at the final product and the sync is good....