audio/video out of sync - GOING NUTS!

[graysky]

I'm trying to re-encode some videos (why re-encod you ask, simple, I wish to have them in another resolution and add a keyframe every 45 frames instead of every 500 which they were originally encoded to) using Virtual dub. When I load one of the avi files, VD tells me "inproper VBR audio encoding source that may introduce up to 10394 ms of skew.

It goes one to tell me to decompress the audio to uncompressed WAV file and recompress with a constant bitrate encoder (bitrate: 132.5 +- 17.9 kbps).

I saved the audio in VD to a wav file and told it to use the wav file as the audio source (compressed to mp3 of course). Long story short, there is STILL the out of sync character in the re-compressed version! What am I doing wrong?

[p_l]

It could be because of bad frames in your source file. Try the VDub MP3 method in King John's Guide to Bad Frames V2. It helped me and others.

Hope it helps you too.

[DivXExpert]

Uh, this might be dumb, but what is the advantage of adding keyframes?

[narked]

Adding more key frames helps in searching (fast forwarding etc) in avis and is also usual for sound syncing and sorting corrupt data. However, as I understand it you do not need to re-encode to add more: Open virtualdub, go to file - open video file. In next window tick off the popup extended open options and select file to open. Click on open. Next window tick off rederive keyframe flags and click on OK. virtualdub adds keyframes as it opens (takes a little time). Then save this avi (direct stream copy on both audio and vid) with new filename. New file has all the new keyframes.

[graysky]

narked - thanks for that tip; I had no idea I could do that... only problem is I like to resize the video to another resolution

Has to be a way to do it!

[DivXExpert]

Does more keyframes mean higher filesizes?

[narked]

No, doesnt make any difference to filesize

[graysky]

...Then save this avi (direct stream copy on both audio and vid) with new filename. New file has all the new keyframes.

I followed your directions and it did re-keyframe the entire avi, but is there a way one can tell VD how many key frames to add in this fashion? I like to have one every 45 frames.

Thanks again

[narked]

well I wasn't sure so I've messed with vb this morning to try it. Result - no, very annoying. Tried it with a divx 5.0.1 movie sample 28 mins long with only 1 keyframe (incomplete download dat). Opened it - now keyframes every 300 frames (default setting). OK, closed file, set max keyframes interval in settings for that codec to 45 frames, tried again. Still at 300, got me irritated now. There must be a way to do this, I'll keep trying (set me another challenge)