How should I re-adjust audio sync?

[j8ee]

Hi!

I have a clip where the audio is out of sync, more than a second too early.

Is there a player that can take care of that? I tried some windows builds of videolan client, but the adjustments didn't work.

Just thinking of it, it would be possible to extract the audio and re-sync it? Which tools to use for that?

/Johan

[jggimi]

The answer to your question is usually "yes" -- it is possible to demux the file and remux with different timing. But...what format is your clip in? The tools and procedures will vary, depending on the type of file.

[j8ee]

Originally posted by jggimi
But...what format is your clip in? The tools and procedures will vary, depending on the type of file.

Thats true... it's in divx, don't know what version or audio quality/type (havn't got the clip here). Will the tools in the gordian knot package manage, most likely? I did some ripping/divx encoding more than a year ago, and don't really remember the procedure. Then I was experimenting with ogg media stream format, and used graphedit mostly, when demuxing or whatever it's called, and oggmux (or oggmachine?) when adding .ogg sound.

But why do people bother to release a 450 Mb movie with sound so horrible out of sync in the first place? 1-2 seconds early...

/Johan

[jggimi]

DivX video is most often packaged in .avi files, though, since you've experimented with ogg, you know there are other possibilities. If the file type is .divx, it is still in AVI format.

First, examine the file with Gspot (http://www.doom9.org/Soft21/Editing/gspot20.zip). It will tell you the codec used in the audio track. You'll need to know if it's MP3, Dolby Digital (.ac3), or Linear PCM (.wav) when remuxing.

Then open the file using Nandub (http://www.doom9.org/Soft21/Encoders/MPEG4/nandub-binary-1.0rc2.rar). This tool supports all different types of audio tracks.

Use the File...Save WAV command. This will demux the audio track, regardless of its actual type. Save the audio file with a file type of .ac3, .mp3, or .wav, etc, depending on the type of audio track.

You're now ready for remuxing.

Use the Video....Direct Stream Copy command. This will tell Nandub not to re-encode the video.

Use the appropriate Audio....MP3/AC3/WAV command to select the audio file you just demuxed.

Use the Audio....Interleaving command to set your audio track delay (or advance with a negative number) in milliseconds. It's at the bottom of the Interleaving window.

Use File...Save AVI to save a new .avi file with new audio timing.

For more details, you can find Nandub procedures listed in www.doom9.org/virtualdub_procedures.htm.