I have the audio to an English-language movie that was only released on VHS in English but has a Japanese DVD release with only the Japanese dub. I want to match up the VHS audio to the DVD video but it's not a simple matter of making sure the length matches. Does anyone have any suggestions on the best way to adjust the audio so that it syncs up with the video?
My suggestion would be to capture the vhs audio & video together, using virtualdub, so you have an avi file with audio synched to a video reference.
Then match video to video by cutting frames where required.
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I have the video and audio captured together on a VHS rip. Is it better to cut frames and cut the audio in the process or expand and compress the audio. When I synched the first spoken line and the last spoken line in the movie, the audio would go in and out of sync throughout the movie.
Match the starts and play through from the beginning with StackHorizontal() in AviSynth to see if/where the video desynchs.
Cutting frames and a slice of audio is the easiest, but can be noticeable clicks or jumps. Better results if you make a note of the cut points then use an audio editor to do a crossfade.
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Space Kaijuu said:
Does anyone have any suggestions on the best way to adjust the audio so that it syncs up with the video?
(Only some?) capture cards sync audio to the video on-the-fly and don't always make a full accounting of "rounding errors" in it's sync-delays (both "+" and "-"). All other things being equal, this causes instances of drift that may or may not cancel out each other across the length of the stream. Editing can exacerbate these errors. This information (for mpeg, as best I know) is fully embedded in the audio stream (.MPA, .MP2).
Your first step might be to convert your audio to .WAV or some other format without time-adjust information and determine if that format remains in sync with your video. If so, you're done.
Failing that, your next step might be to confirm that your video is complete (no dropped or duplicated frames) for it to be your audio-anchor. Failing a "reference" video and/or if your audio is warbling throughout, then, scene by scene or even shot by shot, stretch or compress your audio segments with something like this:
The PaceMaker Plug-in v2.6
http://www.surina.net/pacemaker/
Such software can change the tempo of the audio to fit into the allowed video space. This one may not have fine enough adjustment or good enough quality, but it's freeware and will let you determine if this approach is practical. PaceMaker happens to be a plug-in for WinAmp (and MediaMonkey) but others are stand-alone programs.
Finally, always, always, cut your zoomed-in audio at the 0 dB points at descents, or at rises, uniformly:
When rejoined (at those points), you will never hear "clicks", "pops", or other poor-construction artifacts. If your audio editor doesn't let you visualize your edits this way, you're using the wrong audio editor.
Thanks for all the input. This gives me a lot to think about. I want to retain the best quality that I can from the source audio, so I may have to do some major work to get this audio synced up properly. I haven't found anything that would let me adjust the audio to re-sync in any of the video editing software, which is a shame.