VirtualDubMod Audio Sync Issue

Discussion in 'Video - Software discussion' started by elk1007, Jan 9, 2009.

  1. elk1007

    elk1007 Regular member

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    I'm trying to add an audio stream to an AVI that already has two.
    I know how to do this and how to output the file, but the problems is with the sync of the audio.

    If 'Sync to Audio' is selected under Options, then the audio is PERFECTLY in sync with the video in the preview.
    But once it's output, it's way off.

    Instead of messing with the actual wave file and fixing the offset, is there a way to use 'Sync to Audio' with the output as well?

    I know the little description for 'sync to audio' says it only applies to the preview. I want to apply it to the output as well so that the stream is in sync with the video.

    Any help is appreciated ^.^



    Extra Info:
    The audio stream I'm applying is missing a ~10 second intro of silence in the actual wav file. The other streams have this. When the 'Sync to audio' is selected, the preview will play the new audio stream (the one missing the 10 sec intro), but will add that intro and any other offset needed to sync that stream with the video.

    How can I do this in output too!? T.T
     
  2. davexnet

    davexnet Active member

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    Fix it in an audio editor (perhaps Audacity)
    Open the main file.
    Highlight a 10 secold section from this file. (any part of it will do)
    Use the copy command. Insert (paste) it at the front of
    the file. Then use normalize or volume so that it is inaudible.

    Save the new wave.
     
  3. elk1007

    elk1007 Regular member

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    That doesn't seem to work, as the audio is off in some random parts.

    Somehow though, it's synced perfectly in preview.

    EDIT:

    I'm dubbing the fox audio version into a totoro avi that already has the japanese and disney streams.
    But even if I line up the audio perfectly with the lips, it goes WAY out of sync later in the output o_O

    Also, I check the video and there doesn't seem to be a difference.
     
    Last edited: Jan 9, 2009
  4. davexnet

    davexnet Active member

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    The technique itself works because I've used it myself successfully.

    If the audio is in synch at the beginning but gets worse as the
    thing progresses, playback speed of the audio is either
    too quick or slow.

    Perhaps you can fix it with a time stretch. Does Audacity have this?

    The general technique is to ensure it's in synch at the beginning.
    Skip to the end. For example, if the audio is 5 seconds late at the
    end, use time stretch to make the audio 5 seconds longer.

    If it's out in random places, then something else is going on.
     

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