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Audio synch problems in VirtualDub

Discussion in 'DivX / XviD' started by jamiepjsy, Aug 14, 2004.

  1. jamiepjsy

    jamiepjsy Guest

    I am trying to split a large avi in half using Virtualdub. The problem is that on loading the file I get the message - "VirtualDub has detected an improper VBR audio encoding in the source AVI file and will rewrite the audio header with standard CBR values during processing for better compatibility. This may introduce up to 12074 ms of skew from the video stream. If this is unaccepatble, decompress the *entire* audio stream to an uncompressed WAV file and recompress with a constant bit rate encoder. (bitrate 142.0 +-15.9kbps)"

    When testing the dub, the audio is totally out of sync - does anyone know how I could try correcting this? I've tried putting the time value given in the interleaving option of the audio menu but have had no luck. I also tried saving the audio as a wav file and then using the audio from this rather than the source, but still no luck. Any ideas would be very much appreciated - I seem to have this problem with a lot of files.

    Many thanks
  2. TheTorg

    TheTorg Guest

    If you're making these files, remember next time to use a set bitrate, because not many applications are very friendly to Variable Bit Rate or VBR audio.

    You can try using VirtualDubMod...that might be compatible with VBR audio:

    The dialog tells you that it might (will) skew the audio by up to 12 seconds. This is correctible, but it's not gonna be perfect. You'll just have to eyeball it.

    First, save the audio as a WAV file. Then, you'll probably need to recompress the audio to MP3 so that it doesn't take up all that space. To do this go to the following link and follow the section titled [bold]CDEx[/bold] and the section afterwards:

    Then, use the interleaving settings to change the offset like you were doing before. But the value won't be 12074 ms. The dialog says it will skew the audio up to that much. You need to find out how much it is by watching the video and counting about how far off it is. Adjust the setting based on your estimations, and get it as close as you can. Do this a few times, and you should have it in the right place. Remember: 12000 ms is equal to 12 seconds.

    Good luck. And don't be afraid to post any questions or problems you run into while doing this.

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