AC3 Encoding Errors

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  • Lord_Anselhelm
    Junior Member
    Junior Member
    • Dec 2003
    • 35

    AC3 Encoding Errors

    Hi there

    I've had this problem before, and still not managed to find a solution for it. Even though I've asked in the past, please try and keep an open mind and help me work out how to solve this problem, if not because there isn't another solution to it, but because this will be an annoying afront to my mental intelligence if I accept defeat.

    Basically, when I first started to get dvds, I wanted to make backups of them of a size that would fit easily on to my hard drive. I started doing this about three years ago now, so some of the rips were done to fit on to either 1CD or 2CDs, using 700MB discs. I quickly switched to doing 2CD rips, with two split files, on account of the size and improved audio quality of AC3 on my sound system.

    This was in the days before affordable or quick dvd writers. Since I knew I might have to back these files up to cd, or else have to rip them again (very slow on my old hardware) or resplit the files, I kept them at 700MB single files, which meant a brief pause in the middle when playing back. Now that I have a dvd writer, I've been merging the 2CD rips back into a single 1400MB file, to avoid the pause in the middle during playback, and for ease of file management.

    That's where the problem lies.

    The files are a mixture of divx and xvid files, all with AC3 audio. I've used multiple programs over the few years to rip and code them. Some of them go back together fine, even though (according to AVI Mux GUI) all of them appear to have BAD errors in the AC3 part of CD2 of each rip. Others report an audio DELAY in the CD2 file, and when I put them back together (either with virtualdubmod or AVI Mux GUI), the audio from the CD1 part is fine but the moment it moves into CD2 territory, it desynchs slightly.

    I have a number of rips like this. I don't really want to hear another person suggest to me to rip them again, as it took enough time in the first place to do so. To me, this is more about finding a solution to a very genuine audio problem that will haunt me again and again if I let it slide.

    Can ANYONE help me to work out how to solve this problem? Perhaps a way to delay the audio in the middle of the file, or insert dummy data into the AC3 to fill up the varying amount of delay (usually 13-21ms)? I am open to ideas, as long as they're not to re-rip the files.

    Thanks
  • ElJester
    Junior Member
    Junior Member
    • Jul 2005
    • 16

    #2
    You could try using AC3Fix on the #2 discs

    Comment

    • Lord_Anselhelm
      Junior Member
      Junior Member
      • Dec 2003
      • 35

      #3
      AC3Fix doesn't detect any errors. Besliced detects errors and "fixes" them, which makes the individual files work fine, but doesn't help me merge them without the 2nd file desynching. AVI-Mux GUI seems to detect errors if there's any kind of delay.

      Is there a way to create a dummy ac3 only a few ms long to keep the audio synched when the 2nd file joins?

      Comment

      • tigerman8u
        Lord of Digital Video
        Lord of Digital Video
        • Aug 2003
        • 2122

        #4
        I haven't had that problem with Virtualdub but you could try playing with the audio interleaving properties in Vdub but that's kinda hit and miss. what I would do is de-mux the audio and video. join the video of the two files and audio of the 2 files then mux the audio and video together. this should give you a smooth transition.
        when you join the 2 files are you using "direct stream copy" for both the video and audio ?

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