VirtualDub: re-encoding MPEG->AVI sucks !!

Discussion in 'Amateur Video Production' started by Mike Kleiber, Mar 7, 2004.

  1. Mike Kleiber

    Mike Kleiber Guest

    Ok, I loaded an mpeg video movie into VirtualDub and wanted to re-encode it to an avi file.
    To determine the bitrate of the original mpg file I clicked the VirtualDub menu

    File->File Informationen

    and found an average bitrate of (e.g. 642 kbps). To avoid too much quality loss I entered exactly this
    bitrate into the settings dialog of DivX 5.1 or Xvid and expected to get a target avi file
    of approximately the same size (+/- 5%). Surprisingly the resulting avi file was 2-3 times (!!!)
    larger than the original mpg file.
    What should I think about this fact?

    Is the DivX/Xvid codec so much worse than the mpeg codec?
    Does Virtualdub not show the correct bitrate?
    How can I otherwise re-encode an mpg file to avi with approximately the same quality and file size?

    BTW: I set the audio to DirectStreamCopy

    Mike
     
    Mike Kleiber, Mar 7, 2004
    #1
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  2. Mike Kleiber

    Shez Guest

    In the faraway land of rec.video.desktop, Mike Kleiber
    This last point is almost certainly the problem. VirtualDub uses a
    plugin to decode the video and audio of mpeg files, which results in it
    only seeing the video and audio as raw streams. This means that when you
    ask for Direct Stream Copy of the audio, what you actually get is
    uncompressed PCM audio. What you need to do is recompress the audio to a
    similar bitrate mp3 as the original had.

    If you want to avoid recompressing, use VirtualDubMod (or a dedicated
    demultiplexing program) to demultiplex the mpeg's audio stream, which
    produces an mp2 audio file, and then use that as the audio source in
    Direct Stream Mode.

    -Shez.
    --
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    To reply to reply-to addess remove REMOVE
     
    Shez, Mar 7, 2004
    #2
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