Xvid Audio / Video sync issue

Discussion in 'DivX / XviD' started by Radunn, May 5, 2009.

  1. Radunn

    Radunn Member

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    I've been encoding DV camcorder video to xvid for quite a while in Virtualdub. Initially playback of an encoded DV to Xvid was fine. Lately it and all copies of the same video were out of sync (audio way before video). Using MediaInfo for information the Audio section of the out of sync file is as follows:
    Bit rate mode : Constant
    Bit rate : 32.0 Kbps
    Channel(s) : 2 channels
    Sampling rate : 48.0 KHz
    Resolution : 16 bits
    Stream size : 57.7 MiB (8%)
    Alignment : Split accross interleaves
    Interleave, duration : 33 ms (1.00 video frame)
    Interleave, preload duration : 2500 ms

    What I did was save the xvid AVI MP3 to WAV via Virtualdub, used an audio editor (converted to Wav) then converted back to MP3 using a much higher bit rate (160 Kbps); finally remuxing the new MP3 into the AVI via VirtualdubMod. Having done this and rechecked in MediaInfo the Interleave, preload duration is now 504 ms, with a 160 Kbps bit rate and plays fine (no audio-video sync issue).

    Does a too low bit rate account for audio/video sync issues? In advance thank you
     
  2. attar

    attar Senior member

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    I don't have an answer, but you could take the file with 2500ms preload into VirtualDub.
    Click 'Audio' > 'Interleaving' and set the preload to 500 and see if the effect is the same (save the video with Direct stream Copy).

    Anything I read about preload refers to 200/500 ms as maximum.
     
  3. Radunn

    Radunn Member

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    By default 'Audio - Interleaving - 'preload' is set at 500ms.

    Actually (with no change at Audio/Interleaving)saving it 'direct copy stream' increased 'interleave preload duration' by a few ms. What worked (without having to extract the WAV file etc)was simply to increase the audio bit rate from 32Kbps to 128 - xxx etc; reducing interleave preload to 50x ms
     

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