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Audio not in sync with Video

Discussion in 'MPEG-1 and MPEG-2 encoding (AVI to DVD)' started by Hydro150, Feb 20, 2006.

  1. Hydro150

    Hydro150 Guest

    Hi, when I use DVD santa to transcode a movie from DivX to DVD (VOB, IFO ect...) after the movie has been converted and I view it the audio is not in sync with the sound. Is there a way to fix this or is there a better program that will not do this?
    -Thanks
     
  2. aldaco12

    aldaco12 Active member

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    Un-sync in the movie can occur due to two reasons:
    1) use of a VBR MP3 encoding insted of a MP3 CBR encoding in the AVIs sound ; the sound is in sync in the AVI and becames un-sync aftre you do AVI -> MPG. Usually the delay in the output mpeg is non-constant , that is, it inreases as long as you play the mpeg movie.
    2) sound delay in the original DVD which was not taken into account when you extracted the sound. This is more subtile. Often DVD audio has a constant delay (in ms) which is takein into account during authoring. When you extract the AC3 stream it appears like "English -200 ms delay.AC3".
    If you do DVD -> AC3 you need to take into account this delay, since the AVI sound is put at delay=0. You must, for instanct, keep checked the box 'correct AC3 delay' in ReJug, when you demux the stream. The result is a stream is named, for example: "English -200 ms delay corrected to 0 ms.AC3". If ones rips a DVD without correcting the AC3 delay there is a constant delay from the begginning to the end.

    CORRECTIONS:
    In every case you need to decompress the AVI's sound (VirtualDub; Audio___Full processing mode; File___Save WAV). If the AVI has AC3 sound probably the sound won't be uncompressed by VirtualDub (you can see it by looking to the size: it will be less than 10.1 MB per audio's stream length (in minutes). In this case use VirtualDubMod and do Stream__Stream List__Demux, since VirtualDub adds by default, to the audio, the WAV extension.

    Of 1): Re-encode the sound (the un-compressed WAV or the AC3) adding, using a spohisticated sound encoder like BeSWeet or HeadAC3he, a constant delay (you'll have to detect the delay you need to add 'by ear', if you don't know anything about the original DVD).

    Of 2): Use the WAV as 'audio input' instead of the AVI's movie.
     
    Last edited: Feb 23, 2006
  3. Snow98

    Snow98 Member

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    I have a related problem with my VBR-encoded AVI: I need to adjust for a slight sound skew, which is constant throught the AVI, and every time I try to recompress the sound via Nandub, the unsync becomes variable (i.e. some scenes are in sync, others badly off), so the delay function does not help. Any ideas? Thanks...
     
  4. aldaco12

    aldaco12 Active member

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    Do as I wrote. Never, never, use a VBR MP3 sound. Uncompress it to WAV, first.

    If you want to re-build the AVI, just compress the WAV to MP3 CBR (HeadAC3he in 'alt CBR' preset is fine, then open the AVI with VirtualDubMod. Do Stream___Stream List, disable the old stream, add the new one.
    Set Video__Direct Stream Copy and Save (F7).
    You'll create an AVI with the same video but CBR audio.
    If, as it seldom it occurs, there's a constant A/V delay you can detect (e.g. 0.5 s = 500 ms), enter a delay in HeaAC3he and fix it.
     
    Last edited: Mar 13, 2006
  5. cougar_ii

    cougar_ii Regular member

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    Hi there,

    Here's a solution we used when we had Out Of Sync issues with VSO ConvertXtoDVD, and it might work here too:

    Good Luck !
     
  6. Snow98

    Snow98 Member

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    Cool, Coogar, your solution worked out just fine. I didn't even start understanding the different settings in AVI Mug, just dropped my "bad" file into it and pressed "start". The output is in sync. Thanks a lot.
     
  7. yamihere

    yamihere Member

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    Well, I had a problem with an .avi file. The sound was way off and I couldn't figure out how to fix it using virtual dub (I had been trying to play with the delay values using the audio as it was in the avi file, it turned out I had to first save it as a wav, as described below). Thanks to this thread (and aldaco12) I finally got it. I am going to write down what worked for me incase it helps someone else, and because I am a complete newbie and sometimes have trouble following the advanced users' directions, I am going to write it in baby steps :). All I ended up using was virtualdub.

    1. Open the file ('file'- 'open video file')
    2. click 'audio'- make sure that 'source audio' is checked, then click on 'full processing mode'
    3. click 'file'- 'save wav'

    4. once you've saved the wav file somewhere, go back to 'audio' --
    click on 'WAV audio' file and select the wav file you just saved in step 3.
    make sure also that you click on 'direct stream copy' and that it is checked.
    **if there is a delay on your sound and you know what it is (either that or try various values through trial and error)
    click on 'audio'- 'interleaving' - make sure 'enable interleaving'is checked, then enter a value of the delay where it says 'delay audio track by... ms', using a positive value (i.e., 500) if the audio is playing too early and negative (i.e., -500) if the audio is playing too late.**
    5. Click on 'video'- and make sure that 'direct stream copy' is checked.
    6. click on 'file'- 'save as AVI'
    and you're done.

     
    Last edited: Mar 28, 2006
  8. cougar_ii

    cougar_ii Regular member

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    Hi there,

    FYI, VSO ConvertXtoDVD let's you add those offsets (00ms) directly in the interface.

    There are 2 exceptions movies I have, even with the AviMux GUI 1200ms was needed on a movie to be in sync !

    At least the functionality is built in !
     
  9. Vorban

    Vorban Guest

    I have a related problem. I have an avi file and when i try to convert it to vob the audio seems to be faster than the video.
    The origional avi is perfect though so there is no need for avi-mux. The problem only occurs after the conversion to vob. Is there any way of fixing this?
    Thanks
     
  10. cougar_ii

    cougar_ii Regular member

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    Hi there,

    Yes, the .avi is ok before the convertion, but you might still need AVI MuxGUI to fix the avi before you convert it.

    Did you pass this specific .avi in AViMuxGUI ? did it give you a 00ms delay value ?

    Try to fix the .avi and convert it again !
     

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