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  1. Member Johnbil's Avatar
    Join Date: Sep 2010
    Location: Staten Island, NY
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    Need some advice on creating an FFMPEG command line to do 'Same Quality' video conversions.

    It would need these options:
    1) convert from MP4 to Xvid (using 2 passes)
    2) resetting the resolution to 720x404
    3) use MP3 audio with a 128 bitrate
    4) resulting video should have the same quailty (bit rate) as the original

    I have tried using some FFMPEG based VC converters, but in some cases, I haven't been able to achieve the same quality. I would like to try a command line instead.

    Any help would be appreciated.

    Regards...John B
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  2. Member
    Join Date: Sep 2007
    Location: Canada
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    Originally Posted by Johnbil View Post
    4) resulting video should have the same quailty (bit rate) as the original
    Not possible with lossy codecs like xvid

    You'd need higher bitrates (thus larger filesizes) for simliar quality as the original if you're were not resizing

    This is especially true if your MP4 used more advanced compression like AVC. Going from AVC to xvid is worse than the other way around (you're going from better compression to worse compression)

    -sameq in ffmpeg actually means "same quantizer" as the input file, which is not the same thing as "same quality"
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  3. Member Johnbil's Avatar
    Join Date: Sep 2010
    Location: Staten Island, NY
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    Thanks for the really fast reply. Dumb question, would that apply to all AVI codecs? I usually watch these videos on TV via a DivX compatible DVD player.
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  4. Member
    Join Date: Sep 2007
    Location: Canada
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    Originally Posted by Johnbil View Post
    Thanks for the really fast reply. Dumb question, would that apply to all AVI codecs? I usually watch these videos on TV via a DivX compatible DVD player.
    No, there are "lossless" codecs that are AVI compatible. e.g lagarith, ut video codec, huffyuv, many others . These won't work on your DivX DVD Player

    All lossless codecs are much larger in filesize because the "lossless" nature refers to the uncompressed state, or decoded data from the original video (so they are smaller than the uncompressed size, but not the original compressed video)

    The best you can do for that player - quality wise - is use a low quantizer e.g. q=2 , but the filesize will be large . Sometimes it may stutter unless you use an encoding profile compatible for DivX standalones (the encoding profile e.g. DivX or XviD home theatre profile "caps" bitrate peaks, which may cause stuttering on standalone units, but this potentially reduces quality as well)
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  5. Member Johnbil's Avatar
    Join Date: Sep 2010
    Location: Staten Island, NY
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    OK. Thanks again.
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