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Thread: Video encoding questions

  1. #1
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    Video encoding questions

    Hello,

    I'm trying to encode some files I have (200MB XVID TV Episodes) to MPEG2 format for burning onto a DVD. Using Tovid with the ffmpg option I have a question. I setting a -quality of 9, however after encoding the resulting dialog indicates the following

    Code:
    Final size:      753952 kilobytes
    Target bitrate:  8100 kbits/sec
    Average bitrate: 2497 kbits/sec
    Peak bitrate:    2802 kbits/sec
    The original XVID file is not of stellar quality is it possible that any encoding above 2500 will not make a noticeable difference in quality given the source?

    Thanks!

  2. #2
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    TenPlus1 is offline Grande Half-n-Half Cinnamon Ubuntu
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    Re: Video encoding questions

    Why not just download DeVede from getdeb.net and install that instead... It'll take any video and let you create a DVD Video with menu's, plus it's easy to use...

  3. #3
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    Re: Video encoding questions

    If you use ffmpeg directly or can add parameters to the ffmpeg option, you could use the -sameq option which encodes at the same quality as the source.

    See http://ffmpeg.mplayerhq.hu/ffmpeg-doc.html

  4. #4
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    Re: Video encoding questions

    I'll look at the output tovid passes. I'm willing to bet it passes that by default.

    Bob Out

  5. #5
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    Re: Video encoding questions

    Devede was ok, found it be fairly buggy. I really like the menus I can created with 'todisc' very easily. Plus with tovid I can batch process all my avi's overnight.

    However the quality of the todisc menu's looks questionable (grainy etc).

  6. #6
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    Re: Video encoding questions

    I'll look at the output tovid passes. I'm willing to bet it passes that by default.
    Try "ffmpeg -i [name] -sameq -f dvd [name].mpg" and compare encodings to see if tovid uses sameq.

  7. #7
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    Re: Video encoding questions

    Well it doesn't pass sameq. Here is the actual line that it passes to ffmpeg

    Code:
    nice -n 0 ffmpeg -i "sample.avi"             -target ntsc-dvd -qmin 1 -qmax 31 -b 9000k -ab 224k -ac 2  -r 29.970          -s 720x480   -aspect 4:3  "sameple.tovid_encoded.mpg"
    I guess the question is If my target bitrate is 8100 or 9000 (quality 9 or 10) why is it only encoding to 2400kbps?

  8. #8
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    Re: Video encoding questions

    I guess the question is If my target bitrate is 8100 or 9000 (quality 9 or 10) why is it only encoding to 2400kbps?
    Your comand line is using vbr and a wide range for your quantizer with no bit rate tolerance set. I think you can get it closer to your target bitrate using a different command line.

  9. #9
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    Re: Video encoding questions

    The encoder will only use as many bits as it needs to encode your source. If it is of poor quality to begin with, encoding at an artifically high bitrate will just stuff useless bits.

    With respect to grainy looking menus, I have not heard that one before. You might try svn todisc which uses lossless ppm for the final montages - you may find you get better quality.

    Note: tovid also has a -fit option that is worth looking into - though that is more for encodes that might take up more space than available on a single DVD.

    grepper

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