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Need wisdom in Resizing/Resolution Change of AVI

Discussion in 'DivX / XviD' started by RKeikha, Aug 11, 2005.

  1. RKeikha

    RKeikha Member

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    Hi Guys,

    I would like to resize (reduce the resolution of) an AVI, from its current resolution of 960x528, down to 720x396.

    The file was capture from High Def source, and was encoded with XviD.

    I would really like to find a method of resizing it without having to re-encode the entire AVI again. I'm hoping somebody out there might know how.

    Alternatively, if there is no choice but to re-encode the whole thing, for example by going in VDub and using the resize filter, I would like to know what compression and settings should I use, to MINIMISE any loss of detail.

    Since it has been encoded once already, we've lost some quality already, and if I have to do it again, I want to ensure we don't lose any more, or as little as possible.

    Any advice, or pointer in the right direction would be great.

    Keep up the great posts,
    RK
     
  2. celtic_d

    celtic_d Regular member

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    You can't resize without re-encoding. To preserve detail, use a nice sharp AVISynth resizer. Don't use any VDub filters, choose a nice high quality quant matrix and encode at a suitable fixed quant or do 2 passes at a decent bitrate (bitrate depends on the size of the first pass).

    Re-encoding if done properly will have far less effect on the quality than the downsizing since you have around half the number of pixels.

    One last thing, 396 is not mod16, using 400 would be more efficient.
     
  3. RKeikha

    RKeikha Member

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    Hey,

    Thnx for the feedback. I'm kinda new at all this, so I'm going to try and get AVISynth and see how I can fumble my way through it, and try your approach.

    I don't fully understand all the terms and info you gave about settings, so if there is a guide anywhere I can use, please let me know. Anyways, I'll have a try at it and update the post.

    Anyone else with other ideas or suggestions, by all means feel free to give it. I'm pretty much going to try everything and do a comparison and update this thread.

    Thanks,
    RK
     

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