Uncompressing a compressed Xvid

Discussion in 'DivX / XviD' started by hugekid, Jan 24, 2006.

  1. hugekid

    hugekid Member

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    I have a compressed movie file on my computer that i ripped from one of my DVDs that was encoded with Xvid. I recently got a bigger hard drive and i would now prefer to have a higher quality movie rather than a smaller one. I was wondering if there was a way to directly undo the compression that was done by the encoder and get the original movie quality back. Or do i have to re-rip the movie again?
     
  2. Radunn

    Radunn Member

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    For original quality re-rip the movie. You 'can' re-encode with Huffy or Lossless codec but keep in mind the quality will not improve; it will be as good as the xvid quality.
     
  3. mikej3131

    mikej3131 Regular member

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    Hey radun are you sure this is the case or am i totally off the subject. Ok here is my situation. I downloaded a divx movie file that was a dvdrip originally. I watched it on my computer and saw that it was ok quality. So i used nero to convert it to a DVD-r, which i thought would get better quality. When i dragged and dropped the movie in nero. It said the resolution would increase and so would the frps and the aspect ratio. I burned it and watched it on my dvd player on my tv and i could have sworn it was better picture quality?
     
  4. celtic_d

    celtic_d Regular member

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    The quality would have actually been worse. TV's are just more forgiving. Try comparing both on the same display.
     
  5. mikej3131

    mikej3131 Regular member

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    hmm i see. Ok i will try that tonight when i get home from work. But as for the uncompressing of the divx file to dvdr format in nero. It said the resolution got better and a couple other things. It looked better too. if the movie was originallty a dvdrip that got compressed to a xvid, and then i burned it to dvdr format onto a dvd, wouldnt it go back to the original dvd quality, or atleast be better than the xvid quality on my computer?
     
  6. celtic_d

    celtic_d Regular member

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    Take a small thumbnail image and blow it up. How does it look? Like pixelated crap or the original image that the thumb was created from?

    Same goes for video, you can increase the resolution, but the extra pixels don't come out of nowhere.
     
  7. mikej3131

    mikej3131 Regular member

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    Yes i know when u take a small image and blow it up it becomes pixelated. But this video file i have originally came from a high resolution dvdrip. and then it got compressed to xvid. So when i burn it to nero onto a dvd-r, im guessing it decompresses to its original resolution etc.
     
  8. celtic_d

    celtic_d Regular member

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    Video is nothing more than a series of images. Shrinking the resolution of a video and blowing it back up is no different than doing the same to an image. You just have 24-->29.976 of them per second.
     
  9. putter

    putter Member

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    The reason you see that the quality looks better on your TV after you burned it to a DVD-R than what it looked like as an XviD on your computer is because of the following. The resolution of your TV is much smaller than that of your computer. The resolution of your computer screen is probably about 300% or greater than that of your TV. So the video will mostly always look better on your TV than on your computer.

    Also, once something is lowered in quality, you cannot increase the quality just bu uncompressing it. You'd actually have to apply filters, and a whole bunch of other crap than just to uncompress it. You can't make applesauce and expect to reverse the process and make it an apple again.

    -PutterPlace
     
  10. mikej3131

    mikej3131 Regular member

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    ohh i see. Thanks alot. So is doing all that other stuff like filtering it complicated?
    Also does nero 7 premium do this filtering stuff when converting it to dvd?
     
  11. mikej3131

    mikej3131 Regular member

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    Oh yeah i forgot. When i burn it to nero and it converts it to dvd. It says the resolution gets bigger and the aspect ratio gets bigger and the same with th FRPS? Is that the "filtering and other stuff" you were talking about?
     
  12. celtic_d

    celtic_d Regular member

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    The Aspect Ratio shouldn't change. If it does, you are either cropping or distorting the image. As for the framerate, it shouldn't really change either other than a 3:2 pulldown for a 23.976fps source.

    Resizing I guess counts as a filter. Filtering doesn't really increase quality anyway. For instance if you have a noisy source and you denoise, generally you also loose some detail. If you have a blury source and you sharpen it, you will create some artifacts, etc. Brightening a source or adjusting colours can help though and denoising or sharpening may make it look more pleasing, but you couldn't really call it an increase in quality.

    I think the point is that when you are recompressing to a lossy compressor, you shouldn't expect it to look better, because it is only going to get worse (noticable or not).

    If you want to try out different filters, check out AVISynth. If you use ffdshow for decoding it also has some options, including AVISynth filtering.
     
  13. mikej3131

    mikej3131 Regular member

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    OK THANKS
     

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