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six6
16th November 2003, 07:08
This is concerning DVD->AVI. I'm used to cropping and resizing for Divx encodes to acheive good compression compared to resolution, should I be doing a similar process for mpeg-2?

My reasoning so far against cropping/resizing is this: for around 1 Mbit/sec, my encodes appear closer to original if I don't resize or crop the input through avisynth. I compared the following in CCESetWorkingDir(whatever)
LoadPlugin("mpeg2dec3.dll")
mpeg2source(whatever)
ConvertToYUY2()
AddAudio() to SetWorkingDir(whatever)
LoadPlugin("mpeg2dec3.dll")
mpeg2source(whatever)
crop(whatever)
BicubicResize(whatever)
ConvertToYUY2()
AddAudio() but I suppose one could use any resize filter.

To compare the two videos, I open them via virtualdubmod then resize the video from the second script (width<720 by height<480) to be the same (approx) size as the one from the first script (720 by 480). I assume that this is what a suitable media player (ex: MPC) does during full screen playback of a movie with height<480 and width<720.

Anyway, maybe it seems better because I'm using a $15 used monitor. But can someone else attest that cropping/resizing makes a positive difference in playback quality? I can upload some images if someone wants to see the differences I see.

r6d2
16th November 2003, 23:33
Originally posted by six6
[B]This is concerning DVD->AVI. I'm used to cropping and resizing for Divx encodes to acheive good compression compared to resolution, should I be doing a similar process for mpeg-2?
Well, most stuff you know from AVIs applies as well to MPEG-2.

If you resize, you are either enlarging (you creae info where you had not any) or shrinking (you reduce the amount of information to store).

In both cases resizers are processing you input and it is a lossy process.