basic question-to shrink or not to shrink before conversion to divx/xvid using autoGK

[AceRimmer667]

I am converting some of my films to watch whilst travelling to 700mb
xvid avi files. To shrink or not to shrink before conversion for the best
picture quality for this set size? Conversion time not a major problem!
I have noticed that i can first shrink my movie (taking out extras etc) to
3 or 4 gig in size using DVDShrink with hardly any loss in picture quality.


I can then finally use Auto Gordion Knot to convert my movie files to a
single 700mb xvid file, so what I am wondering is will i get a better overall
result in picture quality when converting a shrunk movie to 700mb, or
converting an unshrunk movie ripped straight from the dvd without using
DVDShrink? I thought at first that an untouched movie (with the extras
deleted as with the shrunk movie) would give the best result, but then
thought if theres no real difference in quality if the files are shrunk first,
perhaps its less hassle of for the divx/xvid conversion program, as it has
far less mb to work with, to convert it to a 700mb movie?

Will the latter give a better result, or am I just getting confused-
any ideas? Thanks :)

[linyx]

No, NEVER shrink it then re-shrink:eek:! Mpeg-2 (what DVDs use) is a lot worse for compressing than xvid, so shrinking first will only hurt the quality.

[citanuL]

You are not shrinking if you use re-author mode and select "no compression" in "compression settings" tab

[CWR03]

DVD Shrink re-encodes the video from one lossy format to another, and every time you do that you lose quality. Think of it as making a Xerox of a document, then Xeroxing the copy over and over.

Ever make a copy of a copy of a key? After 2 or 3 times the copy won't even work.

[linyx]

@citanuL
True, but actually shrinking it then converting is a very bad idea.

[AceRimmer667]

I will guess my argument for the "larger movie of same length giving a worse result as there are more megabytes to work with" just isnt how conversion works, as with two movies of similar original quality, duration and content being converted, the larger one will simply just take longer to convert than the other?

[CWR03]

It's not the larger input alone that makes the difference. It's primarily the length and resolution at a desired bitrate or projected file size that affects quality. As I said, if you degrade the quality by shrinking it before you encode, you'll only end up with a worse-looking encode with the same filesize.

Again, you're copying a copy. You WILL lose quality, totally unnecessarily, and it won't affect the end file size.

[yetanotherid]

Yep, I always rip DVDs to my drive, and if I want to convert them to both AVI and DVD, I get DVD Shrink to re-save the video twice. Once without shrinking for converting to AVI (usually I just re-author and save the "movie only" without compression, removing the extras), and then I save the video with DVD Shrink again allowing it to compress the video for burning to a writeable DVD.