bits/pixel and compressability test

[Forsaken]

i know this is a noobit question but if you could just bear with me, i'm new to this

in the divx5 gknot guide, doom9 says to shoot for .17 to .22 bits/pixel or whatnot (can't remember the exact values) then recommends running a compressability test at 5% then match up those results back in gknot, trying to get a 60% to 80% result (i'm sorry, i know this is vague but i don't know the technical terms)

now when i do that in order to get a 60-80% result, i have to drop my resolution way down to a tiny movie and my bits/pixel shoot way up into the .4 range. i'm not sure which one i should follow, the 60-80% deal or the .17-.22, since i can't get them both

thanks for your help

[jggimi]

Welcome to the forum. Yes, it can be confusing. Here's how I recommend using these numbers.

The b/p*f formula is a model of how many bits per pixel (per frame) you'll be able to get. The number varies, not just due to the length of the content (number of frames), but also -- the aspect ratio. At the same width, for example, there are a lot more pixels per frame of "fullscreen" content then "widescreen" -- and your cropping removes the letterboxes so they're not part of the calculation.

Prior to your first compressibility test, use the b/p*f value as an estimate. Based on this initial estimate, you may want to change resolution, change # of CDs, change audio bitrate....and then run your first compressibility test. From this point forward, you can ignore the b/p*f modelled value, and instead, use the tested values, which are the load percentages.

It is strongly recommended that if you make changes that effect compressibility, such as adding noise filters or changing resizing method, that you re-test. Some forum members retest after any change, such as resolution, as there are small % differences in compressibility. I do that once in a while, if my % values are on the "edge" of commonly acceptable ranges.

[Forsaken]

ok thanks, that's what i'd been doing up until now, i just didn't want to start ripping my DVD collection until i got it right.

thanks again