Resolution and different matrices

[mateo4x4]

HI !
During making 1 CD backup some people set a high resolution for the movie (i.e. 640, 720) and use the matrices with higher coefficients (f.e. Jawor's or EQM V3ULR) to gest a better compressibility. Some people decide to use lower resolutions (544 or 512) and then use high bitrate matrix with low coefficients (i.e 6of9 series). In both cases the compressibility tests can bring the same worths. And what about the quality of the final avi film ? Which way is better ?

And another question: When useing GKnot, there is a window with "Bits/(Pixel*Frame)" value. How sensitive, trustworthy and how important is this is this ? Some say it must be close to 0.200 for 1 CD backup anb about 0.250 for 2 CD's. Does it really determinate what resolution has to be set ?
I just want to know what is the startting point to set a proper matrix and proper resolution for the backup.

Thank You for all suggestions and opinions.

[Teegedeck]

Picking the right resolution isn't an exact science, I'm afraid. See that you don't need to use too high quantizers. What 'too high' is differs, depending on the quantization-matrix.

And using low-bitrate matrices with high resolutions is a bad idea. Rather do it the other way round; lower your resolution and use a good all-purpose matrix like Didée's SixOfNine-HVS. If SixOfNine-HVS doesn't prompt XviD to spit out quants above 8 in 2nd pass, your resolution should be alright.

[Sharktooth]

Well, i prefer to NOT resize even for 1CD backups until there is nothing else left to do.
However some ppl prefer to resize instead of using low bitrate matrices (or filters to achieve better compressibility without loosing too much details).
There is no "best method" coz afterall it's a matter of preference.
Resizing, like filtering and using low bitrate matrices, afterall is a lossy procedure. So, at last, it depends on your personal preferences AND the source material.
The bits/(pixel*frame) formula is a general index of the final quality. Keep in mind it's GENERAL and not all sources may respect the general .200 (or .250) treshold, expecially noisy or high motion sources.

EDIT: The EQM V3ULR matrix was explicitly made for ppl that likes to keep the full/high resolution for 1CD backups. If you're going to resize to a low res (ie. 512) and you want to use one of the EQM V3 matrices just use V3LR.

[mateo4x4]

Thank you Sharktooth,
Thank you Teegedeck :)