bits/(pixel*frame) vs compressibility checks

[poopity poop]

I always choose a resolution that will give me ~.21 b/(p*f) with DivX5, ~.26 b/(p*f) with DivX3.11, and ~.45 b/(p*f)with SVCD's(480x480, altough you only have one resolution to choose from this is a good way of figureing out if you need a 3 CD encode or not...anyway). If a movie is anime/cartoonish then you can go lower by about .02-.03 b/(p*f) if you want to and .03-05 b/(p*f) with SVCD streams if you really want to.


compressibility checks can eat me, but I'm willing to think about them.


My questions:
Are those numbers stated above good assumtions for assigning a resolution?

How exactly do compresibility checks work?

What are good numbers for compressibility checks, and why?

When you get a number for a compressibility check how can you "optimize it by choosing a different resolution?


Basically I want someone to convice me here and write or point me to a good guide. I'm going to take everythiny ou say with a grain of salt unless I know you know your shit. So prove it to me :)

[xzquala]

well, I definately don't know my shit, that seems to be your title.

but I do know that compressability checks actually look at the material you are encoding, where as the bpf just looks at resolution and length.

lest just say you have two movies.

in one movie the director has the camera men stay in one spot. the camera hardly ever moves, no panning, no scrolling.

in the other movie, you have lots of action, lots of funky camera tricks and lots of other things.

the first movie is going to be very compressable, and the second is not right? well a compressability check is going to check that for you.

in gknot, you load a comp check, say for 5%. gknot then makes a temp encode, takes samples from all over the place in the movie, and encodes thirteen frames in a row. then it jumps to the next place.

this will actually tell you just how compressable a movie is.

for me, I was reluctant to do the comp check for a long time. but then I used to do two or three full encodes trying to get the most bang for the bits. doing a comp check has saved me a lot of time, and over all since I am lazy, my rips look much better.

[jggimi]

This thread should probably be moved to the Gordian Knot forum...

A compression check samples (by default) 5% of your content... using the following AviSynth script:SelectRangeEvery(260,13)This samples 13 frames every 260 frames, throughout the content.

[poopity poop]

thanks that's a good analogy. I'll look into it