maximum compression of iso files

hey folks, ive been tinkering around with compressing iso files with umdgen. so ive taken Gands of london from 1GB down to 964MB by removing the .png files and boot file along with the update folder. so far no ill effects. so now ive also taken out the pmf files. compressed at level 9 this makes the file 962MB but the game freezes when you get to the actual start of the game play. i was just wondering if anybody could list what the different files are in the games, what they do and how essential they are to running the game? and does anybody know how to compress them further? i saw a post along the lines of a massive compression of castlevania but i dont have that game!

I ain't no expert, but I read somewhere that if the game has video animation, it is best to copy and paste the smallest sized video, and name it and replace the other larger video files. This helps shrink the ISO to a smaller size. Just thought I'd let you know. And after you got your small ISO, it wouldn't hurt to compress it to a CSO--which in effect makes it even smaller in size.

Dummy files can be ripped.
Background music can be ripped.
Videos can be replaced by a simular format video that runs for only 1 - 0.5 seconds.

try ripping out the other languages, multiplayer mode (if you dont want to use it), the videos as mentioned already can be replaced by the smallest sized one (just copy it and when your replacing the others name it as the file you're replacing) the only exception i think is the intro's can't be touched if i remember correctly, anything that has to do with sound can be ripped (radio, background music, sound effects, etc.)

As to what these files are named, can't really remember (been over a year since i last tinkered with a psp) but i know that video's end with .pmf, sounds i think are either .vag or maybe .pmf as well...everything else is all blurry to me though.

.at3 usually.

so files like snd0.at3 can go? is that sound files? i can play without music but it would be nice to keep sound effects. the file size mentioned earlier was already compressed to .cso, it didnt actually compress a great deal. any idea what .prx files do and if they can be replaced/binned?

here check this link...it'll give you some better insight on the topic and gives a link to some ripkits so you don't have to rip them manually if you can find one made for your game.

http://www.blastprocessing.net/?page_id=65

Good link, cheers staxx