PSP - ISO vs CSO file format

Well i'm thinking, its time for a PSP post. I've been thinking of relevant things to post about the psp and i came up with this since there hasn't been an updat yet on the PSP custom firmware, i decided to post something about the file formats used to store the PSP games and the differences and advantages of using each.

First of this review is for owners that had forgone the warranty of their PSP and converted them to custom firmware for one reason or another. The topics that i will be discussing are tested for Dark Alex's CFW (Custom Firm Ware), ver 3.90 m33-3 which i believe is the latest version. Another thing is that i'm using a PSP slim, and not a Phat, there are differences in the two but i will not discuss them here. So if you have a problem with anything here, and you're using a different version, or have a PSP Phat, i cant help you there since i cant downgrade, or rather wont downgrade and i dont own a PSP Phat.

On to the discussion. The difference of an ISO and a CSO is just the file size it will occupy on your memory card. Basically you can think of it this way comparing it to a picture file format. An ISO is like a BMP image, large file size with no compression, and a CSO is like a JPEG version of the same image, but compressed which has a smaller file size. There are a few minor differences but I'll dive into that later.

Now i'm guessing you are wondering why doesn't everyone use CSO instead, well the answer to that question is load time. ISO file format is a representation of a UMD disc drive but a bit faster to load than a UMD because its is in your memory card and files are accessed quickly and there are no discs that spin around at high speed reading data. An ISO is just basically a container that emulates a disc stuck together in a file. Your CFW is just fooling your PSP telling it that the UMD disc is in fact the ISO file. but enough of that, you just need to remember that an ISO game format is like your UMD disc but has a slightly faster load time. A CSO game file format on the other hand is like your ISO file compressed into a ZIP archive, meaning the PSP has to uncompress the file first before the system reads it. Its not like the ISO where it has a direct access to the files, a CSO file format takes more time and computing power because the PSP need to do a few more thing to access the data.

Now knowing this, there are two ways that the psp loads data from the UMD or your memory card. The first is an initial data load, which is really an easy way of saying that the psp loads most of the game, or the level, or the stage of what your playing and it doesn't access it again until the next stage or level. This is usually is seen with genre games such as puzzle games, strategy games, platform games ect. The difference of CSO and ISO can be seen here during load times of each stage and or level. There is somewhere between a 3 to 8 second delay for the CSO compared to the ISO file format depending on the game. Although this may not seem that much, but for some people a 5 second delay is a bit too much. The other way a PSP loads a game is thru constant access. There are games like God of War, Final Fantasy Crisis Core, Metal Slug Anthology, or even the GTA series where data is constantly read from the Memory card or UMD. Generating encounters, or backgrounds, or random events, then you have the background sounds and music playing, the PSP has a hard time accessing all these file constantly using a CSO file format. Imagine accessing all of these, constantly uncompressing and reading data from the memory card, you will soon realize that your game is slowing down, or is skipping frames, which i can say is a kill joy.

Now that you understand all these, you will have to make a choice now if you want a smoother game experience, but less space on your memory card, or more space on the mem card for games but end up waiting a bit more and for some games reduced efficiency. Id say do both. It is true that if you make all your games into a CSO, you'll have more games to play, but honestly enough, i how many games can you go thru in a day or two. Do you constantly need to change the games you play everytime you open your PS or do you stick to a game or two until you finish them and then load up a new one. Solution is have a mix of file formats. some games with CSO, and some games with ISO. This way you can maximize you r memory card space while maintaining efficiency of your gameplay.

So it comes down to this, below this post are links to programs i use to convert files from ISO to CSO or CSO to ISO. But the software i use requires you to install the Microsoft .net framework into your computer. Why you ask? well i really don't know, it would seem that the program will not run unless you have it in your system. Now fuss no worries, its an easy enough program to use, just select the option you want, example is to select "ISO to CSO" option, browse for the file you want to convert, then just click on the convert button, and thats it. Don't expect too much, compression depends on the game itself. there are games when you convert them like final fantasy give you only a 20% file size difference, but there are games that I've converted that yielded a 60 or even 70% file size difference. You will just need to try them out. I'm guessing that the games with a lot of videos and cut scenes don't compress too well since videos are compressed enough. So try them out and enjoy the experience. If you happen to find a program that converts from file structure to file structure without installing the .NET framework give me a holler, I'll try it out, but really, as the quote goes, "if it ain't broken, then don't fix it..." enjoy ...

Download the Microsoft .Net Framework
Download the PSP ISO Compressor