RAR compression

[bigmicka]

no i dont just mean its text files.

the gameshark images if you open them in notepad will just look like normal characters on a file. its the same with any file being used.

if the same characters are used within the files then it will be highly compressible.

ok take this for example.

"this is a test file and im trying to show James what is happening."

now that sentence is made up of ascii characters and each of those has a code representing a number which can then be converted to a 8bit binary string.

the small letter "a" works out to 61 in decimal on the ascii chart or 10111100 in binary. all characters capital and no capital and non-english symbols are in the ascii chart. but the sentence above does not contain all those characters of the 52 upper and lower case letters or an non english characters only 17 lower case and 1 upper case plus the space character.

so instead of using a 8bit binary to represnt the character you can use a 5bit binary string to represent all the characters in that sentence the charater "a" could then be represented in the binary string of 10000. if you used the 5bit system instead of the 8bit system you would see a relative saving of 3/8ths of the sentence.

hope you can understand that.

mic

[james636]

But most the compression was used to compression the ISO images which range from 700MB to 4GB

[bigmicka]

but what is the iso image made up of? you will find its made up of the same ascii characters as a normal text file. if the same characters are repeated often enough you will get more compression than a file that uses a greater range of characters within the ascii chart.

mic

[james636]

bigmicka, dude, you sound like some guru genius. I told you once you were way over my head Maybe you should get the file and analyze it and tell us how this person was able to apply so much compression.

[james636]

OK, this is what I'll do, I'll take the same material that I unpacked, which is 8.5GB in size and attempt to recompress it. If all the stuff that was explained about one character and another character blah, blah is true, then the outcome of my recompression of the same material should come close to the size in which I originally downloaded it; 185MB, right?

[bigmicka]

so how did it go james, after your experiment you didnt post the results.

mic

[vitualis]

I would bet that those "ISO" images are made to fill a certain size but almost certainly contain mostly null data. Hence, the immense compressibility.

Regards.

[scooby2b2]

I'm in the same boat as you james.....i downloaded a game that was 600meg saved the folder to my documents and inside the folder was 20 rar files i opened the first rar file and inside that rar was an ISO file i extracted the ISO to my documents and it was 4.5gig !!!! now i really wanna know how the hell i can compress a 4.5gig ISO to 600meg ?

also seen a file that was 350meg and extracted to 4.5gig how ?

[iooi]

I was wondering if anyone can help me figure out how to get better compression results with WinRAR and WinAce. I have a file that was compressed by WinRAR to a size of 185MB. But when I unpacked the rar file, The contents' size was an unbelievable 8.5GB .

I just wonder if some one has burned 185 gig of data onto a dual layer dvd disk and finilised it. Created a iso image (maybe) of it and then compressed it... 185 meg of data and then a load of nothingness for the rest....