Compressing - anybody familiar with it?

[baka324]

I was just wondering if anybody around here knows how to use 7zip well. I've seen it compress like a 700mb file to 100mb.

I have no clue how to get it to a very small size...

 

[kbryc08]

hm, that would depend on what you're compressing, yes?

to get the best compression, select 7z as the archive format then select the highest compression level, which will take longer.

 

[baka324]

I tried compressing something on 7zip today, I think I set compression level to Ultra. About 25minutes later, my 1.16gb file turned into a 1.17gb compressed file =__=

 

[desioner]

Are you on Mac or Windows? I'm assuming your on Windows in which case my information won't help you. But just checking.
desioner

 

[baka324]

Yeah I'm running on XP.

 

[Vicare]

Yeah, I've come across such thing. But it's not 7zip, but RAR.
It was a ISO file which is 80MB in zip. But when I extract it, it becomes 300MB. Amazing, there must be some trick, but I don't know.

 

[Denamic]

Compression depends heavily on what you're compressing.
Image files are usually already compressed, so don't bother trying to compress it further.

Exceptions would be older games where we didn't have the processor power to decompress it in real time.
Such as PSX games.

Compression is pretty complicated, and I honestly don't understand much of it myself.
You could try reading up on it here: http://en.wikipedia.org/wiki/Data_compression

In any case, compressing isn't a sure fire way to decrease size, since a lot of the data we handle is already compressed.
Most notably pictures, audio and CD/DVD image files.
Smaller games usually have 'dummy' data in the images so it'll fill out the CD/DVD.
This dummy data is usually very easy to compress, since it's mostly just empty space.
But sometimes it's filled with random data, which makes it harder to compress.

 

[baka324]

I guess this explains why my audio files wont compress haha.