Compressing a 1Gb file into 4Mb file

[dothackjhe]

I've seen this a couple of times before where a file that is around 1 Gb or so could be compressed in rar to around a few Mb. How is this possible?

 

[zigzag3143]

I've seen this a couple of times before where a file that is around 1 Gb or so could be compressed in rar to around a few Mb. How is this possible?

Not usually possible as far as I know. If it were we would be using that algorithm.

 

[dothackjhe]

It's rarely that I see this though. If I remember it right, I first saw this kind of event in a GameCube ISO. It was around 1 Gb or so and was compressed to a few Mb only. And the same thing occurred when I downloaded an ISO of a PS2 DVD (CodeBreaker v10) when in fact I downloaded it as a few Mb only.

 

[pparks1]

Well, if a file is comprised of a series of repeatable recognizable patterns, you could get tons of compression. For example, a file that is all 0's...from start to finish, is easy to zip to almost nothing as all that has to happen is that everything is replaced with 0's when extracted.

 

[dothackjhe]

Now I'm getting the idea. Admittedly I do not know how the algorithm works with this compression stuff aside from the fact that the files are being "compressed" to preserve the integrity of the files and save some disk space.

 

[profdlp]

Think of compression like a long driving trip. In places you might make a lot of turns, requiring a lot of directions like "turn left here, go two blocks, then turn right. Hard to compress. The example pparks1 gave would be like hitting the highway and only needing to know to stay on the road for the next 600 miles.

The first part might require a lot of data to get you just a few miles; the last part is one simple instruction for the next 600 miles.

 

[dothackjhe]

Thanks, great info.

 

[Gornot]

Think of compression like a long driving trip. In places you might make a lot of turns, requiring a lot of directions like "turn left here, go two blocks, then turn right. Hard to compress. The example pparks1 gave would be like hitting the highway and only needing to know to stay on the road for the next 600 miles.

The first part might require a lot of data to get you just a few miles; the last part is one simple instruction for the next 600 miles.

I don't think there is an easier example for this kind of explanation :roflmao: epic!

 

[MikeS104]

With WinRAR or 7Zip you can make a set of 4MB files.

 

[WebMattR]

Another option is one not many people seem to think of, and that's UHARC. I've never found anything that compresses files so well.

WinUHA Website

 

[dothackjhe]

Another option is one not many people seem to think of, and that's UHARC. I've never found anything that compresses files so well.

WinUHA Website

Oh, I didn't know about this. Thanks for the info, this one looks interesting enough.

 

[Sam The Techie]

I wouldnt think it is possible for that level of compression, usually i get around 30-50% compression on a good day!

 

[dothackjhe]

It is possible. But just like the people on this thread said, it will depend on the ISO itself whether it can be compressed to that extent or not.

 

[RealPetChicken]

KGB Archiver - Wikipedia, the free encyclopedia

 

[dothackjhe]

KGB Archiver - Wikipedia, the free encyclopedia

Ahhh. . Looks new. I still prefer winRAR I think. .

 

[Gornot]

Another option is one not many people seem to think of, and that's UHARC. I've never found anything that compresses files so well.

WinUHA Website

+1

UHARC rules... seriously.

 

[dothackjhe]

Another option is one not many people seem to think of, and that's UHARC. I've never found anything that compresses files so well.

WinUHA Website

+1

UHARC rules... seriously.

It looks dated, but I'll go give it a try.

 

[MilesAhead]

I've seen this a couple of times before where a file that is around 1 Gb or so could be compressed in rar to around a few Mb. How is this possible?

If the file is a GB worth of zeros then I can compress it into a few bytes without even resorting to binary. How about "1GBx0.txt" where the text is "1GBx0" ??

Try compressing a BluRay 2 hour movie onto CD and you'll get the idea.
Some data sets compress more easily than others.

 

[Barman58]

The example I tend to use when explaining the concept is to use a digital camera shooting jpeg files.

Take a photograph of a white wall or other plain image and compare file sizes with other complex images from the same camera

 

[Ravi5kumar]

Use 7zip. It compress files perfectly in 7z format. It can compress a 1 GB file to 800 MB. For me 7zip is better than WinZip