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Rar archive compression

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Last response: in Apps General Discussion
February 7, 2011 2:36:03 AM

So I downloaded a rar file which was 699mb and I extracted it out and it was only 636mb. Within the Archive is a folder with a lot of .png's

So then I compressed it myself to see if it would got up but it didn't it stayed exactly at 636mb.

So what is happening was it just that someone was incompetent with the compression or is there hidden data that won't extract.

More about : rar archive compression

February 7, 2011 7:44:27 PM

.png files are already in a compressed format. You can't keep re-compressing a file and have it get smaller each time, even if you use a different compression method.

From Wiki:

PNG uses a 2-stage compression process:

pre-compression: filtering (prediction)
compression: DEFLATE
PNG uses a non-patented lossless data compression method known as DEFLATE, which is the same algorithm used in the zlib compression library.

February 7, 2011 9:27:59 PM

your extract results are normal!
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February 15, 2011 12:04:31 AM

If that is the case then why did it get smaller when I compressed it.


Best solution

February 15, 2011 12:21:19 PM

squareenixx said:
If that is the case then why did it get smaller when I compressed it.

Don't know why the original rar file you got was larger than the actual files, If you look at the rar file you'll be able to see the file count, if they match, you got everything.
February 18, 2011 11:26:08 PM

Best answer selected by squareenixx.
February 19, 2011 7:38:42 PM

This topic has been closed by Mousemonkey