Information on compression ratio
bordelais78
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bordelais78 Posted messages 2 Status Membre -
bordelais78 Posted messages 2 Status Membre -
Hello, I have to submit an assignment asking for various manipulations regarding archiving and creating *.zip files, etc...
I would like to know two things: how can we obtain information about the compression rate of a file as well as the space gained between the normal file and the compressed one? (simple subtraction?)
In addition, I am asked to convert into .zip, .tar, and .cab. I managed to compress with the first two extensions using Keka, but I can't find any software to compress into .cab...
Thanks :)
Configuration: Mac OS X Mountain Lion (10.8.2) / Safari 6.0.2
I would like to know two things: how can we obtain information about the compression rate of a file as well as the space gained between the normal file and the compressed one? (simple subtraction?)
In addition, I am asked to convert into .zip, .tar, and .cab. I managed to compress with the first two extensions using Keka, but I can't find any software to compress into .cab...
Thanks :)
Configuration: Mac OS X Mountain Lion (10.8.2) / Safari 6.0.2
1 answer
Hello,
Wikipedia source:
"The compression ratio ? is related to the ratio between the size b of the compressed file B and the size a of the original file A.
The compression ratio is generally expressed as a percentage. The formula to calculate this ratio is:
? = 100 - ((b/a) * 100)."
Thus, a ratio of 50% means that the size b of the compressed file B is half of a.
The space saved is therefore a - b on the condition that the original file A has been deleted after compression...
As for the .cab format, it was designed by Microsoft. On Mac, we can open them but not create them. On Linux, there is an attempt with lcab.
If you really need to produce .cab archives, then you will have to go through Windows.
Ritchi
Wikipedia source:
"The compression ratio ? is related to the ratio between the size b of the compressed file B and the size a of the original file A.
The compression ratio is generally expressed as a percentage. The formula to calculate this ratio is:
? = 100 - ((b/a) * 100)."
Thus, a ratio of 50% means that the size b of the compressed file B is half of a.
The space saved is therefore a - b on the condition that the original file A has been deleted after compression...
As for the .cab format, it was designed by Microsoft. On Mac, we can open them but not create them. On Linux, there is an attempt with lcab.
If you really need to produce .cab archives, then you will have to go through Windows.
Ritchi
bordelais78
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Okay, that reassures me :) Thank you very much!