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Base92 Compression

Posted on 2007-07-31
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I need information on reading base92 compressed file. I have tried searching on google but got nothing. I will really appreciate any help on this topic.

Thanks,
Nauman.
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Question by:nauman_ahmed
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Axter earned 400 total points
ID: 19603187
Exactly what information are you looking for?

Are you looking for example code?
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by:Infinity08
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I've never heard about base92, but if it's similar to base64, then you can get a lot of resources here :

        http://en.wikipedia.org/wiki/Base64

including code to en- and decode.

However, 92 is an odd value to be using for such an encoding, as it's not a power of 2. So, I'm not sure whether that's the encoding used here.

Where did the file come from ? Do you have more information about that ? Was it generated by an application ? Can you contact somebody who might know more about it ? Is there documentation you have about that file or the encoding ?
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by:Kent Olsen
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xpm uses base 92 for pixel encoding.  Is this what you're looking for?



Kent
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by:nauman_ahmed
ID: 19603335
Thanks for reply. I know about base64 encoding but never heard of base92. I am converting someone's else code that is in VB and it reads a base92 compressed file. Following is a sample that is read from encoded file:

z , d$!' 6K5z/ ]o* -|2 LU- 7<0 KK8 se7 )<0 g4? H0= @hJ [eY NMm B]h ef

I don't think that it is based on base64. Any ideas?

Thanks.
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by:Infinity08
ID: 19603410
>> I don't think that it is based on base64. Any ideas?

Doesn't look like it, no.


>> base92 compressed file.

A compressed file ? An algorithm like Base64 would make the file bigger, so that's probably not the case then here.

Also, 92 is not a power of 2, so an algorithm like base64 would not work very well. So, I'm leaning towards a different algorithm. Maybe something like used in XPM files (as Kdo said) ...

If you have the code in VB, then you can probably figure out that way what the format of the file is. If you're having problems with that yourself, you might want to post the VB code here, and post a link in the VB section. We can then figure out what the code does, and do the same thing in C++.
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by:aatrish2001
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ID: 19606422
Dear friend base 64 is diffrent it use for the attachment over mail.
can you have some document before starting base 92 so that all expert can help you
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by:rstaveley
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Following on from Kent's comment, you might want to Google up the source code for the ppmtoxpm utility, if that's what you are after.

The netpbm distribution http://gnuwin32.sourceforge.net/packages/netpbm.htm looks to be spot on (look in the converter/ppm directory).
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