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> Main > My range coder does not work properly (need help)! |
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donkey7 31 Jan 2005, 21:58
Could someone help me!
I wrote range coder (thing similar to arithmetic coder) based on program written in C by Michael Schindler http://www.compressconsult.com and article by Arturo Campos, but it doesn't work! Their coders work properly. I think that bug is in my decoder. Thanks in advance to anyone who will find the bug!
Last edited by donkey7 on 03 Feb 2005, 15:18; edited 1 time in total |
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31 Jan 2005, 21:58 |
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JohnFound 02 Feb 2005, 16:36
donkey7 wrote: Please reply quickly. Hm, it is message board, not a chat... ...and what actuall is "range coder" ? Regards. |
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02 Feb 2005, 16:36 |
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donkey7 02 Feb 2005, 16:45
Range coder is an entropy coder similar to arithmetic coder. It works by assigning less bits to more frequent symbols (eg. for string 'aaabc' it will assign one bit to symbol 'a', and two bits for symbols 'b' and 'c').
The main difference between arithmetic coder is that range coder outputs bytes instead of bits. Also huffman coder (another entropy coder) can not assign an non integer number of bits to a symbol. If you are not experienced with entropy coders please refer to Arturo Campos and Michael Schindlers websites (I based on their work). |
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02 Feb 2005, 16:45 |
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beppe85 02 Feb 2005, 21:06
I know a bit of theory about arithmetic coder, indeed it acts upon ranges too. But I don't remember to have saw any reference about your 'range coder' in literature(Sedgewick, Knuth, etc)
The World Wide Web wrote: The range encoder is an entropy coder similar to the arithmetic coder or huffman coder. Compared to an arithmetic coder the files are minimally larger (less than 0.01% in most cases) but the operation speed is nearly twice as fast. Seems pretty good. _________________ "I assemble, therefore I am" If you got some spare time, visit my blog: http://www.beppe.theblog.com.br/ and sign my guestmap |
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02 Feb 2005, 21:06 |
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donkey7 03 Feb 2005, 10:37
I need an range coder because I want to write an universal file compressor. I wrote recently an Huffman coder that provides (in most cases) better compression than range coder. So I see that my range coder needs a lot of improvements, but I can't incorporate them because my range coder DOESN'T WORK PROPERLY.
When writing my range coder I based on articles from web, and I almost never refer to literature. |
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03 Feb 2005, 10:37 |
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