Re: Adaptive Huffman algorithm with syllable compression?
- From: newsgroupaddress@xxxxxxxxx
- Date: Fri, 6 Mar 2009 07:51:41 -0800 (PST)
On 5 Mrz., 12:25, "o.bheze" <atom> wrote:
No, really 9 Bits. This is one of the few things I'm really sure.- A fixed code book is used at start. 9 Bit codes for values from 0 to
255.
not 8 bits ?
The codes go in an ascending sequence from 0011 1010 1 for 0x00 till
1011 1010 0 for 0xff.
I had now a closer look at LZW algorithm and no it isn't LZW. Btw. IABC are compressed, the syllable ABC gets its own code (12 Bit long).
not LZW ?
wrote the wrong length for the bit code for syllables in my first
message. The bit code is 16 Bit long, not 12. And, as far as I know at
the moment, no ASCII codes from the original file goes directly to the
compressed file.
No I'm not sure at the moment. I have now a closer look at this andAfter ABCD is compressed the syllables ABC, BCD and ABCD gets its own
12 Bit long codes, and so on.
Are you sure it's not a back pointer and some bits for the string lengh ?
hopefully know more soon.
Maybe someone here can help me. If this algorithm which I tried to
describe above is a common algorithm? For me this algorithm looks like
an adaptive Huffman algorithm with syllable compression. Someone knows
about an algorithm like this? If yes, where can I get more information
about this algorithm?
I don't understand which element make you thinking about Adaptive Huffman.
I guess it's a simple LZ-something
If I avoid repeating sequences in the original file, in the compreesed
file only the bit codes for used characters gets shorter. For example
if at the first position is an x, the codes for the next position gets
shorter as described below:
ASCII / Hex / Code Length
- J / 0x00-0x4a / 9 Bit code
K - j / 0x4b-0x6a / 8 Bit code
k-v / 0x6b-0x76 / 7 Bit code
w, x / 0x77, 0x78 / 5 Bit code
y, z / 0x79, 0x7a / 6 Bit code
{ - / 0x7b-0x8a / 8 Bit code
/ 0x8b-0xff / 10 Bit code
For me this looks like a variant of adaptive Huffman. But at the
moment, I don't understand how the node of the tree changed and I
don't understand how the syllable compression is integrated in this.
This is the reason I asked if this is maybe a common known compression
algorithm. Maybe something like LZ combined with adaptive Huffman? Or
I read something about HuffSyl (Huffman compression with syllables) on
the net, but couldn't find more information about it.
.
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