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The optimal length-limited Huffman code will encode symbol i with a bit string of length h i. The canonical Huffman code can easily be constructed by a simple bottom-up greedy method, given that the h i are known, and this can be the basis for fast data compression. [2]
The two codes (the 288-symbol length/literal tree and the 32-symbol distance tree) are themselves encoded as canonical Huffman codes by giving the bit length of the code for each symbol. The bit lengths are themselves run-length encoded to produce as compact a representation as possible. As an alternative to including the tree representation ...
In computer science and information theory, a Huffman code is a particular type of optimal prefix code that is commonly used for lossless data compression.The process of finding or using such a code is Huffman coding, an algorithm developed by David A. Huffman while he was a Sc.D. student at MIT, and published in the 1952 paper "A Method for the Construction of Minimum-Redundancy Codes".
The LZO library implements a number of algorithms with the following characteristics: Higher compression speed compared to DEFLATE compression; Very fast decompression; Requires an additional buffer during compression (of size 8 kB or 64 kB, depending on compression level)
To make the code a canonical Huffman code, the codes are renumbered. The bit lengths stay the same with the code book being sorted first by codeword length and secondly by alphabetical value of the letter: B = 0 A = 11 C = 101 D = 100 Each of the existing codes are replaced with a new one of the same length, using the following algorithm:
Module level content compression for Apache started with mod_gzip, which is an external extension module, since Apache 1.3. The developers of the Apache 2.0.x servers have included mod_deflate in the codebase for the server to perform a similar GZIP-encoding function. Early versions provided lesser amount of compression than mod_gzip. [3]
The reference implementation is a software library under the terms of Apache License 2.0, written in C. [ 2 ] Since then, the open-source community made attempts to modify Zopfli for optimizing Portable Network Graphics (PNG) files because PNG uses a Deflate compression layer.
Version 5.2 files are dated April 11, 2007. 5.2 runtime does not support applications coded for 5.1 or before. Introduced June 5, 2007, adding code samples for data compression, new video codec support, support for 64-bit applications on Mac OS X, support for Windows Vista, and new functions for ray-tracing and rendering.