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Topic: DEFLATE (algorithm)

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	RFC 2394 (rfc2394) - IP Payload Compression Using DEFLATE
		DEFLATE Algorithm Implementation...............................3 2.1 Compression.................................................3 2.2 Decompression...............................................4 3.
		The deflate format and compression algorithm are based on Lempel-Ziv LZ77 compression; extensive research has been done by the GNU Project and the Portable Network Graphics working group supporting its patent free status.
		DEFLATE Algorithm Implementation The DEFLATE compression algorithm was designed by Phil Katz and its details are publicly available in [Deutsch96].
	www.faqs.org /rfcs/rfc2394.html (1088 words)

	LZ77 and LZ78 (algorithms) - Wikipedia, the free encyclopedia
		LZ77 and LZ78 are the names for the two lossless data compression algorithms published in papers by Abraham Lempel and Jacob Ziv in 1977 and 1978.
		The LZ77 algorithm works by keeping a history window of the most recently seen data and comparing the current data being encoded with the data in the history window.
		The most popular form of LZ78 compression was the LZW algorithm, a modification of the LZ78 algorithm made by Terry Welch.
	en.wikipedia.org /wiki/LZ77 (1107 words)

	Mapping Deflated Files
		So we must have a map which allows us to work out where in the deflated stream a given block of the underlying uncompressed data is — and enough data to allow us to pull this data out of the middle of the deflated stream and inflate it.
		The deflate algorithm works by writing data out in blocks; each block's header indicates either that the block is merely stored (so that blocks of data that do not compress well are stored as-is in the gzip file), or it gives the code lengths and other data needed to construct the decoding tree.
		Deflate streams include backwards references to data earlier in the stream within a given (usually 32Kb) window, so that data need not be duplicated.
	zsync.moria.org.uk /paper200501/ch03s02.html (788 words)

	DEFLATE (algorithm) - Wikipedia, the free encyclopedia
		DEFLATE is a lossless data compression algorithm that uses a combination of the LZ77 algorithm and Huffman coding.
		Source code for DEFLATE compression and decompression can be found in zlib, the freely-available, general-purpose compression library.
		A higher compression ratio version of DEFLATE is implemented by 7-Zip.
	en.wikipedia.org /wiki/DEFLATE_(algorithm) (153 words)

	geekhaven.net (Site not responding. Last check: 2007-10-14)
		The StuffItX algorithms provide very high compression ratios for a high speed compression rate, however they have the slowest decompression rate, and so they are not great for the recipient.
		Deflate and Deflate64 are fairly fast and compress decently, however they have the advantage of being very widespread.
		RAR performs fairly well overall, however it does not perform as well as Deflate in both speed and compression ratio, and since it is also not as widespread, it may not be as good a choice.
	reviews.geekhaven.net /compression (608 words)

	Gzip - TheBestLinks.com - Data compression, GNU, Huffman coding, Patent, ... (Site not responding. Last check: 2007-10-14)
		Gzip is based on the deflate algorithm, which is a combination of LZ77 and Huffman coding.
		'Deflate' was developed in response to patents that covered LZW and other compression algorithms and limited the usability of 'compress' and other popular archivers.
		The zlib compressed data format, the 'deflate' algorithm and the Gzip file format were standardised respectively as RFC 1950, RFC 1951 and RFC 1952.
	www.thebestlinks.com /Gzip.html (283 words)

	Dr. Dobb's \| An Algorithm for Online Data Compression \| April 15, 2003
		Deflate is one of the most popular algorithms, and zlib [2] (http://www.cdrom.com/pub/infozip/zlib/) is one of its most popular implementations.
		Deflate requires a relatively large amount of memory (260 Kb for the compressor and 43 Kb for the decompressor) by default.
		Similar to the Deflate algorithm, it is a combination of the LZ77 algorithm and Huffman-like encoding.
	www.ddj.com /184403560?pgno=5 (3644 words)

	An Explanation of the DEFLATE Algorithm
		A Huffman algorithm starts by assembling the elements of the 'alphabet,' each one being assigned a 'weight' -- a number that represents its relative frequency within the data to be compressed.
		In the variation used by the Deflate standard, there are two additional rules: elements that have shorter codes are placed to the left of those with longer codes.
		Probably the trickiest part of the DEFLATE specification to understand is the way trees are encoded to go along with the data, when that data is compressed with specialized trees.
	www.gzip.org /deflate.html (2167 words)

	[No title] (Site not responding. Last check: 2007-10-14)
		DEFLATE is the algorithm used in the well-known "gzip" file format.
		Note however that in its basic form the EPIC algorithm does not have the ability to detect and adapt to new patterns in the uncompressed data; instead it relies on a fixed pre-programmed description of how the protocol to be compressed is expected to behave.
		The resulting hybrid algorithm offers the best of both worlds: a very high compression ratio for the "well-behaved" parts of the application message, and a good compression ratio even for the portions of the message that cannot be pre-programmed into the compression algorithm.
	mirrors.isc.org /pub/www.watersprings.org/pub/id/draft-price-rohc-sigcomp-user-guide-01.txt (5996 words)

	[No title]
		Compression algorithm (deflate) The deflation algorithm used by gzip (also zip and zlib) is a variation of LZ77 (Lempel-Ziv 1977, see reference below).
		A block is terminated when deflate() determines that it would be useful to start another block with fresh trees.
		So deflate() does not always find the longest possible match but generally finds a match which is long enough.
	www.gzip.org /algorithm.txt (1516 words)

	Deflate - file compression algorithm (Site not responding. Last check: 2007-10-14)
		Deflation is a means of compressing an octet sequence that combines the LZ77 algorithm for marking common substrings and Huffman coding to take advantage of the different frequencies of occurence of byte sequences in the file.
		This algorithm may not be as easy to understand or as efficient as the LZW compression algorithm but Deflate does have the important advantage in that it is not patented.
		The deflate source code is licensed under the terms of the Lisp Lesser GNU Public License, known as the LLGPL.
	opensource.franz.com /deflate (377 words)

	RFC 1951 - DEFLATE Compressed Data Format Specification version 1.3. P. Deutsch. (Site not responding. Last check: 2007-10-14)
		RFC 1951 DEFLATE Compressed Data Format Specification May 1996 * Is compatible with the file format produced by the current widely used gzip utility, in that conforming decompressors will be able to read data produced by the existing gzip compressor.
		RFC 1951 DEFLATE Compressed Data Format Specification May 1996 The code lengths are sufficient to generate the actual codes, as described above; we show the codes in the table for added clarity.
		RFC 1951 DEFLATE Compressed Data Format Specification May 1996 specification per se, and a compressor need not follow it in order to be compliant.
	rfc.sunsite.dk /rfc/rfc1951.html (3062 words)

	[No title] (Site not responding. Last check: 2007-10-14)
		The Deflate Compression Algorithm reference: http://www.gzip.org/zlib/rfc-deflate.html Basic idea: Deflation is a means of compressing an octet sequence that combines the LZ77 algorithm for marking common substrings and Huffman coding to take advantage of different frequency of occurance for each possible values in the file.
		This algorithm may not be as easy to understand or as efficient as the LZW compression algorithm but Deflate does have the big advantage in that it is not patented.
		The LZ algorithm compresses a file by replacing repeated substrings with (Length,Distance) markers which mean during decompression: Go back Distance octets in output stream and copy Length bytes to the output stream.
	opensource.franz.com /deflate/deflate-dist/inflate.cl (828 words)

	freed-newenc-00.txt (Site not responding. Last check: 2007-10-14)
		Network Working Group Ned Freed, Innosoft Internet Draft Deflate and Deflate-base64: Compression Content-Transfer-Encodings April 2000 Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC 2026.
		Deflate Compression The deflate compression format [RFC-1951], as used by the PKZIP and gzip compressors and as embodied in the freely and widely distributed zlib [Gailly95] library source code, has the following features: (1) An apparently unencumbered encoding and compression algorithm, with an open and publicly-available specification.
		The Deflate Content-Transfer-Encoding The deflate encoding process consists of applying the deflate algorithm defined in [RFC-1951] to a MIME object in canonical form.
	ietfreport.isoc.org /idref/draft-freed-newenc (843 words)

	CompressFile Method, File Encoding Control (Site not responding. Last check: 2007-10-14)
		A compression algorithm that combines LZ77 algorithm for creating common substrings and Huffman coding to process the different frequencies of byte sequences in the data stream.
		A compression algorithm that rearranges blocks of data in sorted order and then uses Huffman coding to process different frequencies of data within the block.
		A value of zero specifies that the default compression level appropriate for the selected algorithm should be used, balancing resource usage and the compression ratio of the data.
	www.catalyst.com /support/help/cstools4/visual/html/encode/control/method/compressfile.html (470 words)

	7z - LearnThis.Info Enclyclopedia (Site not responding. Last check: 2007-10-14)
		In computing, 7z is an archive format which allows data compression using a number of compression algorithms.
		The format was initially implemented by the 7-Zip archiver but the file format is public and 7-Zip's implementation of it is publicly available under the GNU LGPL licence.
		The key is generated from a user-supplied passphrase using an algorithm based on the SHA-256 hash algorithm (with a large number of iterations, to make a brute-force search for the passphrase more difficult).
	encyclopedia.learnthis.info /7/7z/7z.html (193 words)

	mod_deflate and Apache 2.0.x \| evolt.org (Site not responding. Last check: 2007-10-14)
		The mod_deflate algorithm uses the ZLIB compression library and the functions in this library do not seem to be as effective at compressing files in real time as the GZIP functions used for mod_gzip.
		With future releases of this module, the authors of mod_deflate may want to compare their algorithm to the one used in mod_gzip to see if there are ways to improve the achieved compression ratio in mod_deflate without compromising server performance.
		Despite the fact that the compression algorithm is not as effective as the one found in mod_gzip, using mod_deflate for Apache 2.0.x is still a quick and effective way to decrease the size of the files that sent to clients.
	www.evolt.org /article/mod_deflate_and_Apache_2_0_x/20/60104 (1129 words)

	DEFLATE (algorithm) - TheBestLinks.com - Algorithm, Gzip, Huffman coding, Lossless data compression, ...
		DEFLATE (algorithm) - TheBestLinks.com - Algorithm, Gzip, Huffman coding, Lossless data compression,...
		DEFLATE, DEFLATE (algorithm), Algorithm, Gzip, Huffman coding, Lossless data...
		Unlike LZW, DEFLATE is widely thought to be free of any subsisting patents, and this has led to its use in gzip compressed files and PNG image files, in addition to the zip format for which Katz originally designed it.
	www.thebestlinks.com /DEFLATE.html (174 words)

	Link Compression Extension - Gnutella Developers (Site not responding. Last check: 2007-10-14)
		The "deflate" scheme is handled by the zlib (http://www.zlib.org/) library (the deflate/ inflate routines).
		The idea is that decompression is fast, so it's OK to be sent compressed data, but the compressing side must decide based on the resources it has available whether it will compress or not.
		The deflate algorithm does not expand already-compressed data by a large factor and emits them as clearly marked non-compressible data (the overhead is limited to roughly 0.1%).
	www.the-gdf.org /wiki/index.php?title=Link_Compression_Extension (472 words)

	Deflate
		Deflate is a compression procedure primarily combining two algorithms together.
		On the one hand a dictionary based algorithm equivalent to LZ77 is used to encode recurring sequences.
		The specification of the deflate procedure is published in RFC 1951: "DEFLATE Compressed Data Format Specification" (by P. Deutsch).
	www.binaryessence.com /dct/imp/en000240.htm (114 words)

	7. Evaluation
		The Deflate compression algorithm is dynamic; it will scan ahead and back in the input data to try to compress more of it.
		That is because the Deflate algorithm is quite efficient with that type of data: it does not need to scan the input backward and it continues to scan forward for longer.
		The Deflate algorithm used in both works best when it is given as much input data to work with at once.
	www.am-utils.org /docs/sca/node7.html (3871 words)

	Zip
		The default algorithm to use can be configured on this page, but you can always change to a different algorithm in the New Archive dialog available from the archive menu.
		Deflate - Deflate is the compression algorithm used by the PKZIP 2.04g file format.
		Deflate64 - The Deflate64™, also know as Enhanced Deflate, compression algorithm is a variation of the Deflate algorithm that uses a 64K sliding window rather than a 32K window in order to compress a sequence of bits.
	www.enriva.com /MagellanExplorer/Documentation/archive_zip.html (324 words)

	And I thought my implementation of Deflate was bad - virtualdub.org
		The Deflate algorithm is also the underlying compression algorithm behind the well-known 'zip' format, and is surprisingly complex, with a sliding window matching algorithm combined with three layers of Huffman trees.
		Deflate should never enlarge a stream by more than a tiny fraction since it allows individual blocks to be stored.
		The way that a Deflate compressor generally works is that it builds a buffer of LZ tokens up to some threshold, builds Huffman trees based on the token statistics, encodes the tokens using the trees, and then flushes out the result.
	www.virtualdub.org /blog/pivot/entry.php?id=134 (1198 words)

	[No title]
		The Huffman trees for each block are independent of those for previous or subsequent blocks; the LZ77 algorithm may use a reference to a duplicated string occurring in a previous block, up to 32K input bytes before.
		The representation used in the "deflate" format limits distances to 32K bytes and lengths to 258 bytes, but does not limit the size of a block, except for uncompressible blocks, which are limited as noted above.
		Each type of value (literals, distances, and lengths) in the compressed data is represented using a Huffman code, using one code tree for literals and lengths and a separate code tree for distances.
	www.ietf.org /rfc/rfc1951.txt (2082 words)

	RFC 4464 - Signaling Compression (SigComp) Users' Guide
		The bytecode for the chosen compression algorithm is uploaded to the UDVM as part of the compressed data.
		DEFLATE is the algorithm used in the well-known "gzip" file format.
		Depending on the mechanism and basic algorithm in use, the assembly code for either the mechanism or the basic algorithm may require modification (e.g., if the algorithm uses 'no more input' to jump to end_of_message, following end_of_message with an input instruction for CRC will not work).
	www.packetizer.com /rfc/rfc4464 (5660 words)

	Secure aircraft communications addressing and reporting system (ACARS) - Patent 6677888 (Site not responding. Last check: 2007-10-14)
		These techniques use simple character substitution algorithms that may protect the information from a casual hacker, but a sophisticated attacker will be able to break the code in a short period of time with nominal computational resources.
		Unfortunately, the encryption algorithms are likely to convert the user data from characters to bits which then have to be encoded again into characters for use with the character-based ACARS protocol, thereby doubling the size of the payload.
		A bit-to-hex encoding algorithm is specified in ARINC 622 for this purpose (4-2).
	www.freepatentsonline.com /6677888.html (8284 words)

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