Abstract: An LZW compressor implementation architecture utilizes a plurality of limited length character tables corresponding to the respective characters of the alphabet. A string is stored by storing the code associated with the string in the character table corresponding to the extension character of the string at a character table location corresponding to the code of the string prefix. A character table is created when the character corresponding thereto is first encountered in the input. The input data character stream is searched by comparing the input stream to the stored strings to determine longest matches therewith. The codes associated with the longest matched strings are outputted so as to provide an output stream of compressed codes. The respective lengths of the character tables are limited in accordance with the frequency of occurrence of the characters of the alphabet.

Abstract: A method and apparatus for coding and decoding information are disclosed. The method is for encoding a message that includes a first set of binary digits. Each binary digit has a first value (“0”) or a second value (“1”). The method includes receiving a first set of binary digits, generating a second set of binary digits in response to the first set of binary digits (Y), and selecting the values of binary digits in the second set such that the number of binary digits having the first binary value in the second set is higher than the number of binary digits having the first binary value in the first set.

Abstract: Apparatus, and an associated method, for facilitating communication of a vector graphic representation, or other content, pursuant to effectuation of a communication service. The content forms, for instance, an animated graphic, such as that used in a mobile communication application to effectuate an animated multi-media message. The vector graphic is encoded according to codewords that function to compress the data prior to its communication upon a radio link. And, once delivered to a receiving station, a decoder decodes the content into unencoded form. Codebooks are utilized and accessed by an encoder and decoder of a sending/receiving station pair.

Abstract: An intelligence bearing signal in the form of a string of digitized analog signals is communicated from a source site to a destination site. The signal is in the form of a string of digitized analog signal samples. A sub-string dictionary, a linked list and an ID list are provided at the source site and the destination site, and are used to compress the intelligence bearing signal for faster transmission.

Abstract: A data compression apparatus has a characterizing point extracting part 1 which extracts data expressing characterizing points included in a plurality of data showing a result of carrying out simulation, quantized data generating part 2 which generates quantized data obtained by quantizing data except for data expressing characterizing points, and file number converting part 3 which converts the same types of quantized data including in the quantized data, into a relating file number. In the case of compressing data, data except for the characterizing points is compressed. If the same quantized data is included at the same address location in the previously-compressed file, the quantized data is replaced with the file number of previously-compression file, thereby compressing data at high efficiency.

Abstract: A method for compressing a message is disclosed, comprising: identifying a block of data within the message which is found in a previous message; generating a pointer identifying the block of data in said previous message; and replacing the block of data with the pointer in the message.

Abstract: A method, and apparatus for accomplishing the method, of compressing data for transmission over a communications channel by receiving one or more data symbols comprising a current data string and at least one subsequent symbol, matching a longest previous data string with the current data string, the previous data string being defined by a code word, placing the code word into a compressed data stream, attempting to extend the current data string by a plurality of symbols, placing, in the event the current data string is extended, a string-extension length indicative of the plurality of symbols into the compressed data stream, and transmitting the compressed data stream though the communications channel.

Abstract: The present invention provides a method, system, and computer program product for encoding (and subsequently decoding) a sequence of periodic byte values that have a vertical correlation (e.g. so that they can be more efficiently stored and/or electronically transmitted for use in a real-time system or resource-constrained system). Redundant values are omitted through use of marker bytes and bits masks which indicate when a set of values is unchanged and which of the set have changed, respectively. In this manner, the resources required for transmitting, processing, and/or storing the values is reduced. In some systems, the reduction may enable shortening the periodic interval length, such that values of a finer granularity can be processed. An example scenario in which the present invention may be used advantageously is for transmitting periodic input data to a robot controller, in order to control movement of the robot.

Abstract: A new LZW compressor implementation architecture utilizes a plurality of character tables corresponding to the respective characters of the alphabet. A string is stored by storing the code associated with the string in the character table corresponding to the extension character of the string at a character table location corresponding to the code of the string prefix. A search for the longest matching string is performed by determining if the character table location is empty corresponding to the code of the currently matched string in the character table associated with the currently fetched character. If the location is not empty, it is storing the code of the string comprising the currently matched string extended by the currently fetched character. This string code is used as the next match with which to continue the search with the next fetched character. When the location is empty, the longest match has been determined to be the currently matched string.

Abstract: A minimum difference from the predictive loop outputs for each block in a predetermined length of time to delete a run common to the blocks and subjects the shifted up data to the Huffman conversion. Thus, the source data of a 96 kHz/24 bits/6 ch format (13.824 MBps) can be compressed at a compression ratio of 0.7 so that the data rate is not greater than 9.6 Mbps determined by the DVD format. Similarly, mode of 192 kHz/24 bits/2 ch format and the like can be realized. A large amount of the linear PCM super-audio data are compressed can be recorded and reproduced in the DVD format, and the recording time is increased.

Abstract: A sliding window type compression scheme is combined with a statistical type compression scheme to provide a dual-mode compression scheme that is optimized for use in compressing operating code in a data storage device. In a sliding window portion of the compression scheme, root and copy items are created, wherein the copy items include a length value and an offset value. The length values and most significant portions of the offset values are then compressed separately in the statistical portion of the compression scheme to form a compressed output which, when combined with the root items form a dually-compressed compressed output. A complimentary decompression scheme is then used to decompress the dually-compressed output.

Abstract: A method, apparatus, article of manufacture for compressing a series of data values is describe. Common and non-common digits between two successive data values are identified, and a compressed data value from the non-common digits and a code identifying the common digits is formed. Compressed data values are decompressed by substituting the digits common between a first and a second data value into the first compressed data value according to the code.

Abstract: A method, and apparatus for accomplishing the method, of compressing data for transmission over a communications channel by receiving one or more data symbols comprising a current data string and at least one subsequent symbol, matching a longest previous data string with the current data string, the previous data string being defined by a code word, placing the code word into a compressed data stream, attempting to extend the current data string by a plurality of symbols, placing, in the event the current data string is extended, a string-extension length indicative of the plurality of symbols into the compressed data stream, and transmitting the compressed data stream though the communications channel.

Abstract: A method and circuit for compression and decompression of data. For compression, successive units of input data are received in first register and second registers. The contents of the registers are used to address a lookup RAM, and the data stored in the lookup RAM is used to address a dictionary RAM. If output data from the dictionary RAM does not match output data from the first and second registers, a value from a dictionary counter is stored in the lookup RAM. If output data from the dictionary RAM matches output data from the first and second registers, data read from the lookup RAM is fed back for storage in the first register. The data from the first and second registers is provided as compressed output data. For decompression, the compressed data are used to populate another dictionary RAM, which is used to reconstruct the uncompressed data.

Abstract: A method for reducing radio frequency interference from a high frequency serial bus by scrambling data signals and reducing the repetition of control signals. Beginning and ending control signals are provided with meaningless signals provided therebetween.

Abstract: A computer operable to encode a string of tokens is described. The string of tokens includes a group of tokens that immediately follow a token having a first value. The Computer operates to select a token value that occurs most often in the group. The computer can then operate to convert the first string of tokens into a second string of tokens by substituting each occurrence of a token-pair unit in the first string with a single token. The token-pair unit includes a first token having the first value and a second token having the selected value. The computer then operates to identify a group of tokens in the second string. The identified group of tokens are those tokens that follow a token having the first value. The computer then operates to Huffman encode the second string. In part, this is accomplished by Huffman encoding the identified group based upon the identified group's local frequencies.

Abstract: The systems and methods relate to the compression of multiple files into a single file called an archive. Before appending the multiple files as one file to be compressed, the systems and methods arrange the order of files to increase the potential of redundancy among neighboring files, thus providing potential improvement in compression ratio and compression speed. In using a dictionary method to compress the multiple files appended as one file, a large dictionary is used in one embodiment to take advantage of potential between-file redundancies. In another embodiment, the redundancy characteristics of the multiple files are examined to dynamically determine the dictionary size. After the dictionary compression method produces an intermediary output data file, the intermediary output data may be separated into multiple sections, and a compression method that is potentially suitable for the data characteristics of each section may be applied.

Abstract: Logic circuitry performs a matching algorithm function. A memory produces a match signal that indicates which memory cells contain data that matches input address data to the memory. A first logic AND function performs a logic AND between a current value of the match signal currently produced by the memory for the input address data with a prior value of the match signal produced by an immediately prior input address data. A buffer holds index data. A second logic AND function compares output of the first logic AND function with the index data. Output of the second logic AND function is returned to the buffer as new index data. Index logic generates an offset based on the index data stored in the buffer. A send byte function asserts a send byte signal when the match signal is zero and when the output of the second logic AND function is zero. A length counter is incremented for every cycle in which the send byte signal is not asserted.

Abstract: A multiple description (MD) joint source-channel (JSC) encoder in accordance with the invention encodes n components of a signal for transmission over in channels of a communication medium. In illustrative embodiments, the invention provides optimal or near-optimal transforms for applications in which at least one of n and m is greater than two, and applications in which the failure probabilities of the m channels are non-independent and non-equivalent. The signal to be encoded may be a data signal, a speech signal, an audio signal, an image signal, a video signal or other type of signal, and each of the m channels may correspond to a packet or a group of packets to be transmitted over the medium. A given n×m transform implemented by the MD JSC encoder may be in the form of a cascade structure of several transforms each having dimension less than n×m. The transform may also be configured to provide a substantially equivalent rate for each of the m channels.

Abstract: A product with stored non-sequential data may be provided using a method that codes the data to a coding pattern using at least one sequence with symbols. The coding pattern may be configured such that an arbitrary subsequence of a predetermined magnitude of the sequence unambiguously defines the position of the subsequence in the sequence. The coding pattern may be reproduced on a product. An apparatus may be adapted to record and decode the coding pattern.

Abstract: A method for compressing text, comprising the steps of splitting a main character string into component strings, and counting the frequency of occurrence of each component string in the main character string and ordering the component strings in their frequency of occurrence. The method also comprises a step of allocating to each component string a token value representative of the component string and determined by the frequency of occurrence of the component string, storing the token value so allocated as a token table in which tokens are associated with component strings, and allocating to each component string in the main character string the token value for that component string from the token table to generate a sequence of token values representing the main character string in a compressed format.

Abstract: An apparatus and method for compressing data is disclosed. The apparatus and method comprise: 1) analysis of the data to identify a relationship between a plurality of data elements in the data, 2) reordering the data based on the identified relationship between the plurality of data elements, and 3) identifying common sequences in the reordered data and storing these references using a lean index. The apparatus and method of the present invention further includes reordering the data to arrange related data elements adjacent to one another, and compressing the reordered data to generate a compressed data set.

Abstract: A character string of which a start point is each address of character string data in an input buffer is rearranged in the predetermined order, so that a rank list is generated. Next, the location of the matching candidate of a character string to be encoded is obtained on the basis of the rank list. Then, the character string to be encoded is compared with a matching candidate, thereby obtaining a matching length. Further, a code is generated using the location of the matching candidate and the matching length, and the code is output as compression data.

Abstract: A method, and apparatus for accomplishing the method, of compressing data for transmission over a communications channel involves receiving one or more data symbols comprising a current data string and at least one subsequent symbol; matching a longest previous data string with the current data string, the longest previous data string being defined by a code word; placing the code word into a compressed data stream; and extending the current data string by a plurality of symbols. Additional steps include: placing, in the event the current data string is the second occurrence of a two symbol string, a length field indicative of the plurality of symbols into the compressed data stream; placing, in the event the current data string is not the second occurrence of the two symbol string, a multi-symbol extension string signaling code word indicative of the plurality symbols into the compressed data stream; and transmitting the compressed data stream through the communications channel.

Abstract: An encoding technique in which numeric data in a set of data is selected and the least significant bits (LSBs) of numeric data values in the numeric data are replaced with a single least significant bit that is shared by the numeric data values in the numeric data.

Abstract: A method and apparatus for reducing data expansion during data compression are provided that allow the coding scheme used to compress data to be swapped between two or more coding schemes. Specifically, a coding window is provided that holds data to be compressed, and the compression potential of data entering or exiting the coding window is calculated. When a first threshold compression potential sum of data entering the window is reached, the coding scheme used to compress the data within the coding window is swapped from one coding scheme to another. A new compression potential sum is set based upon the compression potential of data exiting the window. The compression potential sum comprises a running total of the compression potential of data entering the coding window; and the coding scheme used to compress data within the coding window is swapped from one coding scheme to another when the compression potential sum reaches a first predetermined value.

Abstract: A method of reducing data expansion during data compression is provided that allows the coding scheme used to compress data to be swapped between two or more coding schemes. Specifically, a coding window is provided that allows analysis of the compression potential of data within the coding window. The data within the coding window then is analyzed to determine the compression potential of the data. If the compression potential of the data exceeds a first predetermined value, the coding scheme used to compress the data within the coding window is swapped from one coding scheme to another. Preferably the first predetermined value is programmable and is related to the bit cost required to swap back and forth between coding schemes. The two preferred coding schemes are ALDC Lempel-Ziv 1 coding and a pass-through coding scheme wherein raw data is passed unencoded.

Abstract: This invention provides a data compression method for efficiently compressing data based on data periodicity. To compress an input data stream and output the encoded stream, encoded input data is stored in a moving window having a predetermined size. A partial sequence starting from a given position (entry) in the moving window is compared with a data sequence to be encoded by a plurality of comparators. An entry having a maximum matching length is found by a matching finder in comparison by the plurality of comparators. When matching is found by the matching finder, a pair of offsets up to the entry and a matching length (offsets and matching length) are encoded by a matching code generator. The number of comparators is smaller than the size of the moving window, and some of offsets near offset 0 (0 indicates including no offset), offsets near offset L, offsets near offset 2L, offsets near offsets 3L, . . . are used as entries.

Abstract: An improved LZ77 data compression and decompression method, known as Le′Z99, uses an embedded alphabet to optimize code space and speed in the compressed data.

Abstract: In a data compression method of sequentially sampling an analog input signal at discrete sample points, and classifying a plurality of obtained sample values into a plurality of sections, a sampling string made up of sample values included in each section is set as the first sampling string. A function which takes a sample value at a predetermined sample point included in the first sampling string and is approximated to the first sampling string is generated. A parameter defining the function is output as an element of compressed data. A second sampling string made up of sample values obtained at respective sample points by the function is generated. Predetermined calculation is performed between two sample values at identical sample points in the first and second sampling strings for each section to calculate a new sample value, thereby creating a third sampling string in which a new sample value at an arbitrary sample point is 0.

Abstract: The apparent speed of a connection between a browser at a user station and a proxy or gateway on a network such as the Internet is increased by providing a local proxy at the user station which interacts with a remote proxy. While the remote proxy is retrieving a newly requested World Wide Web page, for example, from the appropriate content provider, it may also be sending to the local proxy a stale cached version of that page. When the new version of the page is finally retrieved, the remote proxy determines the differences between the new version and the stale version, and, assuming the differences do not exceed the new page in size, sends the differences to the local proxy which then reconstructs the new page from the differences and the stale version. The local proxy delivers the new page to the browser, which need not even be aware that a local proxy exists; it is aware only that it received the page it requested.

Abstract: A data compression system and method for compressing data of an input data stream having field widths for holding data values of a data set. Each field width is represented by a field value. The data compression system includes an adaptive processor having an encode module for encoding the input signal and dynamically changing the field widths at various positions in the data stream. This minimizes a storage space required to represent the entire data set. A decode module can be included for decoding the compressed format and producing an output signal having a lossless representation of the input signal.

Abstract: A system and method for performing parallel data compression which processes stream data at more than a single byte or symbol (character) at one time. The parallel compression engine modifies a single stream dictionary based (or history table based) data compression method, such as that described by Lempel and Ziv, to provide a scalable, high bandwidth compression. The parallel compression method examines a plurality of symbols in parallel, thus providing greatly increased compression performance. The method first involves receiving uncompressed data, wherein the uncompressed data comprises a plurality of symbols. The method maintains a history table comprising entries, wherein each entry comprises at least one symbol. The method operates to compare a plurality of symbols with entries in the history table in a parallel fashion, wherein this comparison produces compare results. The method then determines match information for each of the plurality of symbols based on the compare results.

Abstract: A system for compressing and decompressing a data pattern of data bits, so as to obtain a highly compressed data record. In accordance with embodiments of the invention, a group of candidate numbers is provided with each number comprising a sequence of statistically random bits. Bits of a subject data pattern are compared with bits of each candidate of the group of numbers to find a largest sequence of bits of the subject data pattern which match a sequence of bits within any one of the group of candidate numbers. Stored are all of: the data pattern except the matched bits, information designating the candidate number providing a largest matching sequence of bits, locations of the matched bits in the subject data pattern and in the candidate number, and a number encoding a number of the matched bits.

Abstract: A method in a computer system examines a string of two-byte characters and determines if the first byte in each of the two-byte characters is the same. If the first byte is the same in each of the two-byte characters, the method converts the string of two-byte characters into a string of one-byte values by removing the first byte of each of the two-byte characters. A designation value is then concatenated to the string of one-byte values to indicate the value of the first byte removed from each two-byte character.

Abstract: The disclosed data compressor receives an input stream of data characters and provides a corresponding stream of output codes. The compressor generates a sequence of numerically increasing output codes corresponding to numerically increasing contiguous segments of a detected run of the same data character. Non-run characters of the input stream are transmitted directly in synchronism with incrementing the codes of the code sequence. In one embodiment, the number of characters in the run segments are stored together with the respective codes representing the segments. In later encounters of a previously processed run, the stored data is accessed and the stored codes corresponding to the run segments are output as appropriate.

Abstract: A method of coding and compressing telemetry data makes use of the fact that the telemetry frames are typically highly correlated at a distance, .delta., corresponding to commutation or data periodicities. The existence of such periodicity is used to render a portion of each frame to zeros. The next steps are to search for and remove correlations between the bits in a set of frames, denoted {F.sub.i *}. The compression algorithm implementing the method according to the invention has four sub-steps; Data preconditioning, Compression and coding of first frame, F.sub.1, Compression and coding of frames 2-.delta., F.sub.1 -F.sub..delta., and Compression and coding of F.sub..delta.+1 and on, the steady-state mode.

Abstract: A data compression/expansion method and apparatus are provided. The data compression apparatus (70) includes a repetitive symbol detector (72), a shift register (74), a FIFO (76), a byte counter (78), and a map buffer (80). The symbol detector (72) generates an output signal indicating the presence of repetitive symbols in an input data segment (10). The shift register (74) functions as a map generator, producing a map (16) for locating the repetitive symbols in the input segment (10). The FIFO (76) acts as a gate for removing the repetitive symbols from the input segment to produce a compressed output segment (14). The compressed segment (14) and map (16) can then be transmitted to the expansion apparatus (90). The data expansion apparatus (90) includes a buffer (92), a shift register (94), and a multiplexer (95). The buffer (92) temporarily stores the compressed segment (14).

Abstract: The present invention is embodied in a method and system for compressing data using clustering techniques. The invention provides compression of a data ensemble composed of individual data sets. Each individual data set has associated data set context and history contexts. The present invention groups similar data set contexts and history contexts together so as to achieve a reduced total encoding cost. This total cost is minimized by selecting the clustering of the data set and history contexts such that the models or codebooks used to compress tokens are shared between tokens assigned to the same context clusters. Using clustering techniques, the present invention alternately varies the data set context clustering and history context clustering until a minimum total cost is achieved.

Abstract: Messages containing non-dictionary and dictionary data objects are quickly exchanged between sending and receiving devices. Data stores of the devices contain a common dictionary cross-referencing each of multiple data objects with a different dictionary index code. Data objects in the dictionary are likely to be frequently exchanged. Prior to transmission of data objects, the sending device searches its dictionary for each data object. Each data object may include text, graphics, program segments, or another type of data object. If the data object appears in the dictionary, the sending device obtains its dictionary index code. Next, the sending device transmits a message representing the data objects to the receiving device. The message includes multiple subparts each corresponding to a different data object. If a data object is not present in the dictionary, its subpart comprises the content of the data object without any dictionary encoding.

Abstract: A method of lattice quantizing a 24-long data point to minimize storage requirements by acquiring the data point, multiplying each coordinate of the data point by the square root of 8 to form an inflated data point, finding the closest point of the inflated Leech lattice by any method, creating a signal packet, and transmitting the packet to a receiver.

Abstract: A method and apparatus for data, image, video, acoustic, multimedia and general multilevel digital source compression in both lossless and lossy modes is described. The method is universal (no knowledge of source statistics required) and asymptotically optimal in terms of Shannon's noiseless coding theorem. The method utilizes a random walk in Pascal's hypervolume (a multi-dimensional generalization of Pascal's triangle) starting at the apex and proceeding downward, which is directed by the incoming source sequence according to an algorithm, until it terminates at a boundary which has been constructed in such a way that the encoding of each variable length source sequence can be accomplished in a fixed number of bits. Codewords and decoded source sequences can either be computed at the encoder and decoder, respectively, or precomputed and stored at those respective locations. A preprocessing module is used to set up the data for lossless data or image compression.

Abstract: A system for lossy compression of digital data for transmission to a remote location or to a storage medium and subsequently reconstructing the digital data includes an encoder which compares sequences of characters with an encoder database of data records to generate a compressed code. The compressed code includes pointer information relating to locations within the encoder database of data records corresponding within a given average distortion tolerance level per character to the sequences, and update information for the addition to the encoder database of new data records corresponding within the average distortion tolerance level per character to the sequences. The system also includes a decoder for receiving the compressed code, the receiver processing the compressed code to substantially reconstruct the digital data.

Abstract: A method of compressing data, including representations of objects, for future transmission or storage. More specifically, this invention compresses a representation of differences between a base sequence of data and the actual data to be transmitted or stored. Sparse bit masks representing the positions of insertions and deletions from a base sequence are iteratively compressed by representing consecutive sequences of zero-valued bits with single zero-valued bits.

Abstract: A method of compressing data involves receiving a symbol, and a subsequent symbol; determining in a compression dictionary whether the symbol has a valid extension pointer; using, in the event the symbol does have a valid extension pointer, the valid extension pointer to access string extension symbols; determining, in the event the symbol does have a valid extension pointer, whether the string extension symbols equal the at least one subsequent symbol; determining in the compression dictionary, in the event the string extension symbols do not equal the at least one subsequent symbol, whether the symbol has a valid parallel extension; repeating, in the event the symbol has a valid parallel extension, the using step; repeating, in the event the string extension symbols do not equal the at least one subsequent symbol, the determining of whether the symbol has a valid extension pointer; inserting, in the event the symbol does not have a valid extension pointer or in the event the symbol does not have a valid par

Abstract: A method of compressing data involves receiving a symbol, and a subsequent symbol; determining in a compression dictionary whether the symbol has a valid extension pointer; using, in the event the symbol does have a valid extension pointer, the valid extension pointer to access string extension symbols; determining, in the event the symbol does have a valid extension pointer, whether the string extension symbols equal the at least one subsequent symbol; determining in the compression dictionary, in the event the string extension symbols do not equal the at least one subsequent symbol, whether the symbol has a valid parallel extension; repeating, in the event the symbol has a valid parallel extension, the using step; repeating, in the event the string extension symbols do not equal the at least one subsequent symbol, the determining of whether the symbol has a valid extension pointer; inserting, in the event the symbol does not have a valid extension pointer or in the event the symbol does not have a valid par

Abstract: An adaptive compression technique which is an improvement to Lempel-Ziv (LZ) compression techniques, both as applied for purposes of reducing required storage space and for reducing the transmission time associated with transferring data from point to point. Pre-filled compression dictionaries are utilized to address the problem with prior Lempel-Ziv techniques in which the compression software starts with an empty compression dictionary, whereby little compression is achieved until the dictionary has been filled with sequences common in the data being compressed. In accordance with the invention, the compression dictionary is pre-filled, prior to the beginning of the data compression, with letter sequences, words and/or phrases frequent in the domain from which the data being compressed is drawn. The letter sequences, words, and/or phrases used in the pre-filled compression dictionary may be determined by statistically sampling text data from the same genre of text.

Abstract: The apparent speed of a connection between a browser at a user station and a proxy or gateway on a network such as the Internet is increased by providing a local proxy at the user station which interacts with a remote proxy. While the remote proxy is retrieving a newly requested World Wide Web page, for example, from the appropriate content provider, it may also be sending to the local proxy a stale cached version of that page. When the new version of the page is finally retrieved, the remote proxy determines the differences between the new version and the stale version, and, assuming the differences do not exceed the new page in size, sends the differences to the local proxy which then reconstructs the new page from the differences and the stale version. The local proxy delivers the new page to the browser, which need not even be aware that a local proxy exists; it is aware only that it received the page it requested.

Abstract: A computer system includes a compression engine for compressing a decompressed sequence of data to produce a compressed sequence of data. The compression engine encodes each piece of data in the decompressed sequence of data as either a portion of a copy token or as a literal token. Tokens are grouped together into groups of up to 8 tokens and a bitmap holding 8 bits is provided to identify the respective tokens as either copy tokens or literal tokens. The copy tokens encode sub-sequences of data that have previously occurred in the decompressed data sequence. Each copy token is of a like size but includes a variable-sized offset field for encoding an offset between a current occurrence of a sub-sequence of data and a previous occurrence of a sub-sequence of data. The offset field is variable-sized to encode the offset in a minimal number of bits. The computer system also includes a decompression engine for decompressing data sequences that have been compressed using the compression engine.

Abstract: A digital information data recording and reproducing apparatus is disclosed which can reduce an ineffective data portion in a recording data and can effectively use a capacity of a recording medium such as a hard disk, etc. In the apparatus, after the digital information data is compressed and coded, it is subjected to a framing process which uses a fixed length format. An ineffective data is removed from a framing data of the fixed length format obtained by the framing process, and then the data is recorded in the recording medium.