A system and method for concurrent encryption and lossless compression of data with an algorithm executing on a computer platform. The lossless compression component of the algorithm consists of preprocessing the data with a Burrows-Wheeler transformation followed by an inversion ranking transformation in advance of employing an entropy coder, such as binary arithmetic coder. The frequency vector of the Inversion Ranking transformation is then encrypted and transmitted along with the compressed data with only the frequency vector encrypted. Since the frequency vector is required for decompression, no further encryption of the compressed data is necessary to secure the compressed file.

The present disclosure relates to systems and methods for coding. The methods may include receiving at least two contexts, for each of the at least two contexts, obtaining at least one coding parameter corresponding to the context from at least one lookup table, determining a probability interval value corresponding to the context based on a previous probability interval value and the at least one coding parameter, determining a normalized probability interval value corresponding to the context by performing a normalization operation on the probability interval value, determining a probability interval lower limit corresponding to the context based on a previous probability interval lower limit and the at least one coding parameter, determining a normalized probability interval lower limit corresponding to the context by performing the normalization operation on the probability interval lower limit, and outputting at least one byte based on the normalized probability interval lower limit.

The present disclosure provides an encoding method and an encoder for a (n, n(n−1), n−1) permutation group code in a communication modulation system, in which 2.sup.k k-length binary information sequences are mapped to 2.sup.k n-length permutation codeword signal points in a n-dimensional modulation constellation Γ.sub.n. The constellation Γ.sub.n with the coset characteristics is formed by selecting 2.sup.k n-length permutation codewords from n(n−1) permutation codewords of a code set P.sub.n,x.sub.i of the (n, n(n−1), n−1) permutation group code based on coset partition. The constellation Γ.sub.n is a coset code in which 2.sup.k.sup.1 cosets are included and each coset includes 2.sup.k.sup.2 permutation codewords, where k=k.sub.1+k.sub.2, and 2.sup.k≤n(n−1). The present disclosure utilizes the coset characteristics to realize one-to-one correspondence mapping of the binary information sequence set to the permutation code constellation, so that the time complexity of executing the encoder is at most the linear complexity of the code length n.

A client is able to decompress an internal portion of a compressed file on a server without having to download and decompress the part of the compressed file that precedes the internal portion. Initially, when the file is compressed, the state of the compressor, e.g., a dictionary, is periodically captured and stored in association with positions in the compressed file. A server stores the compressor states and positions in association with the compressed file. The client identifies the internal section of the compressed file to the server. The server selects a compressor state whose position is closest to the internal section. The server sends the client the selected compressor state and the internal portion of the compressed file. The client primes a decompressor with the sent compressor state, and the primed decompressor then decompresses the internal portion of the compressed file.

A method for encoding and compressing a bit stream is provided. The method includes: receiving a bit stream; determining whether a first number of bits that are consecutive and identical in the bit stream is greater than or equal to a first preset value; and when the first number is greater than or equal to the first preset value, the first number of bits are encoded as a first code in a first encoding way, wherein the first code is composed of a first prefix and a first suffix, and the first prefix represents what the consecutive bits are and the first suffix represents the first number.

The present disclosure provides an encoding method and an encoder for a (n, n(n1), n1) permutation group code in a communication modulation system, in which 2.sup.k k-length binary information sequences are mapped to 2.sup.k n-length permutation codeword signal points in a n-dimensional modulation constellation .sub.n. The constellation .sub.n with the coset characteristics is formed by selecting 2.sup.k n-length permutation codewords from n(n1) permutation codewords of a code set P.sub.n,x.sub.i of the (n, n(n1), n1) permutation group code based on coset partition. The constellation .sub.n is a coset code in which 2.sup.k.sup.1 cosets are included and each coset includes 2.sup.k.sup.2 permutation codewords, where k=k.sub.1+k.sub.2, and 2.sup.kn(n1). The present disclosure utilizes the coset characteristics to realize one-to-one correspondence mapping of the binary information sequence set to the permutation code constellation, so that the time complexity of executing the encoder is at most the linear complexity of the code length n.

The present application discloses video data encoding and decoding methods and apparatuses, so as to conveniently perform data encoding and decoding on video data. The method includes: arithmetic encoding, where the arithmetic encoding includes: obtaining a binary symbol of image data; and if the binary symbol is a most probable symbol (MPS), updating a first encoding interval corresponding to the MPS in a logarithm domain, and if the first updated encoding interval is less than a preset range of an arithmetic encoding interval, performing normalization processing on the first encoding interval in the logarithm domain; or if the binary symbol is a least probable symbol (LPS), updating a second encoding interval corresponding to the LPS in an original number domain, and performing normalization processing on the second encoding interval in the original number domain.

An arithmetic encoder is provided for converting an event sequence comprised of a plurality of events to an information sequence comprised of at least one information piece, and includes a core engine for receiving an event of the event sequence, and a probability estimate from a probability estimator, and generating zero or more pieces of the information sequence responsive to the received event and the probability estimate by bounding the ratio of events to information pieces. An arithmetic encoder is provided that is capable of constraining a number of events in at least one event sequence as a function of the number of generated information pieces in at least one information sequence. An arithmetic decoder is provided for converting an information sequence comprised of at least one information piece to an event sequence comprised of a plurality of events, and includes a core engine for processing at least one information piece of the information sequence from the sequencer responsive to a probability estimate received from a probability estimator to generate at least one event by accounting for a bounded ratio of events to information pieces in the information sequence.

The present invention relates to a method and apparatus for compression and decompression of a numerical file. The compression method comprises: read a numerical file, convert each numerical element into a 32-bit floating point number; combine all the numbers to form a binary numerical file; group the binary numerical file into a n-bit sequence pattern; generate a Huffman tree based on frequency of occurrences of a plurality of unique bit patterns present in the binary numerical file; generate codewords and replace unique bit patterns with codewords so that a compressed binary numerical file is generated. A method for decompression comprises: read a compressed binary numerical file having codewords; fetch a part or entire compressed binary numerical file using an address dictionary; replace the codewords with unique bit patterns using a Huffman tree such that a decompressed binary numerical file being generated.

A system and method for high-speed transfer of small data sets, that provides near-instantaneous bit-level lossless compression, that is ideal for communications environments that cannot tolerate even small amounts of data corruption, have very low latency tolerance, where data has a low entropy rate, and where every bit costs the user bandwidth, power, or time so that deflation is worthwhile. Where some loss of data can be tolerated, the system and method can be configured for use as lossy compression.