Techniques are provided for implementing additional compression for existing compressed data. Format information stored within a data block is evaluated to determine whether the data block is compressed or uncompressed. In response to the data block being compressed according to a first compression format, the data block is decompressed using the format information. The data block is compressed with one or more other data blocks to create compressed data having a second compression format different than the first compression format.

Methods, systems, and apparatus, including computer-readable storage media for hardware compression and decompression. A system can include a decompressor device coupled to a memory device and a processor. The decompressor device can be configured to receive, from the memory device, compressed data that has been compressed using an entropy encoding, process the compressed data using the entropy encoding to generate uncompressed data, and send the uncompressed data to the processor. The system can also include a compressor device configured to generate, from uncompressed data, a probability distribution of codewords, generate a code table from the probability distribution, and compress incoming data using the generated code table.

There is provided a computer implemented method of compressing a baseline dataset comprising a sequence of a plurality of instances of a plurality of unique data elements, the method comprising: providing a weight function that calculates an increasing value for a weight for each one of the plurality of instances of each one of the plurality of unique data elements in the baseline dataset, as a function of increasing number of previously processed sequential locations of each of the plurality of instances of each respective unique data element within the baseline dataset relative to a current sequential location of the baseline dataset, computing an encoding for the baseline dataset according to a distribution of the weight function computed for the plurality of unique data elements in the baseline dataset, and creating a compressed dataset according to the encoding.

A noise determination apparatus includes an acquisition unit and a determination unit. The acquisition unit acquires n-branch tree structure data. The n-branch tree structure data includes information on the presence or absence of a point for a divided region obtained by dividing, by an n-branch tree structure including a plurality of layers, a spatial region represented by point cloud data including information on a position of a point, and includes, for the divided region including only one point, a sign representing the point instead of information on a divided region in a layer lower than the divided region. The determination unit determines a point represented by the sign to be noise in a layer higher than a predetermined layer.

According to one embodiment, a compression device includes a coding information generation unit. The unit determines code lengths that are respectively associated with a plurality of symbols, based on a frequency of occurrence of each of the plurality of symbols. When the plurality of symbols include one or more first symbols that are respectively associated with one or more first code lengths exceeding an upper limit, the unit changes the first code lengths to the upper limit, selects, from one or more second symbols of the plurality of symbols that are respectively associated with one or more second code lengths shorter than the upper limit, at least one symbol in descending associated code length order, changes at least one code length associated with the symbol to the upper limit.

Systems and methods herein provide for adaptive subband compression of power signals in a power system. In one embodiment, a system includes an encoder is operable to partition sensor measurements into frequency subbands (e.g., including an interharmonic subband), centered at integer multiples of the power system's fundamental frequency (e.g., 50 Hz or 60 Hz). The encoder may also be operable to detect active subbands, and to compress the at least one active subband. The system also includes a data concentrator operable to transmit the at least one compressed subband to a processor for analysis. The system also includes a decoder at a processing location (a substation, a concentrator, or the control center) operable to parse the compressed waveforms into subbands, to interpolate and decompress at least one compressed subband, and to synthesize the decompressed subbands as an approximation of the original waveform (e.g., subject to reconstruction error requirements).

The method involves sequentially encoding the plurality of data packets, which involves, for a data packet, obtaining a reference data packet, obtaining a mask packet indicative of which of the bits in the data packet are predictable and which of the bits in the data packet are not predictable obtaining change history data indicative of previously changed bits of the mask packet, determining an updated mask packet based on the mask packet, the data packet, and the reference data packet, determining updated change history data based on the change history data, the mask packet, and the updated mask packet, determining, as unpredictable bits, all those bits of the data packet that are indicated as not predictable by the updated mask packet, and generating an encoded data packet including a representation of the updated change history data and a representation of values of the unpredictable bits of the data packet.

A two-dimensional square constraint encoding and decoding method and device, relating to the fields of data storage and data communication. The encoding method includes caching a one-dimensional data stream, and dividing the one-dimensional data stream into several sets of one-dimensional 2-bit data; according to an encoding table, encoding each set of 2-bit data into a 3*2 two-dimensional codeword in sequence by an encoder, and then cascading all the two-dimensional codewords into a two-dimensional constraint array in a specified order; the decoding method includes reading the two-dimensional constraint array by a decoder, and dividing the two-dimensional constraint array into several 3*2 two-dimensional codewords; decoding each two-dimensional codeword into the one-dimensional 2-bit data in sequence through a decoding table, and then successively assembling the generated one-dimensional 2-bit data into the one-dimensional data stream and outputting.

Systems, apparatuses, and methods related to bit string compression are described. A method for bit string compression can include determining that a particular operation is to be performed using a bit string formatted according to a universal number format or a posit format to alter a bit width associated with the bit string from a first bit width to a second bit width and performing a compression operation on a bit string formatted according to a universal number format or a posit format to alter a bit width associated with the bit string from a first bit width to a second bit width. The method can further include writing the bit string having the second bit width to a first register, performing an arithmetic operation or a logical operation, or both using the bit string having the second bit string width, and monitoring a quantity of bits of a result of the operation.

Approaches to dictionary-based data compression are disclosed, including those in which a Zbuffer is used to identify phrases that represent uncompressed data and/or to generate decompressed data by combining a set of overlapping occluded phrases.