373 results about "Huffman coding" patented technology

A robust method to compress relations close to their entropy while still allowing efficient queries. Column values are encoded into variable length codes to exploit skew in their frequencies. The codes in each tuple are concatenated and the resulting tuplecodes are sorted and delta-coded to exploit the lack of ordering in a relation. Correlation is exploited either by co-coding correlated columns, or by using a sort order that can leverage the correlation. Also presented is a novel Huffman coding scheme, called segregated coding, that preserves maximum compression while allowing range and equality predicates on the compressed data, without even accessing the full dictionary. Delta coding is exploited to speed up queries, by reusing computations performed on nearly identical records.

The invention provides an electrocardiogram signal compression and de-compression system. The invention uses the sign characteristics of the coefficients of the discrete cosine transform type IV and the characteristics of quantization of spectrum to perform the differential pulse code modulation of the spectrum for preserving the high frequency characteristics of the spectrum of the discrete Fourier transform. The invention also uses the Huffman coding to increase the compression ratio. Different from the conventional compression technology, the invention uses the fact that the quantization values of the spectrum in the high frequency are almost the same to increase the compression ratio and preserve the characteristics of high frequency components of the spectrum.

In a method for coding an audio signal to obtain a coded bit stream, discrete-time samples of the audio signal are transformed into the frequency domain to obtain spectral values. The spectral values are coded with a code table having a limited number of code words of different lengths to obtain spectral values coded by code words, the length of a code word assigned to a spectral value being that much shorter the higher the probability of occurrence of the spectral value is. A raster is then specified for the coded bit stream, the raster having equidistant raster points and the distance between the raster points depending on the code table(s) used. In order to obtain error-tolerant Huffman coding, priority code words, which represent particular spectral values which are psychoacoustically more important than other spectral values, are so arranged in the raster that the start of each priority code word coincides with a raster point.

Methods, devices, and systems for coding and decoding audio are disclosed. At least two transforms are applied on an audio signal, each with different transform periods for better resolutions at both low and high frequencies. The transform coefficients are selected and combined such that the data rate remains similar as a single transform. The transform coefficients may be coded with a fast lattice vector quantizer. The quantizer has a high rate quantizer and a low rate quantizer. The high rate quantizer includes a scheme to truncate the lattice. The low rate quantizer includes a table based searching method. The low rate quantizer may also include a table based indexing scheme. The high rate quantizer may further include Huffman coding for the quantization indices of transform coefficients to improve the quantizing/coding efficiency.

Systems, devices and methods are provided to compress data, and in particular to code and decode data. One aspect of the present subject matter is a data structure. The data structure includes a field representing a decoding structure to decode canonical Huffman encoded data, and a field representing a symbol table. The decoding structure includes a field representing an accelerator table to provide a 2^N-deep direct-index lookup to provide high-frequency symbols for high-frequency data and to provide bracketing indices for low-frequency data. The decoding structure also includes a field for a binary search table to provide a low-frequency symbol index using a binary search bounded by the bracketing indices provided by the accelerator table. The symbol table is adapted to provide a symbol associated with the low-frequency index.

In a data compression device having a plurality of Huffman coders given identification (ID) values, respectively, to produce Huffman codes together with the corresponding ID codes obtained from the ID values, a re-coding portion is included to change a sequence of the ID values so that a reduction is accomplished about a code amount of the Huffman codes and the ID codes obtained from the ID value sequence and is operable to re-code an input data sequence again by Huffman coders indicated by the changed ID values. Such re-coded Huffman codes and ID codes based on the changed ID values are produced as output data signals.

A surveillance image is acquired from a surveillance camera. Supplement information (such as date and time, and surveillance camera number) relating to the surveillance image is acquired. By imaging the supplement information, supplement information image data is generated. A quantized discrete cosine transform coefficient block obtained by conducting discrete cosine transform and then quantization on surveillance image data of the surveillance image is added to a quantized discrete cosine transform coefficient block obtained by conducting discrete cosine transform and then quantization on the supplement information image data. A resultant sum is subjected to Huffman encoding. The result is recorded.

Real-time reduction of CPU overhead for data compression is performed by a processor device in a computing environment. Non-compressing heuristics are applied on a randomly selected data sample from data sequences for determining whether to compress the data sequences. A compression potential is calculated based on the non-compressing heuristics. The compression potential is compared to a threshold value. The data sequences are either compressed if the compress threshold is matched, compressed using Huffman coding if Huffman coding threshold is matched, or stored without compression.

Huffman encoding, particularly from a packed data format, is simplified by using two different table formats depending on code length. Huffman tables are also reduced in size thereby. Decoding is performed in reduced time by testing for the length of valid Huffman codes in a compressed data stream and using an offset corresponding to a test criterion yielding a particular test result to provide a direct index into Huffman table symbol values while greatly reducing the size of look-up tables used for such a purpose.

There is disclosed a decoder circuit (20) for decoding input data coded using a variable length coding technique, such as Huffman coding. The decoder circuit (20) comprises an input buffer (100), a logic circuit (150) coupled to the input buffer (100), and an output buffer (700) coupled to the logic circuit (750). The logic circuit (750) includes a plurality of computational logic stages for decoding the input data, the plurality of computational logic stages arranged in one or more computational threads. At least one of the computational threads is arranged as a self-timed ring, wherein each computational logic stage in the ring produces a completion signal indicating either completion or non-completion of the computational logic of the associated computational logic stage. Each completion signal is coupled to a previous computational logic stage in the ring. The previous computational logic stage performs control operations when the completion signal indicates completion and performs evaluation of its inputs when the completion signal indicates non-completion.

A system, method and computer program product having optimal matching to a known or measured probability distribution encodes data without the use of an excessively large lookup table. An encoder constructed according to the present invention uses two or more different encoding methods in combination. In one embodiment, Huffman coding by table lookup is combined with computational generation, such as by using an exponential Golomb equation. The most commonly occurring elements are looked up in a small Huffman table, while the remaining elements are coded with the equation. In another embodiment, data is encoded using two or more equations. In yet another embodiment, data is encoded using multiple tables in conjunction with one or more equations.

The invention relates to an intra-class coefficient scrambling-based JPEG image encryption method. The method comprises the following steps: firstly reading in a JPEG image file, acquiring a Huffman coding table and image data which undergoes JPEG coding compression, carrying out decoding to acquire all the non-zero quantized DCT coefficient numerical values and positions and carrying out classification; selecting a password, carrying out chaotic iteration by utilizing the password, so as to generate a chaotic sequence, and scrambling the non-zero coefficients and 8*8 block of each class by utilizing the chaotic sequence; and carrying out entropy coding on a scrambled quantized DCT coefficient matrix, and writing the coded data into the JPEG image file so as to complete intra-class coefficient scrambling-based JPEG image encryption. According to the method disclosed in the invention, scrambling is carried out on different classes of quantized DCT coefficients through the chaotic sequence, and the quantized DC coefficients and the non-zero AC coefficients are processed by directly using one encryption scheme, so that the safety and the high efficiency are both considered; and the encrypted images are similar to clear text image files in the aspect of size, and have high compression ratios.

Exemplary method, system, and computer program product embodiments for efficient one-pass cache-aware compression are provided. In one embodiment, by way of example only, an output of a fast compressor to Huffman encoding for achieving the one-pass cache-aware compression by using a predetermined Huffman-tree upon determining by the fast compressor a final representation of each data byte.

Methods and systems that leverage the advantages of Huffman coding to increase processing efficiency of a data-stream while simultaneously minimizing storage requirements are provided. Decoding efficiency and table storage requirements can be balanced to produce systems that can be adapted for use in high-end network infrastructure applications and for low-resourced portable consumer devices. The systems and methods are operative in decoding data streams using multi-symbol codes and sign information, including AAC and MP3 data streams. A hierarchical structure of tables is described as having primary tables, secondary tables, tertiary tables and so on. Optimization balances processing requirements, table storage requirements and the described systems and methods may be implemented on a variety of processing platforms.

A fast loss less image compression system based on neighborhood comparisons compares pixel value differences with neighboring pixels and replaces such pixel values with the minimum of the differences. A marker is attached to a block of pixels, such that all the pixels in that block are compared with neighbors of one direction. The marker indicates how all of the pixels in that block are compared. Intermittent Huffman-tree construction is used such that one tree is used for several frames. Huffman coding is used to compress the resulting frame. A single Huffman-tree is constructed once every predetermined number of frames. The frequency of Huffman-tree construction can be performed according to the instantaneous availability of processor time to perform the construction. When more processing time is available, the Huffman-trees are computed more frequently. Such frequency variation can be implemented by using an input video frame buffer. If the buffer is a certain size, then processor time for Huffman-tree construction is available.

Fast and efficient data compression can be carried out. Original image data are subjected to wavelet transform. The obtained wavelet-transformed data are classified and bit allocation is determined. Based on the determined bit allocation, the wavelet-transformed data are quantized and quantized data are obtained. The quantized data are classified into 0 data and non-zero data. Binary classification information data indicating this classification are also obtained. The classification information data are coded according to a coding method having a comparatively simple operation, such as Huffman coding and run length coding. The multi-valued, non-zero data are coded according to a coding method having a high compression efficiency although having a comparatively complex operation, such as universal coding and Golomb-Rice coding.

A method and system for a compression scheme used with program executables that run in a reduced instruction set computer (RISC) architecture such as the PowerPC is disclosed. Initially, a RISC instruction set is expanded to produce code that facilitates the removal of redundant fields. The program is then rewritten using this new expanded instruction set. Next, a filter is applied to remove redundant fields from the expanded instructions. The expanded instructions are then clustered into groups, such that instructions belonging to the same cluster show similar bit patterns. Within each cluster, the scopes are created such that register usage patterns within each scope are similar. Within each cluster, more scopes are created such that literals within each instruction scope are drawn from the same range of integers. A conventional compression technique such as Huffman encoding is then applied on each instruction scope within each cluster. Dynamic programming techniques are then used to produce the best combination of encoding among all scopes within all the different clusters. Where applicable, instruction scopes are combined that use the same encoding scheme to reduce the size of the resulting dictionary. Similarly instruction clusters are combined that use the same encoding scheme to reduce the size of the resulting dictionary.