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375 results about "Huffman coding" patented technology

In computer science and information theory, a Huffman code is a particular type of optimal prefix code that is commonly used for lossless data compression. The process of finding or using such a code proceeds by means of Huffman coding, an algorithm developed by David A. Huffman while he was a Sc.D. student at MIT, and published in the 1952 paper "A Method for the Construction of Minimum-Redundancy Codes".

Using gain-adaptive quantization and non-uniform symbol lengths for improved audio coding

Techniques like Huffman coding can be used to represent digital audio signal components more efficiently using non-uniform length symbols than can be represented by other coding techniques using uniform length symbols Unfortunately, the coding efficiency that can be achieved by Huffman coding depends on the probability density function of the information to be coded and the Huffman coding process itself requires considerable processing and memory resources. A coding process that uses gain-adaptive quantization according to the present invention can realize the advantage of using non-uniform length symbols while overcoming the shortcomings of Huffman coding. In gain-adaptive quantization, the magnitudes of signal components to be encoded are compared to one or more thresholds and placed into classes according to the results of the comparison. The magnitudes of the components placed into one of the classes are modified according to a gain factor that is related to the threshold used to classify the components. Preferably, the gain factor may be expressed as a function of only the threshold value. Gain-adaptive quantization may be used to encode frequency subband signals in split-band audio coding systems. Additional features including cascaded gain-adaptive quantization, intra-frame coding, split-interval and non-overloading quantizers are disclosed.
Owner:DOLBY LAB LICENSING CORP

Dual-transform coding of audio signals

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.
Owner:HEWLETT PACKARD DEV CO LP

Data compression, control program for controlling the data compression

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.
Owner:NEC CORP

Real-time reduction of CPU overhead for data compression

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.
Owner:IBM CORP

Object and fractal-based binocular three-dimensional video compression coding and decoding method

The invention provides an object and fractal-based binocular three-dimensional video compression and decompression method. In binocular three-dimensional video coding, a left channel is used as a basic layer, a right channel is used as an enhancement layer, and the left channel is encoded by an independent motion compensation prediction (MCP) mode. The object and fractal-based binocular three-dimensional video compression coding method comprises the following steps of: firstly, acquiring a video object partition plane, namely an Alpha plane by a video partition method, encoding the initial frame of a left eye through block discrete cosine transformation (DCT), and performing block motion estimation / compensation coding on a non-I frame of the left eye; secondly, determining the area attribute of an image block by utilizing the Alpha plane, and if the block is not within a video object area of the current code, not processing an external block, and if the block is within the video object area of the current code completely, searching the most similar matching block by a full-searching method in a previous frame of an internal block, namely a reference frame searching window of a left eye video; and finally, compressing coefficients of an iterated function system by a Huffman coding method, and if part of pixels of the block are within the video object area of the current code, and the other part of pixels are not within the video object area of the current code, processing a boundary block independently. The right channel is encoded by a MCP mode and a disparity compensation prediction (DCP) mode, the MCP is similar to the processing of the left eye, and the block with the minimum error is used as a prediction result. When the DCP coding mode is performed, the polarization and directionality in a three-dimensional parallel camera structure are utilized fully.
Owner:BEIHANG UNIV

Variable-length, high-speed asynchronous decoder circuit

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.
Owner:THE TRUSTEES OF COLUMBIA UNIV IN THE CITY OF NEW YORK

Multiple Technique Entropy Coding System And Method

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.
Owner:DROPLET TECH

Intra-class coefficient scrambling-based JPEG image encryption method

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.
Owner:CHANGAN UNIV

Method and system for compressing reduced instruction set computer (RISC) executable code

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.
Owner:IBM CORP
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