Techniques for lossless compression of a digital image using prior image context.

Techniques for lossless compression of a digital image using prior image context.

A video decoding method includes: performing entropy decoding processing on an encoding block of a video image frame to obtain a quantized coefficient block of residual data corresponding to the encoding block; calculating quantization coefficients in the quantized coefficient block to obtain an implicitly derived index value; determining a transformation mode of the encoding block according to the implicitly derived index value and a value of an index identifier included in the encoding block; and performing inverse transformation processing on an inverse quantization result of the quantized coefficient block based on the transformation mode of the encoding block.

A video decoding method includes: performing entropy decoding processing on an encoding block of a video image frame to obtain a quantized coefficient block of residual data corresponding to the encoding block; calculating quantization coefficients in the quantized coefficient block to obtain an implicitly derived index value; determining a transformation mode of the encoding block according to the implicitly derived index value and a value of an index identifier included in the encoding block; and performing inverse transformation processing on an inverse quantization result of the quantized coefficient block based on the transformation mode of the encoding block.

A feature data encoding method, an encoder, a feature data decoding method, and a decoder are provided. The feature data encoding method includes following steps. A transform unit is divided into a plurality of sub-blocks and N sub-transform units. A reference origin and a LSC are determined in an i-th sub-transform unit of the sub-transform units, and an original coordinate of the last significant coefficient of the i-th sub-transform unit is modified to a specific coordinate. The i-th sub-transform unit is scanned from a specific sub-block of the i-th sub-transform unit, and significant feature coefficients in the i-th sub-transform unit are individually encoded as coded data.

A video encoding method includes obtaining a video bitstream; encoding the video bitstream based on a residual coding scheme and signaling information; and outputting the encoded video bitstream. Encoding the video bitstream includes: obtaining residual information associated with the video bitstream, wherein the residual information includes at least a remainder; obtaining a transform coefficient based on a current state, a Rice parameter, and a next state; and encoding the residual information based on the transform coefficient.

A method for subdividing an interval during entropy decoding for a bitstream representing a set of video pictures is provided. A sub-interval value is computed by (i) performing an initial right bit-shifting operation on a probability estimator value to reduce a length in bits of the probability estimator value, (ii) multiplying the right bit-shifted probability estimator value by a range value representing the interval, (iii) performing another right bit-shifting operation on a result of the multiplication, and (iv) adding a constant value to a result of the other right bit-shifting operation, wherein the probability estimator value is associated with a probability of a bin having a particular value. The sub-interval value computed based on the right bit-shifted probability estimator value is used to update the interval.

A method for processing a vide signal, according to the present invention comprises generating a reference picture list based on a current picture reference flag for a current picture, obtaining motion information about a current block in the current picture, and restoring the current block using the motion information of the current block and the reference picture list relating to the current picture.

A point cloud encoding method includes the following. For one or more points in the current coding block, an optimal prediction mode is determined by using a RDO mechanism, where a distortion parameter D in the RDO mechanism is determined according to a reconstruction distortion, and a bitrate parameter R in the RDO mechanism is determined according to a bitrate. A prediction value of the one or more points is determined by predicting the one or more points using the optimal prediction mode. A residual of the one or more points is determined according to the prediction value of the one or more points. Encoding bits are determined by encoding according to the optimal prediction mode and the residual, and the encoding bits are signaled into a bitstream.

Video decoding innovations for multithreading implementations and graphics processor unit (“GPU”) implementations are described. For example, for multithreaded decoding, a decoder uses innovations in the areas of layered data structures, picture extent discovery, a picture command queue, and/or task scheduling for multithreading. Or, for a GPU implementation, a decoder uses innovations in the areas of inverse transforms, inverse quantization, fractional interpolation, intra prediction using waves, loop filtering using waves, memory usage and/or performance-adaptive loop filtering. Innovations are also described in the areas of error handling and recovery, determination of neighbor availability for operations such as context modeling and intra prediction, CABAC decoding, computation of collocated information for direct mode macroblocks in B slices, reduction of memory consumption, implementation of trick play modes, and picture dropping for quality adjustment.