摘要:
Methods, systems, and computer programs for encoding and decoding image are described. In some aspects, an input data block and a prediction data block are accessed. A projection factor is generated based on a projection of the input data block onto the prediction data block. A scaled prediction data block is generated by multiplying the projection factor by the prediction data block. A residual data block is generated based on a difference between the input data block and the scaled prediction data block. In some aspects, a prediction data block, a residual data block, and a projection factor associated with the residual data block are accessed. A scaled prediction data block is generated by multiplying the projection factor by the prediction data block. An output data block is generated by summing the residual data block and the scaled prediction data block.
摘要:
An encoding method for encoding video data by adjusting a quantization parameter, the video data being partitioned into blocks comprising sets of quantized transform coefficients. The method includes, for a set of quantized transform coefficients corresponding to one of the blocks, collecting statistics, wherein the statistics comprise the number of quantized transform coefficients and the sum of the non-rounded quantization value of the quantized transform coefficients in the set. The method also includes deriving a step size based on the statistics, mapping the derived step size to a closest quantization parameter value, and quantizing a next block using the mapped quantization parameter value.
摘要:
Methods of encoding and decoding for video data are described for encoding or decoding coefficients for a transform unit. In particular, the sign bits for the non-zero coefficients are encoded using sign bit hiding. Two or more sets of coefficients are defined for the transform unit and a sign bit may be hidden for each set, subject to satisfaction of a threshold test. The sets may correspond to coefficient groups that are otherwise used in multi-level significance map encoding and decoding.
摘要:
Methods and devices for video coding are described. When encoding a non-zero coefficient group (CG) prior to the last such group in a group scan ordering within a transform block, data representative of the true (x,y)-position of the last non-zero transform coefficient in a scan ordering within that CG is modified, to improve coding efficiency, based upon at least one of (a) an intra-prediction mode used to encode the block and (b) at least one coefficient group neighboring that CG. Upon decoding a CG thus encoded, the modification is un-done to retrieve the true (x,y)-position.
摘要:
Methods of encoding and decoding sign information for non-zero coefficients in a block of video with transform skipped. The methods include context-based coding of a flag that signals if all signs are the same in the block; using a finite state machine to determine contexts for coding of sign information, some of which may be context-based coded and some of which may be non-context-based coded; context-based coding of sign information wherein the context is based upon the signs of neighbouring coefficients; context-based coding of sign information, where the sign information is a prediction of the sign; and using a dedicated context to code signs with a sign flag indicating whether signs in a transform skipping block have been inverted to preserve a dominant sign bias.
摘要:
Methods of encoding and decoding sign information for non-zero coefficients in a block of video with transform skipped. The methods include context-based coding of a flag that signals if all signs are the same in the block; using a finite state machine to determine contexts for coding of sign information, some of which may be context-based coded and some of which may be non-context-based coded; context-based coding of sign information wherein the context is based upon the signs of neighbouring coefficients; context-based coding of sign information, where the sign information is a prediction of the sign; and using a dedicated context to code signs with a sign flag indicating whether signs in a transform skipping block have been inverted to preserve a dominant sign bias.
摘要:
Encoding and decoding methods are presented that used offset-based adaptive reconstruction levels. The offset data is inserted in the bitstream with the encoded video data. The offset data may be differential data and may be an index to an array of offset values from which the differential offset is calculated by the decoder. The offset to an adaptive reconstruction level may be adjusted for each slice. The offsets may be specific to a particular level/index and data type. In some cases, offsets may only be sent for a subset of the levels. Higher levels may apply no offset, may apply an average offset, or may apply the offset used for the highest level having a level-specific offset.
摘要:
Methods, systems, and computer programs for encoding and decoding image are described. In some aspects, an input data block and a prediction data block are accessed. A projection factor is generated based on a projection of the input data block onto the prediction data block. A scaled prediction data block is generated by multiplying the projection factor by the prediction data block. A residual data block is generated based on a difference between the input data block and the scaled prediction data block. In some aspects, a prediction data block, a residual data block, and a projection factor associated with the residual data block are accessed. A scaled prediction data block is generated by multiplying the projection factor by the prediction data block. An output data block is generated by summing the residual data block and the scaled prediction data block.
摘要:
Methods and devices are described for entropy coding data using an entropy coder to encode quantized transform domain coefficient data. Last significant coefficient information is signaled in the bitstream using two-dimensional coordinates for the last significant coefficient. The context for bins of one of the coordinates is based, in part, upon the value of the other of the coordinates. In one case, instead of signaling last significant coefficient information, the number of non-zero coefficients is binarized and entropy encoded.
摘要:
Methods and devices for video coding are described. If an intra-prediction mode to be used in encoding a block of residual data is in a specific predetermined class, e.g., the horizontal class, then at least a portion of a quantized transformed block of residual data is transposed during encoding. Likewise, if an intra-prediction mode that was used to generate an encoded block of residual data is in such a class, then at least a portion of an entropy-decoded block of residual data is transposed during decoding.