摘要:
This disclosure describes techniques for coding transform coefficients for a block of video data. According to these techniques, a video coder (a video encoder or video decoder) determines whether a block of video data is a luma block or a chroma block. If the block of video data is a luma block, the video coder adaptively updates a VLC table index value based on a code number cn and value of a scaling factor. However, if the block of video data is a chroma block, the video coder adaptively updates the VLC table index value based on the code number cn and without using the scaling factor. The video coder uses the updated VLC table index value to select a VLC table of a plurality of VLC tables that are used to encode or decode the block of video data.
摘要:
This disclosure relates to techniques for reducing a cost of coding prediction information in video coding. Video blocks in a generalized P/B (GPB) frame are encoded using up to two motion vectors calculated from reference pictures in two separate reference picture lists that are identical. When one of the reference picture lists is preferred over the other reference picture list, the preferred reference picture list may be used for unidirectional prediction, by default. When a GPB frame is enabled such that the first and second reference picture lists are identical, either of the first and second reference picture lists may be used for unidirectional prediction. The techniques include coding one or more syntax elements indicating that a video block is coded using one of the unidirectional prediction mode with respect to a reference picture in a reference picture list and the bidirectional prediction mode using less than two bits.
摘要:
This disclosure relates to techniques for reducing a cost of coding prediction information in video coding. Video blocks in a generalized P/B (GPB) frame are encoded using up to two motion vectors calculated from reference pictures in two separate reference picture lists that are identical. Video blocks of a GPB frame may, therefore, be encoded using a bidirectional prediction mode with a first motion vector from a reference picture in a first reference picture list and a second motion vector from the same or substantially similar reference picture in a second reference picture list. The techniques include jointly coding the first and second motion vectors for a video block of a GPB frame. The techniques include coding the first motion vector relative to a first motion predictor generated from a motion vector of a neighboring block, and coding the second motion vector relative to the first motion vector.
摘要:
In one example, a video decoder is configured to determine whether a component of a transform unit of a coding unit of video data includes at least one non-zero coefficient based on a codeword for the transform unit, determine whether the transform unit is split into sub-transform units based on the codeword, and decode the transform unit based on the determinations. In another example, a video encoder is configured to determine whether a component of a transform unit of a coding unit of video data includes at least one non-zero coefficient, determine whether the transform unit is split into sub-transform units, select a codeword from a variable length code table, wherein the variable length code table provides an indication that the codeword corresponds to the determinations, and provide the codeword for the transform unit.
摘要:
A video coding method comprises dividing a coefficient vector into two or more sub-vectors, each sub-vector having a length less than or equal to a length of the coefficient vector, indicating a size of each sub-vector and a position of each sub-vector within the coefficient vector, and forming a block corresponding to each sub-vector.
摘要:
For a block of video data, a video encoder can signal to a video decoder a selected intra-prediction mode using a codeword that is mapped to a modified intra-prediction mode index. The video decoder can receive the codeword, determine the modified intra-prediction mode index corresponding to the codeword, determine most probable modes based on a context, map the modified intra-prediction mode index to an intra-prediction mode index by comparing the modified intra-prediction mode index to the mode indexes of the most probable modes, and determine the selected intra-prediction mode used to encode the block of video data based on the intra-prediction mode index.
摘要:
This disclosure relates to techniques for reducing the amount of additional data encoded with a block encoded using intra-predictive coding. Particularly, the techniques provide apparatus and methods of applying a smoothing filter to prediction samples used in intra-predictive coding. For example, in fixed mode-dependent intra-predictive coding, a video encoder may determine the type of smoothing filter applied to prediction samples based on block size and intra-prediction mode combination associated with the current block, where the combination is used to look up a filter in a first filter table. In adaptive mode-dependent intra-predictive coding, the encoder uses two filters, one from the first filter table and another from a second filter table, applies both filters, and determines which yields better results. When the second filter table filter yields better results, the encoder encodes a filtering indication. When a filter from the first filter table is used, no filtering indication is encoded.
摘要:
This disclosure describes techniques for coding video data. As one example, this disclosure describes a coded block pattern (CBP) for a coding unit (CU) of video data that indicates whether or not each of a luminance component (Y), a first chrominance component (U), and a second chrominance component (V) include at least one non-zero coefficient. According to another example, this disclosure describes a CBP that indicates whether respective blocks of a CU include at least on non-zero coefficient. The CBP described herein may be mapped to a single variable length code (VLC) code word. The VLC code word may be used by a coder to code the CU of video data.
摘要:
This disclosure describes techniques for coding transform coefficients for a block of video data. According to these techniques, a video coder (a video encoder or video decoder) stores a first VLC table array selection table in memory, and an indication of at least one difference between the first VLC table array selection table and a second VLC table array selection table. The video coder reconstructs at least one entry of the second VLC table array selection table based on the first VLC table array selection table using the stored indication of the difference between the first VLC table array selection table and a second VLC table array selection table. The video coder uses the reconstructed at least one entry of the second VLC table array selection table to code at least one block of video data.
摘要:
This disclosure describes techniques for coding transform coefficients for a block of video data. According to these techniques, a video coder (a video encoder or video decoder) determines whether a block of video data is a luma block or a chroma block. If the block of video data is a luma block, the video coder adaptively updates a VLC table index value based on a code number cn and value of a scaling factor. However, if the block of video data is a chroma block, the video coder adaptively updates the VLC table index value based on the code number cn and without using the scaling factor. The video coder uses the updated VLC table index value to select a VLC table of a plurality of VLC tables that are used to encode or decode the block of video data.