Abstract: A method and apparatus for loop filter processing of video data in a video encoder or decoder are disclosed. Embodiments according to the present invention conditionally allow sharing of loop filter parameters. In one embodiment, sharing of loop filter information between the current block and a neighboring block is determined according to a condition. If the condition indicates that sharing of loop filter information is allowed, a merge flag is coded and incorporated in the video bitstream in an encoder, and a merge flag is parsed from the video bitstream and decoded in a decoder. In one embodiment, the condition depends on region partitioning of the picture, where region partitioning partitions the picture into regions and the region may correspond to a slice or a tile. The condition is set to indicate that sharing of loop filter information is allowed if the block and the neighboring block are in a same slice/tile.

Abstract: A method and apparatus for deriving a motion vector predictor (MVP) candidate set for motion vector coding of a current block. Embodiments according to the present invention determine a redundancy-removed spatial MVP candidate set by removing any redundant MVP candidate from the spatial MVP candidate set. The redundancy-removal process does not apply to the temporal MVP candidate. In another embodiment of the present invention, a redundancy-removed spatial-temporal MVP candidate set is determined and the number of candidates in the redundancy-removed spatial-temporal MVP candidate set is checked to determine whether it is smaller than a threshold. If the number of candidates is smaller than the threshold, a zero motion vector is added to the redundancy-removed spatial-temporal MVP candidate set. The redundancy-removed spatial-temporal MVP candidate set is then provided for encoding or decoding of the motion vector of the current block.

Abstract: A method and apparatus for luma-based chroma intra prediction for a current chroma block are disclosed. The chroma intra predictor is derived from reconstructed luma pixels of a current luma block according to the chroma sampling format. Depending on the chroma sampling format, either sub-sampling, down-sampling or no processing is applied to the reconstructed luma pixels in horizontal or vertical direction. The information associated with the chroma sampling format can be incorporated in the sequence parameter set (SPS), the picture parameter set (PPS), the adaptation parameter set (APS) or the slice header of a video bitstream.

Abstract: A method for performing localized multihypothesis prediction during video coding of a coding unit includes processing the coding unit. More particularly, the step of processing the coding unit further includes: obtaining at least two sets of motion information derived from a set of coded units for multihypothesis motion compensation of the coding unit; and utilizing a linear combination of a plurality of pixel values derived from the at least two sets of motion information derived from the set of coded units as a predicted pixel value of the coding unit. An associated apparatus is also provided.

Abstract: A method and apparatus for de-quantizing a transform coefficient from a quantization level are disclosed. Embodiments according to the present invention avoid overflow of the de-quantized transform coefficient by clipping the quantization level adaptively before reconstructing the transform coefficient. In one embodiment, the method comprises receiving a decoded quantization level for the transform coefficient of a transform unit, wherein the decoded quantization level is decoded by an entropy decoder or is being processed by the entropy decoder. The clipping range is determined and then the decoded quantization level is clipped to the clipping range to generate a clipping-processed quantization level. A de-quantized transform coefficient can be generated using the clipping-processed quantization level. In another embodiment, the decoded quantization level is always clipped to [?N, M], where M and N are positive integers.

Abstract: A method and apparatus for context-adaptive Start arithmetic coding (CABAC) of a syntax element are disclosed. The bin string corresponding to a syntax element is processed by context-adaptive arithmetic coding with a reduced number of contexts using the bin-level bypass mode, bin-level context sharing, or both. The syntax element belongs to a group comprising merge_idx, ref_idx_lc/ref_idx_10/ref_idx_11, pred_type, and cu_qp_delta. In one embodiment, the syntax element corresponds to merge_idx and three bins of the bin string with bin indices corresponding to 1, 2 and 3 are coded in the bin by-pass mode. In another embodiment, the syntax element corresponds to ref_idx_lc/ref_idx_10/ref_idx_11 and one or more bins of the bin string with bin indices larger than 1 for larger than 2 are coded in the bin bypass mode.

Abstract: A method for performing localized multihypothesis prediction during video coding of a coding unit includes: dividing the coding unit into a plurality of sub-coding units; and performing motion vector prediction of each of the sub-coding units. More particularly, the step of performing motion vector prediction of each of the sub-coding units further includes: obtaining a plurality of motion vectors for multihypothesis motion compensation of a specific sub-coding unit of the sub-coding units from a plurality of other sub-coding/coding units. The method further includes performing multihypothesis motion compensation on the specific sub-coding unit according to the plurality of motion vectors, and more particularly, includes utilizing a linear combination of a plurality of pixel values of the plurality of other sub-coding/coding units as a predicted pixel value of the specific sub-coding unit. An associated apparatus is also provided.

Abstract: In a block-based motion compensated system, coding noises may arise due to lossy operations. Adaptive loop filter (ALF) is a technique used to improve the quality. A pixel adaptive (PA) ALF method was developed that uses the Sum-modified Laplacian Measure (SLM) to classify pixels and applies a respective ALF filter to each pixel according to the SLM. While the PA ALF achieves better performance over a conventional single filter (SF) based ALF, the PA ALF causes higher complexity and consumes more power due to the high complexity and per-pixel filter switching. Accordingly region based ALF scheme is disclosed which allows adaptive filter selection on a region by region basis and does not require per-pixel filter switching. In one embodiment according to the present invention, a picture is divided into M×N regions. The region based ALF also allows region merging for the M×N regions to improve performance.

Abstract: A method and apparatus for loop processing of reconstructed video in an encoder system are disclosed. The loop processing comprises an in-loop filter and one or more adaptive filters. The filter parameters for the adaptive filter are derived from the pre-in-loop video data so that the adaptive filter processing can be applied to the in-loop processed video data without the need of waiting for completion of the in-loop filter processing for a picture or an image unit. In another embodiment, two adaptive filters derive their respective adaptive filter parameters based on the same pre-in-loop video data. In yet another embodiment, a moving window is used for image-unit-based coding system incorporating in-loop filter and one or more adaptive filters. The in-loop filter and the adaptive filter are applied to a moving window of pre-in-loop video data comprising one or more sub-regions from corresponding one or more image units.

Abstract: A method for performing local motion vector derivation during video coding of a coding unit includes: processing a plurality of sub-coding units in the coding unit; and performing motion vector prediction of each of the sub-coding units. More particularly, the step of performing motion vector prediction of each of the sub-coding units further includes: deriving a motion vector of a specific sub-coding unit of the sub-coding units by utilizing at least one motion vector of at least one other sub-coding/coding unit. Thus, the method performs motion compensation on the specific sub-coding unit according to the motion vector of the specific sub-coding unit. An associated apparatus is also provided.

Abstract: An apparatus and method for deriving a motion vector predictor (MVP) or a MVP candidate for a current block are disclosed. Embodiments according of the present invention receive a first motion vector associated a first reference picture in a first reference picture list and a second motion vector associated with a second reference picture in a second reference picture list of a spatially neighboring block. A MVP or at least one MVP candidate associated with a selected reference picture in a selected reference picture list for the current block is then determined based on the first reference picture, the second reference picture and the selected reference picture according to a pre-defined priority order. The MVP or MVP candidate is determined depending on whether the first reference picture is the same as the selected reference picture or whether the second reference picture is the same as the selected reference picture.

Abstract: A method and apparatus for deriving MVP (motion vector predictor) for a block for three-dimensional video coding or multi-view video coding are disclosed. Embodiments according to the present invention replace an unavailable inter-view MV of one neighboring block with a disparity vector derived from depth data of a subset of a depth block corresponding to one neighboring block. A method and apparatus for generating additional candidates for motion vector prediction associated with Merge mode or AMVP (Inter) mode for a block are disclosed. Embodiments according to the present invention generate one or more additional MVP candidates to add to the MVP list if the MVP list size is less than a given list size. The additional MVP candidates are generated either by reducing precision of an available MVP in the MVP list or by adding an offset to the available MVP in the MVP list.

Abstract: An apparatus and method of deriving a motion vector predictor (MVP) for a current MV of a current block in Inter, Merge or Skip mode are disclosed based on motion vector (MV) attribute search. The system determines first MV attribute search comprising whether a given MV pointing to the target reference picture in the given reference list, or whether the given MV pointing to the target reference picture in other reference list, and determines second MV attribute search comprising whether the given MV pointing to other reference pictures in the given reference list, or whether the given MV pointing to the other reference pictures in the other reference list. The MVP for the current block is then determined from the neighboring blocks according to a search order.

Abstract: A method and apparatus for deriving a motion vector predictor (MVP) candidate set for a block are disclosed. Embodiments according to the present invention generate a complete full MVP candidate set based on the redundancy-removed MVP candidate set if one or more redundant MVP candidates exist. In one embodiment, the method generates the complete full MVP candidate set by adding replacement MVP candidates to the redundancy-removed MVP candidate set and a value corresponding to a non-redundant MVP is assigned to each replacement MVP candidate. In another embodiment, the method generates the complete full MVP candidate set by adding replacement MVP candidates to the redundancy-removed MVP candidate set and a value is as signed to each replacement MVP candidate according to a rule. The procedure of assigning value, checking redundancy, removing redundant MVP candidate are repeated until the MVP candidate set is complete and full.

Abstract: A coding system includes a decoding block and a reconstruction loop with first and second adaptive restoration blocks. The decoding block receives and decodes an encoded bitstream to derive residues, prediction information, and adaptive restoration information. The reconstruction loop reconstructs a current frame according to the residues and prediction information. The first adaptive restoration block performs restoration on a first set of processed data according to a first set of the adaptive restoration information, and the second adaptive restoration block performs restoration on an output of the first adaptive restoration block according to a second set of the adaptive restoration information.

Abstract: A method and apparatus for deblocking of reconstructed video are disclosed. In one embodiment, the method divides a block boundary into two sub-boundaries and separates lines or column across the sub-boundaries into two groups. The deblocking filter decision for each group is determined based on the lines or columns in the respective group. In another embodiment, the method divides block edges of blocks in the LCUs into two edge groups, where the first edge group corresponds to horizontal block edges between two LCUs and the second edge group corresponds to remaining block edges not included in the first edge group. The number of lines processed by a vertical filter in the first edge group is less than the number of lines processed by a vertical filter in the second edge group. Accordingly, a system embodying the present invention has reduced storage requirement.

Abstract: Methods and apparatuses for processing of coded video using ALF are disclosed. Embodiments according to the present invention apply ALF with constrained data range to reconstructed video data. The ALF parameters comprise a center coefficient, one or more non-center coefficients, and an offset term. As an example, the constrained data range for the center coefficient is selected from [0.0, 2.0) and [0.5, 1.5). In another example, the constrained data range for said one or more non-center coefficient is selected from [?1.0, 1.0) and [?0.5, 0.5). The constrained data range can also be applied to the offset term. For example the range of [?2D/N, (2D?1)/N) can be applied to the offset term, wherein D denotes pixel bit depth and N is a power-of-two integer. Alternatively, the constrained data range for the offset term can be [?2M,2M), wherein M is an integer.

Abstract: A method and apparatus for deblocking of reconstructed video in a video coding system are disclosed. Embodiments according to the present invention determine boundary strength between two blocks without checking whether the block boundary is a coding unit (CU) boundary. In one embodiment according to the present invention, the method comprises determining whether any of the two blocks is Intra coded. If any of the two blocks is Intra coded, the boundary strength is assigned a first value. Otherwise, additional decision processing is performed to determine the boundary strength. In another embodiment, said determining the boundary strength for the block boundary comprises determining whether the block boundary is a TU boundary and whether any of the two blocks contains coefficients. In yet another embodiment, said determining the boundary strength for the block boundary comprises determining whether the two blocks have different reference pictures or different motion vectors.

Abstract: A method and apparatus for improved intra chroma prediction mode coding are disclosed. Intra prediction exploits the spatial correlation within a picture or within a picture region. In practice, a picture is divided into blocks and the intra mode prediction is performed on a block basis. In newer coding systems, multiple intra coding modes such as Vertical mode, Horizontal mode, DC mode and Diagonal mode, have been used to improve the coding efficiency of intra coding. Furthermore, a Luma_mode has also been used in intra prediction of chroma component to further improve the performance in the High Efficiency Video Coding (HEVC) standard being developed. However, the mode selection information for intra prediction has to be conveyed to the decoder for proper operation. Spatial features in a picture often exist in both luma and chroma components. The intra luma prediction mode and intra chroma prediction mode will have high probability to be the same.

Abstract: A method and apparatus for reconstructing a high-resolution image based on multiple low-resolution images are disclosed. The method and apparatus incorporating an embodiment according to the present invention reconstructs the high-resolution image based on a kernel regression method using a modified kernel function. The kernel function takes into consideration of registration reliability of regression residue and rotational motion within the multiple low-resolution images. The registration reliability adjusts weighting on the regression residues according to local gradient estimated between neighboring values. Furthermore, multi-scale regression residue is used to alleviate impact of noise.