Abstract:
Methods of adaptive transform type based on transform unit (TU) size for enhancement layer (EL) coding and multiple motion candidates for EL coding based on corresponding base layer (BL) video data are provided. One method selects a transform type from multiple allowable transform types based on the TU size and applies the selected transform type to the transform units of the inter-layer prediction processed data. Another method derives multiple motion candidates for the EL video data coded in Merge mode or Inter mode based on motion information associated with the corresponding BL video data.
Abstract:
A method and apparatus for coding video data using Inter prediction mode or Merge mode in a video coding system are disclosed, where the video data is configured into a Base Layer (BL) and an Enhancement Layer (EL), and the EL has higher spatial resolution or better video quality than the BL. In one embodiment, at least one information piece of motion information associated with one or more BL blocks in the BL is identified. A motion vector prediction (MVP) candidate list or a Merge candidate list for the selected block in the EL is then determined, where said at least one information piece associated with said one or more BL blocks in the BL is included in the MVP-candidate list or a Merge candidate MVP candidate list or the Merge candidate list. The input data associated with the selected block is coded or decoded using the MVP candidate list or the Merge candidate list.
Abstract:
A method and apparatus for coding video data in a scalable or three-dimensional video coding system are disclosed. In one embodiment, context for the input data associated with an inter-layer or inter-view coding syntax element of a current block in an enhancement-layer (EL) or a dependent view is formed or the input data is parsed to identify the context based on information associated with one or more neighboring blocks, information associated with the current block, or both. In another embodiment, encoding or decoding is applied to the input data associated with the current block in the EL using inter-layer texture prediction based on the BL block in the BL, wherein a flag indicating whether there is any transform coefficient coded for the current block is signaled.
Abstract:
A method and apparatus for inter-layer prediction for scalable video coding are disclosed. Embodiments of the present invention utilize weighted prediction for scalable coding. The weighted prediction is based on the predicted texture data and the inter-layer Intra prediction data derived from BL reconstructed data. The inter-layer Intra prediction data corresponds to the BL reconstructed data or up-sampled BL reconstructed data. The predicted texture data corresponds to spatial Intra prediction data or motion-compensated prediction data based on the second EL video data in the same layer as the current EL picture. Embodiments of the present invention also utilize the reference picture list including an inter-layer reference picture (ILRP) corresponding to BL reconstructed texture frame or up-sampled BL reconstructed texture frame for Inter prediction of EL video data. The motion vector is limited to a range around (0,0) when the ILRP is selected as a reference picture.
Abstract:
A method and apparatus for significance map coding for 4×4 TUs (transform units) and 8×8 TUs of video data are disclosed. The method comprises receiving at least one context selection table for a first TU associated with a first color component and generating a derived context selection table for a second TU associated with a second color component from said at least one context selection table. The first TU has a first size comprising of 4×4 and 8×8. The second TU has a second size comprising of 4×4 and 8×8. The second size is different from the first size, the second color component is different from the first color component, or both the second size is different from the first size and the second color component is different from the first color component. The derived context selection table is then used for significance map processing of the second TU.
Abstract:
A method and apparatus for deriving a scaled MV (motion vector) for a current block based on a candidate MV associated with a candidate block are disclosed. Embodiments according to the present invention increase effective scaling factor of motion vector scaling. In one embodiment, a distance ratio of a first picture distance between a current picture and a target reference picture pointed to by a current motion vector of the current block to a second picture distance between a candidate picture corresponding to the candidate block and a candidate reference picture pointed to by the candidate MV is computed. The scaled MV is then generated based on the candidate MV according to the distance ratio, where the scaled MV has an effective scaling ratio between −m and n, and wherein m and n are positive integers greater than 4. The values of m and n can be 8, 16 or 32.
Abstract:
A video coding system generating candidates for Merge Mode with Motion Vector Difference (MMVD) with reduced resource usage is provided. The system receives data to be encoded or decoded as a current block of a current picture of a video. The system identifies multiple MMVD candidates for different offset positions based on a merge candidate of the current block. The system generates reference samples for the identified MMVD candidates. The system reconstructs the current block or encodes the current block into a bitstream by using the generated reference samples. The system processes the MMVD candidates in separate groups: a first group of vertical MMVD candidates and a second group of horizontal MMVD candidates. The system generates the reference samples for the identified MMVD candidates by applying a vertical filter to source reference samples of horizontal MMVD candidates and then applying a horizontal filter to outputs of the vertical filter.
Abstract:
Methods and apparatus of for video coding using sub-block based affine mode are disclosed. In one method, if affine fallback is used or the control-point motion vectors are the same, the sub-block based affine mode is disabled in order to reduce computational complexity. According to another method for video coding using a coding tool belonging to a coding tool group comprising Prediction Refinement with Optical Flow (PROF) and Bi-Directional Optical Flow (BDOF), predictor refinement is derived for pixels of a target subblock of the current block, where a step to derive the predictor refinement comprises to derive gradients for the pixels of the target subblock of the current block and to right-shift the first gradients by a common shift.
Abstract:
Video encoding methods and apparatuses in a video encoding system receive an input residual signal of a current block by a shared transform circuit, apply horizontal transform and vertical transform by a shared transform circuit to generate transform coefficients, apply quantization and inverse quantization to generate recovered transform coefficients, apply inverse vertical transform and inverse horizontal transform to the recovered transform coefficients by the shared transform circuit to generate a reconstructed residual signal for the current block, and encode the current block based on quantized levels of the current block. The shared transform circuit and a coefficient buffer in the folded 4-time transform architecture reuse computation resources in each transform stage. In some embodiments of the folded 4-time transform architecture, a hierarchical design for block size grouping is implemented with fixed throughput for uniform hardware scheduling.
Abstract:
Various schemes for managing search memory are described, which are beneficial in achieving enhanced coding gain, low latency, and/or reduced hardware for a video encoder or decoder. In processing a current block of a current picture, an apparatus determines a quantity of a plurality of reference pictures of the current picture. The apparatus subsequently determines, for at least one of the reference pictures, a corresponding search range size based on the quantity. The apparatus then determines, based on the search range size and a location of the current block, a search range of the reference picture, based on which the apparatus encodes or decodes the current block.