Abstract: Methods for filter-unit based in-loop filtering in a video decoder and encoder are disclosed. In one embodiment, filter parameters are selected from a filter parameter set for each filter based on a filter index. In another embodiment, the picture is partitioned into filter units according to filter unit size, which can be selected between a default size and other size. When other size is selected, the filter unit size may be conveyed using direct size information or ratio information. In another embodiment, a merge flag and a merge index are used to convey filter unit merge information. A method for filter-unit based in-loop filtering in a video encoder for color video is disclosed. In one embodiment, the method incorporates filter syntax in the video bitstream by interleaving the color-component filter syntax for the FUs.

Abstract: A method and apparatus for video processing of reconstructed video in a reconstruction loop are disclosed. An embodiment according to the present invention performs padding for the blocks in the slice boundaries according to a processing order. Each of the one or more reconstructed blocks at slice boundaries is padded according to a padding order. In-loop filtering is applied to the reconstructed slice according to the processing order, wherein the reconstructed slice is filtered by referencing the one or more padded blocks. The padding order can be vertical-edge first and then horizontal-edge, or horizontal-edge first and then vertical-edge. Various embodiments are disclosed regarding whether padding for a later padded block in the processing order is skipped or not in the overlapped area. The present invention is also applied to adaptation blocks for block-based in-loop filtering in slice boundaries.

Abstract: A method and apparatus for processing reconstructed video using in-loop filter in a video coding system are disclosed. The method uses chroma in-loop filter indication to indicate whether chroma components are processed by in-loop filter when the luma in-loop filter indication indicates that in-loop filter processing is applied to the luma component. An additional flag may be used to indicate whether the in-loop filter processing is applied to an entire picture using same in-loop filter information or each block of the picture using individual in-loop filter information. Various embodiments according to the present invention to increase efficiency are disclosed, wherein various aspects of in-loop filter information are taken into consideration for efficient coding such as the property of quadtree-based partition, boundary conditions of a block, in-loop filter information sharing between luma and chroma components, indexing to a set of in-loop filter information, and prediction of in-loop filter information.

Abstract: A method and apparatus for sharing information in a video coding system are disclosed. Embodiments according to the present invention use an information sharing flag to determine whether to share in-loop filter information in the picture level. The information sharing flag may be incorporated in the sequence level, the picture level or the slice level to indicate whether information sharing is enabled. Multiple information sharing flags may also be used to adaptively control information sharing. Furthermore, method and apparatus of using multiple Adaptation Parameter Sets (APSs) for information sharing of in-loop filters are disclosed. APS identifiers of in-loop filters may be incorporated in the slice header to allow each of the in-loop filters select respective filter information from the multiple APSs. A flag is incorporated in SPS to indicate whether multiple APS or single APS is used. Various exemplary syntax designs are disclosed to illustrate information sharing.

Abstract: An apparatus and method for sample adaptive offset to restore intensity shift of processed video data are described. In a video coding system, the video data are subject to various processing such as prediction, transformation, quantization, deblocking, and adaptive loop filtering. Along the processing path in the video coding system, certain characteristics of the processed video data may be altered from the original video data due to the operations applied to video data. For example, the mean value of the processed video may be shifted. Therefore, the pixel intensity shift has to be carefully compensated or restored to alleviate the artifacts. Accordingly a sample adaptive offset scheme is disclosed that can take into consideration of the dynamic characteristics within a frame using a region partition scheme. Furthermore, the sample adaptive offset scheme also supports multiple SAO types that can be tailored to the characteristics of processed video data and achieve better quality.

Abstract: For sample adaptive offset, classification may be used to classify the pixels into multiple categories and pixels in each category are offset compensated using an offset value for the category. The classification may be based on values of the current pixel and its neighboring pixels before SAO compensation. Therefore, the SAO compensated pixel cannot be written back to the current pixel location until the category for all pixels are determined. An embodiment of the present invention stores the relation between the current pixel and said one or more neighboring pixels so that the SAO compensated current pixel can replace the current pixel without buffering the to-be-processed pixels for classification. The SAO process may be performed on a region by region basis to adapt to the local characteristics of the picture. Rate-distortion optimization (RDO) is often used to guide the mode decision, such as region splitting/region merging decision.

Abstract: A method and apparatus for processing in-loop reconstructed video using an in-loop filter is disclosed. In the recent HEVC development, adaptive loop filtering (ALF) is being adopted to process in-loop reconstruction video data, where ALF can be selectively turned ON or OFF for each block in a frame or a slice. An advanced ALF is disclosed later that allows a choice of multiple filter sets that can be applied to the reconstructed video data adaptively. In the present disclosure, pixels of the in-loop reconstructed video data are divided into a plurality of to-be-filtered regions, and an in-loop filter from a filter set is determined for each to-be-filtered region based on a rate-distortion optimization procedure. According to one embodiment of the present invention, computation of cost function associated with the rate-distortion optimization procedure is related to correlation values associated with original video data and the in-loop reconstructed video data.

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: In a block-based motion compensated system, coding noises may arise due to lossy operations such as quantization. Deblocking is often used to alleviate visibility of coding artifacts by applying filtering across block boundaries adaptively. In the recent HEVC development, adaptive loop filtering (ALF) is being adopted to process deblocked reconstruction frames. Adaptive loop filtering is applied to reconstructed video data across multiple frames to reduce visibility of coding artifacts in the temporal domain. In a HEVC system, conventional ALF can be selectively turned ON or OFF for each block in a frame or a slice. The advanced ALF disclosed here allows a choice of multiple filter sets that can be applied to the reconstructed video data adaptively. Furthermore, the advanced ALF adopts a new unit for the filtering process to apply so that more flexible and/or localized processing can be provided.

Abstract: A method for processing video image is provided to perform a motion vector filtering process on the image after being processed by a motion estimation process. The motion vector filtering process adjusts the motion vectors derived for each block in a video sequence, so that the motion vector of each block and the actual moving direction of the corresponding object in the image tend to conformity. Then, the blocks with similar motion vectors are merged and blocks with radical motion vectors are corrected, thereby reducing distortion of the output image and the number of bits used to represent the motion information, which in turns increases the efficiency of compression process.

Abstract: A method for processing video image is provided to perform a motion vector filtering process on the image after being processed by a motion estimation process. The motion vector filtering process adjusts the motion vectors derived for each block in a video sequence, so that the motion vector of each block and the actual moving direction of the corresponding object in the image tend to conformity. Then, the blocks with similar motion vectors are merged and blocks with radical motion vectors are corrected, thereby reducing distortion of the output image and the number of bits used to represent the motion information, which in turns increases the efficiency of compression process.

Abstract: The present invention provides a method and apparatus for interframe wavelet video coding which comprises Motion Compensated Temporal Filtering and Discrete Wavelet Transform Coding to obtain: 1. compressed quantification error and scalability on temporal analysis and spatial analysis, and 2. scalability on Motion Information (MI) data so that the performance of wavelet video coding on low bitrate can be improved. A method for partitioned coding on MI is proposed: 1. to partitioned coding a motion vector according to the spatial block, the temporal frame, or the numeric precision; 2. to partition motion vectors to a plurality of layers, and, when the video bitstream changes, only the required MI is put into the final bitstream. Accordingly, the performance of wavelet video compression on low bitrate is greatly improved while the compression rate on high bitrate is only a little lower.