Lv Zhuoyi

Bio: Lv Zhuoyi is an academic researcher from Huawei. The author has contributed to research in topics: Motion vector & Encoder. The author has an hindex of 2, co-authored 9 publications receiving 60 citations.

An affine motion compensation framework for high efficiency video coding

Abstract: As the translational motion model used in recent video coding standards cannot represent the complex motion such as rotation and zooming well, a simple local affine motion compensation framework supporting multiple reference frames is proposed in this paper to characterize the complex motion. Besides, since the commonly used fast motion estimation for affine motion model is still quite complex, a fast gradient based affine motion estimation algorithm is proposed to decrease the encoder complexity. The proposed algorithm is implemented into the test model of the newest video coding standard High Efficiency Video Coding (HEVC). Experimental results show that the bit rate reduction for sequences with complex motion can be up to 16.8%.

Image prediction method and device

Abstract: An image prediction method and device are disclosed. The method includes: obtaining a first reference unit of an image unit, where respective predicted images are obtained for the image unit and the first reference unit by using a same affine model; obtaining motion information of basic motion compensation units at two or more preset positions in the first reference unit; and obtaining motion information of a basic motion compensation unit of the image unit according to the motion information. In this way, motion information of the first reference unit using a same affine motion prediction model is reused, and a more accurate motion vector of a current image unit is obtained, improving prediction accuracy and maintaining encoding and decoding complexity, thereby improving encoding and decoding performance.

Video encoding/decoding method and device

Abstract: The present disclosure provides a video encoding/decoding method and apparatus, so that usage of a background picture is synchronized on an encoder side and a decoder side. In this solution, a background picture that is to be used as a reference picture is determined, background-picture indication information is used to indicate a time point from which the background picture is used as the reference picture, the encoder side encodes to-be-coded video pictures by using the background picture as the reference picture from the time point indicated by the background-picture indication information, to generate a primary bitstream, and the encoder side transmits a background-picture bitstream, the background-picture indication information, and the primary bitstream to the decoder side.

Video coding method, video decoding method, video coding apparatus, and video decoding apparatus

Abstract: Embodiments of the present disclosure disclose a video coding method which includes: obtaining a current picture, motion vector precision of the current picture according to the current picture, where the motion vector precision includes a search step size set, and each search step size in the search step size set is less than a pixel unit; obtaining a current block and a reference picture of the current block; determining a search start point in the reference picture, and searching, from the search start point, for a target integer pixel by using a pixel unit as a search step size; searching, from the target integer pixel, for a match block of the current block according to the motion vector precision; obtaining motion vector information and a prediction residual signal; and the reference picture, the motion vector information, and the prediction residual signal into a bitstream.

Efficient background picture coding for videos obtained from static cameras

Abstract: With the exponential growth of surveillance videos, conference videos and sports videos, videos with static cameras present an unprecedented challenge for high-efficiency video coding technology. The existing schemes developed for these videos mostly encode the background as the long-term reference (LTR) to further improve the coding efficiency. However, since the bit allocation of the long-term background reference is not intensively studied, the coding efficiency is still unsatisfactory. Based on the stability analysis of the video content, an efficient background picture coding algorithm for videos obtained from static cameras, which is embedded with the basic unit level bit allocation, is proposed in this paper. Experimental results reveal that on top of the default mode in HEVC, our method offers the performance with 10.8% BD-rate reduction on average. Compared with the state-of-the-art algorithm, it still outperforms for kinds of test sequences with negligible increases of computational complexity in both encoder and decoder.

An Efficient Four-Parameter Affine Motion Model for Video Coding

Abstract: In this paper, we study a simplified affine motion model-based coding framework to overcome the limitation of a translational motion model and maintain low-computational complexity. The proposed framework mainly has three key contributions. First, we propose to reduce the number of affine motion parameters from 6 to 4. The proposed four-parameter affine motion model can not only handle most of the complex motions in natural videos, but also save the bits for two parameters. Second, to efficiently encode the affine motion parameters, we propose two motion prediction modes, i.e., an advanced affine motion vector prediction scheme combined with a gradient-based fast affine motion estimation algorithm and an affine model merge scheme, where the latter attempts to reuse the affine motion parameters (instead of the motion vectors) of neighboring blocks. Third, we propose two fast affine motion compensation algorithms. One is the one-step sub-pixel interpolation that reduces the computations of each interpolation. The other is the interpolation-precision-based adaptive block size motion compensation that performs motion compensation at the block level rather than the pixel level to reduce the number of interpolation. Our proposed techniques have been implemented based on the state-of-the-art high-efficiency video coding standard, and the experimental results show that the proposed techniques altogether achieve, on average, 11.1% and 19.3% bits saving for random access and low-delay configurations, respectively, on typical video sequences that have rich rotation or zooming motions. Meanwhile, the computational complexity increases of both the encoder and the decoder are within an acceptable range.

Method and apparatus of video coding with affine motion compensation

Abstract: An encoding or decoding method with affine motion compensation includes receiving input data associated with a current block in a current picture, and deriving a first affine candidate for the current block including three affine motion vectors for predicting motion vectors at control points of the current block if the current block is coded or to be coded in affine Merge mode. The affine motion vectors are derived from three different neighboring coded blocks of the current block. An affine motion model is derived according to the affine motion vectors if the first affine candidate is selected. Moreover, the method includes encoding or decoding the current block by locating a reference block in a reference picture according to the affine motion model. The current block is restricted to be coded in uni-directional prediction if the current block is coded or to be coded in affine Inter mode.

Video signal processing method and device

Abstract: An image decoding method, according to the present invention, can comprise the steps of: deriving a spatial merge candidate of a current block; generating a merge candidate list for the current block on the basis of the spatial merge candidate; acquiring motion information on the current block on the basis of the merge candidate list; and performing motion compensation for the current block by using the motion information.

Block-Composed Background Reference for High Efficiency Video Coding

Abstract: A block-composed background reference method is proposed in this paper for High Efficiency Video Coding (HEVC). For a group of picture (GoP), the first reconstructed picture is served as an initial background reference, which probably includes foreground content. In the subsequent coding, some background coding tree units (CTUs) in every picture are selected to be compressed with high quality. These reconstructed CTUs are used to update the background reference as well as replace the foreground content. Finally, a high-quality background reference is generated to better exploit the long-term temporal correlation in the video. There are three key technical contributions in the proposed coding scheme. First, the background reference is generated gradually by block updating instead of picture updating, which makes the scheme free of bit-rate burst and more suitable for real-time applications and can generate high-quality background reference even with complicated foreground. Second, we propose an approach to select background CTUs by taking both temporal and spatial smoothness into account. Third, we propose a model to decide the coding parameters of the selected background CTUs based on the overall picture activity, which essentially pursues the GoP-level optimal performance when making CTU-level decision. The proposed background reference is implemented into HEVC, and the experimental results demonstrate a significant improvement in coding efficiency. Compared with HEVC, our method can averagely save 14% bits in surveillance and conferencing sequences with negligible increase of encoding and decoding complexity. In particular, it can still averagely save 7.3% bits in HEVC general test sequences. Obviously, the proposed scheme can be applied to more general video contents.

Frame rate up-conversion coding mode

Abstract: Methods, apparatuses, and computer-readable medium are provided for a frame rate up-conversion coding mode, where a bilateral matching mode can be used to determine motion information. In various implementations, local illumination compensation is disallowed from being used for a block when a bilateral matching mode is used for the block. In various implementations, a bilateral matching mode is disallowed from being used when local illumination compensation is used for the block.