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    FLEXIBLE COEFFICIENT CODING IN VIDEO COMPRESSION
    1.
    发明公开
    FLEXIBLE COEFFICIENT CODING IN VIDEO COMPRESSION 审中-公开

    公开(公告)号：US20240040124A1

    公开(公告)日：2024-02-01

    申请号：US18358094

    申请日：2023-07-25

    申请人： Apple Inc.

    发明人： Alican NALCI ,  Yunfei ZHENG ,  Hilmi Enes EGILMEZ ,  Yeqing WU ,  Yixin DU ,  Alexandros TOURAPIS ,  Jun XIN ,  Hsi-Jung WU ,  Arash VOSOUGHI ,  Dzung T. HOANG

    IPC分类号： H04N19/13 ,  H04N19/70 ,  H04N19/61 ,  H04N19/176

    CPC分类号： H04N19/13 ,  H04N19/70 ,  H04N19/61 ,  H04N19/176

    摘要： A flexible coefficient coding (FCC) approach is presented. In the first aspect, spatial sub-regions are defined over a transform unit (TU) or a prediction unit (PU). These sub-regions organize the coefficient samples residing inside a TU or a PU into variable coefficient groups (VCGs). Each VCG corresponds to a sub-region inside a larger TU or PU. The shape of VCGs or the boundaries between different VCGs may be irregular, determined based on the relative distance of coefficient samples with respect to each other. Alternatively, the VCG regions may be defined according to scan ordering within a TU. Each VCG can encode a 1) different number of symbols for a given syntax element, or a 2) different number of syntax elements within the same TU or PU. Whether to code more symbols or more syntax elements may depend on the type of arithmetic coding engine used in a particular coding specification. For multi-symbol arithmetic coding (MS-AC), a VCG may encode a different number of symbols for a syntax element. For example, to encode absolute coefficient values inside a TU after performing a transform such as the discrete cosine transform (DCT), a VCG region may be defined around lower-frequency transform coefficients and for that VCG M-symbols can be encoded the absolute coefficient values. Another VCG region can be defined around the higher-frequency transform coefficients to encode K-symbols, where K may be different than M. For binary arithmetic coders (BACs), FCC allows for coding a variable number of syntax elements in different VCGs. In this case, one VCG in a TU may code M-syntax elements associated with signaling the absolute coefficient value, where each one of the M-syntax elements may have 2-symbols. Probability models and context derivation rules may be tailored for each VCG in a given TU or PU. Since each VCG may code a different number of symbols or syntax elements in different spatial locations of a TU or PU, different context models may be used for each VCG to provide better granularity for entropy modeling for arithmetic coding. Furthermore, different VCGs may also use different entropy coders including combinations of arithmetic coding, Golomb-Rice coding, Huffman coding.

    CONTEXT MODELING IN ENTROPY CODING
    3.
    发明公开
    CONTEXT MODELING IN ENTROPY CODING 审中-公开

    公开(公告)号：US20240129472A1

    公开(公告)日：2024-04-18

    申请号：US18468900

    申请日：2023-09-18

    申请人： Apple Inc.

    发明人： Yeqing WU ,  Yunfei ZHENG ,  Alican NALCI ,  Yixin DU ,  Hilmi Enes EGILMEZ ,  Guoxin JIN ,  Alexandros TOURAPIS ,  Jun XIN ,  Hsi-Jung WU

    IPC分类号： H04N19/13 ,  H04N19/129 ,  H04N19/176

    CPC分类号： H04N19/13 ,  H04N19/129 ,  H04N19/176

    摘要： Improved lossless entropy coding techniques for coding of image data include selecting a context for entropy coding based on an ordered scan path of possible context locations. A symbol for a current location within a source image may be entropy coded based on a context of prior encoded symbols of other locations within source images, where the context is selected based on an ordered scan path enumerating a series of potential context locations within one or more source images. To select a context, a predetermined number of prior symbols may be selected by qualifying or disqualifying locations in the scan path, and then the current symbol may be encoded with a context based on prior symbols corresponding to the first qualifying context locations in the order of the scan path.

    HARDWARE FRIENDLY DESIGN FOR MOTION FIELD PROCESSING AND QUALITY IMPROVEMENT OF MOTION FIELD
    5.
    发明公开
    HARDWARE FRIENDLY DESIGN FOR MOTION FIELD PROCESSING AND QUALITY IMPROVEMENT OF MOTION FIELD 审中-公开

    公开(公告)号：US20240340438A1

    公开(公告)日：2024-10-10

    申请号：US18593281

    申请日：2024-03-01

    申请人： Apple Inc.

    发明人： Yeqing WU ,  Yunfei ZHENG ,  Yixin DU ,  Alican NALCI ,  Hilmi E. EGILMEZ ,  Guoxin JIN ,  Alexandros TOURAPIS ,  Jun XIN ,  Hsi-Jung WU

    IPC分类号： H04N19/52 ,  H04N19/105 ,  H04N19/124 ,  H04N19/127 ,  H04N19/154 ,  H04N19/172 ,  H04N19/176

    CPC分类号： H04N19/52 ,  H04N19/105 ,  H04N19/124 ,  H04N19/127 ,  H04N19/154 ,  H04N19/172 ,  H04N19/176

    摘要： Techniques are proposed to improve temporal motion projection in video coding. Candidate reference frames available for use in temporal motion projection are sorted in processing order according to scores assigned based on estimates of the reference frames' suitability for prediction. Such estimates may be based on temporal distance between each candidate reference frame and that reference frame's prediction references. Estimates may be based, for each reference frame, based on an estimate of coding quality of a reference frame from which the respective candidate reference frame makes a prediction reference. Once sorted, the candidate reference frames may be processing in the sorting order to supply prediction data to a current frame that is to be coded from the candidate reference frames. Additionally, hardware friendly designs of motion field hole filling and motion vector smoothing operations are proposed. Such designs can reduce hardware implementation complexity and benefit hardware parallel processing in several aspects: by removing the dependency among different processing block rows for hole filling and motion vector smoothing so that it is becomes easier and friendlier to achieve hardware parallel processing; by reducing the hardware bandwidth loading overhead; by improving hardware pipeline throughput; and/or by avoiding adding a line buffer to store the data from the above row since a line buffer will increase hardware cost.

    MOTION VECTOR CODING SIMPLIFICATIONS
    7.
    发明公开
    MOTION VECTOR CODING SIMPLIFICATIONS 审中-公开

    公开(公告)号：US20240073438A1

    公开(公告)日：2024-02-29

    申请号：US18452194

    申请日：2023-08-18

    申请人： Apple Inc.

    发明人： Yeqing WU ,  Yunfei ZHENG ,  Guoxin JIN ,  Yixin DU ,  Alican NALCI ,  Hilmi Enes EGILMEZ ,  Jun XIN ,  Hsi-Jung WU

    IPC分类号： H04N19/513 ,  H04N19/176

    CPC分类号： H04N19/513 ,  H04N19/176

    摘要： Techniques are disclosed for improved video coding with virtual reference frames. A motion vector for prediction of a pixel block from a reference may be constrained based on the reference. In as aspect, if the reference is a temporally interpolated virtual reference frame with corresponding time close to the time of the current pixel block, the motion vector for prediction may be constrained magnitude and/or precision. In another aspect, a bitstream syntax for encoding the constrained motion vector may also be constrained. In this manner, the techniques proposed herein contribute to improved coding efficiencies.