Wedge mode is a crucial compound prediction mode for predicting a block that includes motion object boundaries in the AV1 video codec. The current AV1 design incorporates 16 block shape adaptive modes, utilizing a set of handcrafted one-dimensional blending masks, which are predefined and applied to the blending process of combining two predictors. However, this design lacks flexibility to cater to various types of motion object boundaries in real-world scenarios. This paper proposes an extended wedge mode to replace the original design. The proposed method features novel components such as relaxed block sizes and number of modes limitation, mathematically derived non-linear based two-dimensional masks for the blending process, and more efficient mode signaling methods. The experimental results of the proposed method evaluated with the AOM reference software under the AOM common test conditions demonstrate that it provides an averaged YUV Bjøntegaard Delta rate reduction of 0.3 % for random access and 0.7 % for low delay configurations without a major increase in complexity.
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