Alibaba Group Holding Limited

Guibin Lu

Chang Zhou

Haohui Xu

Kaiyan Chu

Cao Shen

Wenfei Jiang

This application discloses methods and apparatuses for intra prediction mode selection, one method comprising: acquiring a gradient amplitude and a gradient angle of each element in a prediction block; analyzing statistics on the gradient angles and generating a gradient angle histogram of the prediction block; if the texture smoothness of the prediction block is greater than a first pre-determined threshold value, determining that the prediction block is a first-type prediction block, and setting a prediction mode of the first-type prediction block to comprise a direct current prediction mode and a planar prediction mode; and if the texture smoothness of the prediction block is less than a second pre-determined threshold value, determining that the prediction block is a second-type prediction block, and setting an angular prediction mode of the second-type prediction block to comprise an angular prediction mode corresponding to the maximum peak value in the gradient angle histogram.

Rapid selection method for video intra prediction mode and apparatus thereof

A method, an apparatus and a coder for selecting an optimal reference frame in HEVC coding are disclosed. The method includes obtaining optimal reference frames of prediction units spatially adjacent to a current prediction unit, and determining an optimal reference frame of the current prediction unit based on a correlation between optimal reference frames of the spatially adjacent prediction units in a same layer depth for prediction unit(s) of a minimum layer depth. In this way, an ergodic rate distortion cost calculation is not needed to be performed at least for the prediction unit(s) of the minimum layer depth, and the corresponding optimal reference frame is directly determined using the correlation, thus reducing the amount of calculations and enhancing the coding efficiency.

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Hangzhou, China

Guibin Lu