Alibaba Group Holding Limited

Kaiyan Chu

Chang Zhou

Wenfei Jiang

Haohui Xu

Cao Shen

Guibin Lu

Dawei Mei

A method including selecting a first definition and a second definition from multiple levels of definition, and determining a first resolution and a second resolution that respectively correspond to the first definition and the second definition; transcoding a first part of content of a media file based on the first resolution and the second resolution and according to a preset transcoding rule, and recording a first real-time quantization parameter (QP) value and a second real-time QP value in the transcoding process; determining whether the first real-time QP value and the second real-time QP value meet a preset detection rule; if the determining result is no, adjusting the first resolution and/or adjusting the second resolution; and transcoding the non-transcoded part in the media file according to the adjusted first resolution and/or second resolution. The transcoding method and apparatus increase the transcoding speed of a media file.

Transcoding method and apparatus

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.

Growing community of inventors

Hangzhou, China

Kaiyan Chu