Introduction

Title: A Fast and Efficient Inter Mode Decision Algorithm for the H.264/AVC Video Coding Standard
Original: https://www.scitepress.org/Papers/2013/45278/45278.pdf
Level: IEEE
Year : 2013
Organization: University of the West of England
resource download: https://download.csdn.net/download/yanceyxin/88041688

Conclusion: Based on the spatial uniformity and temporal stationarity characteristics of the current macroblock, the experimental results show that compared with the high-complexity algorithm in the JM16.1 reference software, the computational complexity of the algorithm is reduced by 66.90%, and it has tolerance performance ability to decline.

Interpretation of thesis

core principle

Mode decision for h264

h264 supports various intra-frame prediction modes and inter-frame prediction modes to achieve efficient encoding;

Intra-frame prediction uses the spatial redundancy between adjacent macroblocks in the frame. Intra-frame macroblocks in h264 include I4_MB, I8_MB, and I16_MB; I16_MB has four directions of prediction, namely horizontal, vertical, plane, and DC; I4_MB has nine types Direction prediction, I8_MB is the same as I16_MB, there are four kinds;

Inter-frame prediction uses time redundancy between different frames, and has different block sizes, 16x16, 16x8, 8x16, 8x8, 4x8, 8x4, 4x4;
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mode decision : use RDCsost to determine the best prediction mode; (simplified in x264 The decision formula of mode decision)

proposed algorithm

Considering that the motion and residual information of the skip mode is not encoded, the algorithm determines the skip mode as early as possible is the key;

Homogeneous/uniform detection: Determine whether it is homogeneous/uniform by detecting the pixel value of the current macroblock MB; the following process, where α is set to 5%, in MB, Th1 is equal to 14, and in subMB is set to 4; level1 includes skip, 16x16, 16x8, 8x16, level2 includes 8x8, 8x4, 4x8, 4x4.
insert image description here Stability detection: Temporal stationarity refers to the stillness between consecutive frames in the time direction. This paper uses SAD to detect, where the threshold TH_S is determined according to QP, as shown in Table 1;