A hierarchical classification-based approach to Inter Mode Decision in H.264/AVC

The H.264/AVC standard achieves a high coding efficiency compared with previous standards. However, it does so at a very high computational cost, with motion estimation being one of the most demanding subsystems. In this paper a hierarchical classificationbased approach to the Inter Mode Decision (MD) problem is proposed. A first classifier detects SKIP/Direct modes while a second one is able to decide whether using a large (16×16, 16×8 and 8×16) or a small mode (8×8, 8×4, 4×8 and 4×4). The same procedure is applied at SubMacroblock level. The suggested classifiers are binary and linear. The input features that feed both classifiers have been carefully selected. A novel cost function that pays more attention to the most critical samples during the classifier training process has been designed. The results are very promising: a 64 % computational saving of the total encoding time with respect to JM10.2 is achieved with negligible degradation in the rate-distortion performance.