An Improved H.264 Fast Inter-Mode Decision Algorithm

S.-H. Yang and K.-H. Wang (Taiwan)


Fast mode selection, motion estimation, video coding, and H.264/AVC


The H.264 video coding standard substantially improves compression performance by using more flexible coding options, notably the inter-mode selection. The introduced flexibility, however, significantly increases the encoding complexity. In this paper, a new H.264 fast inter-mode decision algorithm is presented to resolve the performance/complexity dilemma. The proposed method integrates the coded block pattern and information of the co-located macroblock to avoid RDcost evaluations of all possible modes. More zero blocks in the current macroblock and a co-located macroblock of M types (larger matching blocks in motion estimation) imply a higher chance of choosing the SKIP mode or M types for the current macroblock. Experimental results show that the proposed algorithm achieves an average 75% reduction in encoding time at medium-to-low bit rates with negligible degradation in visual quality. In addition to the significant improvement in computation reduction, the proposed method involves no ad-hoc thresholds and imposes fewer restrictions on implementation. Extensive comparisons with other state-of-the-art fast mode decision algorithms confirm the superiority of the proposed method.

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