Fast decision on picture adaptive frame/field coding for H.264

The new H.264 video coding standard supports picture and macroblock level adaptive frame/field coding, which can improve coding efficiency when coding interlaced sequences. A good design of an encoder needs to support all these modes and be able to decide which one is the most appropriate mode for encoding a macroblock or picture. It could be argued that the optimal solution can be found by employing a multi-pass strategy, that is to encode a macroblock or picture using all possible coding modes, and by selecting the one that yields the best coding performance. Unfortunately the computational complexity of such a multi-pass encoder is relatively high. In this paper, we propose a novel single-pass algorithm based on motion activity detection. The proposed scheme is performed in a pre-analysis stage and can reduce complexity by approximately 40%-60% compared to the two-pass frame/field encoder, while maintaining similar coding efficiency.