RDoptimized competition scheme for efficient motion prediction H.264MPEG4AVC is the latest video codec provided by the Joint Video Team, gathering ITUT and ISOIEC experts. Technically there are no drastic changes compared to its predecessors H.263 and MPEG4 part 2. It however significantly reduces the bitrate and seems to be progressively adopted by the market. The gain mainly results from the addition of efficient motion compensation tools, variable block sizes, multiple reference frames, 14pel motion accuracy and powerful Skip and Direct modes. A close study of the bits repartition in the bitstream reveals that motion information can represent up to 40% of the total bitstream. As a consequence reduction of motion cost is a priority for future enhancements. This paper proposes a competitionbased scheme for the prediction of the motion. It impacts the selection of the motion vectors, based on a modified ratedistortion criterion, for the Inter modes and for the Skip mode. Combined spatial and temporal predictors take benefit of temporal redundancies, where the spatial median usually fails. An average 7% bitrate saving compared to a standard H.264MPEG4AVC codec is reported. In addition, on the fly adaptation of the set of predictors is proposed and preliminary results are provided.

A fast inter mode decision algorithm in H.264AVC for IPTV broadcasting services The new video coding standard H.264AVC employs the ratedistortion optimization (RDO) method for choosing the best coding mode. However, since it increases the encoder complexity tremendously, it is not suitable for realtime applications, such as IPTV broadcasting services. Therefore we need a fast mode decision algorithm to reduce its encoding time. In this paper, we propose a fast mode decision algorithm considering quantization parameter (QP) because we have noticed that the frequency of best modes depends on QP. In order to consider these characteristics, we use the coded block pattern (CBP) that has 0 value when all quantized discrete cosine transform (DCT) coefficients are zero. We also use both the early SKIP mode and early 16x16 mode decisions. Experimental results show that the proposed algorithm reduces the encoding time by 74.6% for the baseline profile and 72.8% for the main profile, compared to the H.264AVC reference software.