Fast Mode Decision Based on All-Zero Block in H.264/AVC

In H.264/AVC, it is a common phenomenon that the transformation coefficients of a block are quantized to zero. Such block is called a all-zero block (AZB). in the process of mode decision, if a AZB can be detected early, the overhead of following transformation and quantization can be avoided. This will lead magnificent saving in encoding time. A fast mode decision algorithm based on AZBs detection in H.264/AVC is proposed in this paper. We present a more precise threshold based on the analysis on the theory of integer transform and quantization. Then, a more efficient mode decision algorithm is proposed based on the probabilities of inter/intra modes. The simulation results show that the proposed algorithm achieve better performance in encoding time saving with ignorable PSNR degradation and a Litter bit rate saving, compare to the exist mode decision algorithms.