Exact threshold for zero-block detection in H.264/AVC

The motion search algorithm based on zero-block detection was successfully used in H.263, H.26L etc to accelerate the speed of video coding. H.264/AVC is also a video coding scheme based on motion estimation and prediction, so the motion search method based on zero-block detection will also be effective to speed up its video coding. The key of such method is to select the exact threshold for the zero-block detection so as to improve the speed of video coding with neither causing too much decreasing of picture quality nor causing too much increasing of bit-rate in the mean time. Considering the threshold for zero-block detection in H.264/AVC having been proposed was not yet the exact one, the authors analyzed the upper limit of threshold theoretically and gave the range of threshold for the zero-block detection in H.264/AVC, and then deduced the exact threshold for 4×4 luminance block¿s zero-block detection. Experimental results show that in the module of 4×4 luminance block¿s transform and quantization, the exact threshold has the same PSNR and bit-rate as that of without zero-block detection in any case.