Fast Rate Distortion Optimized Quantization Method Based on Early Detection of Zero Block for HEVC

This paper presents an efficient zero block early detection method to accelerate Rate Distortion Optimized Quantization (RDOQ) for High Efficiency Video Coding (HEVC). RDOQ brings significant improvement of coding performance, but it results in high computational complexity to determine the best quantization levels with rate and distortion optimization operations. It is worthwhile to detect all-zero-quantized blocks before RDOQ since a lot of transform units are zero blocks after RDOQ process. In this paper, we analyze the transform coefficients characteristics in zero blocks firstly. And then, the relationship among the zero block detection thresholds, transform unit sizes and quantization parameters is studied. An adaptive zero block detection model is designed to speed up RDOQ process. Experimental results show that the proposed method achieves 44.10% and 41.68% quantization time saving with only average 0.16% and 0.01% BD-Rate loss under random access and low delay configuration, respectively.