主要论述了在H.264或者AVS(信息技术先进音视频编码系列标准)到MPEG-2转码过程中的QP(quantization parameter)映射问题。通过分析理论无失真的映射曲线(以下简称理论曲线)的数据保真和码率特性,发现了理论曲线和实际应用(高质量视频应用,有限带宽网络视频传输,质量自适应调整的视频点播)的不适应之处,基于对上述不同应用的具体分析,得到了一系列对应于应用的QP映射曲线,可以很好地满足相对应的应用要求。同时提出了利用这些H.264/AVS到MPEG-2转码过程中的QP映射曲线的几点建议。

This paper presents the issue of QP mapping in H.264 or AVS to MPEG-2 transcoding process. The theoretic QP mapping curve is deduced by analysis of H.264/AVS and MPEG-2 quantization schemes. Then, the mismatching between the theoretic curve and practical application is found. Based on the requirements of different applications, such as high fidelity video application, video transmission on limited bandwidth networks and video on demand with adaptive quality adjustment, a series of QP mapping curves is obtained by experiments and analysis. These curves are customized for predefined parameters, and they can be easily modified to meet specific applications.