基于小波变换的Dirac视频编解码器分析

Analysis of the Dirac codec based on wavelet transform

Dirac视频编解码算法是BBC提出的一套方案,同时给出比特流语法及软件实现的开源代码且无专利。本文对其中关键技术进行分析:采用块交叠运动补偿和小波变换进行自适应算术编码的混合编解码方案。使用msu视频质量测试软件对Dirac和Snow及X264在低速运动、快速运动、混合运动情况下的图像质量分别进行了比较。实验结果表明,Dirac的图像质量最稳定,但存在赝像;X264在对象快速运动时质量较差;Snow质量居中。最后分析了Dirac目前存在的问题,进一步研究方向及应用前景。

The Dirac video codec is proposed by BBC R＆D with the supply of matched bitstream syntax and the opensource code, and it has no patent. This paper analyzes the key technologies of it, which includes a hybrid codec structure of overlapped block-based motion compensation, wavelet transform, and adaptive arithmetic coding. Meanwhile, use the msu video quality measurement tool to compare the video quality of Dirac with Snow and X264 under the circumstances of slow motion, fast motion and mixed motion objects. Experimental results show that the video quality of Dirac codec is the most stable one, but artifact exists; comparatively, X264 performs worse on fast motion objects; Snow places in the middle. In conclusion, the problems Dirac faced, the further research direction, and application ProsPect are analyzed in detail.