混合视频编码标准由于采用基于块的运动补偿预测和变换量化,从而使解码图像在块边界产生干扰视觉的不连续性,尤其在低码率下,易形成块效应。由于滤波法、凸集投影法、交叠正交变换等可作为信号处理中去除块效应的技术方案,为此在对视频编码的系统结构进行分析的基础上,实现了基于交叠正交变换时间域预滤波和后置滤波的去块效应视频混合编码方案,并讨论了实现这一方案的框架结构和交叠模式选择等关键技术问题,最后给出了实验结果,对比实验结果显示,该方案在提供相当的编码性能基础上,能有效地改善视频图像的块效应现象。

The visual disturbing discontinuities at the block boundaries, which are called block artifacts,might arise in the reconstructed pictures,especially in low bit-rate applications,because the block-based motion compensation prediction,transform and quantization are adopted in the hybrid video coding standards.A deblocking filter,projections onto convex sets,and lapped orthogonal transform behave as the candidate technologies for reducing the block effects in signal processing.This paper analyzes and integrates the systematic architecture of video coding,achieves a deblocking hybrid video coding framework on the basis of a lapped orthogonal transform with time-domain pre- and post-filtering,and discusses the key technology issues including overlap mode choice within the framework.The experimental outcomes are shown to improve the subjective quality of video pictures with a comparative rate-distortion performance,compared to the traditional framework.