基于非抽样小波字典的低速率视频编码

目前,大多数视频编码器所采用的核心编码技术都是基于分块DCT(discreted cosine transform)变换对帧预测误差进行编码,在极低编码速率下,这类编码器往往会产生人眼敏感的方块效应.而基于匹配跟踪冗余信号分解的视频编码器具有比H.263编码器更高的编码性能,但由于该算法需要在一个冗余字典里搜索最佳匹配误差结构的原子函数,其实现所需要的运算量比传统的编码器要高很多,因此影响了这种编码器的效率.提出了基于树形结构的非抽样小波字典的匹配跟踪算法,能够充分利用字典函数之间存在的滤波结构关系,使得整个算法实现的计算量显著下降.同时,考虑到相邻帧运动信息的连续性,最后还给出一种基于晶格结构的有效原子位置信息编码方法.实验结果表明,该算法保持了原有的编码性能,在视频编码应用中具有很好的实用价值.

Low Bit-Rate Video Coding Based on Undecimated Wavelet Dictionary

Currently, the core techniques of most video coders are based on blocked DCT (discreted cosine transform) transform. At very low bit-rates, video coders of this class always produce visual-sensible block artifacts. Recently, the video coders based on matching pursuit have been proved to have super coding efficiency, compared with the H.263 standard. However, the computation complexity is much too higher, because of laboriously searching optimal atoms in a redundant dictionary. A video coding algorithm based on undecimated wavelet dictionary is proposed, which incorporates multiresolution characteristics of the wavelet transform and assorts to filter the scheme between dictionary functions, to reduce the computation complexity of the original algorithm greatly. Considering the continuity of motion information in the neighboring frames, an entropy coding method of atom position based on a hygrid structure is given. The experimental results show that this algorithm keeps the original coding results and has the desirable application value.