IP电视中的视频转码技术

为了使带宽不同的用户能通过互联网观看数字电视节目,提出了一种将卫星数字电视网络直播的IP(in ternetprotoco l)电视应用方案,采用运动矢量重估计技术来实现M PEG(m ov ing p icture experts group)-2视频到低码率的M PEG-4视频的实时转换,从而避免用户带宽的限制。提出了一种运动重估计算法,通过建立运动矢量反向查找表,利用相似宏块重叠面积来优化候选运动矢量的搜索过程,用帧内相邻宏块运动矢量进行估计等方法,显著提高视频转码效率并保证质量。实验结果表明:在视频转码过程中,与采用PM V fast(pred ictive m otion vector fie ld adaptive searchtechn ique)搜索算法相比,该算法能节省40%左右的编码时间,而峰值信噪比降低不足0.3 dB,显著提高了转码效率。

Video transcoding technology in IPTV applications

An IPTV(internet protocol TV) application scheme was developed to broadcast DVBS(digital video broadcasting-satellite) video live to users with different internet bandwidths.Motion re-estimation was used to transcode MPEG(moving picture experts group)-2 video to lower bitrate MPEG-4 video real time to avoid bandwidth limits.The motion re-estimation algorithm builds an inverse MV(motion vector) lookup table using the overlap area to speed up the MV search and estimates the MV based on the neighbor macroblock's MV.The algorithm efficiently improves the transcoding while maintaining video quality.Simulations show that the video transcoding process uses 40% less encoding time than the PMVfast(predictive motion vector field adaptive search technique) algorithm with the PSNR(peak signal-to-noise ratio) reduced by less than(0.3 dB.)