Research On Rate Control Of Feedback-free Distributed Video Coding

With the rapid development of information technology such as mobile communication and wireless network,there have been many video application scenarios with limited coding resources,and new requirements have been put forward for the video coding scheme.The traditional video coding scheme can not meet the requirements of the new video application scenarios because of its high coding complexity.Distributed video coding scheme can meet the requirements of the video application scenarios with limited coding resources and has been widely concerned because of its low coding complexity,high compression efficiency and strong robustness.Distributed video coding scheme can be divided into feedback distributed video coding scheme and feedback-free distributed video coding scheme according to the existence of feedback channel.The rate control scheme can be divided into decoder rate control scheme and encoder rate control scheme.The former sends feedback information to the encoder to control the rate and can allocate rate accurately,but on the other hand,the delay is too high,besides the feedback channel will bring a lot of problems such as the high cost of hardware.The latter control the rate at the encoder,and the feedback channel is not necessary in this way.So the encoder rate control scheme has a great advantage over decoder rate control scheme.But the encoder rate control scheme has to estimate how many rate is needed before allocating rate,and because of the only one chance of allocating rate,the encoder has to estimate rate accurately,the complexity of the encoder will increase accordingly,and will influence compression performance.To solve these problems,this paper propose a high reconstruction quality feedback-free distributed video coding scheme.The work is divided into the following three parts: 1)A hierarchical fast block motion estimation algorithm is proposed to generate the low complexity side information at the encoder,the complexity of the estimation of the side information is reduced and the quality of the estimation of the side information is improved.2)A hybrid coding mode selection algorithm which combine the frame coding mode selection algorithm with the block coding mode selection algorithm is proposed to reduce the complexity of the encoder and reduce the rate which is needed at the decoder.3)A rate estimation algorithm is proposed,in the rate estimation algorithm,the rate is estimated by the theoretical formula and add the additional rate which is based on the lookup table to improve the accuracy of the rate estimation.Because of the diversity of the video sequence and the characteristics of the lookup table,The rate estimated by the theoretical formula is weighted to reduce the probability of the under estimation of the rate and improve the decoding quality.Experiments show that the proposed scheme can improve the rate distortion performance of the DVC system effectively.