Research On Perceptual-based Coding Mode Decision For Distributed Video Coding

Distributed video coding(DVC)exploits inter-frame correlations at the decoder side,thus keeping a low encoder complexity.This characteristic makes DVC suitable for wireless video applications which have limited computational capability and power supply.Determing the coding mode before encoding a frame can better adapt to the spatial quality variationof the predicted frame(Side Information)and help to improve the coding performance.Because the final receivers of video sequences are human eyes,this paper focuses on performing coding mode decision from the perceptual point of view.The main contributions of this paper are as follows:First,this paper proposes a low-delay encoder-side perceptual-based coding mode decision sheme.The proposed technique avoids using motion vectors which are obtained through intensive computation in the coding mode decision process.In this way,the encoder delay is significantly reduced.To better capture the visually sensitive distorted regions,this paper introduces a Gaussian filter and performs skin information analysis to give the distortions of distortion-sensitive regions more attention.Moreover,to eliminate the decoding delay caused by repeated channel decoding,this paper exploits intra coding technique to deal with the visually distorted macroblocks.Experimental results show that the proposed techniques can reduce the encoding delay caused by coding mode decision process from at least1.1?10~5 ms to at most 12ms.When the side information generation time is not included,the decoding delay can be reduced from 12s to 1ms.Though the rate-distortion performance of the proposed codec is on average 0.16dB lower than the state-of-the-art perceptual-based DVC codec,the perceptual quality of the decoded video sequence is much better.Second,this paper proposes a low-delay decoder-side perceptual-based coding mode decision scheme.The proposed decoder-side perceptual-based coding mode decision method integrates a side information estimation technique.By doing this,the proposed coding mode decision method can further improve the coding performance by dynamically changing the decision parameters.Moreover,this paper periodically introduces macroblock-based skip mode to the key frames which are used to generate side information.In this way,a new group of pictures(GOP)structure which can better remove the residue between frames is realized.Experimental results show that the codec can further improve the coding performance while keeping a low encoding and decoding delay.Compared with the state-of-the-art perceptual-based DVC codec,the average rate-distortion performance improves by 1.1dB.When compared with the famous DISCOVER DVC codec,the average rate-distortion performance improves by1.8dB.In addition,the perceptual quality of decoded video sequences is also significantly improved.