This study presents a rate-distortion (RD) optimised quantisation algorithm for direct current (DC) coefficients of the Wyner-Ziv (WZ) frames in unidirectional distributed video coding. As the side information (SI) co...
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This study presents a rate-distortion (RD) optimised quantisation algorithm for direct current (DC) coefficients of the Wyner-Ziv (WZ) frames in unidirectional distributed video coding. As the side information (SI) could be viewed as a 'corrupted' version of the original WZ frame, the correlation noise (WZ-SI) can be interpreted as a virtual channel with an error pattern. In this study, the distortion caused by virtual channel errors, besides quantisation errors, is analysed emphatically for unidirectional WZ videocoding. In their presented quantisation algorithm, a novel RD model is developed to find out the optimal quantisation step size, in which the quantisation distortion and virtual channel error distortion together with the encoding rate are formulated using the quantisation step size without feedback channels. Then the RD optimal step size for DC coefficients can be solved through minimising the RD cost. In simulations, the comparison of RD performance between their proposed algorithm and the quantisation method used in distributedcoding for video services (DISCOVER) is presented. Experimental results show that the proposed RD optimised quantisation for DC coefficients can improve the average peak signal-to-noise ratio of WZ frames by 0.4-1.2 dB for quarter common intermediate format (QCIF) sequences and 0.2-0.4 dB for common intermediate format (CIF), at the expense of increasing the encoding complexity slightly.
Typical distributedvideocoding architecture always controls rate at the decoder via a feedback channel, which is not realistic in application. In order to remove the feedback channel, an efficient encoder rate contr...
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ISBN:
(纸本)9780819497215
Typical distributedvideocoding architecture always controls rate at the decoder via a feedback channel, which is not realistic in application. In order to remove the feedback channel, an efficient encoder rate control method is proposed for unidirectional distributed video coding in this paper. First a low-complexity motion estimation method is proposed to create estimated side information at the encoder, in which the motion consistency between frames is utilized to reduce the search range and obtain accurate motion vectors. Then the conditional entropy of each bitplane is computed based on the inter-bitplane correlation, which is further curve-fitted as the estimated rate. Experimental results show that our proposed encoder rate control method could estimate the required rate accurately with much lower complexity.
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