Title :
Rate-Distortion Analysis of Motion-Compensated Interpolation at the Decoder in Distributed Video Coding
Author :
Tagliasacchi, Marco ; Frigerio, Laura ; Tubaro, Stefano
Author_Institution :
Politecnico di Milano, Milan
Abstract :
This letter analyzes the coding efficiency of distributed video coding (DVC) schemes that perform motion-compensated interpolation at the decoder. The decoder has access only to the key frames, when generating the side information for intermediate frames. Therefore, the true motion field necessary for this operation is not directly available, and the motion vectors must be estimated at the decoder side, thus introducing displacement estimation errors. The accuracy of the motion-compensated interpolation at the decoder depends on several factors: 1, the overall motion complexity; 2, the temporal coherence of the motion field; and 3, the temporal distance between successive key frames. Adopting a state-space model and a Kalman filtering framework, we obtain an estimate of the displacement error variance. This is used to determine the rate-distortion function of the overall coding scheme, that takes into account both intra-coded key frames and DVC-coded frames. The proposed model shows that motion-compensated interpolation is unable to achieve the coding efficiency of conventional motion-compensated predictive coding. In addition, the model provides a good estimate of the group of pictures size that optimizes the coding efficiency. Experimental results on real video sequences validate the results of the proposed model.
Keywords :
Kalman filters; computational complexity; decoding; interpolation; motion compensation; rate distortion theory; state-space methods; video coding; DVC-coded frames; Kalman filtering framework; decoder; displacement error variance; displacement estimation errors; distributed video coding; intra-coded key frames; motion complexity; motion field temporal coherence; motion vectors; motion-compensated interpolation; rate-distortion analysis; state-space model; video sequences; Coherence; Decoding; Estimation error; Interpolation; Kalman filters; Motion analysis; Motion estimation; Performance analysis; Rate-distortion; Video coding; Distributed video coding; motion analysis; video coding;
Journal_Title :
Signal Processing Letters, IEEE
DOI :
10.1109/LSP.2007.896187