Content Adaptive Wyner-ZIV Video Coding Driven by Motion Activity

In distributed video coding (DVC), the video statistics are exploited, partially or totally at the decoder. A particular case of DVC, Wyner-Ziv video coding deals with lossy source coding with side information at the decoder and allows moving part or the entire motion estimation task to the decoder. In this context, it is the decoder responsibility to obtain the side information, a guess of the encoded Wyner-Ziv frame and the encoder only sends parity bits to improve its quality. In this paper, a technique targeting the improvement of the quality of the side information, and thus of the rate-distortion performance of the Wyner-Ziv codec is proposed. This is achieved by adaptively adjusting the size of the motion interpolation structure (or GOP length) according to the motion activity along the sequence. Experimentally, this allows to achieve gains up to 0.8 dB without performing any motion estimation or complex mode decision at the encoder.