New prediction schemes for scalable wavelet video coding

A Scalable Video Coder (SVC) can be conceived according to different kinds of spatio-temporal decomposition structures which can be designed to produce a multiresolution spatio-temporal subband hierarchy which is then coded with a progressive or quality scalable coding technique [1-5]. A classification of SVC architectures has been suggested by the MPEG Ad-Hoc Group on SVC [6]. The so called t+2D schemes (one example is [2]) performs first an MCTF, producing temporal subband frames, then the spatial DWT is applied on each one of these frames. Alternatively, in a 2D+t scheme (one example is [7]), a spatial DWT is applied first to each video frame and then MCTF is made on spatial subbands. A third approach named 2D+t+2D uses a first stage DWT to produce reference video sequences at various resolutions; t+2D transforms are then performed on each resolution level of the obtained spatial pyramid. Each scheme has evidenced its pros and cons [8,9] in terms of coding performance. From a theoretical point of view, the critical aspects of the above SVC scheme mainly reside: i) in the coherence and trustworthiness of the motion estimation at various scales (especially for t+2D schemes); ii) in the difficulties to compensate for the shift-variant nature of the wavelet transform (especially for 2D+t schemes); iii) in the performance of inter-scale prediction (ISP) mechanisms (especially for 2D+t+2D schemes). In this document we recall the STool scheme principles, already presented in [10]. We present an STool SVC architecture and compare it with respect other SVC schemes. Some main advancements and new solutions are detailed and the related results presented. Our software implementations are based on the VidWav reference software [11,12].