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]

A fully scalable wavelet video coding scheme with homologous inter-scale prediction

In this paper, we present a fully scalable wavelet-based video coding architecture called STP-Tool, in which motion-compensated temporal-filtered subbands of spatially scaled versions of a video sequence can be used as a base layer for inter-scale predictions. These predictions take place in a pyramidal closed-loop structure between homologous resolution data, i.e., without the need of spatial interpolation. The presented implementation of the STP-Tool architecture is based on the reference software of the Wavelet Video Coding MPEG Ad-Hoc Group. The STP-Tool architecture makes it possible to compensate for some of the typical drawbacks of current wavelet-based scalable video coding architectures and shows interesting objective and visual results even when compared with other wavelet-based or MPEG-4 AVC/H.264-based scalable video coding systems

Fully Scalable Video Coding Using Redundant-Wavelet Multihypothesis and Motion-Compensated Temporal Filtering

In this dissertation, a fully scalable video coding system is proposed. This system achieves full temporal, resolution, and fidelity scalability by combining mesh-based motion-compensated temporal filtering, multihypothesis motion compensation, and an embedded 3D wavelet-coefficient coder. The first major contribution of this work is the introduction of the redundant-wavelet multihypothesis paradigm into motion-compensated temporal filtering, which is achieved by deploying temporal filtering in the domain of a spatially redundant wavelet transform. A regular triangle mesh is used to track motion between frames, and an affine transform between mesh triangles implements motion compensation within a lifting-based temporal transform. Experimental results reveal that the incorporation of redundant-wavelet multihypothesis into mesh-based motion-compensated temporal filtering significantly improves the rate-distortion performance of the scalable coder. The second major contribution is the introduction of a sliding-window implementation of motion-compensated temporal filtering such that video sequences of arbitrarily length may be temporally filtered using a finite-length frame buffer without suffering from severe degradation at buffer boundaries. Finally, as a third major contribution, a novel 3D coder is designed for the coding of the 3D volume of coefficients resulting from the redundant-wavelet based temporal filtering. This coder employs an explicit estimate of the probability of coefficient significance to drive a nonadaptive arithmetic coder, resulting in a simple software implementation. Additionally, the coder offers the possibility of a high degree of vectorization particularly well suited to the data-parallel capabilities of modern general-purpose processors or customized hardware. Results show that the proposed coder yields nearly the same rate-distortion performance as a more complicated coefficient coder considered to be state of the art

A Fully Scalable Video Coder with Inter-Scale Wavelet Prediction and Morphological Coding

In this paper a new fully scalable - wavelet based - video coding architecture is proposed, where motion compensated temporal filtered subbands of spatially scaled versions of a video sequence can be used as base layer for inter-scale predictions. These predictions take place between data at the same resolution level without the need of interpolation. The prediction residuals are further transformed by spatial wavelet decompositions. The resulting multi-scale spatiotemporal wavelet subbands are coded thanks to an embedded morphological dilation technique and context based arithmetic coding. Dyadic spatio-temporal scalability and progressive SNR scalability are achieved. Multiple adaptation decoding can be easily implemented without the need of knowing a predefined set of operating points. The proposed coding system allows to compensate some of the typical drawbacks of current wavelet based scalable video coding architectures and shows interesting visual results even when compared with the single operating point video coding standard AVC/H.264

State-of-the-Art and Trends in Scalable Video Compression with Wavelet Based Approaches

3noScalable Video Coding (SVC) differs form traditional single point approaches mainly because it allows to encode in a unique bit stream several working points corresponding to different quality, picture size and frame rate. This work describes the current state-of-the-art in SVC, focusing on wavelet based motion-compensated approaches (WSVC). It reviews individual components that have been designed to address the problem over the years and how such components are typically combined to achieve meaningful WSVC architectures. Coding schemes which mainly differ from the space-time order in which the wavelet transforms operate are here compared, discussing strengths and weaknesses of the resulting implementations. An evaluation of the achievable coding performances is provided considering the reference architectures studied and developed by ISO/MPEG in its exploration on WSVC. The paper also attempts to draw a list of major differences between wavelet based solutions and the SVC standard jointly targeted by ITU and ISO/MPEG. A major emphasis is devoted to a promising WSVC solution, named STP-tool, which presents architectural similarities with respect to the SVC standard. The paper ends drawing some evolution trends for WSVC systems and giving insights on video coding applications which could benefit by a wavelet based approach.partially_openpartially_openADAMI N; SIGNORONI. A; R. LEONARDIAdami, Nicola; Signoroni, Alberto; Leonardi, Riccard

Motion estimation and signaling techniques for 2D+t scalable video coding

We describe a fully scalable wavelet-based 2D+t (in-band) video coding architecture. We propose new coding tools specifically designed for this framework aimed at two goals: reduce the computational complexity at the encoder without sacrificing compression; improve the coding efficiency, especially at low bitrates. To this end, we focus our attention on motion estimation and motion vector encoding. We propose a fast motion estimation algorithm that works in the wavelet domain and exploits the geometrical properties of the wavelet subbands. We show that the computational complexity grows linearly with the size of the search window, yet approaching the performance of a full search strategy. We extend the proposed motion estimation algorithm to work with blocks of variable sizes, in order to better capture local motion characteristics, thus improving in terms of rate-distortion behavior. Given this motion field representation, we propose a motion vector coding algorithm that allows to adaptively scale the motion bit budget according to the target bitrate, improving the coding efficiency at low bitrates. Finally, we show how to optimally scale the motion field when the sequence is decoded at reduced spatial resolution. Experimental results illustrate the advantages of each individual coding tool presented in this paper. Based on these simulations, we define the best configuration of coding parameters and we compare the proposed codec with MC-EZBC, a widely used reference codec implementing the t+2D framework

MASCOT : metadata for advanced scalable video coding tools : final report

The goal of the MASCOT project was to develop new video coding schemes and tools that provide both an increased coding efficiency as well as extended scalability features compared to technology that was available at the beginning of the project. Towards that goal the following tools would be used: - metadata-based coding tools; - new spatiotemporal decompositions; - new prediction schemes. Although the initial goal was to develop one single codec architecture that was able to combine all new coding tools that were foreseen when the project was formulated, it became clear that this would limit the selection of the new tools. Therefore the consortium decided to develop two codec frameworks within the project, a standard hybrid DCT-based codec and a 3D wavelet-based codec, which together are able to accommodate all tools developed during the course of the project