Transform Domain Wyner-Ziv Video Research Articles

Evaluating a feedback channel based transform domain Wyner–Ziv video codec

Wyner–Ziv (WZ) video coding—a particular case of distributed video coding (DVC)—is a new video coding paradigm based on two major Information Theory results: the Slepian–Wolf and Wyner–Ziv theorems. In recent years, some practical WZ video coding solutions have been proposed with promising results. One of the most popular WZ video coding architectures in the literature uses turbo codes based Slepian–Wolf coding and a feedback channel to perform rate control at the decoder. This WZ video coding architecture has been first proposed by researchers at Stanford University and has been after adopted and improved by many research groups around the world. However, while there are many papers published with changes and improvements to this architecture, the precise and detailed evaluation of its performance, targeting its deep understanding for future advances, has not been made. Available performance results are mostly partial, under unclear and incompatible conditions, using vaguely defined and also sometimes architecturally unrealistic codec solutions. This paper targets the provision of a detailed, clear, and complete performance evaluation of an advanced transform domain WZ video codec derived from the Stanford turbo coding and feedback channel based architecture. Although the WZ video codec proposed for this evaluation is among the best available, the main purpose and novelty of this paper is the solid and comprehensive performance evaluation made which will provide a strong, and very much needed, performance reference for researchers in this WZ video coding field, as well as a solid way to steer future WZ video coding research.

High-rate quantization and transform coding with side information at the decoder

We extend high-rate quantization theory to Wyner–Ziv coding, i.e., lossy source coding with side information at the decoder. Ideal Slepian–Wolf coders are assumed, thus rates are conditional entropies of quantization indices given the side information. This theory is applied to the analysis of orthonormal block transforms for Wyner–Ziv coding. A formula for the optimal rate allocation and an approximation to the optimal transform are derived. The case of noisy high-rate quantization and transform coding is included in our study, in which a noisy observation of source data is available at the encoder, but we are interested in estimating the unseen data at the decoder, with the help of side information. We implement a transform-domain Wyner–Ziv video coder that encodes frames independently but decodes them conditionally. Experimental results show that using the discrete cosine transform results in a rate-distortion improvement with respect to the pixel-domain coder. Transform coders of noisy images for different communication constraints are compared. Experimental results show that the noisy Wyner–Ziv transform coder achieves a performance close to the case in which the side information is also available at the encoder.