Category Archives: Compression

Article accepted into IEEE TCSVT

Our article about side information effectiveness in distributed video coding has been accepted in IEEE Transactions on Circuits and Systems for Video Technology.

The abstract follows:

The rate-distortion performance of a distributed video coding system strongly depends on the characteristics of the side information. One could naively think that the best side information is the one with the largest PSNR with respect to the original corresponding image. However, previous works have shown that this is not always the case and a reduction of the side information MSE does not always translate into better rate-distortion performance for the complete system. The scope of this paper is to explore a set of metrics other than the PSNR and explicitly designed to classify the side information with respect to its impact on the end-to-end compression performance. A first contribution is to define an experimental framework that can be used to meaningfully compare different metrics for side information evaluation. As a second contribution, our analysis allows to understand why in some cases PSNR-based metrics provide a fairly reliable estimation of the side information quality, while in other cases they do not. This analysis also allows us to introduce a set of new metrics that are better adapted for side information effectiveness evaluation, and that are based on a suitable power of the absolute difference between side information and the original image, or on the Hamming distance between the respective transform coefficients. Besides their theoretical interest, these new metrics can also improve the rate-distortion performance of some distributed video coding systems such as the hash-based ones. We observe improvement up to 74 % rate reduction in a simple study case.

Thèse : compression et streaming vidéo multivues

Three-years contract to achieve a PhD degree.
The topic is the problem of interactive streaming of multiview video.
Multiview video is composed of several video sequences, each corresponding to a different point of view. Interactive acces to this video requires switches from one view to another. This is problematic from the point of view of predictive coding: making prediction from one image to a second one belonging to another view is complex (all inter-view dependencies should be taken into account); independent coding is not effective. Possible solutions are based on distributed video coding.

Links: Paper on IMVS + DVC.

See also papers by G. Cheung.