Institut d'Électronique et de Télécommunications de Rennes
UMR CNRS 6164

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Soutenance de thèse

Adrià ARRUFAT soutient sa thèse intitulée :

Multiple transforms for video coding

La soutenance aura lieu le vendredi 11 Décembre 2015 à 10:00, en amphi Bonnin (bâtiment 5) à l’INSA de Rennes.

Abstract :

State of the art video codecs use transforms to ensure a compact signal representation. The transform stage is where compression takes place, however, little variety is observed in the type of transforms used for standardised video coding schemes : often, a single transform is considered, usually a Discrete Cosine Transform (DCT). Recently, other transforms have started being considered in addition to the DCT. For instance, in the latest video coding standard, High Efficiency Video Coding (HEVC), the 4x4 sized blocks can make use of the Discrete Sine Transform (DST) and, in addition, it also possible not to transform them. This fact reveals an increasing interest to consider a plurality of transforms to achieve higher compression rates. This thesis focuses on extending HEVC through the use of multiple transforms.

A coding scheme that incorporates and boosts the use of multiple transforms is introduced : several transforms are made available to the encoder, which chooses the one that provides the best rate-distortion trade-off. Consequently, a design method for building systems using multiple transforms is also described. With this coding scheme, significant amounts of bit- rate savings are achieved over HEVC, especially when using many complex transforms. However, these improvements come at the expense of increased complexity in terms of coding, decoding and storage requirements. As a result, simplifications are considered while limiting the impact on bit-rate savings.






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