SADWT for efficient mesh based video coding

The application of SADWT (shape adaptive discrete wavelet transform) has been widely proposed for object-oriented video coding, making it possible to transform and code the arbitrarily-shaped regions obtained by a segmentation of the scene content (which are usually objects in the sense of being a visually observable part of the image context). We present an application which is not restricted to objects but is meant to deal with any kind of region that is desired to be treated in a special way according to the coding objectives. Hereby, the main idea is to achieve a more efficient use of the available bits on areas with high prediction error (important for very low bit-rate coding) or skin-coloured areas (important for video telephony or conferencing). The coding of these areas can be independent, i.e. without taking into account the rest of the image, or could be controlled by multi-object bit distribution algorithms. Promising results for subjective quality tests have already been obtained at fixed bit rates with fixed and variable allocation strategies and our 2D irregular mesh based video coder, as well as for very-low bit-rate coding.