THE EFFECT OF MOTION VECTOR TRUNCATION ON SPATIALLY SCALABLE WAVELET BASED VIDEO CODERS

In this paper we describe how to properly handle motion vectors in spatially scalable wavelet based video coders. When a lower resolution version of the original sequence is received, the decoder has to scale the motion vectors accordingly. We demonstrate that motion vector truncation is not the right choice and that better results can be obtained by interpolating the subsampled sequence to full resolution by means of the wavelet synthesis low-pass filter. We illustrate the results of experiments carried out with an in-band wavelet based fully scalable coder that performs spatial analysis followed by temporal filtering. Emphasis is given to the computation of the Overcomplete DWT in the spatially scalable scenario. 1