Spatio-temporal scalability for MPEG video coding

The existing and standardized solutions for spatial scalability are not sat isfactory, therefore new approaches are very actively explored recently. Th e goal of this paper is to improve spatial scalability of MPEG-2 for progre ssive video. In order to avoid problems with too large bitstreams of the ba se layer produced by some of the hitherto proposed spatially scalable coder s, spatio-temporal scalability is proposed for video compression systems. I t is assumed that a coder produces two bitstreams, where the base-layer bit stream corresponds to pictures with reduced both spatial and temporal resol ution while the enhancement layer bitstream is used to transmit the informa tion needed to retrieve images with full spatial and temporal resolution, I n the base layer, temporal resolution reduction is obtained by B-frame data partitioning, i.e., by placing each second frame (B-frame) in the enhancem ent layer, Subband (wavelet) analysis is used to provide spatial decomposit ion of the signal. Full compatibility with the MPEG-2 standard is ensured i n the base layer. As compared to single-layer MPEG-2 encoding at bit rates below 6 Mbits/s, the bitrate overhead for scalability is less than 15% in m ost cases.