Scalable MPEG video coding with improved B-frame prediction

Recently, there is a great interest in video codecs that implement the functionality of spatial scalability. Unfortunately, those MPEG-2 and MPEG-4 coders which exhibit such a functionality produce much more bits than corresponding single layer coders. This bitrate overhead can be reduced by application of spatio-temporal scalability as proposed by the authors. The base layer bitstream corresponds to pictures with reduced both spatial and temporal resolution while the enhancement layer bitstream is used to transmit the information needed to retrieve images with full spatial and temporal resolution. Full compatibility with the MPEG standards is ensured in the base layer where temporal resolution reduction is obtained by B-frame data partitioning, i.e. by placing each second frame (B-frame) in the enhancement layer only. Improved prediction of B-frames in the enhancement layer is proposed in this paper. The idea is to combine temporal forward and backward prediction with spatial interpolation. Experimental results prove a clear improvement of the MPEG-2-compatible scalable coding efficiency for the scheme proposed.