Fast motion estimation for real-time shape-adaptive MPEG-4 encoding

This paper presents a fast motion estimator which can be used for real-time MPEG-4 encoding of arbitrarily shaped video objects. The approach is based on an existing algorithm which has already been applied successfully to format conversion. To exploit it for shape-adaptive coding, the algorithm has been adapted to the special properties of the MPEG-4 standard. With this new tool it becomes possible to encode arbitrarily shaped video objects (CIF, 25 Hz) in real-time with a MPEG-4 software encoder at a Pentium III 500 MHz. The real-time capability has to be paid by a slight loss of coding efficiency (about 0.2 dB in terms of rate-distortion measurements), compared to the MPEG-4 verification model.