Decoder-side hierarchical motion estimation for dense vector fields

Current video coding standards perform motion estimation at the encoder to predict frames prior to coding them. Since the decoder does not possess the source frames, the estimated motion vectors have to be transmitted as additional side information. Recent research revealed that the data rate can be reduced by performing an additional motion estimation at the decoder. As only already decoded data is used, no additional data has to be transmitted. This paper addresses an improved hierarchical motion estimation algorithm to be used in a decoder-side motion estimation system. A special motion vector latching is used to be more robust for very small block sizes and to better adapt to object borders. With this technique, a dense motion vector field is estimated which reduces the rate by 6.9% in average compared to H.264 / AVC at the same quality.