A fast motion vector composition method for temporal transcoding

When some incoming frames are dropped for the frame-rate conversion in transcoding, new motion vectors for outgoing bit-stream need to be computed. In this paper, we propose a fast motion vector composition method followed by motion vector refinement scheme to generate the outgoing motion vector from the incoming motion vectors instead of performing a full-scale motion estimation. The proposed method performs better and is simpler than the conventional bilinear interpolation. We also discuss a fast-search motion vector refinement scheme. The proposed fast-search motion vector refinement scheme provides video quality comparable to that achieved by performing a full-scale full-search motion estimation but with much less computations.