An Efficient Motion Vector Composition Scheme for Arbitrary Frame Down-Sampling Video Transcoder

A new motion vector composition scheme, which we call spatial dominant vector selection (SDVS), for arbitrary down-sampling of precoded video using cascaded pixel domain transcoder is presented. The SDVS uses the existing relationship between pixels of a frame and its reference frame(s) via motion vectors and selects a dominant motion vector from a set of candidate vectors to minimize prediction errors. Compared with the existing methods, experimental results show performance gain, in terms of both quality and bit rate, with reduced computation. We also propose a refinement method that adaptively adjusts the search range to further improve the performance at marginal cost