Sub-pixel motion compensation interpolation filter in AVS [video coding]

In order to reduce the bit rate of video signals, motion compensation prediction is applied in modern video coding technology. This is a form of temporal redundancy reduction in which the current coding frame is predicted by a motion compensated prediction from some other already decoded frames according to a motion vector. As real motion has arbitrary precision, many video coding standards allow motion vectors to have "sub-pixel" resolution. The 1/4-pel displacement vector resolution is a part of AVS (audio video system). In order to estimate and compensate 1/4-pel displacements, the image signal on sub-pel position has to be generated by interpolation. This paper introduces a new 1/4-pel interpolation method, named as two steps four taps interpolation (TSFT). Compared with the 1/4-pel interpolation method of H.264, 11% spatial complexity is reduced, computation complexity is about the same, and a little more average SNR is gained.