Method of adaptive interpolation filtering in video coding

An apparatus for motion compensation with fractional pixel accuracy in a video coding system, the apparatus comprising one or more electronic circuits configured to:

• receive input data associated with one or more current blocks in a current picture;
• determine one or more current MVs (motion vectors) associated with said one or more current blocks;
• locate one or more reference blocks in a reference picture according to said one or more current MVs;
• and
• for each of said one or more current MVs corresponding to a fractional-pixel location:
• generate interpolated reference samples at non-integer locations based on existing reference samples in one reference block by using an interpolation filter set adaptively according to at least one of pixel location or pixel characteristics, wherein the interpolation filter set comprises a longer-tap filter and a shorter-tap filter, wherein the longer-tap filter is configured to generate a first interpolated reference sample, the shorter-tap filter is configured to generate a second interpolated reference sample, and the first interpolated reference sample is farther from a related block boundary than the second interpolated reference sample, wherein the shorter-tap filter is applied to generate the interpolated reference samples in an overlapped area between said two adjacent blocks, and wherein the block boundary separates reference pixels from current pixels in a current block among the one or more current blocks;
• and
• encode or decode one current block using a temporal predictor including the interpolated reference samples.