Patent ID: 8009736

Claim:
A storage device storing a coded video signal created by a method, comprising: interpolating motion vectors for a pixelblock in a current frame, the pixelblock to be coded according to bi-directional prediction with reference to a pair of reference frames in the sequence, wherein the interpolation includes, for at least one motion vector: generating a scale factor (Z) based on a ratio of time differences (Δ 1 /Δ 2 ) among the current frame and the pair of reference frames, the first time difference (Δt 1 ) representing a temporal difference between the current frame and a first of the reference frame and the second time difference (Δt 2 ) representing a temporal difference between the two reference frames, the scale factor representing the ratio multiplied by a power of two (Z=2 N *(Δt 1 /Δt 2 )) subject to rounding, generating a first motion vector for the pixelblock (mv PB1 ) according to a first derivation based on a motion vector extending between the reference frames (mv REF ), the first derivation being mv PB1 =mv REF *Z/2 N , generating a second motion vector for the pixelblock (mv PB2 ) based on a second derivation mv REF , predicting video data for the pixelblock from video data of the first and second reference frames according to the generated motion vectors mv PB1 and mv PB2 , coding a difference between actual video data of the pixelblock and predicted video data of the pixel block, and outputting the coded difference to a channel as coded video data of the pixelblock.