PREDICTION CODING METHOD, PREDICTION DECODING METHOD, PREDICTION CODER AND PREDICTION DECODER

摘要

PURPOSE:To improve the coding efficiency for a motion vector by making a difference among motion vectors smaller than that of a conventional device. CONSTITUTION:A delay circuit 41 delays a motion vector. A delay circuit 42 delays an identification bit. A vector correction circuit 43 multiplies the value of a motion vector delayed by the delay circuit 41 by 1/2 when an inter-frame mode is switched into an in-field mode based on an identification bit for a preceding/succeeding block and multiplies the motion vector by 2 when the inter-field mode is switched into the in-frame mode. An adder circuit 44 subtracts the motion vector corrected by the vector correction circuit 43 from the motion vector to be supplied. A variable length coding circuit 45 applies variable length coding to a difference from the motion vector from the adder circuit 44.