Patent ID: 7149250

Claim:
A method for encoding a sequence of video data according to a process in which several types of data are identified, said data consisting of so-called Video Object Planes (VOPs) that are either intra coded VOPs (I-VOPs), coded using information only from themselves, or predictive coded VOPs (P-VOPs), coded using a motion compensated prediction from a past reference VOP, or bidirectionally predicted VOPs (B-VOPs), coded using a motion-compensated prediction from past and future reference VOPs, said encoding method including a coding step of each VOP and, before said coding step, a motion estimation step performed between the current VOP and the previous one, said motion estimation step itself comprising a decision process concerning the type of VOP to be coded and based on the sub-steps of: carrying out a motion estimation between a VOP number N (VOP N) and the previous one (VOP N- 1 ); on the basis of said motion estimation, computing a so-called coherence factor, provided for quantifying the sequence motion; on the basis of a comparison of said coherence factor with a predetermined threshold, taking a final decision on the type of the current VOP, said current VOP being a B-VOP or not according to the value of said coherence factor with respect to said threshold.