When a block (MB22) of which motion vector is referred to in the direct mode contains a plurality of motion vectors, 2 motion vectors MV23 and MV24, which are used for inter picture prediction of a current picture (P23) to be coded, are determined by scaling a value obtained from averaging the plurality...http://www.google.fr/patents/US7733960?utm_source=gb-gplus-shareBrevet US7733960 - Motion vector calculation method
