Patent ID: 7031387

Claim:
A B picture mode determining method of a video coding system comprising the steps of: setting SAD initial values of each mode in consideration of an overhead bit of a 4×4 and 16×16 intra prediction mode, a forward prediction mode, a backward prediction mode, a bi-directional prediction mode and a direct prediction mode; calculating SAD values of each mode on the basis of the set SAD initial values; and selecting a mode having the smallest SAD value among the SAD values of each mode as a macro block prediction mode for a B picture coding, wherein the SAD initial value of the 4×4 intra prediction mode is defined as QP 0 (QP)×Order_of_prediction_mode+24×QP 0 (QP) the Order_of_prediction_mode a probability order that determines the 4×4 intra prediction mode according to a mode of a neighboring block.