METHOD AND APPARATUS FOR ENCODING AND DECODING MOTION VECTOR

The present invention relates to a method for encoding/decoding a motion vector and an apparatus thereof, and comprises the steps of: selecting a candidate motion vector set for a current motion vector, selecting a prediction motion vector from the candidate motion vector set, and judging whether or not the prediction motion vector is predictable in a decoding apparatus. If the prediction motion vector is predictable, the current motion vector is encoded using a motion vector prediction mode that indicates a prediction motion vector and a prediction possibility. If the prediction motion vector is not predictable, the current vector is encoded using a motion vector prediction mode that indicates a default prediction motion vector and a prediction impossibility. According to the invention, the method and the apparatus can provide information for searching for the prediction motion vector and share a certain function for the search without directly notifying the prediction motion vector for the current motion vector to the decoding apparatus so that the current motion vector may be encoded and/or decoded by selecting the prediction motion vector according to the motion vector prediction mode, and the motion vector prediction mode may be transmitted to the decoding apparatus. Therefore, the amount of encoded bits can be reduced and the performances of the motion vector prediction and compensation can be improved. [Reference numerals] (AA) Start of encoding a motion vector; (BB) End of encoding a motion vector; (S500) Selecting a candidate motion vector set; (S502) Selecting a prediction motion vector from the candidate motion vector set; (S504) Is the prediction motion vector selected in a decoding apparatus predictable?; (S506) Encoding a current motion vector using the prediction motion vector and a motion vector prediction mode instructing a prediction possibility (a first encoding); (S508) Encoding the current motion vector using a default prediction motion vector and a motion vector prediction mode instructing a prediction impossibility (a second encoding)