Patent ID: 8649439

Claim:
A decoding circuit for decoding a current macroblock, the decoding circuit comprising: a transferring unit executing a data transfer with an external memory located outside of the decoding circuit, wherein the decoding circuit operates in a plurality of modes, including a direct mode in which the current macroblock to be decoded does not have any motion vectors and a motion vector of the current macroblock is specified using a motion vector of another macroblock that has already been decoded; a buffer holding a motion vector of a macroblock; a decoding unit judging whether the current macroblock has been encoded by the direct mode and specifying a motion vector of the current macroblock using the motion vector held in the buffer, when the current macroblock has been encoded by the direct mode; an external memory transfer instructing unit instructing the transferring unit to transfer the motion vector specified by the decoding unit to the external memory; and a buffer transfer instructing unit instructing the transferring unit to transfer a motion vector of a reference macroblock from the external memory to the buffer, before the decoding unit judges whether the current macroblock has been encoded by the direct mode, the reference macroblock being referenced when the current macroblock has been encoded by the direct mode.