Patent ID: 7406206

Claim:
A method of decoding a bitstream in a keyframe-based graphic animation method, the bitstream obtained by encoding key value data of an orientation interpolator representing the rotation of an object in each keyframe, the method comprising: restoring rotational differential data entropy-encoded by quantizing a rotational differential value representing the rotation of the object by as much as a difference between rotation transformations applied to the object by quatemion key value data of each keyframe; restoring entropy-decoding information including an entropy decoding mode indicating an entropy decoding method for the rotational differential data; restoring inverse circular differential pulse code modulation (DPCM) information including the order of an inverse DPCM operation, which indicates whether to perform the inverse DPCM operation on the rotational differential data entropy-decoded according to the entropy decoding mode; and restoring quantization information including the number of inverse quantization bits which is used to restore the rotational differential value, by inverse-quantizing the rotational differential data on which the inverse circular DPCM operation has been performed according to the order of the inverse DPCM operation.