Patent ID: 7903734

Claim:
A moving image decoding method of decoding encoded moving image data, which is generated by decomposing each frame of moving image data into a plurality of subbands, and encoding a plurality of coefficients for each subband from upper to lower bits for respective bitplanes or sub-bitplanes using the bitplane encoding method in JPEG2000 for a predetermined unit, using a computer to perform the steps of: a calculation step of, for every decoding of a video frame, calculating a time difference ΔT between a decoding process time DT taken in a decoding process of the video frame and a target decoding time T for the decoding process and adding the calculated time difference ΔT to an accumulated time difference TT to update the accumulated time difference TT; a non-decoding pass determination step of determining passes that are not to be decoded based on the updated accumulated time difference TT; a pass decoding step of reclaiming the plurality of coefficients of the plurality of subbands from encoded data of passes other than the passes determined in the non-decoding pass determination step; and a subband composition step of generating frame data by compositing the coefficients of the plurality of subbands reclaimed in the pass decoding step, wherein the non-decoding pass determination step includes steps of: managing a table that represents a correspondence between an index Q and a non-decoding pass number NDP(Sb) of a subband Sb, deciding a value of the index Q in accordance with the updated accumulated time difference TT; selecting the number NDP(Sb) for each subband Sb uniquely defined by the decided value of the index Q from the table, and setting lower passes for each subband Sb, the number of which is the selected NDP(Sb), as the passes that are not to be decoded.