Patent ID: 7673153

Claim:
An audio/video data processing apparatus comprising: processing means for compressing audio/video data into a plurality of compression blocks, each compression block having a first data length, a predetermined number of compression blocks forming a track data file including key data; encrypting means for separating each compression block into a plurality of units and for encrypting each unit as an encryption block having a second data length smaller than the first data length, the key data including initial values for decrypting each encryption block wherein the first data length is a data length of an integer multiple greater than one of the second data length; storage means for storing the encryption blocks; editing means for one of (a) dividing one track data file into two edited track data files and (b) combining two track data files into one edited track data file, said editing means creating new key data for the edited track data file(s) such that re-encryption of encryption blocks is not performed for the edited track data file(s); and control means for writing the encryption blocks in said storage means so that data positioned in a same encryption block is also positioned in a same compression block, said control means reading the encryption blocks from said storage means in units of compression blocks.