MPEG-21标准的主要内容有哪些？

Part 1: Vision, technologies, and strategy

Part 2: Digital Item Declaration (DID)

Part 3: Digital ltem ldentification (DII)

Part 4: Intellectual property management protection (IPMP)

Part 5: Rights Expression Language (REL)

Part 6:Rights Data Dictionary (RDD)

Part 7: Digital ltem Adaptation (DIA)

Part 8: Reference software

Part 9: File format

Part 10: Digital Item Processing (DIP)

Part 11: Evaluation methods for persistent association technologies

Part 12: Test bed for MPEG-21 resource delivery