Fixed-Length Block Encryption for Variable Packet Content
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Solution Overview
Problem
The MMT/TLV scheme's variable packet size complicates recording and playback of 4K and 8K content, leading to difficulties in managing fragmented data and inefficient encryption processes, particularly when editing or deleting content, as the boundaries of encrypted data units cannot be easily determined, causing issues with buffer control and reproduction.
Innovation Solution
A content recording apparatus that encrypts data in fixed-length blocks, including invalidated regions unnecessary for playback, and records the size of these regions, allowing for simplified recording, editing, and reproduction operations by maintaining data integrity and alignment with ECC block sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If variable-length packets are recorded directly in fixed-length blocks, then recording efficiency improves, but data alignment and reproduction accuracy deteriorate
Solution Approach 1:
The patent segments the variable-length packet data into fixed-length blocks by inserting invalidation data to fill gaps. This segmentation allows efficient fixed-block recording while maintaining the ability to accurately identify valid data boundaries during reproduction, thus resolving the contradiction between recording efficiency and data alignment precision.
2Productivity
If encryption is performed on variable-length content without invalidation regions, then encryption speed improves, but editing and deletion operations become complex
Solution Approach 1:
The patent applies preliminary action by pre-defining invalidation regions during the encryption process. These regions are marked in advance to indicate where valid data ends and unnecessary data begins. This preliminary marking simplifies subsequent editing and deletion operations, as the system can directly reference these pre-defined boundaries without complex analysis of encrypted data structures.
3Ease of operation
If fixed-length blocks are used for encryption, then buffer control simplifies, but handling variable-length packet boundaries becomes difficult
Solution Approach 1:
The patent introduces invalidation data as an intermediary element between the variable-length packet structure and fixed-length encryption blocks. This intermediary marker clearly delineates packet boundaries within the fixed-block framework, simplifying buffer control while providing explicit information about where valid packet data ends and padding begins, thus resolving the boundary handling complexity.
Data Source
AI summary
A content recording apparatus includes an obtaining unit which obtains a content having a variable-length packet structure, an encrypter which generates encrypted data by encrypting the content, and a recorder which records the encrypted data in a block unit having a fixed length in a recording medium. The encrypted data includes an invalidated region unnecessary for reproduction of the content. The recorder records a size of the invalidated region in the recording medium.