Blu-ray Disc Copy Protection via Wobbled and Straight Pit Segmentation
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Solution Overview
Problem
Existing Blu-ray Disc (BD) recording technologies face challenges in accurately detecting and reproducing disc information, especially when copy protection information is encoded in wobbled pits, as current methods fail to differentiate between BD-RE and BD-ROM, leading to potential read errors and illegal copying.
Innovation Solution
The solution involves encoding disc information and copy protection information in both wobbled and straight pits, using bi-phase modulation and alternate wobble structures to prevent easy detection by unauthorized devices, while ensuring reliable data retrieval and encryption decryption processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If copy protection information is encoded in wobbled pits using HFM modulation, then data security is enhanced, but detection accuracy deteriorates due to inability to differentiate from BD-RE structures
Solution Approach 1:
The patent segments the pit structure into two distinct types: wobbled pits for copy protection information and straight pits for main data. This segmentation allows the reproducing apparatus to differentiate between BD-ROM and BD-RE structures, resolving the detection accuracy issue while maintaining the security benefits of HFM modulation in wobbled pits
Solution Approach 2:
The patent applies different pit structures to different functional areas: wobbled pits with HFM modulation are used specifically for copy protection information in the PIC area, while straight pits are used for main data in the data area. This local differentiation enables accurate detection and reproduction without compromising security
2Ease of operation
If disc information is recorded as straight pits in BD-ROM, then detection is simplified, but demodulation time increases due to RF signal detection requirements
Solution Approach 1:
The patent separates disc information into two categories with different recording methods: copy protection information in wobbled pits that can be detected by push-pull method (faster), and main data in straight pits using conventional RF detection. This segmentation optimizes detection speed for critical security information while maintaining compatibility for data storage
3Device complexity
If a single detection scheme is used for all disc types, then device complexity is reduced, but reliability deteriorates due to read errors on incompatible formats
Solution Approach 1:
The patent implements a universal detection capability by enabling the reproducing apparatus to handle both wobbled pit (HFM) and straight pit structures through a single device. The system automatically identifies pit type and applies appropriate detection methods, providing multi-format compatibility without requiring separate detection schemes for BD-ROM and BD-RE
Data Source
AI summary
A recording medium, such as a high-density and/or read-only recording medium, such as BD-ROM, which contains copy protection information encoded in intermittent or alternate wobbled pits, and to methods and apparatuses for forming, recording, and reproducing data on the recording medium.