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Method and device for adding or extracting a secondary information signal to/from a RLL code sequence

A sequence and signal technology, applied in the field of binary signals

Inactive Publication Date: 2005-10-26
KONINK PHILIPS ELECTRONICS NV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0005] LML defects are physically visible to pits (and possibly to lands) with the appropriate analytical means available for disk inspection (e.g. Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM))

Method used

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  • Method and device for adding or extracting a secondary information signal to/from a RLL code sequence
  • Method and device for adding or extracting a secondary information signal to/from a RLL code sequence
  • Method and device for adding or extracting a secondary information signal to/from a RLL code sequence

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Embodiment Construction

[0021] A preferred embodiment of the invention will be described below in terms of EFM modulation coding as applied in the CD standard.

[0022] figure 1 A flowchart indicating the basic steps of one coding scheme for providing a hidden channel is shown. In step S100, hidden channel bits to be encoded are input or provided to an encoding operation. Then, a previous RLL bit stream is extracted or fed back from a coded sequence (step S101). Then, the RLL polarity of the predetermined run length of the SYNC structure provided in the RLL bit stream is detected in step S102. In step S103, the detected RLL polarity and the input hidden channel bits are comprehensively considered to set a predetermined merged bit structure. In fact, the predetermined merging bit structure is set according to the detected RLL polarity so as to obtain a predetermined polarity in the predetermined run length of the subsequent S0 synchronization structure. After that, a (dk) bit stream in which "1" i...

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Abstract

The invention relates to a method and device for adding or extracting a secondary information signal to / from a runlength-limited code sequence. A polarity of a runlength at a first predetermined position of the runlength-limited code sequence is detected (S102) and a parameter reflecting the degree of freedom that is present in the runlength-limited channel code, e.g. the selection of a merging bit pattern in the CD-standard, is set on the basis of the detected polarity so as to obtain a predetermined polarity of a runlength at a subsequent second predetermined position of the runlength-limited code sequence (S103). The predetermined polarity then corresponds to a binary value of the secondary information. Thus, a side-channel with a small capacity is provided, which is positioned very close to the physical channel such that the secondary information is hard to be detected from the EFM bit stream. Therefore, the side-channel can be used as a hidden channel for copy protection purposes. The invention also relates to a record carrier and binary signal comprising the secondary information.

Description

technical field [0001] The invention relates to a method for adding secondary information such as information of a covert channel for copy protection purposes to an RLL (runlength-limited) coded sequence which can be recorded on a record carrier or encoded from an RLL Methods and apparatus for extracting sequences. Furthermore, the invention relates to a record carrier and a binary signal for storing RLL coded sequences. Background technique [0002] The invention can be used with record carriers with normal RLL encoding. RLL coding is characterized by two parameters (d+1) and (k+1), which specify respectively the maximum and minimum run lengths that may occur in the coded sequence (in the channel bitstream). For example, the DVD format uses an RLL encoding of (d=2, k=10), called EFMPlus. [0003] Furthermore, merging bits can be used to insert a transition in order to minimize the low-frequency content of the RLL coded sequence. Thereby, the function of DC control can b...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G11B20/00G11B20/10G11B20/14H03M5/14H03M7/14H03M7/46
CPCG11B20/0063G11B20/00086H03M7/46H03M5/14G11B2020/1461G11B20/00579G11B2020/1469G11B20/1426H03M5/145G11B20/1217G11B20/00615G11B2020/1218G11B2220/2545G11B2220/2562G11B2020/1225
Inventor W·M·J·M·科尼J·C·塔尔斯特拉A·A·M·斯塔林J·P·J·赫姆斯凯克
Owner KONINK PHILIPS ELECTRONICS NV