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EFM data decoding method for CD machine system

A technology of data decoding and optical disc drive, which is applied in the field of data decoding of 8 to 14 modulation, and can solve the problems of picking discs, easily scratched discs, and non-compliant 14-bit data, so as to improve reliability and avoid picking or The effect of not being able to read the data

Inactive Publication Date: 2003-03-19
VIA TECH INC
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] As the reading speed of optical discs is getting higher and higher, it is easy to read the optical disc at a reading rate of 40 times or more than 40 times, and the characteristics of the optical disc are easy to scratch, etc. , it is easy to have 14-bit data that does not conform to the above EFM modulation rules. If there is no proper EFM data decoding processing, it will be handed over to the subsequent demodulation module for processing, which will reduce the reliability of data reading, or even cause chip picking or reading. Problems such as no data

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  • EFM data decoding method for CD machine system
  • EFM data decoding method for CD machine system
  • EFM data decoding method for CD machine system

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Embodiment Construction

[0026] figure 2 To show the waveform diagram of an example where 14-bit data waiting for EFM decoding may not conform to EFM modulation rules, please refer to figure 2 . Try to give a correct 14-bit data EFM DATA waiting for EFM decoding as an example, this EFM DATA=14'h1220, wherein 14' represents 14 bits, and h represents hexadecimal notation (the following expressions are also the same), as in 2 Carry means:

[0027] EFM DATA=0001, 0010, 0010, 00b, if the waveform of this EFM DATA is read correctly, it is as follows figure 2 shown in . However, due to factors such as reading the disc at a very high read rate, or the disc happens to be scratched, etc., it is possible to obtain such figure 2 The two waveforms of EFMDATAE1 or EFM DATAE2 shown in , since the same programming state of these two waveforms lasts less than 3 EFM CLK cycles, these two waveforms do not conform to the EFM modulation rule. In this example, EFMDATAE1 is a falling edge Transition early, while EF...

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Abstract

The EFM data decoding method in CD machine system includes the following steps: inputting serial data; taking out from the serial data 14 bits of data to be EFM decoded; looking up the corrected EFM decoding table to convert the 14 bits of data into 8 bits of data; and outputting the 8 bits of data. The corrected EFM decoding table has data of converting 14 bits data not conforming the EFM modulation rules to 8 bits data, and may be used to convert the 14 bits data not conforming the EFM modulation rules to most possible 8 bits data. The present invention can raise data read reliability.

Description

technical field [0001] The present invention relates to a decoding method when reading data from an optical disc, and in particular to a method for decoding data of Eight to Fourteen Modulation (Eight to Fourteen Modulation for short EFM) when reading a CD disc (Compact Disk). Background technique [0002] In order to adapt to the characteristics of optical discs and increase the reliability of optical disc data reading, when data is stored on optical discs, EFM and Reed-Soloman code modulation processing will be performed, and the order of data storage will be disrupted by interleaving. Therefore, when reading data from a CD, the data must first be decoded by EFM data. Please refer to figure 1 , which shows a schematic diagram of a part of the reading process in a CD-ROM (hereinafter referred to as CD-ROM) optical disc, wherein the radio frequency data (Radio Frequency Data referred to as RF DATA) obtained by inductive laser passes through the data shaping circuit 100 to g...

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G11B7/00G11B20/14G11B20/18H03M7/00H03M13/00
Inventor 欧阳世龙
Owner VIA TECH INC