JP2007213686A - Data reproducing method and data reproducing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reproduce data with excellent handleability for a user by performing processing in appropriate processing time for detecting information for copyright protection. <P>SOLUTION: In the data reproducing method, in the processing of detecting watermark information, the retry processing is limited even when the detection fails during setup, and the weighting of the retry processing is changed so as to detect the watermark information when it is identified that the watermark information is surely recorded. Thus, the processing is performed in the appropriate processing time for the detecting the information for the copyright protection. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a data reproduction method and a data reproduction apparatus.

  DVDs include DVD-ROM, which is a read-only medium, and recordable DVDs (DVD-R, DVD-RAM, DVD-RW, etc.) that can record data, and are widely used. In DVD-ROM, a disc on which content such as a movie is recorded is manufactured, CSS (Content Scramble System) is adopted as a copyright protection technology, and copy restrictions are applied.

  Blu-ray discs (hereinafter abbreviated as BD) are attracting attention as large-capacity recording media, and standardization is progressing as high-quality image recording media. BD employs AACS (Advanced Access Content System) as copyright protection technology. Non-Patent Document 1 “Pre-recorded Video Book v0.90” on page 13, FIG. 3-1, describes that some key information is recorded on pre-recorded media.

  Patent Document 1 is a copyright protection technology for information recording media. Patent Document 1 introduces a method of using a physical index for content reproduction. For example, the AACS key information can be embedded using a physical index described in Patent Document 1.

  Further, as an example of changing the embedding strength in the digital watermark embedding method and detection method, the one disclosed in Patent Document 2 is disclosed.

JP 2005-182889 A JP 2002-158978 A (Http://www.aacsla.com/specifications/specs) “Pre-recorded Video Book v0.90” page 13, FIG. 3-1.

  The technique introduced in Patent Document 1 shows a physical index in a ROM disk. However, Patent Document 1 does not describe a retry process when a physical index read fails. FIG. 4 of Patent Document 1 shows a method related to recording of a physical index, and the detection level of pattern A or pattern B differs depending on how much the pits carved on the disc deviate from the center line. Come. When the deviation from the center is large, the detection of the pattern A or the pattern B is easy, but when the deviation from the center is small, the detection of the pattern A or the pattern B becomes difficult. For this reason, it is necessary to consider that a retry process can be performed correctly when it cannot be detected.

  The above problems are solved by the invention described in the claims.

  According to the present invention, detection of information for copyright protection can be performed in an appropriate processing time, and data that is convenient for the user can be reproduced.

  The watermark information for copyright protection recorded on the recording medium according to the present invention will be described. Here, for explanation, it is assumed that content is recorded in advance on a disc like a DVD-ROM disc, and the recorded data is recorded by pits on the disc. Here, this is called a ROM disk.

  FIG. 4 explains a physical index which is also mentioned in Patent Document 1. An example of a method for recording a signal indicating the pattern A or the pattern B is shown because the pits carved on the disc are shifted from the center line. In the present invention, this is called watermark information. The detection level of pattern A or pattern B varies depending on how much the watermark information deviates from the center line. When the deviation Δx from the center is large, the detection of the pattern A or the pattern B is easy. However, when the deviation Δx from the center is small, the detection threshold is small and it is difficult to detect the pattern A or the pattern B. become.

  Here, the watermark information is used for copyright management. Key information for encrypting the copyright-protected content, recording it on a recording medium, and decrypting the encryption applied to the content during playback. In this case, it is necessary to read watermark information for content reproduction. For example, in a ROM disk on which movie software is recorded, the content cannot be reproduced normally only by reading the recorded data, and a decryption key for decrypting the scramble applied to the content is required. Normal reproduction is possible by reading this key from the ROM disk and unscrambling the content.

  As described above, when the watermark information is recorded so as to indicate the pattern A or the pattern B due to the deviation from the center of the pit, if the deviation Δx is small, the watermark information cannot be detected. In this case, re-detection of watermark information can be attempted by retry processing. FIG. 1 shows the flow of processing for detecting watermark information recorded on a recording medium according to the present invention. When the recording medium is inserted into the playback device, first, a recording medium discrimination process is performed in ST10. Next, in ST11, it is determined whether it is a ROM disk or not. “Y” indicates Yes and “N”. In the following description, it is assumed that data scrambled for copyright protection is recorded on the ROM disk. Normally, when a medium is determined, adjustment processing according to the type of the medium is performed, but the description thereof is omitted. If it is not a ROM disk, the setup process is completed so far (ST13), and the next command is entered. In the case of a ROM disk, processing for reading watermark information is performed in ST12. In ST12, the area where the watermark information is recorded is accessed, and the watermark information is read and detected. If the watermark information is detected, the detected watermark information is temporarily stored, and the setup ends when the watermark information has been detected. Until the end of setup is sometimes called loading.

  Here, in the case of an optical disc, it is usually preferable that the setup time is short. This is because when the setup is completed, the user can move to a desired process. For this reason, the watermark information detection ST61 in the setup does not perform a retry even if the watermark information cannot be detected in the first detection, or performs only a minimal retry process, and ends the setup. n indicates the number of retries, and the minimum number of retries is n. When no retry is performed, n = 0. Here, at the time of detecting watermark information, if it is unclear whether watermark information is recorded, repeating the retry process despite the absence of watermark information may unnecessarily prolong setup time. Become. Of course, in order to detect watermark information, when a predetermined address is read out, it may be performed in parallel if necessary data acquisition and adjustment processing can be performed simultaneously at the same address. Absent.

  Next, after the setup is completed, reproduction of content is instructed by a command from the reproduction application in ST14. When a playback command is received, first, in ST15, it is confirmed whether or not the watermark information for unscrambling the content has been detected, and if so, the watermark is determined in ST19 in accordance with the determined command response. The key information detected from the information is transferred. At this time, if the watermark information is a decryption key for decrypting the cipher applied to the content, the key is not transferred as it is, but is subjected to processing such as encryption so that it is not read out and received by the application side. You may make it pass. If the detection of watermark information is not completed in ST15 in the setup process, the detection of watermark information is attempted again in ST16. At this time, since there is a request from the application, it is certain that the watermark information is recorded. Therefore, even if the watermark information cannot be detected by the first watermark information reading process, a number of retries are performed. Repeatedly tries to detect watermark information. In ST62, the number of detection retries is m. If watermark information is detected in ST17 due to re-detection, the decryption key is transferred to the application. If the watermark information cannot be read even after retrying in ST17, an error flag indicating that detection is impossible is returned to the application in ST18.

  In this way, by changing the number of retry processes between detection of watermark information during the setup process and readout after setup, the setup time can be prevented from being prolonged and an appropriate detection operation can be performed. For example, if setup is in progress, no retry is performed with n = 0, and after setup, m ≧ 1 retry is permitted. Alternatively, n times are retried at ST61 during setup, and m times (n <m) are retried at ST62 after setup. In this way, by controlling the weighting of retries during and after setup, the end of the setup process can be shortened and an appropriate detection operation after setup can be performed.

  In addition, for detection of watermark information during the setup process, by lowering the threshold value for watermark information detection during readout after setup, the detection accuracy is lowered but the probability that watermark information can be detected is increased. Further, if the detection accuracy of watermark information is increased by repeating the detection a plurality of times, the retry is repeated or the number of repetitions is increased. Also, since the reading performance may be degraded due to scratches or defects in the recording medium, if watermark information is recorded in multiple locations, access multiple locations when retrying after setup. By detecting, the probability of detection can be increased.

  Further, in order to detect the watermark information, a process for changing the parameter of the reproduction signal detection in the retry process may be added. In some cases, the probability of watermark information detection can be increased by changing the adjustment of the signal amplitude, or changing the characteristics of the waveform equalizer circuit, the characteristics of the band pass filter, and the servo characteristics.

  Next, a data reproducing apparatus for detecting this watermark information will be described. FIG. 2 shows an example of the configuration of the optical disk reproducing apparatus. Reference numeral 21 denotes a recording medium, which is a ROM disk here. The content recorded on the ROM disk 21 is reproduced using the pickup 22. The signal from the pickup 22 is subjected to amplification and waveform equalization processing by the AFE circuit so that a main signal for reproducing the content and a servo signal for focus and tracking of the pickup are generated. Arithmetic processing is performed. The main signal is sent to the reproduction signal processing circuit 24 and subjected to signal processing such as demodulation, error correction and deinterleaving. At this time, the data is processed while being stored in the memory 25. The track shift detection circuit 26 detects the track shift amount, and the watermark information detection circuit 27 reads the watermark information. This can be detected by a tracking error signal, for example. The servo control circuit 31 of the pickup performs not only the above-described focus and tracking control but also control such as access processing up to the reading position. The rotation control circuit 33 controls the motor 32 to rotate the disk at a desired number of rotations. The system control circuit 30 controls the overall operation, and as shown in FIG. 1, from the start of medium determination processing to the end of setup, an instruction to access a desired data area, and retry control. For example, when it is determined that the disc is a ROM disk by the discrimination process, an area containing watermark information is accessed and the watermark information detection operation is performed. In the retry process, the pickup is moved so as to access a predetermined area, and the detection operation is performed.

  FIG. 3 shows a configuration example of the recording area of the optical disc. In an optical disc, disc management information called lead-in 501 is usually recorded on the innermost periphery. Main data is recorded on the outer periphery as a lead-out area 504 and an intermediate area therebetween as a user data area 503.

  When the disc is inserted, the disc type is first determined, and when the adjustment is completed, the management information is read out. If watermark information is recorded in this area, it is possible to reduce the time until the end of the setup by controlling to read the watermark information at the same time as reading the data in the management area. Further, depending on the type of the disc, there is an area on the inner periphery where information about the disc called BCA (Burst Cutting Area) 502 is recorded.

  Next, a method for identifying whether or not watermark information is recorded on the ROM disk will be described. Whether or not copyright protection is necessary for the content depends on the judgment of the content owner, so it is not always necessary to scramble and encrypt the content. In such a case, there is no need to read watermark information. Thus, depending on the type of content, there are cases where watermark information is recorded and cases where it is not recorded. For this reason, when watermark information is not recorded, performing watermark detection is a wasteful process, and a malfunction may occur when considering erroneous detection. Therefore, it is useful to be able to identify whether the disc has watermark information recorded therein. Flag that can be used to identify whether or not a disc has watermark information recorded in an area in which information that must be reproduced is recorded when it is determined to be a ROM disc in the process up to setup described above. By recording, appropriate retry processing can be performed without performing useless detection processing.

  FIG. 5 shows the data structure of a Blu-ray disc. The Blu-ray disc is data called a cluster having a minimum recording unit of 64 kbytes. The configuration of the cluster is LDC (Long Distance Code), BIS (Burst Indicator Subcode), and synchronization signal. The recorded main data is added with error check code and error correction code. In this configuration, 32 error correction codes are added to the data. When this is expressed in the form of Reed-Solomon code, RS (248, 216, 33) is obtained. The LDC is 496 bytes × 38 bytes × 4. On the other hand, data such as address information is recorded as BIS. BIS is 496 bytes × 1 byte × 3. In this area, for example, by recording a flag indicating whether or not the disc has watermark information recorded in the BIS, it becomes possible to easily identify whether or not the watermark information is recorded. When recording the presence / absence of watermark information in the BIS, a flag indicating the presence / absence may not be simply recorded, but may be recorded with encryption or digital authentication so that it cannot be tampered with.

  Similarly, by recording information related to whether or not the watermark information is recorded in the BCA area, the data in the BCA area is read out by the setup process, so that the user data area is not accessed and read. The presence or absence of watermark information can be identified during setup. In addition, by detecting the watermark information after confirming the presence or absence of the watermark information, detection is not performed to perform unnecessary retry when there is no watermark information, and if there is watermark information, retry is performed to ensure detection. By performing this, the detection accuracy can be improved.

  Whether or not video content such as a movie is copyright-protected can be confirmed by determining whether or not the data is scrambled. For example, in the case of image data compressed by the MPEG-2 system, header information including address information called a packet header is always described at a specific cycle. By determining whether this portion can be detected periodically, it is possible to determine whether the data is scrambled.

  Next, a case will be described in which watermark information is embedded regardless of whether the content is copyrighted. For example, in the case of a ROM disk, if watermark information is always recorded, it is necessary to perform a watermark information detection process by determining that the medium is ROM. In such a case, since it is known that the watermark information is always recorded, the watermark information is detected by retry even during setup. The watermark information itself is detected by assigning a predetermined code such as “00” or “FF” when copyright protection is not required for the content. It can be identified that the watermark information has no copyright protection.

  By performing the watermark information detection process in this way, the setup process time can be shortened. Further, when it can be identified that the watermark information is recorded, the detection rate can be improved by reliably detecting the watermark information.

  In addition, detection of information for copyright protection can be performed in an appropriate processing time.

It is the figure which showed an example of the processing method of the watermark information detection of this invention. 1 shows an example of the configuration of a playback apparatus used for watermark information detection according to the present invention. It is the figure which showed the structural example of the area | region where the information in the optical disk was recorded. It is the figure which showed an example of the embedding method of watermark information. It is the figure which showed the structure of the recording cluster of a Blu-ray disc.

Explanation of symbols

ST10 ... Medium discrimination processing, ST11 ... Judgment whether it is ROM, ST12 ... Detection of watermark information,
ST13 ... end of setup process, ST14 ... acceptance of playback command,
ST15 ... Determination of whether watermark information has been detected, ST16 ... Redetection of watermark information,
ST17 ... Judgment whether or not watermark information detection is OK, ST18 ... Add watermark information undetectable flag,
ST19 ... Transfer of watermark information to application

Claims (8)

In a data reproduction method for reading information from a recording medium and performing reproduction processing,
Determining the type of the inserted recording medium;
Reading watermark information recorded on the recording medium;
Outputting information relating to watermark information read from the recording medium,
If the watermark information recorded on the recording medium cannot be detected,
Whether detection of the watermark information is in the setup process or after the setup process,
A data reproduction method characterized by switching a processing method for reading watermark information. In the data reproduction method according to claim 1,
If the setup process is in progress, control is performed not to perform the retry process for reading watermark information.
A data reproduction method characterized by switching control so as to perform a retry process after a setup process. In the data reproduction method according to claim 1,
If the setup process is in progress, the watermark information read retry process is limited to n times,
A data reproduction method characterized by switching control so as to limit the retry process to m times (n <m) after the setup process. In the data reproduction method according to claim 1,
A data reproduction method comprising performing a retry by changing a parameter used for detecting a data reproduction signal in a retry process after the setup process. In a data reproduction apparatus that reads information from a recording medium and performs reproduction processing,
A rotation control circuit for controlling the rotation of the recording medium;
An optical pickup for reading data recorded on a recording medium;
A servo control circuit for performing focus, tracking and access control of the optical pickup;
A reproduction signal processing circuit for reproducing the signal read by the optical pickup;
A detection circuit that detects watermark information from a signal read from the optical pickup;
Watermark information is recorded on the recording medium,
Detecting watermark information recorded by the detection circuit;
If the watermark information recorded on the recording medium cannot be detected,
Whether detection of the watermark information is in the setup process or after the setup process,
A data reproduction apparatus characterized by switching a processing method for reading watermark information. In the data reproducing device according to claim 5,
If the setup process is in progress, control is performed not to perform the retry process for reading watermark information.
A data reproducing apparatus, wherein the control is switched so as to perform a retry process after a setup process. In the data reproducing device according to claim 5,
If the setup process is in progress, the watermark information read retry process is limited to n times,
A data reproducing apparatus, wherein the control is switched so as to limit the retry process to m times (n <m) after the setup process. In the data reproducing device according to claim 5,
A data reproduction apparatus, characterized in that, in a retry process after a setup process, a parameter used for detection of a data reproduction signal is changed to perform a retry.

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