JPH0944995A - Digital recording and reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the complete copying of data by changing the error correcting ability with respect to a reproduced digital data. SOLUTION: At the time of recording data, a prescribed error correction encoding processing is applied to digital data by superposing error patterns outputted from an error pattern table 23 on the digital image data in adder 14, an ID adding circuit 16 and then the data are recorded on a recording medium. At the time of reproducing the data, at first, error corrections based on internal sign parities are performed in an RS decoder 27 with respect to the data read out from the recording medium. Next, after an ID is detected in an ID detecting circuit 28, rearrangements of external sign units based on the ID are performed in an external sign blocking circuit 29. Besides, after the ID was decoded, the ID is also supplied to an error generating circuit 33. When both error patterns coincide with each other, a normal reproduced picture is outputted and when both patterns do not coincide with each other, a degraded picture display is performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital recording / reproducing apparatus for recording / reproducing digital data on / from a recording medium, and more particularly to a device capable of limiting complete copying of the digital data. Regarding

[0002]

2. Description of the Related Art As is well known, in recent years, techniques for digitizing and processing image signals have advanced, and even in the field of image recording, recording and reproducing digitized image data with respect to a magnetic tape. Digital VTRs (video tape recorders) are becoming popular. The greatest feature of this digital VTR is that an error correction code represented by RS (Reed Solomon) code can be used.

By using this error correction code, it is possible to remove an error in the digital image data reproduced from the magnetic tape, and therefore it is possible to reproduce an image without any deterioration. Here, the error correction code is composed of m + p bytes obtained by adding p bytes of parity bytes to m bytes of digital image data to be recorded on the magnetic tape. It is possible to correct even byte errors of bytes.

In particular, in the field of digital VTR, as shown in FIG. 4, by using two error correction codes in a product code configuration for two-dimensionally arranged digital image data, burst error is generated. The error correction ability is also improved. In this case, of the product codes, the first coding is called an outer code and the latter coding is called an inner code.

However, such a digital VTR
In the conventional digital recording / reproducing apparatus represented by, it is possible to accurately correct the error that has occurred in the reproduced digital data, so that a complete copy of the digital data recorded on the recording medium is easily created. For,
Addressing the issue of copyright infringement has become an unavoidable concern, and this is one of the factors preventing its spread.

[0006]

As described above, in the conventional digital recording / reproducing apparatus, since a complete copy of the digital data recorded on the recording medium is easily created, there is a problem of copyright infringement. Because you need to deal with
It has a problem that its spread is hindered.

Therefore, the present invention has been made in consideration of the above circumstances, and by changing the error correction capability for reproduced digital data, it is possible to restrict the complete reproduction of digital data. It is an object of the present invention to provide an extremely good digital recording / reproducing device.

[0008]

In a digital recording / reproducing apparatus according to the present invention, error correction coding processing is performed on digital data to record it on a recording medium, and the data read from the recording medium is based on the error correction code. It is intended for those that perform error correction processing. Then, with respect to the data that is subjected to the error correction coding process and recorded on the recording medium, a recording unit that adds a predetermined error pattern data set in advance and records the recording medium, and the data read from the recording medium, A reproducing means is provided for canceling the error pattern data added by the recording means and performing an error correction process based on the error correction code.

According to the above-mentioned structure, at the time of recording, the predetermined error pattern data set in advance is added to the data which is error-correction coded and is recorded on the recording medium, and the data is recorded on the recording medium. Then, at the time of reproduction, the error pattern data added to the data read from the recording medium is canceled and the error correction processing based on the error correction code is performed, so that the error pattern data added at the time of recording is notified. Only when using the same error pattern data as the recorded error pattern data,
It is possible to cancel the error pattern data added to the reproduction data, and it becomes possible to reproduce the digital data recorded on the recording medium in a complete form. In other cases, the error pattern data including the error pattern data is included. Only digital data can be reproduced, and complete reproduction of digital data can be restricted, and the problem of copyright infringement can be solved.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings. First, FIG. 1 shows the configuration of the recording system of the digital VTR described here. In FIG. 1, reference numeral 11 is an input terminal to which digital image data is supplied. The digital image data supplied to the input terminal 11 is the outer code blocking circuit 12
And is divided into m bytes for the first error correction coding of the product code.

The digital image data output from the outer code blocking circuit 12 is the RS encoder 1
3 is supplied to each of the data blocks in units of m bytes,
By adding the outer code parity of p bytes, R
Outer coding processing by the S code is performed.

The digital image data after the outer coding process output from the RS encoder 13 is supplied to an adding circuit 14 and an error pattern output from an error pattern generating circuit 21 described later is added to the outer code block. . In this case, the error pattern added here is
It contains more errors than the limit of error correction by outer code.

Then, the outer coded data to which the error pattern is added by the adder circuit 14 is supplied to the inner code blocking circuit 15 to be n for the next error correction coding.
It is divided into bytes. This inner code blocking circuit 1
The data output from 5 is supplied to the identification information (ID) addition circuit 16, and for each data block having an n-byte length,
An i-byte length identification information ID is added.

At this time, the ID addition circuit 16 also adds the encrypted error pattern number output from the encryption circuit 22 described later as the identification information ID. Then, the data with the identification information ID output from the ID addition circuit 16 is supplied to the RS encoder 17,
Inner-coded processing by the RS code is performed by adding q-byted inner-coded parity to each data block having a length of n + i bytes.

The digital image data after the inner coding process output from the RS encoder 17 is supplied to a modulation circuit 18 and subjected to a channel coding process, and then recorded on a magnetic tape 20 via a recording head 19. To be done.

Here, reference numeral 23 in FIG. 1 denotes an error pattern table, which stores a table of error patterns to be overlapped with the outer code output from the RS encoder 13 by the adder circuit 14. The error pattern table 23 sends to the error pattern generation circuit 21 an error pattern corresponding to the generation pattern number requested by the error pattern generation circuit 21.

The error pattern generating circuit 21 is
The error pattern sent from the error pattern table 23 is output to the addition circuit 14. Further, the error pattern generation circuit 21 sends the generation pattern number of the error pattern output to the addition circuit 14 to the encryption circuit 22.

The encryption circuit 22 performs the encryption processing on the generation pattern number output from the error pattern generation circuit 21 based on the encryption key output from the encryption key generation circuit 24, thereby the above-mentioned ID. The adder circuit 16 generates an encrypted error pattern number that should overlap the inner code output from the inner code blocker 15.

Next, FIG. 2 shows the structure of the reproducing system of the digital VTR. That is, the data recorded on the magnetic tape 20 as described above is read by the reproducing head 25. The data read by the reproducing head 25 is supplied to the demodulation circuit 26 and subjected to channel decoding processing, and then supplied to the RS decoder 27 and subjected to error correction processing based on the inner code parity.

The data after the error correction processing based on the inner code parity output from the RS decoder 27 is supplied to the ID detection circuit 28 and the identification information ID is detected,
It is supplied to the outer code blocking circuit 29, rearranged in units of outer code based on the identification information ID, and supplied to the adding circuit 30.

Further, of the identification information ID detected by the ID detection circuit 28, the encrypted error pattern number is supplied to the decryption circuit 31, and the decryption key generation circuit 3 is supplied.
After being decrypted, that is, decrypted, based on the decryption key output from No. 2, it is supplied to the error pattern generation circuit 33. The error pattern generation circuit 33 reads the corresponding error pattern from the error pattern table 34 based on the input error pattern number and outputs it to the addition circuit 30.

As described above, the outer code data output from the outer code blocking circuit 29 and the error pattern output from the error pattern generating circuit 33 are added to the adding circuit 30.
Error pattern generation circuit 33
If the error pattern output from is equal to the error pattern added during recording, the error pattern added during recording will be canceled.

The outer code data of which the error pattern has been canceled by the adder circuit 30 is sent to the RS decoder 3
5 and is subjected to error correction processing based on the outer code parity. After that, the data after the error correction processing based on the outer code parity output from the RS decoder 35 is
After being supplied to the synthesizing circuit 36 and converted into the original digital image data, it is taken out through the output terminal 37 and provided for image display.

On the other hand, if the error pattern output from the error pattern generation circuit 33 does not match the error pattern output from the error pattern generation circuit 21 during recording, the addition circuit 30 adds the error pattern during recording. Since the error pattern is not canceled, the adder circuit 3
In the outer code data output from 0, the RS decoder 35
Error exceeding the error correction capability of the RS decoder 27, that is, an error due to the added error pattern.
Since there is an error including an error that was missed by the inner code correction processing by the, the error correction processing by the outer code of the RS decoder 35 does not sufficiently function, and a deteriorated image display is performed.

Here, FIG. 3 shows how the outer code parity, the identification information ID and the inner code parity are added to the digital image data at the time of recording, and the original digital image data is restored on the basis of these additional data at the time of reproduction. Is shown. That is, FIG. 3A shows the digital image data supplied to the input terminal 11 during recording,
The figure (b) shows the output of the RS encoder 13, the figure (c) shows the output of the ID addition circuit 16, and the figure (d) shows the output of the RS encoder 17. Further, during reproduction, FIG. 3D shows the output of the demodulation circuit 26, FIG. 3C shows the output of the RS decoder 27, and FIG.
Shows the output of the adder circuit 30, and FIG.
6 output is shown.

According to the above-described embodiment, first, in the recording system, the magnetic tape 20 is added to the digital image data by adding the preset known error pattern and its encrypted generation pattern number. I am recording. Also,
In the reproducing system, the encrypted generation pattern number is decrypted on the basis of the decryption key obtained from the decryption key generation circuit 32, and the error pattern designated from the error pattern table 34 by the decrypted generation pattern number. By taking out and adding to the reproduced data,
The error pattern added at the time of recording can be canceled.

In this case, the user of the digital VTR sets the error pattern table 34 corresponding to the error pattern added to the video source tape and the key for decrypting the generation pattern number from the supplier of the video source tape. The decryption key generating circuit 32 and the decryption key generating circuit 32 are paid in advance and purchased in advance. At this time, the decryption key generation circuit 32 and the error pattern table 34 sold to the user
In order to prevent unauthorized falsification and copying, it is assumed that the information is supplied to the user in the form of an IC (integrated circuit) card, for example.

For this reason, only the user who pays the regular price correctly deciphers the encrypted generation pattern number and adds the same error pattern as the error pattern added at the time of recording to the reproduced data to cancel it. It becomes possible to reproduce the digital image data in perfect form, and other users can reproduce only the digital image data with many errors. It becomes possible to restrict reproduction, and it is possible to solve the problem of copyright infringement. It should be noted that the present invention is not limited to the above-described embodiment, and can be variously modified and implemented without departing from the scope of the invention.

[0029]

As described above in detail, according to the present invention,
By changing the error correction capability for the reproduced digital data, it is possible to provide an extremely good digital recording / reproducing apparatus capable of restricting the complete reproduction of the digital data.

[Brief description of drawings]

FIG. 1 is a block diagram showing a recording system of an embodiment of a digital recording / reproducing apparatus according to the present invention.

FIG. 2 is a block configuration diagram showing a reproduction system in the same embodiment.

FIG. 3 is a diagram for explaining the transition of additional data at the time of recording and reproduction in the same embodiment.

FIG. 4 is a diagram for explaining a product code configuration of an error correction code.

[Explanation of symbols]

 11 ... Input terminal, 12 ... Outer code blocking circuit, 13 ... RS encoder, 14 ... Addition circuit, 15 ... Inner code blocking circuit, 16 ... ID addition circuit, 17 ... RS encoder, 18 ... Modulation circuit, 19 ... Recording Head, 20 ... Magnetic tape, 21 ... Error pattern generation circuit, 22 ... Encryption circuit, 23 ... Error pattern table, 24 ... Encryption key generation circuit, 25 ... Playback head, 26 ... Demodulation circuit, 27 ... RS decoder, 28 ... ID detection circuit, 29 ... Outer code blocking circuit, 30 ... Addition circuit, 31 ... Decoding circuit, 32 ... Decryption key generation circuit, 33 ... Error pattern generation circuit, 34 ... Error pattern table, 35 ... RS decoder, 36 ... Combining circuit, 37 ... Output terminal.

Claims (5)

[Claims] 1. A digital recording / reproducing apparatus for performing error correction coding processing on digital data to record the digital data on a recording medium and performing error correction processing on the data read from the recording medium based on the error correction code. A recording unit that adds predetermined preset error pattern data to the data that has been subjected to error correction coding processing and is recorded on the recording medium, and recording data read from the recording medium. A digital recording / reproducing apparatus comprising: a reproducing unit that cancels the error pattern data added by the recording unit and performs an error correction process based on the error correction code. 2. The recording means extracts a first error pattern table containing a plurality of types of error pattern data and predetermined error pattern data from the first error pattern table, and records the error pattern data on the recording medium. First adding means for adding to the data to be recorded, and identification data for specifying the error pattern data added by the first adding means to be encrypted and added to the data to be recorded on the recording medium. 2 adding means, the reproducing means reads the encrypted identification data from the data read from the recording medium, and decodes the decoding data; and a plurality of storage means stored in the first error pattern table. A second error pattern table containing a plurality of types of error pattern data corresponding to the types of error pattern data Selecting means for extracting error pattern data corresponding to the identification data decoded by the decoding means from the second error pattern table, the error pattern data extracted by the selecting means, and the data read from the recording medium. 2. The digital recording / reproducing apparatus according to claim 1, further comprising a calculating unit that calculates the error pattern data and cancels the error pattern data added to the data read from the recording medium. 3. The first error correction coding processing means for performing one-way error correction coding processing on the two-dimensionally arranged digital data, and the first error correction code. And a second error correction coding processing means for performing error correction coding processing in the other direction on the data subjected to the error correction coding processing in one direction by the coding processing means. And adding the error pattern data to the data subjected to the error correction encoding processing in one direction by the encoding processing means, and the reproducing means based on the error correction code in the other direction with respect to the data read from the recording medium. First error correction processing means for performing error correction processing, and data subjected to error correction processing based on the error correction code in the other direction by the first error correction processing means are based on the error correction code in the one direction. Error correction processing A second error correction processing means for applying the error pattern data to the data subjected to the error correction processing based on the error correction code in the other direction by the first error correction processing means. The digital recording / reproducing apparatus according to claim 1, wherein the digital recording / reproducing apparatus is provided. 4. A first error correction coding processing means for performing one-way error correction coding processing on two-dimensionally arranged digital data, and a first accommodating plural kinds of error pattern data. Error pattern table and predetermined error pattern data are taken out from the first error pattern table and added to the data subjected to the one-way error correction coding processing by the first error correction coding processing means. The first adding means and the identification data for specifying the error pattern data added by the first adding means are encrypted, and the one-way error correction coding processing is performed by the first error correction coding processing means. A second adding means for adding to the processed data; and a second error correction coding processing means for applying the error correction coding processing in the other direction to the output of the second adding means. A recording unit configured to record the data subjected to the error correction coding processing in the other direction by the second error correction coding processing unit on a recording medium; and the data read from the recording medium. From first error correction processing means for performing error correction processing based on the error correction code in the other direction, and data subjected to error correction processing based on the error correction code in the other direction by the first error correction processing means, Decoding means for reading and decrypting the encrypted identification data, and corresponding to a plurality of types of error pattern data stored in the first error pattern table,
A second error pattern table accommodating a plurality of types of error pattern data, a selection means for extracting error pattern data corresponding to the identification data decoded by the decoding means from the second error pattern table, and this selection means. Calculating means for calculating the error pattern data extracted from the recording medium and the error pattern data added to the data read from the recording medium, and an output of the calculating means for calculating the error pattern data. A digital recording / reproducing apparatus comprising: a reproducing unit including a second error correction processing unit that performs an error correction process based on a one-way error correction code. 5. The decryption means is configured to decrypt the identification data based on key information for decryption given from the provider side of the recording medium to the reproducer side of the recording medium. Claims 2 and 4 characterized in that
The digital recording / reproducing apparatus according to any one of the above.