JP2000036750A - Data transmission equipment and data reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain improvement in reliability, even in the case of a still image by temporarily stopping detection due to a first detecting means when a second detecting means detects that first data are not changed, and restarting the temporarily stopped detection due to the first detecting means, when the second detecting means detects that the first data are changed. SOLUTION: Regenerative data are sent from a pickup 10, which reads out a signal on a disk 11, to an extension and demodulation processor 13. At the extension and demodulation processor 13, the data are demodulated and extended corresponding to a modulation system. A detector 14 for embedded data detects transmission data as many as the number of repetition from pixel blocks, in which the transmission data are embedded. A majority decision device 15 makes a majority decision for each bit for the transmission data detected as many as the number of repetition and composes the transmission data of majority data. An error corrector 16 detects and corrects an error corresponding to an error-correcting code in the transmission data.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to image data and audio data which have different data (data hiding, watermark).
More particularly, the present invention relates to a method and an apparatus for detecting embedded data from transmitted data.

[0002]

2. Description of the Related Art Data hiding is a technique for embedding identification information and annotations in image, voice, and text data.
It has been studied so far. Recently, identification information has been embedded in data to protect copyrights, and has been applied as a technique for preventing unauthorized operations.
These technologies are based on Nikkei BP's Nikkei Electronics
(1997.2.24 P149-P162).

[0003]

However, there is no description on how to specifically reproduce data that is repeatedly embedded as described above.

[0004] The embedding strength of data and the effect on the original data are in a conflicting relationship. The data to be embedded is embedded so as to be inconspicuous with the original data, and the embedded data may change due to conversion of the data, making detection impossible. Therefore, the detection of the embedded data is not limited to one time, but is detected several times continuously. Here, when the data does not change, for example, in the case of video data, such as a still image, the detection result does not change even if it is continuously detected, so that the reliability cannot be improved.
Therefore, it is necessary to devise ways to improve the reliability even in the case of a still image.

[0005]

In order to achieve the above object, the present invention relates to a reproducing apparatus for reproducing data, wherein the data includes first data which is image and audio information, and the first data. Data demodulating means for demodulating the first and second data, and a first detecting means for detecting second data embedded in the demodulated data. Means, and second detection means for detecting that the first data has not changed,
When the second detection means detects that the first data has not changed, the detection by the first detection means is temporarily stopped, and the first data is transmitted by the second detection means. Another object of the present invention is to provide a data reproducing apparatus characterized in that the detection by the first detecting means, which has been temporarily stopped, is restarted when a change is detected.

[0006]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of a flow of processing for detecting embedded data. Here, a case will be described as an example in which other information such as copy control information is embedded in video data. However, the data is not limited to video, and is not limited to audio or text. Embedded data may be missing due to MPEG encoding processing for compressing video data. Therefore, detection of embedded data is repeatedly performed a plurality of times in order to improve reliability. At this time, if the video is a still image, the detected embedded data does not change.

For this reason, even if the detection is repeated a plurality of times, the reliability cannot be improved, and the probability of erroneous detection increases. Here, when the still image detection unit detects that the image is a still image, the detection is temporarily stopped, and a standby state is set until the video is no longer a still image.
When the still image detecting means detects that the image is no longer a still image, the detection of the embedded data is restarted.

As a method for compressing moving pictures, MPE
In some cases, the G method is used. However, in this method, encoding is performed by taking the difference between consecutive images, and in such a case, the data of the difference is monitored.
If there is no change, it is determined that the image is a still image.

As described above, when data does not change, for example, in the case of video data, such as a still image, the detection result of embedded data does not change even if it is continuously detected, so that data is biased. By temporarily stopping the detection of embedded data, unbiased detection can be performed, and reliability can be improved. Also,
The same effect can be obtained by stopping the counter for counting the number of detections without stopping the detection of the embedded data.

FIG. 2 shows an embodiment of the flow of encoding / decoding processing for information transmission.

In FIG. 1, information bits to be transmitted: nbi
t (b0, b1, b2,..., bn-1), and an error correction code for performing error correction when an error occurs in an information bit: mbit (bn, bn + 1,..., bn) + m-1) and transmission data: n + mbit (b0, b1, b2,... bn, bn + 1... bn + m-1)
And In order to reduce the influence of the change in data caused by the transmission system, the same transmission data is repeatedly transmitted a plurality of times (P times).

Here, the repetition method is b0, b0, b0... B0 P times for each bit b1, b1, b1... B1 P times:: bn + m-1, bn + m-1 , bn + m-1 ... bn + m-1 P times or transmission data as one unit (b0, b1, b2, ... bn + m-1), (b0, b1, b2, ... bn + m-
1),... P times, etc., whichever way goes.

The above is the transmission side. This repeated transmission data is sent to the receiving side via the transmission system. On the receiving side, a decision is made by majority decision on the repeatedly transmitted transmission data. If the data of b0 is transmitted P times, the value of the more received data for P b0 data is
Let it be the value of b0. Similarly, each bit (b0, b1, b2,... B
For each of n, bn + 1... bn + m-1), P data is collected, a majority decision is made, and transmission data (n + mbit) is obtained.
Thereafter, the information bit error is detected or corrected by the m-bit error correction code, and the correct information bit (nbit) is detected.
Get.

[0015] By transmitting information using such a method, even when the error rate of the data is high due to the transmission system and the error cannot be corrected, the error rate of the transmitted data can be reduced by performing a majority decision. Correction by an error correction code can be made possible.

FIG. 3 shows an embodiment of the processing flow of the transmission means shown in FIG. This is an example in which transmission data is temporarily mixed with image data and transmitted. The data to be mixed is not particularly limited, such as audio data.

In FIG. 1, transmission data is prepared P times so that it can be repeatedly transmitted with an error correction code added thereto, and the transmission data is embedded in image data. The point to embed is predetermined or
It is assumed that the information of the embedding point is transmitted in advance by another means. The image data corresponding to the embedding point is converted according to the value of each information bit.

These are subjected to image compression in the same manner as data of other pixel blocks, and are modulated as necessary. The data processed in this way is recorded on a medium such as a package medium (for example, CD, DVD, etc.) and transmitted, or transmitted as it is by radio waves such as broadcast.

Next, as a receiving means, package media and the like are received by a reproducing device, and in the case of radio waves, received by a receiver, and subjected to demodulation processing in accordance with a modulation method. Thereafter, the compressed data is decompressed. Here, the transmission data is detected from the pixel data of the pixel block in which the transmission data is embedded by means for detecting the transmission data embedded in the image data. The transmission data obtained in this way is detected from P places for each bit, and a majority decision is made. This is performed for n + m bits to obtain transmission data,
An error is corrected by the error correction code included in the transmission data, and a correct information bit is obtained.

By using such a method, information bits can be transmitted mixed with data, information with a low error rate can be obtained, and additional information with high reliability can be transmitted.

FIG. 4 shows an embodiment of a processing method for embedding information bits in image data. One natural image is replaced as data, and in order to perform embedding processing on the image, the image is first divided into square pixel blocks of 8 × 8 pixels. One of the pixels is replaced with 64 pieces of data having a fixed number of bits. If the data is 8-bit data, the data has 512 levels of resolution.

Here, when this pixel block is a point where transmission data is embedded, processing is performed according to the value of each bit of the transmission data. For example, when the bit of the transmission data embedded at that point is “1”, the value of the data is converted so that the sum of the 64 pixel data is a multiple of 512,

[0023]

(A0 + a1 + a2 + ... + a63) mod 512 = 0 (m
(od indicates the remainder of the division) If the bit is “0”, the sum of 64 pixel data is set to 256, which is a multiple of 512

[0024]

(A0 + a1 + a2 +... + A63) mod 512 = 256 The values of data a0 to a63 are converted. The value of 512 (and 0, 256) used in this case is not particularly limited, but a larger value means that the original data is largely converted instead of being easy to determine and reducing errors. Become.

When embedding transmission data, 5
It is also possible to convert the data value so as to be in the range of 12 ± α (eg, α = 64).

In this manner, 64 pixels of one pixel block are used.
The pixel data is converted, and the transmission data is divided into bits and embedded.

If these transmission data are compressed / expanded after being embedded, they may not be accurately reproduced. In consideration of such cases, the determination of transmission data after reception is

[0028]

(A0 + a1 + a2 +... + A63) mod 512 = 0, not limited to 0, and 0 ± α (α is determined by a compression method or the like.
≤64).

Here, an example in which the transmission data is embedded in the sample value has been described. However, it is also possible to embed the transmission data in a frequency-converted value such as DCT or FFT.

FIG. 5 shows an example of points for embedding transmission data in an entire natural image. The transmission data is embedded at (n + m) × P points in the image data.

At the time of reception, P b0 bits are collected from the embedding point of b0, and a majority decision is made. This is performed for n + m bits to obtain the transmission data after the majority decision.
By repeatedly embedding each bit of the transmission data at a plurality of points in this way, it is possible to make a majority decision at the time of reception and to correctly reproduce information bits.

FIG. 6 shows an embodiment of a signal processing apparatus for performing encoding / decoding processing for information transmission according to the present invention. In the present embodiment, an example is shown in which information of several tens of bits is superimposed on image data and recorded and reproduced on a disk such as a DVD.

1 is a recording information bit, 2 is an error correction code adding device, 3 is a repetitive data generating device, 4 is recording image data, 5 is a pixel block dividing device, 7 is a transmission data embedding device, and 8 is compression and modulation. A processing device, 9 is a recording / reproduction switching SW, 10 is a pickup, 11 is a disc,
12 is a spindle motor, 13 is a decompression and double tone processing device, 14 is a device for detecting embedded data, 15 is a majority decision device, 16 is an error correction device, 17 is a system control device, 18 is a reproduction output control device, and 19 is reproduction. Image data.

In the figure, a recording information bit 1 is information of copy control necessary at the time of reproduction, for example, and controls such as reproduction inhibition and output inhibition based on the information. The error correction code adding device 2 adds a parity as an error correction code to the recording information bit 1, and the repetition data generation device 3 repeatedly transmits the transmission data with the error correction code added to the recording information bit 1. Duplicate as many times as you want. The recording image data 4 is original image data, which is encoded in a predetermined format and transmitted. The pixel block dividing device 5 divides the original image data into 8 × 8 pixel blocks to embed the data in the original image data. The transmission data embedding device 7 adds the divided
A process for embedding transmission data to which an error correction code has been added is performed. In this process, transmission data is embedded a plurality of times, one bit at a time, at a predetermined point.

The data generated in this way is compressed by the compression and modulation processing device 8 and subjected to modulation processing according to the recording format. As a result, recording data conforming to the recording format is generated. The recording data is written on the disk 11 by the pickup 10. The spindle motor 12 is a motor for rotating the disk 11.

At the time of reproduction, the recording / reproduction switching SW 9 is switched to the reproduction side, and the reproduction data is sent from the pickup 10 that has read the signal of the disk 11 to the decompression and multi-tone processing device 13. In the decompression and double tone processing device 13,
Demodulation according to the modulation method is performed and decompressed. From this data, the embedded data detection device 14 detects the transmitted data from the pixel block in which the transmitted data is embedded by the number of repetitions. The majority decision device 15 makes a majority decision on transmission data detected by the number of repetitions for each bit, and configures the transmission data with the larger data. The error correction device 16 detects and corrects information bit errors using the error correction code included in the transmission data. The information bits thus reproduced have a low probability of being erroneous. If the reproduction information bit is copy control information and is copy prohibition information, the system control unit 17 controls the reproduction output control unit 18 to stop outputting the reproduction image data 19.

It is assumed that this recording information bit 1 is composed of 32 bits, and that the transmission data is composed of a total of 46 bits of 6 bits of error correction code and 8 bits as a signal indicating the head of data. When 2000 embedding points are set in one screen, transmission can be repeated about 43 times. Here, assuming that the error rate in the transmission system is 0.1, the probability that an error is included in a bit after a majority decision is made at the time of reproduction is 1 × 10E-11. If the error rate in the transmission system is 0.2, 5 × 10
It is about E-6. With this error rate, when convolutional decoding is performed using a 6-bit error correction code, the error rate is 1 × E−9 to 10 and the probability of an error occurring can be kept low.

FIG. 7 shows another embodiment of the flow of the encoding / decoding process for information transmission according to the present invention. Those having the same numbers as those in FIG. 2 indicate the same ones.

In this figure, similarly to FIG. 2, there are information bits (n bits) to be transmitted, and a conversion table for converting the information bits according to a certain rule is provided. The converted data is referred to as transmission data (n + m bit). I do. In order to reduce the influence of the data change caused by the transmission system, the same transmission data is repeatedly transmitted a plurality of times (P times). Here, by transmitting the number of repetitions: P in advance by another means, if there are a plurality of types of transmission systems and the optimal number of repetitions differs from each other,
The number of repetitions can be set according to the transmission system.
For example, when the transmission system is a disk, the number of repetitions is determined from the compression / expansion rate during recording and reproduction and the error rate of the disk, and the value is recorded in a specific portion on the disk, for example, in the TOC area. Make sure to play it first. By using such a method, transmission data can be transmitted with the number of repetitions suitable for the transmission system.

For example, in order to transmit image data, M
When compression such as PEG is performed, in the MPEG data format, since a header exists for each picture of a screen, the number of repetitions P may be multiplexed as additional information in the header. Further, the number P may be multiplexed in GOP units. In this case, the multiplexing number P can be transmitted in units of pictures and GOPs, and optimal repetition for image data can be performed.

Here, since the value of the number of repetitions P may be falsified when it is decrypted, in order to keep the value of P secret, it is difficult to decrypt it by encrypting and recording it, and the algorithm is strengthened. be able to.

By transmitting information using such a method, when there are a plurality of types of transmission systems and the optimum number of repetitions differs, the number of repetitions can be set according to the transmission system. As a result, by performing the majority decision, the error rate of the transmission data can be reduced, and correction using the error correction code can be performed. Further, by the same method, it is also possible to transmit a point at which transmission data is embedded and a threshold value for determination.

FIG. 8 shows another embodiment of the flow of the encoding / decoding process for information transmission according to the present invention. 1 are the same as those in FIG.

In the figure, information bits (nbi
t), which has a conversion table for converting information bits according to a certain rule, and sets the converted data as transmission data (n + mbit). At this time, it is desirable that the converted data is data that is not easily mistaken for other data. In order to reduce the influence of the data change caused by the transmission system, the same transmission data is repeatedly transmitted a plurality of times (P times). This is the transmitting side. This repeated transmission data is sent to the receiving side through the transmission system. On the receiving side, the transmission data that has been repeatedly transmitted is determined by majority decision for the number of repetitions. If this data is digital data, P
/ 2 or more. The majority decision is performed P times for n bits for each bit to obtain transmission data (n + mbit).
After that, it is inversely converted into information bits using a table reverse to that at the time of conversion to obtain the original information bits (n bits).

By transmitting information using such a method, even when the error rate of the data is high due to the transmission system and the error cannot be corrected, the error rate of the transmitted data is reduced by performing the majority decision. Correction by an error correction code can be made possible.

FIG. 9 shows another embodiment of the encoding process for information transmission according to the present invention.

In this figure, as in the method shown in FIG. 4, information is embedded in units of pixel blocks, and the information bits to be transmitted are K bits (for example, K = 6). For example, assuming that the information bits are embedded at L positions in one natural image, when the information bits are “00_0000”, L information bits are embedded in the X portion of the pattern in the natural image, and the information bits “00_0001” are embedded. At times, L information bits are embedded in the Y portion of the next pattern. As described above, information data is embedded in correspondence with 64 types of embedding patterns that do not overlap all pixel blocks in the case of 6 bits. here,
The minimum number of pixel blocks included in one natural image is K ×
L (64 × 60 = 3840) blocks are required. If the number is less than this, the embedding patterns overlap, and the probability of erroneous detection when determining the corresponding information bit increases.

In this way, by embedding the information bits, the receiving side can determine whether or not the information bits are embedded based on whether or not there is a specific embedding pattern corresponding to the information bits. The information bit can be determined depending on which embedding pattern matches or is close to. In the case where the embedding method shown in FIG. 4 converts the value into a value within a predetermined range, or depending on an error occurring in the transmission system, in addition to the embedding pattern, a case where the embedding location is detected may occur. When examining the pattern of a part, it approximates to only one pattern, and the information can be determined.

A predetermined pattern may be used as the embedding pattern. However, if the information of the embedding pattern corresponding to each information bit is encrypted and transmitted before transmitting data, An embedding pattern according to the system can be used.

FIG. 10 shows an embodiment of a still image detection process according to the present invention.

The detection of a still image can be performed by monitoring information such as luminance and color difference data or RGB data at the same position in the video. FIG. 10 shows an example of a process of detecting a still image by monitoring a luminance value.

A luminance value is detected at a predetermined position. In the next frame or field, the luminance value at the same position is detected and compared with the previous luminance value. If they are the same, the value of n is increased by one. Otherwise n
Is set to “0”, and the next frame or field is detected. If n exceeds a certain value, it is determined that the image is a still image.

By setting a plurality of monitoring positions, even a video in which only a part moves and the other part does not move can be detected as a part still image.

When the video data is encoded by the still picture detecting means, it is detected that the picture is a still picture, and a code indicating this is sent together with the data. At this time,
A part of the data is written into, for example, a reserved area in the data, a part of the ID area, or an area of data that is not actually used. Alternatively, writing may be performed during a vertical field blanking period or a horizontal synchronization period.

Then, by detecting this code, it is easy to detect a still image even during reproduction, and the circuit load for detecting a still image can be reduced. This code can be recorded as embedded data. Even if still image information is erroneously detected, detection of embedded data is only temporarily stopped, so that the detection time may be long, but there is little effect.

[0056]

According to the present invention, in a transmission in which another additional information bit such as copy prohibition is superimposed on image or audio data and transmitted, when the data does not change, for example, if it is video data, it is like a still image. In such a case, since the detection result of the embedded data does not change even if the detection is continuously performed, by temporarily stopping the detection of the embedded data, the detection without bias can be performed, and the reliability can be improved.

When the video data is encoded by the still image detecting means, it is detected that the image is a still image, and a code indicating the detection is sent together with the data. At this time,
A part of the data is written into, for example, a reserved area in the data, a part of the ID area, or an area of data that is not actually used. Detecting this code makes it easier to detect still images during playback,
The circuit load for detecting a still image can be reduced.

[Brief description of the drawings]

FIG. 1 is a flowchart showing an embodiment of a flow of processing for detecting embedded data according to the present invention.

FIG. 2 is a diagram showing an embodiment of a flow of an encoding / decoding process for information transmission according to the present invention.

FIG. 3 is a diagram showing an embodiment of a processing flow of a transmission unit.

FIG. 4 is a diagram showing an embodiment of a processing method for embedding information bits in image data.

FIG. 5 is a diagram illustrating an example of points at which transmission data is embedded in an entire natural image.

FIG. 6 is a system configuration diagram showing one embodiment of a signal processing device for performing encoding / decoding processing for information transmission according to the present invention.

FIG. 7 is a flowchart showing another embodiment of the flow of encoding / decoding processing for information transmission according to the present invention.

FIG. 8 is a flowchart showing another embodiment of the flow of the encoding / decoding process for information transmission according to the present invention.

FIG. 9 is a diagram showing another embodiment of a processing method for embedding information bits in image data according to the present invention.

FIG. 10 is a flowchart showing an embodiment of still image detection processing according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Recording information bit, 2 ... Error correction code addition apparatus, 3 ... Repetition data generation apparatus, 4 ... Recording image data, 5 ... Pixel block division apparatus, 7
... Transmission data embedding device, 8 ... Compression and modulation processing device, 9 ... Recording / reproduction switching SW, 10 ... Pickup, 11 ... Disk, 12 ... Spindle motor, 13 ... Decompression and double tone processing device
14: embedded data detection device, 15: majority decision device, 16: error correction device, 17: system control device, 18: reproduction output control device, 1
9: Reproduction image data.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5C053 FA21 FA23 FA30 GB14 JA30 KA01 KA24 LA06 5C063 AA01 AC01 AC10 CA23 CA36 CA40 DA13 DA20 5J064 AA00 BA15 BB08 BC01 BC02 BC14 BC20 BD02 BD03

Claims (10)

[Claims] In a reproducing apparatus for reproducing data, the data includes first data that is information of an image or sound and second data that is additional information of the first data. Data demodulating means for demodulating the first and second data, first detecting means for detecting second data embedded in the demodulated data, and detecting that the first data has not changed And a second detecting means for detecting that the first data has not changed. The second detecting means temporarily stops the detection by the first detecting means, and The first detecting means
A data reproducing apparatus characterized in that when it is detected that the data has changed, the detection by the first detecting means which has been temporarily stopped is restarted. 2. The method according to claim 1, wherein
If the data is information for performing copy control, reproduction or output of the first data is controlled in accordance with the copy control information detected by the first detection means. Data reproducing device. 3. The method according to claim 1, wherein
Detecting means for monitoring a specific position of the first data, wherein the monitoring means detects that the data at the specific position has not changed. apparatus. 4. The method according to claim 1, wherein
Detecting means for monitoring a plurality of positions of the first data, detecting which part of the data at the plurality of positions monitored by the monitoring means has not changed, and A data reproducing apparatus characterized in that the detection by the second detecting means is partially stopped for a portion which has not changed. 5. A reproducing apparatus for reproducing data, wherein the data has recorded therein first data which is information of images and sounds and second data which is additional information of the first data. Data demodulating means for demodulating the first and second data, first detecting means for detecting second data embedded in the demodulated data, and indicating that the first data has not changed Third detection means for detecting a signal;
When the third detection means detects that the first data has not changed, the detection by the first detection means is temporarily stopped, and the third detection means causes the first detection means to temporarily stop the detection. A data reproducing apparatus characterized in that when it is detected that the data has changed, the detection by the first detecting means which has been temporarily stopped is restarted. 6. First data which is information of an image or sound,
Means for embedding the second data in the first data, means for embedding the second data in the first data, and conversion into a format for transmitting the first data in which the second data is embedded Data conversion means for performing the processing and second detection means for detecting that the first data has not changed,
When the second detection means detects that the first data has not changed, it converts the data into a format for transmitting the first data. A data transmission device characterized by adding a signal shown. 7. The method according to claim 6, wherein the second data is:
If the information is for performing copy control, transmission and reproduction control is performed in accordance with the second data, and the second data is rewritten in accordance with the copy control. . 8. A method according to claim 6, wherein when the second detection means detects that the first data has not changed, a start signal indicating that the first data has stopped changing, and a start signal indicating that the change has started. A data transmission apparatus characterized in that an end signal that has been changed no longer when detected is added to a format for transmitting the first data is added. 9. The apparatus according to claim 6, wherein said second detecting means includes a monitoring means for monitoring a specific position of said first data, and said data at said specific position is not changed by said monitoring means. A data transmission device characterized in that a data transmission is detected. 10. The data processing system according to claim 6, wherein said second detecting means includes monitoring means for monitoring a plurality of positions of said first data, and wherein said plurality of positions are monitored by said monitoring means. Data for detecting whether the portion has not changed, and adding a signal indicating the detected unchanged portion when converting the signal into a format for transmitting the first data. Transmission equipment.