KR970008408B1 - An apparatus for preventing digital image copy - Google Patents

Abstract

An apparatus for preventing a copy of a digital image is disclosed. The apparatus has a signal transmission unit and a source decoding unit. The signal transmission unit comprises a source encoding unit(10) for encoding an analog signal using a changed time stamp and a modulation unit for modulating the image signal from the source encoding unit to transmit through a channel. The source decoding unit(40) decodes a transmitted signals through the channel using the time stamp to provide a displayable image signal. Thereby, the copy of image data is easily prevented by changing the time stamp and a clock.

Description

Copy protection device of digital image

1 is a block diagram of a conventional copy protection apparatus for digital TV broadcasting.

2 is a block diagram of a copy protection apparatus of a digital image according to the present invention.

3 and 4 are diagrams showing another embodiment of the source code part of FIG.

FIG. 5 is a detailed configuration diagram of the time stamp converter and the clock blur of FIG. 2, FIG. 3, and FIG.

* Explanation of symbols for main parts of the drawings

1: Receiver 2: Descrambler

3: decryption unit 4: image restoration unit

5: copy protection part 6: D / A conversion part

7,50: monitor 10: source code portion

11: Register 12: Adder

13 random number generator 20 modulator

30: demodulation unit 40: source decoding unit

41: video decoder 42: video output unit

43: time stamp detector 101,111,121: A / D conversion unit

102, 113, 123: video code 103: time stamp generator

104: time stamp converter 112,122: time stamp input unit

114,124: image data buffer 115,125: format unit

116,126: system clock generator 117,127: clock blur

118,129 Oscillator 119,128 Counter

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for copy protection of digital images, and more particularly, to an apparatus for preventing a viewer from copying broadcast contents without permission through a VCR. Conventionally, in the case of analog broadcasting such as the PAL NITS method, when a broadcasting station transmits a video signal for a program that needs copy protection, several horizontal scanning lines are randomly variably added to and blanked from the original vertical blanking and synchronization signals. By transmitting, the viewer can watch while the viewer does not feel the difference in the broadcast screen, but when recording with a home VCR, normal recording is impossible due to the deviation of the vertical synchronization signal.

In the case of digital broadcasting, digital information is transmitted through a communication channel, and vertical and horizontal synchronous myths cannot be transmitted, so that vertical and horizontal signals are generated by a receiving device. Is output, the copy protection is not performed by the signal of the broadcasting station.

1 is a configuration diagram of a copy protection apparatus of a conventional digital TV broadcast.

Conventionally, the copy protection apparatus of digital TV broadcasting, as shown in FIG. 1, receives the encrypted digital output signal and the encrypted data output from the receiving unit 1 and the receiving unit 1, which receive the image compressed digital broadcast signal and the copy protection signal from the broadcasting station. Desorambler (2) for reading and key for operation from various media are used to recover compressed coated data through VCL (Varible Lenght Coer) and DCT (Discrete Cosine Transform) of descramble (2) Copy restoration which outputs the image data restored by the image restoration unit 4 and the image restoration unit 4 in a displayable image format, and in the case of an image signal that requires copy protection, by adding a few vertical synchronization signals and variably generating them. And a D / A (Digital / Analog) converting section 6 for converting the digital output signal of the section 5 and the copy protection section 5 into an analog signal and outputting the analog signal. signal The converted video signal is displayed on the monitor 7.

Since the copy protection unit 5 is in the receiving device, the copy protection unit 5 operates in the case of a program requiring copy protection by transmitting a signal for operating the copy protection unit 5 from the transmitting side or the DVDCR side. Although the screen is displayed, recording was not possible due to the shaking of the sync signal when recording to the VCR.

In addition, when the user removes the copy protection unit 5 that generates a variable vertical registration signal for the purpose of copying, the decryption unit 3 detects the presence of the copy protection unit 5 and operates the descrambler 2. By restoring the image, it is impossible to restore the image, or the encryption decryption unit 3 and the copy protection unit 5 are formed as one chip so that the user cannot remove only the copy protection unit 5.

However, since the copy protection device of the conventional digital TV broadcast has to generate the shaking of the synchronization signal from the copy protection unit 5 in the reception device itself, if the copy protection unit 5 is illegally manufactured, the copy protection is prevented. When the board is manufactured, the output of the image restoring unit 4 can be connected to the input of the descrambler 2 so that the descrambler 2 operates so that the copy protection device can be removed. 5) and the descrambler (2) must be present together, there is a problem that can not be applied to the application field only the copy protection system, not the encryption of the video signal.

In order to solve the above problems, the present invention provides a copy protection device for digital video to prevent unauthorized duplication of output analog video in digital wired and wireless broadcasting, DVCR, and CD-I by modifying a synchronization signal at a transmitting side. There is this.

A video signal transmission means comprising a source code means for encoding an analog video signal using a time stamp modified by the analog video signal, and a modulation means for modulating a video signal output from the source code means and transmitting a channel; And a source decoding means for decoding the signal transmitted through the decoding signal and decoding the signal output from the demodulation means into a displayable video signal using a time stamp.

Hereinafter, with reference to the accompanying drawings will be described an embodiment of the present invention;

2 is a block diagram of a copy protection device of a digital image according to the present invention. FIG. 2 is a block diagram of a transmitter of a digital video signal, and FIG. 2B is a block diagram of a receiver of a digital video signal. .

An apparatus for preventing copying of a digital image according to the present invention includes a source coder 10 and a modulator 20, as shown in FIGS. 2A and 2B, to recover an analog image signal. It consists of a receiver.

The source code unit 10 is an A / D (Analog / Digital) converter 101, an image code 102, a time stamp generator 103, and a time stamp converter 104. The encoded analog video signal is encoded using the converted time stamp.

The A / D converter 101 converts an input analog video signal into a digital signal.

The time stamp generator 103 generates a time stamp, which is a reference time of the vertical registration signal, every vertical registration time by using the image digital signal output from the converter 101.

The time stamp output from the time stamp converter 104 is changed.

The video encoder 102 compresses and encodes the digital video signal output from the A / D converter 101 using the modified time stamp output from the time stamp converter 104.

The modulator 20 modulates the encoded video signal output from the video code 10 and transmits the modulated video signal through a channel.

The decoder 30 demodulates the modulated signal transmitted through the channel.

The source decoder 40 is composed of an image decoder 41, an image output unit 42, and a time stamp detector 43. The source decoder 40 uses a time stamp to transmit a signal output from the demodulator 30. The video signal that can be displayed on the monitor 50 is restored.

The video decoder 41 decodes the digital video signal output from the demodulator 30 and outputs the transmitted time stamp value to the time stamp detector 43.

The time stamp detector 43 detects a time stamp value from the signal output from the image decoder 41 and generates a vertical synchronization signal.

The image output unit 42 converts the digital image signal output from the image decoder 41 into an analog image signal using the vertical synchronization signal output from the time stamp detector 43, and outputs the analog image signal to the monitor 50.

The input analog video signal is A / D converted by the A / D converter 101, and the output signal of the A / D converter 101, which is A / D converted, is timed at every vertical synchronous time by the time stamp generator 103. Used to generate a stamp.

The time stamp generated by the time stamp generator 103 is converted into a value different from the original time stamp value by the time stamp converter 104 and then input to the image encoder 102 to be output from the A / D converter 101. It is used to compressively encode a digital video signal.

The encoded video signal output from the video encoder 102 is modulated by the modulator 20 and transmitted through a wired or wireless channel.

The signal transmitted through the wired or wireless channel is restored to the digital signal in the demodulator 30 and the signal restored to the digital signal is decoded into a video signal in the video decoder 41 and transmitted simultaneously to restore the synchronization signal of the output video. The time stamp value is output to the time stamp detector 43.

The signal output from the video decoder 41 detects the time stamp value in the time stamp detector 43 and generates a vertical synchronization signal.

The video signal decoded from the video decoder 41 is converted into an analog video by the video output unit 42 and output to the monitor 50 in accordance with the resin synchronization signal output from the time stamp detector 43.

That is, when the vertical synchronization signal is modified by a period of several horizontal scan lines through the time stamp converter 104 of the source coder 10, the image output unit 42 of the receiver outputs an image in accordance with the changed vertical synchronization signal. In the monitor 50, if the screen shake does not occur and the recording is made on the home VCR, the mechanical device records according to the deformed vertical synchronization, so that the clean image without the shake during the playback cannot be seen.

3 is a configuration diagram showing another embodiment of the source code unit 10 of FIG. 2 and can be applied to a system standard of the International Motion Picture Standardization Group (MPEG).

As shown in FIG. 3, the source coder 10 includes an A / D converter 1110, a time stamp inputter 112, a video coder 113, a video data buffer 114, a formatter 115, And a system clock generator 116 and a clock blur 117.

The A / D converter 111 converts the input analog video signal into a digital signal.

The system clock generator 116 is composed of an oscillator 118 and a counter 119, and controls the operation of the entire system and generates a system clock necessary for encoding or encoding an image.

The oscillator 118 generates a vibration, and the counter 119 counts a signal output from the oscillator 118 to generate a system time clock (STC).

The clock blurring unit 117 transforms the normal time stamp, that is, the presentation time stamp (PST) and the decoding time stamp (DTS) by transforming the system time clock (STC), which is a clock output from the system clock generator 116. This function is to generate a vibration in the clock of the receiver to prevent copying of the analog VCR.

The degree of vibration of the clock of the receiver should be less than or equal to the maximum vanity vertical synchronization signal at which the screen shake does not occur in the output device of the receiver.

The time stamp input unit 112 detects and deforms the time at which the vertical synchronization signal is generated in the image signal output from the A / D converter 111 by using the modified clock output from the clock blur 117. .

That is, the time stamp input unit 112 detects the PTS and the DTS, which are information indicating the time to sample, and modifies it according to the output signal of the clock blur 117.

The PTS and DTS are included in the Biz Stream for transmission in order to synchronize video or audio signals digitally. The receiver uses this information to transmit the video and audio related to the values of the PTS and DTS. A time point for displaying and encoding voice information is found and displayed and decoded.

The image encoder 113 encodes an image signal output from the time stamp input unit 112.

That is, the video coder 113 increases the amount of information when the video signal is transmitted digitally. Therefore, in order to reduce the amount of information, the video coder 113 uses Decoding Time Stamp (DTS) coding, motion estimation and compensation coding, Digital Pulse Code Modulation (DPCM) coding, and Huffmam. This is to reduce the amount of information of a transmitted video signal by encoding the video signal using coding, subband coding, or the like.

The image data buffer 114 performs a memory function in which an irregular image signal output from the image encoder 113 is output at a constant speed.

That is, the video signal output from the video coder 113 reduces the average amount of information, but the amount of information generated is irregular, so that the buffer memory buffering the video signal is required. The video data buffer 114 is connected to the video coder 113. It buffers irregular information inputted from and outputs it at a constant speed.

The formatter 115 includes a system clock reference (SCR) output from the system clock generator 116 to divide, combine and convert the image data output from the image data buffer 114 to be transmitted. Perform the function.

The SCR is time information received by the receiver to perform a function for the system clock of the receiver to match the clock of the transmitter.

The vibration generated in the oscillator 118 is counted in the counter 119 to generate a system clock reference (SCR), and the STC output from the system clock generator 116 blurs the time stamp in the clock blur 117. In order to be fast or late, a random delay is output to the time stamp input unit 112.

The analog video signal is converted into a digital signal by the A / D converter 111, and then the PTS is detected by the time stamp input unit 112 in accordance with the modified STC output from the clock blur unit 1170. .

The PTS output from the time stamp input unit 112 is transformed into a PTS, and then, the image signal is encoded by the image coder 113 and then buffered to adjust the output speed in the image data buffer 114.

The image data output from the image data buffer 114 is transmitted from the format unit 115 to the sub-modulator 20 formatted for transmission including the SCR by using the STC output from the system clock generator 116. Output is sent over the channel.

4 is a schematic diagram showing another embodiment of the source coder 10 of FIG. 2 and may be applied to a system standard of an international video standardization group (MPEG).

As shown in FIG. 4, the source coder 10 includes an A / D converter 121, a time stamp inputter 122, a video coder 123, a video data buffer 124, and a formatter 125. , A system clock generator 126, and a clock blur 127.

The A / D converter 121 converts an analog video signal input like the A / D converter 111 of FIG. 3 into a digital signal.

The system clock generator 126 is composed of an oscillator 118 and a counter 119 like the system clock generator 116 of FIG. 3 to generate the system clock STC.

The time stamp input unit 122 detects the time when the vertical synchronization signal is generated in the video signal output from the A / D converter 121 using the STC output from the system clock generator 126.

That is, the time stamp input unit 122 detects the DTS by the PTS.

The image encoder 123 encodes an image signal output from the time stamp input unit 122 like the image encoder 113 of FIG. 3, and the image data buffer 114 of the image data buffer 114 of FIG. 3. As shown in FIG. 2, the memory module outputs an irregular video signal output from the video encoder 123 at a constant speed.

The clock blurring unit 127 functions like the clock blurring unit 117 of FIG. 3 to randomly delay the STC output from the system clock generation unit 126 so as to be fast or late, thereby distorting and deforming the clock.

The format unit 125 transforms the SCR, which is a signal value for synchronizing with the receiving system, by using the modified STC output from the clock streaming unit 127 and outputs the image data output from the image data buffer 124. Performs a formatting function to split, combine and convert the data into a form suitable for transmission.

The vibration generated by the oscillator 129 is counted by the counter 128 to generate an STC, and the input analog video signal is converted into a digital signal by the A / D converter 12.

In the digital signal output from the A / D converter 121, the PTS is detected by the time stamp input unit 122 according to the STC output from the system clock generator 126, and the image signal is received by the video code 123. Is encoded and then buffered to match the output speed in the image data buffer 124.

The STC output from the system clock generator 126 is randomly delayed by the clock blur 127 so as to be fast or late and is output to the formatter 125.

The image data output from the image data buffer 124 is formatted in a format suitable for transmission in the format unit 1250 using the modified STC output from the clock blur unit 127 and then output to the modulator 20. Transmitted through the channel.

FIG. 5 is a detailed configuration diagram of the time stamp converter 104 and the clock blurs 127 and 117 of FIGS. 2, 3, and 4.

The time stamp converter 104 and clock blurring portions 117 and 127 are composed of a register 11, an adder 12, and a random number generator 13 as shown in FIG.

The register 11 latches the time stamp output from the time stamp generator 103 and the STC output from the system clock generators 116 and 126, and the random number generator 13 has a maximum of +3 and a minimum of -3. The value of the horizontal scanning line generation period of the degree is randomly generated, and the adder 12 adds the data value output from the register 11 and the data value output from the random number generator 13.

The signals output from the time stamp generator 103 and the system clock generators 115 and 126 are latched in the register 11 and then added to the random numbers of the maximum +3 to the minimum -3 generated by the random number generator 13 and the adder. A time stamp or modified STC added and modified at 12 is input to the video encoder 102, the time stamp input unit 112, and the format unit 125.

The present invention constructed and operated as described above selectively modifies the time stamps and clocks in the commercial broadcasting field of digital satellite broadcasting and digital cable TV, and video data through media such as CD and DVCR to prevent illegal copying of programs. In this case, the boxer prevention can be adjusted at the transmitter in accordance with the determination of the program source.

Claims (10)

Video signal means comprising: source code means for encoding an analog video signal using a modified time stamp and modulation means for modulating the video signal output from the source code means and transmitting a channel; And demodulating means for demodulating a signal transmitted through the channel and source decoding means for decoding the displayable video signal using a signal time stamp output from the demodulating means. . 3. The apparatus of claim 2, wherein the source code means comprises: A / D conversion means for converting an analog video signal into a digital signal, time stamp conversion means for modifying a time stamp output from the A / D conversion means, and the time stamp. And a video encoding means for encoding a video signal output from the A / D conversion means by using the modified time stamp output from the conversion means and outputting the image signal to the modulation means. . 2. The apparatus of claim 1, further comprising: an A / D conversion means for converting the source code means source analog video signal into a digital signal, a system clock generation means for generating a system clock, and a clock outputted from the system clock generation means. A time stamp input means for detecting and transforming a time at which an image signal output from the A / D conversion means is generated using a blurring means, a modified clock output from the clock blurring means, and the time stamp input means The video signal means for encoding the video signal output from the video signal, an image data buffer means for adjusting the output speed of the video signal output from the video code means, and a clock output from the system clock generation means. To format the video signal output from the data buffer means. Copy protection apparatus for a digital image, characterized in that the format means is configured to output to the modulating means. The apparatus of claim 1, wherein the source code means comprises: an A / D conversion means for converting an analog image signal into a digital signal, a system clock generation means for generating a system clock, and a clock output from the system clock generation means. Time stamp input means for detecting the time when a vertical synchronization signal is generated in the video signal output from the A / D conversion means, video code means for encoding the video signal output from the time stamp input means, and the video code means Formatting a video signal output from the image data buffer means by using a clock blur means for transforming the clock output from the clock, and a modified clock output from the clock blur means for outputting to the modulation means Copying room of a digital image, characterized in that the format means Intelligent device. 2. The apparatus of claim 1, wherein the source decoding means comprises: video decoding means for decoding a signal output from the demodulation means, a time stamp for detecting a time stamp from a time stamp output from the video decoding means, and generating a vertical synchronization signal. And a video output means for converting the video signal output from the video encoding means to the monitor by using the detection signal and the registered signal output from the time stamp detection means. Prevention device. 3. The apparatus according to claim 2, wherein said time stamp converting means comprises: a register for latching a time stamp value output from said time stamp generating means, random number generating means for randomly generating a horizontal scanning line generation period value, and said register and random number generating means And copying means for adding data values output from the digital image. 4. The apparatus of claim 3, wherein the clock blurring means comprises: a register for latching a clock output from the system clock generating means, random number generating means for randomly generating a horizontal scan line generation period value, and a register and a random number generating means. A copy protection device for a digital image, characterized by comprising means for adding an output data value. 5. The apparatus of claim 4, wherein the clock blurring means comprises: a register for latching a clock output from the system clock generating means, random number generating means for randomly generating a horizontal scan line generation period value, and a random number generating means from the register and random number generating means. A copy protection device for a digital image, characterized by adding data values to be output and adding means. The digital image display apparatus of claim 3, wherein the system clock generating means comprises an oscillator for generating vibration, and a counter for generating a system time clock (STC) by counting a signal output from the oscillator. Copy protection device. The digital image copying method of claim 4, wherein the system clock generating means comprises an oscillator for generating vibration, and a counter for generating a system time clock (STC) by counting a signal output from the oscillator. Prevention device.