JPH0563077B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a color video signal concealment device used for analog image transmission, analog image recording, etc.

[Conventional technology]

FIG. 3 is an example of a block diagram of the encryption section of a conventional video signal concealment device, where 1 is an analog video signal, 2 is a buffer amplifier, 3 is a phase-locked oscillator (hereinafter referred to as PLO), 4 is a sampling clock,
5 is an A/D converter; 11 is a frame memory into which a digitized video signal is temporarily taken; 18 is an address counter; 9 is an encryption key; 20
is a memory read mapper, 12 is a D/A converter,
22 is an encrypted analog video signal.

FIG. 4 is a block diagram of a decoding section of a conventional video signal concealment device, in which 22 is an encrypted analog video signal, 2 is a buffer amplifier, 3 is a PLO,
4 is a sampling clock, 5 is an A/D converter,
18 is an address counter for addressing pixels to be accessed in the frame memory 11, 23 is a read address, 24 is a write mapper that maps write addresses, 9 is an encryption key, 25 is a write address, 11 is a frame memory, 12 is a D/A The converter 17 is a decrypted analog video signal.

Next, the operation will be explained. In the encryption section shown in FIG. 3, the PLO 3 obtains a sampling clock 4 synchronized with the analog black-and-white video signal 1 input to the buffer amplifier 2, and using it, the A/D converter 5 quantizes the analog black-and-white video signal. . The quantized video signal is written to the frame memory 11, but the reading is not done in the same order as the writing, but is read out in a different order mapped by the memory readout mapper 20. For example, as shown in FIG. 6, there is a method of randomly changing the reading order for each pixel within one frame. A mapper based on random numbers is used to rearrange the order, and the mapper is rearranged according to an externally given encryption key 9. Frame memory 11 with read order changed
The output is output as an encrypted analog video signal 22 by the D/A converter 12. Although this encrypted analog video signal 22 is in the form of a normal video signal, an image will not be reproduced even if it is input to the receiver as is.

On the other hand, in the decoding section shown in FIG. 4, the encrypted analog video signal 22 passes through the buffer amplifier 2, and the PLO 3 generates a sampling clock 4 synchronized with the input encrypted analog video signal 22. The encrypted analog video signal 22 is
The data is quantized by the D converter 5 based on the sampling clock 4 and written into the frame memory 11, but the order in which it is written into the memory must be exactly the same as the order in which it is read out in the encryption section of FIG.
The memory write mapper 24 performs the same memory address mapping as the memory read mapper 20 of the encryption section. When the encryption key 9 is used, the memory write mapper 24 of the decryption section will only write the same key to the decryption section as the encryption key 9 used for encryption in the encryption section. The memory read mapper 20 performs the same memory address mapping. When the contents of the frame memory 11 written in this way are read out, the signals whose order has been changed in the encryption section are decoded back to the original state, and then sent through the D/A converter 12 to the decoded analog video signal. Get 22.

[Problem that the invention seeks to solve]

Conventional video signal secret transmission equipment is configured as described above, so it works well for black and white video signals, but when applied to color video signals, the spectrum of the color carrier signal expands, and when transmitted in the normal video signal band, it becomes difficult to display composite images. There was a problem in that it could not be played.

This invention was made to solve the above-mentioned problems, and even when used for color video signals, the spectrum of the color carrier wave has little spread, and the video signal can be transmitted through a normal analog video signal transmission path. The purpose is to obtain a secure transmission device.

[Means for solving problems]

The color video signal secret transmission device according to the present invention replaces samples line by line, does not include color burst signals in the samples to be replaced, and transfers samples to lines with the same color carrier phase within an effective pixel area. It is designed to transfer samples.

[Effect]

In the color video signal secret transmission device according to the present invention, sample replacement is performed line by line between lines whose reference phases of color carrier waves are equal, thereby widening the spectrum of an encrypted analog video signal. This enables transmission without running out of bandwidth even on a normal video signal transmission path.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of an embodiment of a color video signal concealment device encryption section according to the present invention.
1 is an analog video signal, 2 is a buffer amplifier,
3 is a phase-locked oscillator (PLO), 4 is a sampling clock, 5 is an A/D converter, 6 is a line counter, 7 is a write line address, 8 is a read line mapper, 9 is an encryption key, 10 is a read line address , 11 is a frame memory, 12 is a D/A converter, and 13 is an encrypted analog video signal.

FIG. 2 is a block diagram of an embodiment of the color video signal concealment device decoding section according to the present invention.
is the analog video signal encrypted and transmitted by the encryption section, 2 is the buffer amplifier, 3 is the PLO, 4
is the sampling clock, 5 is the A/D converter, and 6 is the sampling clock.
is a line counter, 14 is a read line address, 15 is a write line mapper, 9 is an encryption key, 16 is a write line address, 11 is a frame memory, 12 is a D/A converter, 17 is a decrypted analog video signal It is.

Next, the operation will be explained.

In the encryption section shown in FIG. 1, an analog video signal 1 to be kept confidential is guided to a PLO 3 and an A/D converter 5 via a buffer amplifier 2.
The PLO 3 generates a sampling clock 4 that is synchronized with the input video signal and has a frequency that is an integral multiple of the color carrier frequency (for example, 4fsc, fsc: color carrier frequency), and uses the sampling clock 4 to control the A/D converter. 5 performs quantization of the input analog video signal 1. The line counter 6 addresses the frame memory 11 into which the quantized video signal is written based on the sampling clock. A video signal including a quantized synchronization signal and a color burst is written to the frame memory 11 based on the write line address 7, and at the same time, the frame memory 11 is read out according to the starting line address 10. In addition, the frame memory 11 has a duffle buffer structure in frame units or field units. The read line address 10 of the frame memory 11 is randomly mapped by the read line mapper 8 based on the output of the line counter 6. In an NTSC composite color video signal, the phase of the color carrier wave is inverted every other line in the field, so in order not to disturb this rule, the readout line mapper 8 replaces each line using M-sequence random numbers, etc. Let's do it. In other words, at the beginning of frame readout, instead of reading out the first line, other odd-numbered lines are read out, and then a certain even-numbered line is read out, so that data on lines with different reference phases are not mapped. Operate Line Matsu Par 8. After satisfying the above conditions, the read line mapper 8 uses the encryption key 9.
The mapping can be changed depending on the
This encryption key 9 is conveyed to the decryption side by some method. The contents of the frame memory 11 read based on the read line address 10 mapped by the read line mapper 8 are returned to an analog signal by the D/A converter 12 and output as an encrypted analog video signal 13. be done.

On the other hand, the configuration of the encryption/decryption unit in Figure 2 is almost the same as the configuration of the encryption unit in Figure 1; the difference is that the line mapper used for mapping read lines in the encryption unit is used in the This is where it is used to specify the line address. That is,
Analog video signal 13 encrypted by the encryption unit
After A/D converting, when writing to the frame memory 11, the video signal with the line order replaced is mapped and written in exactly the same order as the read address of the frame memory of the encryption section. Restoring to the original order.
This frame memory 11 also has a double buffer configuration, in which a video signal is written while being restored on the one hand, and at the same time a frame or field that has already been restored is read out.
A decoded analog video signal 17 is obtained through A conversion.

FIG. 5 shows the above line replacement for encryption and decryption.

〔Effect of the invention〕

As described above, according to the present invention, the color video signal secret transmission device digitizes only the effective pixel area excluding the synchronization signal and color burst of the analog video signal, and data is transmitted between lines having the same reference phase among the line data. Since the configuration is configured to perform the replacement, the spread of the spectrum of the color carrier wave of the color video signal is suppressed, and there is an effect that decoded images can be obtained even when transmitted through a normal video signal transmission path.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an encrypting section of a color video signal concealing device according to an embodiment of the present invention, FIG. 2 is a block diagram of a decoding section of a color video signal concealing device according to an embodiment of the present invention, and FIG. 4 is a block diagram showing an example of an encrypting section of a conventional video signal concealing device. FIG. 5 is a block diagram showing an example of a decoding section of a conventional video signal concealing device. FIG. FIG. 6 is an explanatory diagram of data replacement in a conventional video signal concealment device. 1 is analog video signal, 2 is buffer amplifier, 3 is PLO, 4 is sampling clock, 5
is an A/D converter, 6 is a line counter, 7 is a write line address, 8 is a read line mapper, 9 is an encryption key, 10 is a read line address, 11 is a frame memory, 12 is a D/A converter, 13 is a Encrypted analog video signal, 1
4 is a read line address, 15 is a write mapper, 16 is a write line address, 17 is a decrypted analog video signal, 18 is an address counter, 19 is a write address, 20
is the readout mapper, 21 is the readout address,
22 is an encrypted analog video signal, 23 is a read address, 24 is a write mapper, 2
5 is a write address. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] 1. A buffer amplifier that receives a composite color analog video signal as input, and a phase synchronized oscillator that generates a sampling clock having a frequency that is an integral multiple of the color carrier frequency in synchronization with the output of the buffer amplifier.
An A/D converter that uses the sampling clock output from the phase synchronized oscillator to sample the composite color analog video signal including the synchronization signal and color burst output from the buffer amplifier; A frame memory has a double buffer structure in frame or field units so that the video signal sampled by the oscillator can be read out at the same time as the video signal that has already been sampled, and the sampling output from the phase synchronized oscillator. We focused on the fact that the line counter, which uses a clock to count the number of lines of the video signal and instructs the write address of this frame memory, and the reference phase of the color carrier of the composite color video signal are inverted line by line. However, it is assumed that the data of one line in the area excluding the horizontal/vertical synchronizing signal and color burst is replaced with another line only in lines with the same reference phase, and the contents are replaced by an externally given encryption key. A readout line mapper that outputs the readout address of the frame memory according to mapping based on random numbers such as a changing M sequence, and a readout line mapper that performs D/A conversion on the output of the frame memory and outputs an encrypted analog composite color video signal. a buffer amplifier that inputs the analog composite color video signal encrypted by the encryption unit; and a phase synchronization unit that generates a sampling clock synchronized with the output of the buffer amplifier. an oscillator, an A/D converter that samples the encrypted analog video signal output from the buffer amplifier, and an A/D converter that simultaneously captures the video signal sampled by the A/D converter while restoring the line replacement. , a frame memory with a double buffer structure for reading out decoded video signals that have already been captured,
Counting the number of lines of a video signal using a sampling clock output from the synchronous oscillator, and obtaining a line counter for instructing a read address of the frame memory and an encryption key used for encryption in the encryption section. A write line mapper performs the same mapping as the frame memory read line mapper of the encryption section, and a D/A converter that performs D/A conversion on the output of the frame memory and outputs a decrypted analog composite color video signal. 1. A color video signal secret transmission device comprising: a decoding section having a decoder; 2. When reading lines in the encryption unit, in addition to replacing the lines in the area excluding the synchronization signal and color burst, the data in the area is read in the opposite direction to the scanning direction, and the data in the decryption unit frame memory is read out in the opposite direction to the scanning direction. 2. The color video signal secret transmission device according to claim 1, wherein the color video signal is decoded by performing line replacement and reverse scanning writing of the data again during writing.