JP2007294099A - Digital transmission device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To receive a digital signal processed to prevent illegal copying by other devices and to normally reproduce the signal. <P>SOLUTION: An ID decoder 15 detects a control bit for protecting a copyright. On the basis of an ID signal transmitted from a display 2, it is specified that a device connected by an ID detection circuit 22 is the display 2. On the basis of these pieces of information, a switch circuit 16 is set. When it is specified that the connected device is the display 2, the switch circuit 16 is set to a terminal 16B side, and a video signal is scrambled by a key signal K1 from the display 2. Thus, the signal scrambled to be output is descrambled by the descrambler 34 of the display 2. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a digital VTR that digitizes and records / reproduces a video signal, and particularly relates to scrambling for copyright protection of the digital VTR.

  Digital VTRs have been developed that digitize video signals and record them on tape. In a digital VTR, since a video signal is digitized and recorded, there is almost no deterioration in image quality, and it is easy to make a copy thereof. For this reason, an illegal copy may be made and copyright may be infringed. Thus, for example, several scramble systems have been proposed in which a key signal composed of a pseudo random code is superimposed on a digital video signal and output.

  When such strong scrambling is applied, the video signal cannot be reproduced without knowing the key for descrambling. For this reason, if the key is not known, it is not possible to create a copy with another VTR, and an illegal copy can be prevented from being created.

  However, if the video signal is output after being scrambled, not only recording with another VTR can be prevented, but also monitoring with a display cannot be performed. In other words, the purpose of scramble is to prevent illegal duplication from being made, and does not prohibit monitoring. When a digital video signal is scrambled and output, a descrambler is provided on the display to scramble the scramble. It becomes impossible to monitor.

  Accordingly, it is an object of the present invention to provide a digital VTR that can prevent illegal duplication in other VTRs and that is allowed to be reproduced in a device unrelated to duplication such as a display.

  In the digital VTR in which the playback digital video signal is scrambled and output when copyright protection is required, the control bit information for copyright protection and the connected device This is a digital VTR that is scrambled according to the type of information.

  The present invention is connected to detection means for detecting a control bit for copyright protection in a digital VTR which scrambles and outputs a reproduced digital video signal when copyright protection is required. A device specifying means for specifying the type of the connected device, a scramble means for scrambling the reproduction signal with the key signal, a key signal from the connected device, and an internal key signal are selectively supplied to the scramble means. The digital VTR includes a selection unit, and controls the selection unit according to the control bit for protecting the copyright and the type of the connected device to perform the scramble process.

  The present invention is connected to detection means for detecting a control bit for copyright protection in a digital VTR which scrambles and outputs a reproduced digital video signal when copyright protection is required. Control for copyright protection, comprising device specifying means for specifying the type of the device being scrambled, scrambling means for scrambling the playback signal by the key signal, and selection means for selectively outputting the key signal to the outside This is a digital VTR that is scrambled by controlling the selection means in accordance with the bit and the type of connected device.

  Since scrambling is controlled according to the type of connected device, illegal duplication in other VTRs is prevented, and reproduction is permitted in a device unrelated to duplication such as a display.

  As described above, according to the present invention, since scrambling is controlled according to the type of connected device, illegal duplication in other VTRs can be prevented and, for example, display is not related to duplication. There is an effect that reproduction is permitted in the apparatus.

  An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of the present invention. In FIG. 1, 1 is a reproduction-side VTR, 2 is a display, and 3 is a recording-side VTR. In the VTR 1 on the reproduction side, 19 is an analog video signal output terminal, 20 is a digital video signal output terminal, 21 is a key signal input terminal, and 23 is an ID signal input terminal. In the display 2, 31 is a digital video signal input terminal, 32 is a key signal output terminal, and 33 is an ID signal output terminal. In the VTR 3 on the recording side, 41 is an input terminal for a digital video signal.

  The digital video signal output terminal 20 of the reproduction side VTR 1 is connected to the digital video signal input terminal 31 of the display 2 and also connected to the digital video signal input terminal 41 of the recording side VTR 3. The key signal input terminal 21 of the recording side VTR 1 and the key signal output terminal 32 of the display 2 are connected. The ID signal input terminal 23 of the reproduction side VTR 1 and the signal output terminal 33 of the display 3 are connected.

  In this example, the playback signal of the VTR 1 on the playback side can be monitored on the display 2 and recording on the VTR 3 on the recording side is prohibited.

  In the VTR 1 on the recording side, a digital video signal is compressed and recorded on the tape 11 using a high efficiency code such as DCT. This digital video signal must be prohibited from being copied for copyright protection. Thus, when the recording signal of the tape 11 needs to protect the copyright, a copyright bit is set in the reproduction signal.

  The reproduction signal of the tape 11 is reproduced by the head 12 and supplied to the signal processing circuit 13. The signal processing circuit 13 performs signal processing such as error correction coding processing and inverse DCT conversion, and a baseband digital video signal is output from the signal processing circuit 13. The digital video signal from the signal processing circuit 13 is supplied to the D / A converter 24 and also supplied to the scrambler 14.

  The output of the signal processing circuit 13 is supplied to the ID decoder 15. The ID decoder 15 detects whether or not the copyright bit in the reproduction signal from the tape 11 is set. The output of the ID decoder 15 is supplied to the switch controller 17. The switch controller 17 is supplied with the output of the ID detection circuit 22. An ID signal indicating the type of device is supplied to the ID detection circuit 22 from an ID signal input terminal 23. The ID detection circuit 22 detects the type of device connected based on this ID signal.

  The switch controller 17 forms a switch control signal based on the information on the presence / absence of the copyright bit obtained from the ID decoder 15 and the information on the connected device obtained from the ID detection circuit 22. This switch control signal is supplied to the switch circuit 16. When the copyright bit is set and the connected device is a display, the switch circuit 16 is set to the terminal 16B side. If the copyright bit is set but the connected device is not a display, the switch circuit 16 is set to the terminal 16A side.

  The digital video signal is converted into an analog video signal by the D / A converter 24. This analog video signal is output from the analog output terminal 19. A key signal is supplied to the scrambler 14 via the switch circuit 16. The key signal from the key signal generation circuit 18 is supplied to the terminal 16A of the switch circuit 16. The key signal from the key signal input terminal 21 is supplied to the terminal 16B of the switch circuit 16.

  The digital video signal from the signal processing circuit 13 is scrambled by the key signal from the switch circuit 16. The scrambled digital video signal is supplied to the digital video signal output terminal 20.

  Now, assume that the copyright bit of the reproduction signal of the tape 11 is set. Then, it is assumed that an ID signal indicating a display is generated from the ID generation circuit 37 of the display 2 and this ID signal is detected by the ID detection circuit 22 of the VTR 1. At this time, the switch circuit 16 is set to the terminal 16B side.

  When the switch circuit 16 is set to the terminal 16B side, the key signal K1 generated from the key signal generation circuit 36 of the display 2 is sent to the scrambler 14 via the switch circuit 16 of the VTR1. Therefore, the output video signal is scrambled with the key K1.

  In the display 2, the digital video signal input terminal 31 receives the scrambled digital video signal from the VTR 1 on the reproduction side. A signal from the input terminal 31 is supplied to a descrambler 34. The descrambler 34 is supplied with a key signal K1 from a key signal generation circuit 36.

  As described above, the input digital video signal is scrambled by the key signal K 1 from the key signal generation circuit 36. The same key signal K1 is sent to the descrambler 34. Therefore, the descrambler 34 can unscramble.

  The descrambler 34 unscrambles the digital video signal. The output of the descrambler 34 is supplied to the signal processing circuit 35. The output of the signal processing circuit 35 is supplied to the CRT 38. A video screen based on the recording signal of the tape 11 is reproduced by the CRT 38.

  The scrambled digital video signal is supplied to the video signal input terminal 41 of the recording side VTR 3 from the playback side VTR 1. This digital video signal is supplied from the input terminal 41 to the signal processing circuit 42. Since the input signal is scrambled, the signal processing circuit 42 cannot reproduce the video signal. For this reason, even if the output of the signal processing circuit 42 is recorded on the tape 44 by the head 43, a copy of the tape 11 of the recording side VTR 1 cannot be created.

  As described above, in one embodiment of the present invention, reproduction on the display 2 can be performed while prohibiting creation of an illegal copy, such as creating a copy of the tape 11 of the VTR 1 on the reproduction side, on the VTR 3 on the recording side. The

  In the above-described embodiment, in the VTR 1 on the reproduction side, the digital video signal is expanded by the signal processing circuit 13 and scrambled with respect to the baseband digital video signal. However, the compressed digital video signal may be scrambled and output from the digital video signal output terminal 20.

  FIG. 2 shows another embodiment of the present invention. In the above-described embodiment, the key signal generating circuit 36 is provided on the display 2 side, and the digital video signal is scrambled using the key signal on the display 2 side. In this embodiment, the key signal on the VTR 1 side is used. The key signal from the generation circuit 18 is used for scrambling.

  That is, the switch controller 17 forms a switch control signal based on the information on the presence / absence of the copyright bit obtained from the ID decoder 15 and the information on the connected device obtained from the ID detection circuit 22. This switch control signal is supplied to the switch circuit 26. When the copyright bit is set and the connected device is a display, the switch circuit 16 is turned on, and the key signal K1 from the key signal generation circuit 18 is sent from the output terminal 21 via the switch circuit 26. Is output. This key signal is supplied to the descrambler 34 of the display 2. Therefore, the scramble can be solved on the display 2 side.

  In this embodiment as well, it goes without saying that the compressed digital video signal may be scrambled and output from the digital video signal output terminal 20.

  In the above description, only the display can be played back, and playback is prohibited in other VTRs. However, what can be played back is not limited to the display. For example, it is possible to create a system that permits copying only with a specific VTR.

  According to the present invention, since scrambling is controlled according to the type of connected device, illegal copying in other VTRs is prevented, and playback is permitted in a device unrelated to copying, such as a display. Is done.

It is a block diagram of one Example of this invention. It is a block diagram of the other Example of this invention.

Explanation of symbols

14 scrambler 15 ID decoder 16 switch circuit 18 key signal generating circuit 30 descrambler 36 key signal generating circuit

Claims (5)

When copyright protection is required, in a digital VTR that scrambles and outputs a playback digital video signal,
A digital VTR that is scrambled in accordance with control bit information for copyright protection and information on the type of connected device. When copyright protection is required, in a digital VTR that scrambles and outputs a playback digital video signal,
Detection means for detecting control bits for copyright protection;
Device identification means for identifying the type of connected device;
Scrambling means for scrambling the playback signal with a key signal;
A selection means for selectively supplying a key signal from the connected device and an internal key signal to the scramble means;
A digital VTR in which the selection means is controlled and scrambled according to the control bit for protecting the copyright and the type of the connected device. When copyright protection is required, in a digital VTR that scrambles and outputs a playback digital video signal,
Detection means for detecting control bits for copyright protection;
Device identification means for identifying the type of connected device;
Scrambling means for scrambling the playback signal with a key signal;
Selecting means for selectively outputting a key signal to the outside,
A digital VTR in which the selection means is controlled and scrambled according to the control bit for protecting the copyright and the type of the connected device.   4. The digital VTR according to claim 1, wherein the digital video signal output after being scrambled is a baseband digital video signal.   4. The digital VTR according to claim 1, wherein the digital video signal to be output after being scrambled is a compressed digital video signal.

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