JP3676679B2 - Method and apparatus for transferring data with a video signal so that no data is recorded - Google Patents

Description

[0001]
The present invention relates to video, and more particularly to transferring data in a video signal so that the data is not recorded by a standard video recorder.
[0002]
[Background of the invention]
The inventors of the present invention can receive and use additional information (data) that can be received and used by a receiving device (eg, a TV set or display device), eg, not recorded by a standard video recorder for security reasons. It has been recognized that it would be desirable to have the ability to change the video signal so that the signal is transferred.
[0003]
This problem of transferring video data without recording seems to have not been recognized since early. For example, a vertical blanking interval of a video signal may be used to transfer (non-video) data such as a closed title, but a standard VHS type VCR is Record the VBI and the data. However, current digital video recorders do not record VBI. Future digital recorders, for example, record only the amplitude portion of VBI.
[0004]
[Summary of Invention]
In the present invention, the transfer to the receiving device (eg, transfer between coaxial cables) generally remains, and any data in a portion of the video signal that is not recorded by some general or standard video recording or storage device How to arrange is disclosed.
[0005]
The data is used by non-recording devices such as on demand (compatible) TV sets, for example for video signal control or descrambling. This approach is not limited to specific video or TV standard devices.
[0006]
[Embodiment of the Invention]
Some video (eg, television) systems, including scrambling systems, pass data in either clear or encrypted text during the vertical blanking period of the video signal. (This data is usually not part of or required for a video image)
See, for example, US Patent Application “Method and Apparatus for Scrambling High-Definition Television Signals,” which is incorporated herein by reference in its entirety, and which is shared by Pending and Ryan et al. N. , Filed January 14, 2000, attorney document number M-8137US.
[0007]
In this case, a system using encryption is based on a receiving apparatus having a unique key decryption technique. In consumer electronic device applications, the management of these keys for large numbers of devices causes significant costs to be incurred. In many cases, system security that is sufficient at low cost can be created with a small number of re-used keys. In order to provide benefits to copyright holders (which refers to copyrights relating to video content), it is desirable to recommend not recording certain types of video content from video players or set-top boxes.
[0008]
FIG. 1A shows that a video display device or cable TV set-top box 14 scrambles the output video and uses the descrambling key while the display device 18 (TV set) on demand descrambles the video for display purposes. It shows the desired connection to provide.
[0009]
As shown in the related FIG. 1B, without the technique of the present invention, the device 14 can scramble the video while the video can still be recorded and additional copies can be recorded in multiple recording / It is created by using a playback device (device 13 or the like).
[0010]
Each of these copies can be played back on (recording) device 13 and viewed on display device 18. From the copyright owner's point of view, this is not desirable and is an act of ruining the method of the present invention. In FIG. 1B, a non-demanding device such as device 13 records the video and its vertical and / or horizontal blanking period.
[0011]
By recording the entire video stream including the descrambling key shown in FIG. 1A as “analog video scrambled with data”, device 13 is a problem for the copyright owner. The resulting video recording can still be played back on the (problem) playback device 13 (video recorder) that does not meet the requirements, and is shown as “scrambled video” in FIG. 1B. The signal can still be seen on the display device 18 as required, as shown in FIG.
[0012]
Accordingly, the present invention is directed to a method and apparatus for hiding or hiding data (such as encryption or descrambling keys) in a video signal. This prevents hidden data from being recorded by the standard (not on demand) video recorder in question.
[0013]
That is, only a special (not on demand) video receiver or recorder can extract and use the hidden data. This approach is not limited to high definition television (HDTV), as disclosed in the above referenced pending application, and is generally applicable to situations using analog video transfer with digital video storage / recording can do.
[0014]
The method for high definition television (pending application) is an example of this approach. Here, by shifting the position (in time) of the edge of the sync pulse in a predetermined manner, a significant screen flickering indicator (active video time shifting for scrambling) is transmitted as hidden data. Is done. The edge position of the shifted sync pulse represents an encoded variation of “hidden” data.
[0015]
More generally, when it is desirable to control the use (eg, recording or display) of a video signal during reception, and in particular, control data (“hidden” by the standard video recorder in question (not on demand). This approach is effective when the “data” itself is not easily recorded.
[0016]
As shown in FIG. 1C (similar to FIG. 1B), many types of current standard NTSC and PAL video recording / playback devices 12 are available on demand video players or set-top boxes. Erase the vertical and horizontal blanking periods of the scrambled analog video signal output from (source) 14. This has the advantage of automatically removing the associated hidden data located in the blanking period.
[0017]
In the case shown in FIG. 1C, the scrambled analog video signal without scrambled ring data transferred from the non-problematic recording / playback device (recorder) 12 to the display device 18 (TV set) is thereby Cannot descramble. This is because the recording action by the device 12 removes the hidden data which is the descrambling key. The purpose of preventing recording is now achieved.
[0018]
Thus, FIG. 1C generally shows the results intended by the present invention. Here, a video signal that does not record “hidden” data in the scrambled analog video and cannot de-scramble any video recording because there is no essential unrecorded descrambling key It becomes. This actually prevents unauthorized recording.
[0019]
In contrast, the recording device 13 in question, as in FIG. 1B, can record hidden data, if available, so that it can be passed along the display device 18 during playback. .
[0020]
Other suitable data concealment methods (in addition to placement in the blanking interval) are: (1) use of a high frequency carrier that is within the transmission bandwidth of the video cable and outside the bandwidth of the storage device; Phase modulation of the sync pulse of the video signal, as in the referenced pending application. All variations of the above technique may be applied to chromaticity signals as well as luminance signals.
[0021]
For high-definition televisions that compete with NTSC / PAL video, the above-described method of using any part of the blanking interval to hide data is commercially utilized by high-definition video recorders. It may not be suitable because it is not. These recorders may be newly designed to record the effective display area and the horizontal and vertical blanking periods. This conventionally includes encoded data in the vertical blanking interval.
[0022]
These types of recorders, for example, record a portion of the video signal going from a blanking (or black) level to a peak white level (including a blanking period) with some margin for overshoot. . For example, the CCIR-601 standard defines an 8-bit number system for transferring digital component video signals.
[0023]
Here, the black level is represented by level 16 of 256 possible levels (10 hex) and the white level is represented by level 235 (EBhex). In this case, levels from 1 to 254 (01hex to FEhex) are considered legal, and levels from 0 and 255 (00hex and FFhex) are reserved for the transfer of sync words.
[0024]
An analog representation of the waveform of such a typical (conventional) high definition video signal is shown in FIG. Here, the associated voltage levels are shown as voltage (right margin) and digital value (left margin). FIG. 2 shows the start of one video line (without actual display information) and the next video line, thereby including two horizontal sync pulses.
[0025]
One way to achieve the data placement of the present invention that is effective with such standard video recorders is to place the data signal in a portion of the video signal (in terms of amplitude). Here, the video signal is generally reserved for sync pulses (sync), ie, blanking or pulses that fall from the black level to the sync chip level. This is outside the amplitude range recorded by the potential HD video recorder described above.
[0026]
For example, a PAL video signal with blanking at 0 volts has a sync tip at -300 millivolts. Also, for example, a 525 sequential, 720 sequential, 1080 interlaced or 1080 sequential analog component video signal (HDTV) has a next blanking of 0 volts and a sync chip of -300 millivolts as shown in FIG. Follow EIA-770. A standard three level sync pulse for HDTV is shown in FIG.
[0027]
This data concealment method allows only the corresponding digital component video signal (eg according to CCIR-601, SMPTE 274M, 293M or 296M) to represent those portions of the analog video signal down to about -48 millivolts (01 hex). Therefore, it is effective. (This assumes that at some point in the recording device, the video signal is of course digitized.)
Subsequent analog video levels need to be clipped when digitized (see FIG. 2) and represented (in the digital domain) as the smallest possible value 01 hex (8 bits). Thus, information in analog video signals below -48 millivolts is lost when converted to a digital representation of a CCIR-601 type signal.
[0028]
Therefore, when this digital component video signal is converted to analog form, it is not possible to produce a negative going pulse with sufficient amplitude. In most cases, in the digital video domain, it is the responsibility of certain integrated circuits to receive certain sync words (values) and convert them to analog sync pulses with sufficient negative amplitude. A specific sequence of FFhex and 00hex, and additional bytes may be used to indicate the start of lines, fields or vertical blanking periods and their end.
[0029]
Thus, a device that converts analog video to digital component video for internal recording and processing (eg, some video recorders), such as recording device 12 in FIG. Essentially remove hidden hidden data.
[0030]
In particular, data transferred in this manner is generally not available in digital video formats that are valid for handling by software. The insensitivity of software greatly expands the scrambling system.
[0031]
For more details, refer to FIG. 3, which shows a waveform related to the waveform of FIG. 2, which is a vertical blanking period of a typical analog component video signal according to the EIA-770.1 HDTV standard (FIG. A plurality of video lines including the upper part of FIG.
[0032]
The lower part of FIG. 3 shows the same waveform (hatching) of possible data hiding arrangements according to the invention. The illustrated data hiding arrangements are all below the blanking level and in VBI. FIG. 3 is for the luminance component of the video signal. The data itself may be encoded in a convenient digital communication format consistent with the general representation shown in FIG. FIG. 3 shows a possible arrangement (hatching area) in the VBI for the data packet shown in FIG.
[0033]
Thus, FIG. 3 shows how the vertical blanking period is for placing data (hatched area) that is not recorded because it is VBI (or HBI) and because it is below the blanking level. Indicates what is used (bottom). Some digital recorders play VBI and do not play back below the blanking level.
[0034]
FIG. 4 shows an example of a typical video line of FIG. Here, data is appended according to the present invention, and therefore corresponds to one of the hatched regions in FIG. 3 with the ongoing and subsequent sync pulses. In this case, the line is in VBI (see FIG. 3), and the example representing 8-bit concealment data “payload” with a value of 00001100 (in binary) is a change where there is a normal horizontal sync pulse in this line of VBI It is shown.
[0035]
This digital representation of Oline includes several values with the following hex values. Sample down to 10, 01, line reminder at 01, sample down to 10, 10. Analog signal levels below the digitization threshold (here 01 hex) are clipped when digitized. Naturally clipped values are thereby removed (not recorded by standard recorders that perform digitization).
[0036]
FIG. 5 shows a block diagram of a typical video encoder that may be an IC (integrated circuit) that converts Y, Cb, Cr and synchronous multiplexed component video to Y, Pb, Cr component video. Such encoders are used in cable TV set-top boxes or video recorders.
[0037]
In some cases, these ICs have six digital-to-analog converters: composite (NTSC or PAL), S-Video (brightness and chromaticity), and component video (Y / Pb / Pr or GBR). ing. FIG. 5 shows a modification of three component DACs (having digital-analog converters 40a, 40b, 40c).
[0038]
The digital encoder of FIG. 5 includes an exemplary input multiplexed component video bus 30 that transfers Y, Cb, Cr, and synchronized video components to the demultiplexer input port and video sync generation circuit 34. The resulting output component video from the demultiplexer 34 is directed to a sync processor 38 that adds a sync component to a Y component. The resulting Y, Cb, Cr components are converted to analog video components Y, Pb, Pr by digital-to-analog converters 40a, 40b, 40C, respectively.
[0039]
FIG. 6 shows a modified variant of the encoder of FIG. 5 that functionally adds encoded data as additional synchronization pulses in the VBI as shown in FIG. The encoder of FIG. 6 includes an additional timing and video sync generation circuit 44. The circuit 44 includes a shift register 45a that supplies serial data to the input terminal of the pulse shaping filter 45b. The circuit 44 is connected to a data register (memory) 48 that receives data concealed at its input port 46 for insertion into the VBI portion of the video signal.
[0040]
A complementary decoder (assembled, eg, the display device 18 in response to the request in FIG. 1C) receives the modified video signal transferred from the encoder of FIG. 6 and extracts the added data signal; The video and extracted data are for example supplied separately to the descrambler. In the descrambler, the extracted data is used as a descrambling key.
[0041]
The above described alternative method of placing data in a video signal using a high frequency carrier to “hide” the data can be understood by referring to FIG. In general, video recorders either use video sampling prior to recording, or have some limited bandwidth over which analog information can be recorded. FIG. 7A shows video signal frequency (horizontal axis) versus signal amplitude (vertical axis). In general, video transmission media such as coaxial cables have a wider bandwidth than standard recording devices have.
[0042]
As shown in FIG. 7 (A), the data is concentrated in the high region of the spectrum (shown as fdata in FIG. 7 (A)) and due to its inherent data storage limitations Is converted to a format that is transferred in a high frequency band fdata that cannot react (record). (Storage capacity is a finite resource that must always be reserved.) Thus, this provides data to the recorder across the transfer media so that the recorder cannot record.
[0043]
As described above, this is desirable to prevent the recording of certain types of concealment data. Clearly it is useful that the video device on demand (eg, TV set) must respond to the video signal at the carrier frequency fdata and include an appropriate data demodulator. Appropriate demodulation techniques are well known.
[0044]
FIG. 7B shows such an encoder for performing the technique of FIG. This encoder is typically present in a source device such as a set top box or video player 14 of the type in FIG. The incoming video, which is a standard video, is applied at terminal 52.
[0045]
Note that this encoder is typically used for each video component into which data is inserted. Note that typical appended data is applied to only one component of the video. The necessary analog-to-digital or digital-to-analog conversion has been shown conventionally.
[0046]
The incoming video applied at terminal 52 is connected at node 54 to a typical sync separator 56. The video input at the node 54 is applied to one input terminal of the summer 78. The horizontal and vertical separated blanking pulses (in the digital domain) from the sync separator 56 are applied to the load / shift control terminal of a typical shift register 60.
[0047]
At the same time, input data (eg, descrambling or decryption key) is generated externally by one of the usual methods and is an input terminal that is an input terminal to the buffer 64 as a parallel multi-bit signal 62 is applied.
[0048]
The output signal from the buffer 64 is parallel data applied in parallel at the terminal of the shift register 60. This input data responds to the applied horizontal and vertical blanking pulses and is output as serial output data to one input terminal of the modulator 68.
[0049]
The other input terminal of the modulator 68 is connected to an oscillator 70 that operates at the frequency fdata. The modulator 68 is any suitable type of modulator using, for example, FM, AM, FSK, PSK, QPSK, or the like. The modulated serial data output from the modulator 68 is applied to the other input terminal of the summer 78. The summer 78 outputs the combined input video and out-of-band data to its output terminal 80.
[0050]
A complementary decoder typically present in a display device (TV set) 18 that meets the type requirements in FIG. 1 (C) is shown in FIG. 7 (C). Input video and data, which are essentially the same signals as the output of the terminal 80 of the encoder of FIG.
[0051]
This combined video and data signal is connected to an arbitrary low-pass filter 96 and output as an output video at a terminal 100. At the same time, the input video at terminal 90 is applied at node 92 to the input terminal of a typical sync separator 94. Furthermore, the required analog-to-digital or digital-to-analog conversion has been shown conventionally. The input video is typically one component of component video and is a component that transfers data.
[0052]
The signals output from the sync separator 94 are horizontal and vertical blanking pulses, which are applied to the shift / load control terminal of the shift register 112. At the same time, the input video and data signal at terminal 90 are applied to the input terminal of bandpass filter 104. The band pass filter 104 outputs the filtered signal to the input terminal of the demodulator 110.
[0053]
Demodulator 110 is complementary to modulator 68 in the encoder of FIG. The other input terminal of the demodulator 110 is connected to an oscillator 106 that outputs a signal at a preset frequency fdata to match the frequency of the encoder.
[0054]
The resulting serial data output from the demodulator 110 is applied to the serial input terminal of the shift register 112. The shift register 112 outputs output parallel data to the input terminal of the buffer 118 in response to a control signal applied at the shift / load terminal.
[0055]
The buffer 118 outputs the separated output data required for descrambling at its terminal 120, for example. Thus, the device on demand has the video at terminal 100 and the data at terminal 120 (the descrambling key), respectively, and can typically perform descrambling by any algorithm associated with the scrambling technique. it can.
[0056]
While the above method is for most of the modifications to the luminance video signal component, it can also be applied to the chrominance video signal component.
[0057]
Chroma components (eg, Cr, Cb) are baseband signals that are just luma components. Chroma components can be modified or added in a manner similar to luma components. In particular, the chroma component includes VBI and HBI portions: the chroma component does not typically include such a sync pulse, but can have an added pulse. In addition, the chromaticity component also has a high frequency component that is added in a manner as shown in FIG.
[0058]
Another approach to data transfer in a “hidden” (non-recordable) manner is to modulate the position of a typical sync pulse edge over time. Most digital video recorders do not record a horizontal sync signal, but instead extract low frequency timing information from the horizontal sync signal and replay and reinsert it during playback.
[0059]
By creating the phase modulation synchronization signal, information can be transferred between transfer media not recorded by the recording device. (This is the method described above, which is a pending application by Ryan et al.)
FIG. 8A shows a typical 3-level sync pulse for HDTV, as also shown in FIG. In FIG. 8B, the sync pulse of FIG. 8A is modified by the present invention so that the rising edge of the modified 3-level sync pulse remains in the same type of position.
[0060]
On the other hand, the rising edge and the subsequent falling edge are modulated after a considerable time. Similarly, in FIG. 8C, the two falling edges in the modified sync pulse are delayed in time. This type of code system uses the modulated edge position to transfer the descrambling key to an appropriate decoder, allowing descrambling of the accompanying video signal. Or, the difference between these types of sync pulses can be used to transfer other information. That is, the modulated edge position represents a descrambling key value. This is the synchronous edge modulation technique disclosed in the above-mentioned patent application.
[0061]
Further modifications will be apparent to those having ordinary skill in the art in light of this disclosure. Therefore, the above description and illustrations should not be construed as limiting the scope of the invention which is defined by the appended claims.
[Brief description of the drawings]
FIG. 1 (A) shows a general system for playback of scrambled analog video. FIG. 1B shows the overall system of FIG. 1A with records demonstrating the technical problem of the recording / playback device in question. FIG. 1C shows a recording system having no problem.
FIG. 2 shows a prior art video waveform.
FIG. 3 shows a modified vertical blanking interval (VBI) waveform.
FIG. 4 shows another modified VBI waveform.
FIG. 5 shows a conventional video encoder.
FIG. 6 shows a modified video encoder.
FIG. 7A shows a frequency spectrum for data arrangement. 7B and 7C show an encoder and a decoder for executing the method of FIG. 7A, respectively.
FIGS. 8A, 8B, and 8C show synchronous modulation for data placement. FIG.

Claims (8)

A method of transferring the data by a video signal, the data being data not recorded by a specific video recorder ,
Providing the data;
Encoding the data;
Changing a predetermined portion of the blanking period of the video signal by inserting the encoded data into the video signal ;
Transferring the modified video signal via an analog video transmission line ,
The method , wherein the blanking period of the modified video signal is not recorded by a particular video recorder. The predetermined portion is below a selected voltage level;
The method of claim 1 . The predetermined portion is at or above a predetermined frequency;
The method of claim 1 . A method of receiving data with a modified video signal, the data being encoded in a blanking period of the modified video signal and not recorded by a particular video recorder,
Receiving the modified video signal via an analog video transmission line;
Transferring the video portion of the modified video signal;
Extracting encoded data from a blanking interval of the modified video signal;
Decoding the extracted encoded data;
A method comprising: An encoder for transferring data encoded with a video signal, the data being data not recorded by a specific video recorder;
An input video terminal for receiving the video signal;
An input data terminal for receiving the data;
A sync separator connected to the input video terminal;
An encoding circuit connected to the data input terminal and the sync separator for encoding the data;
Connected to the encoding circuit and the input video terminal, changes a predetermined part of the blanking period of the video signal according to the encoded data, and outputs the changed video signal via an analog video transmission line And a totalizer
The encoder, wherein the changed blanking period of the video signal is not recorded by the specific video recorder . The predetermined portion is below a selected voltage level;
The encoder according to claim 5 . The predetermined portion is at or above a predetermined frequency;
The encoder according to claim 5 . A decoder for receiving the data with a modified video signal, wherein the data is data not encoded by a particular video recorder encoded in a blanking period of the modified video signal;
A video input terminal for receiving the modified video signal via an analog video transmission line;
A video output terminal connected to the input terminal;
An extraction circuit that has an input terminal connected to the video input terminal and extracts the data from a blanking period of the changed video signal;
And a data output terminal connected to the extraction circuit and outputting the extracted data .

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