JP3337019B2 - Video signal format conversion circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generates a video signal of a video signal system different from a standard television signal from a digital video signal, adjusts a time delay by a delay element of a filter circuit, and outputs the adjusted signal. The present invention relates to a video signal format conversion circuit configured to perform video signal modification for preventing duplication of any video signal.

[0002]

2. Description of the Related Art In a conventional video signal format conversion circuit, video output is based on a standard television signal format. However, depending on the market, not only the standard television signal system but also standard television such as a luminance / color difference signal or an RGB signal may be used in response to recent demands for higher image quality or system or device configuration and connection. Video equipment that handles a video signal system different from the signal system has appeared.

On the other hand, with the spread of devices for recording and reproducing video signals such as VTRs, for example, from the viewpoint of copyright protection of video software, for example, a video signal modification method of Macrovision Corporation (US Pat. 4631603,
Nos. 4577216 and 4819098) are known. Such duplication prevention by video signal modification is applied to a standard television signal system and is often applied at the time of signal system conversion, but there is no example implemented for a non-standard television signal.

[0004]

In order to cope with these systems, it has become necessary to perform signal system conversion corresponding to a non-standard television signal system. In addition, non-copyright protection of non-standard television signals and the like is obviously disadvantageous in terms of protection of intellectual property rights. Therefore, it has been necessary to apply a video signal modification for preventing duplication to a video signal of a non-standard television signal system.

An object of the present invention is to solve such a problem,
Converts and outputs a video signal of a standard television signal format and a video signal of a second video signal format from a digital video signal of the first video signal format, and prevents duplication of any of the video signal formats. The object of the present invention is to provide a video signal conversion circuit capable of applying a video signal modification for a video signal.

[0006]

In order to achieve the above object, the present invention provides a method for converting a digital video signal into an analog video signal.
Video signal format conversion circuit that converts the
Digital luminance signal and first and second digital color difference signals
A signal conversion matrix circuit that outputs
Outputs a standard television video signal as a signal
In this case, the band limit of the first and second digital color difference signals is
Filter with multiple time delay elements used for
To avoid duplication of analog video signals
At least modifying means for modifying the digital luminance signal.
The analog video signal of the non-standard television system.
When outputting a video signal, the time delay element of the filtering circuit
Is used as a delay circuit.
Be configured as follows. The modifying means is the first digital color difference.
Try to modify the signal as well.

[0007] By doing so, the digital video signal of the first video signal system is converted into a video signal of the standard television signal system and a video signal of the second video signal system with a minimum circuit configuration. This makes it possible to apply video signal modification to any video signal format to prevent duplication.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. In the following embodiments, the first video signal system is a time-sequentialized digital luminance signal and color difference signal, the converted second video signal system is an analog signal format, and the standard television signal is mainly The following describes an example in which the NTSC system is used and the macro vision system is used as a method for preventing duplication. More specifically, the first video signal system is a digital video signal stream according to the CCIR-601 standard, the second video signal system is an analog YUV signal, and the standard television signal is an NTSC system. Is taken as an example.
Explain the light. When a standard television signal is output
Signal in the form of a luminance / color difference signal and composite signal
Is output.

FIG. 1 is a block diagram showing an embodiment of a video signal conversion circuit according to the present invention, wherein 1, 2, 3, 7, 8,
19, 20, 21 and 49 are signal input terminals, 4 is a clock generation circuit, 5 is a synchronization signal generation circuit, 6 is a matrix circuit, 9 is a latch circuit, 9, 10, 11, 27 is a latch circuit, 12 is a delay circuit, 13, 14, 38, 39 and 40 are signal interpolation circuits,
5, 16, and 17 are signal level conversion circuits, 18 is a serial signal circuit that receives a command from a microcomputer (not shown), 22, 23, 24, 28, 31, 34, and 3
6, 41, 42, 50, 51 and 52 are selectors,
When the selection signal S is "1", the input B is output to the output O. When the selection signal S is "0", the input A is output to the output O.
6 is a filtering circuit composed of a plurality of time delay elements and the like;
0 is a multiplier (multiplication) circuit, 32, 37, 4
Reference numerals 3 and 44 denote adder circuits; 33 denotes a duplication preventing signal generating circuit that generates a signal for modifying a video signal to prevent duplication;
Is a synchronizing signal gradient generating circuit, 53, 54, and 55 are DA converter circuits, and 56, 57, and 58 are output circuits. FIG. 2 is a signal waveform diagram of a digital video signal stream according to the CCIR-601 standard input to the input terminal 1 or 7.

First, the case of outputting a normal standard television signal will be described. In FIG. 1, a clock signal serving as a system reference is input from an input terminal 2, a reset signal for initializing a system state is input from an input terminal 3, and a clock signal and a reset signal are supplied to various parts of the system by a clock signal generation circuit 4. (Not shown). Input terminals 19, 2 from a microcomputer (not shown)
Mode setting signals and the like are input to the serial signal circuit via 0 and 21 to set the mode of each part of the system (only a part is shown). The signal shown in FIG. 2 is input from the input terminal 1 or 7. The 8-bit mode or the 16-bit mode in FIG.
Input to the matrix circuit 6.

In the matrix circuit 6, a latch circuit 9,
The signals Y, Cb, and C are obtained from the time series by
r, and the outputs of the latch circuits 10 and 11 are interpolated by the signal interpolation circuits 13 and 14 to the same number as the number of pixels of the luminance signal. The luminance signal Y is delayed by a predetermined time in the delay circuit 12 in order to correct the time delay of the signal in the signal interpolation circuits 13 and 14. The outputs of the delay circuit 12 and the signal interpolation circuits 13 and 14 are converted by a signal level conversion circuit into a signal level suitable for signal processing and, at the same time, multiplied by a predetermined coefficient, thereby being converted into a YUV signal. The outputs U and V of the level signal conversion circuits 16 and 17 are
The signals are supplied to filtering circuits 25 and 26 for band limitation.

Here, a video signal modification method of Macrovision Inc. (US Pat. Nos. 4,631,603 and 4,577,216).
No. 4819098), the method for preventing duplication includes:
A pulse whose pulse height changes within a range in which the pulse height exceeds the video signal level or is equal to the pedestal level is applied to the luminance signal, thereby causing the AGC of the video signal recording / reproducing apparatus to malfunction. Further, by inverting the phase of the chrominance subcarrier serving as a reference for color signal processing only in a plurality of horizontal synchronization signal periods in a predetermined horizontal synchronization signal period, a malfunction of the color signal processing circuit of the video signal recording / reproducing apparatus is caused. And other methods.

In order to realize these, the duplication preventing signal generating circuit 33 controls the selectors 22, 23, 24 and 28 to modify the color signals. The luminance signal is delayed by the latch circuit 27 so as to provide a corresponding delay to the luminance signal. The outputs of the latch circuit 27 and the selector 28 are multiplied by the cosine wave signal cos and the sine wave signal sin from the color subcarrier generation circuit (not shown) by the multiplier circuits 29 and 30, and added by the addition circuit 32 to obtain the color. Converted to a signal.

On the other hand, a synchronizing signal is added to the luminance signal Y by a synchronizing signal gradient generating circuit 35 and a selector 36. Further, the pulse signal from the duplication prevention signal generation circuit 33 is added by the addition circuit 37 here. Thus, the modification of the video signal is completed by the duplication prevention signal. These modifications can be added or canceled by mode setting from a microcomputer (not shown).

After the luminance signal and the chrominance signal processed as described above are subjected to pixel interpolation by the signal interpolation circuits 38 and 40, the luminance signal is converted into an analog signal by the DA conversion circuit 53 via the selector 50 and output. Output to terminal 56. After the color signal is added with the offset value by the adding circuit 43, it is converted to an analog signal by the DA converter 55 via the selector 52, and output from the output terminal 58. The luminance signal and the chrominance signal pass through selectors 41 and 42,
4 and becomes a composite signal, enters the DA converter circuit 54 via the selector 51, is converted into an analog signal, and is output from the output terminal 57. Here, the selectors 50, 51, 52 are provided with DA conversion circuits 53, 5,
4 and 55 for selecting the signal input for test.
In normal use, the input A is always selected.

Next, the operation of the present invention for outputting a non-standard television signal will be described. 1, a clock signal as a reference of the system is input from an input terminal 2, a reset signal for initializing a system state is input from an input terminal 3, and a clock signal and a reset signal are supplied to various parts of the system by a clock signal generation circuit 4. Supplied (not shown). From a microcomputer (not shown), a mode setting signal or the like is input to the serial signal circuit via input terminals 19, 20, and 21 to set the mode of each part of the system (only a part is shown). Here, the difference from the normal case is that the control signal Y is output to output the YUV signal.
UV is set to “1”. The signal shown in FIG. 2 is input from the input terminal 1 or 7. 2 in FIG.
The bit mode or the 16-bit mode is switched by a signal at the input terminal 8 and is input to the matrix circuit 6.

In the matrix circuit 6, the latch circuit 9,
The signals Y, Cb, and C are obtained from the time series by
r, and the outputs of the latch circuits 10 and 11 are interpolated by the signal interpolation circuits 13 and 14 to the same number as the number of pixels of the luminance signal. The luminance signal Y is delayed by a predetermined time in the delay circuit 12 in order to correct the time delay of the signal in the signal interpolation circuits 13 and 14. The outputs of the delay circuit 12 and the signal interpolation circuits 13 and 14 are converted by a signal level conversion circuit into a signal level suitable for signal processing and, at the same time, multiplied by a predetermined coefficient, thereby being converted into a YUV signal.

When the obtained YUV signal is output,
Not only can the video signal be modified by the duplication prevention signal,
Since the signal processing at the subsequent stage for the luminance signal is different from the signal processing for the color difference signal, the temporal matching between the luminance signal and the color difference signal is broken. Therefore, according to the present invention, the filtering circuits 25, 2
The time matching of the luminance signal and the color difference signal is ensured by using the time delay element of No. 6.

FIG. 3 shows an example of the configuration of a filtering circuit 25 composed of a plurality of time delay elements. Similarly, the filtering circuit 26
Can also be realized with a similar configuration. Since such a filter circuit is a general configuration example of a digital filter, only the operation relating to the present invention will be described here, and the description of the operation as an original filter circuit will be omitted. In the figure, 59 and 60 are input terminals, 61 is an output terminal, 62, 63, 64, 65, 66, 67, 68, 6
9, 70, 71 are time delay elements, 72, 73, 74, 7
5, 76, 77, 78, 79, 80 are addition circuits, 81,
82, 83, 84, 85, 86, 87, 88 and 89 are coefficient units, and 90 and 91 are selectors.

The signal input from the input terminal 60 undergoes a time delay by passing through a time delay element 62 and the like. Originally, a desired filtering characteristic is achieved by multiplying the time-delayed signal by a coefficient and adding it. In the present invention, these time delay elements are used as a delay circuit. Therefore, a level signal of “1” is applied to the input terminal 59 and the selector 9
By switching between 0 and 91, the time delay elements are reconnected in series. The operation is clear from FIG. Here, an example has been described in which a filtering circuit using ten time delay elements has nine time delay elements connected in series, but the system configuration is not limited to this. That is, in order to obtain desired characteristics for a standard television signal, the number of time delay elements is not limited to the above, and the number of directly connected time delay elements is not limited to the above.
It is sufficient if the number does not exceed the number of time delay elements used for the standard television signal. With this configuration, it is possible to absorb a difference in the amount of time delay in the subsequent stage.

Returning to FIG. 1, the YUV signal obtained by the matrix circuit 6 is input to filtering circuits 25 and 26 for adjusting the time delay, and can absorb the difference in the amount of time delay including the subsequent stage. The output is given only a time delay. The output is input to a selector 31 which selects one of the signals directly for a signal interpolation circuit and the other for a signal subjected to a video signal modification for preventing duplication. Here, when the video signal modification for preventing duplication is not performed, the output of the filtering circuit 26 is directly output, and when the video signal modification for preventing duplication is performed, the output of the filtering circuit 26 and the selector 28 is passed. The output signal is output. The output of the selector 31 is
4 is selected and output from the selector 34, and is input to the signal interpolation circuit 40. Since the luminance signal is the same as in the normal case, the description is omitted.

The signal interpolated by the signal interpolation circuit 39 is selected by the selector 41, added to the offset value selected by the selector 42 and added by the addition circuit 44, and supplied to the DA conversion circuit 54 via the selector 51. , And output from the output terminal 57. The signal interpolated by the signal interpolation circuit 40 is added to the offset value by the addition circuit 43,
The signal is supplied to the A conversion circuit 55 and is output from the output terminal 58 as an analog signal.

Here, the difference in the amount of time delay between the luminance signal and the color difference signal will be briefly described. As is clear from FIG. 1, the difference between the processing of the luminance signal and the processing of the chrominance signal mainly depends on whether the signal has passed through a selector or an addition circuit, and the amount of time delay in each component is at most several clocks or about tens of clocks. is there. On the other hand, the characteristics of the filtering circuit for the standard television signal may directly affect the image quality, and generally require a longer time delay element than the difference in the amount of time delay between the luminance signal and the color difference signal. And

As described above, according to the present invention, a standard television signal and a non-standard television signal are converted from time-series digital luminance signals and color difference signals of the first video signal system. The YUV signal can be output without adding any time delay element, and any video signal output can be subjected to video signal modification for preventing duplication.

Next, a second embodiment of the present invention will be described with reference to FIG. Also in the second embodiment, the first
As in the embodiment, the first video signal system is CCIR-60.
In the case of a digital video signal stream according to one standard, the second video signal system is an analog YUV signal, and the standard television signal is an NTSC system.
Will be described as an example. A standard television signal is output
The form of the luminance / color difference signal and composite signal
Is output .

Here, the difference between the first embodiment and the second embodiment is that the second matrix circuit 45 uses RGB.
Signals can also be selected and output, and this RGB signal can be subjected to video signal modification to prevent duplication. Since a method of generating an RGB signal from a YUV signal is well known, a description thereof will be omitted.

As described above, according to the present invention, a standard television signal and a non-standard television signal are converted from a time-series digital luminance signal and color difference signal of the first video signal system. The RGB signals can be output without adding any time delay element, and any video signal output can be subjected to video signal modification for preventing duplication.

In the above embodiment, the first video signal system is a digital luminance signal and a color difference signal which are time-sequentialized, the second video signal system is an analog signal format, and the standard television signal system is the NTSC system. In the above case, an example in which the macro vision method is used as a method for preventing duplication has been described. However, the present invention is not limited to this, and the video signal format can be appropriately changed from the above embodiment. It is valid. In the above-described embodiment, the macro vision system has been described as an example of the video signal modification system for preventing duplication. However, the present invention is not limited to this, and the present invention is not limited to this case. , Its effectiveness is not diminished.

[0029]

According to the present invention, the first circuit is constructed with a minimum circuit configuration.
Video signal of the standard television signal format and the video signal of the second video signal format can be converted and output from the video signal of the video signal format of any one of the above. Video signal modification for

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of a signal format conversion circuit according to the present invention.

FIG. 2 is a signal waveform diagram illustrating a signal input in an embodiment of the present invention.

FIG. 3 is a block diagram showing an example of a configuration of a filtering circuit including a plurality of time delay elements used in the present invention.

FIG. 4 is a block diagram showing a second embodiment of the signal format conversion circuit according to the present invention.

[Explanation of symbols]

 6 Matrix circuit 25, 26 Filtering circuit

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-98289 (JP, A) JP-A-58-123289 (JP, A) JP-A-63-211981 (JP, A) JP-A-63-1981 107281 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) H04N 5/91, 5/92, 7/01 H04N 7/167, 9/79

Claims (2)

(57) [Claims] 1. A digital video signal is converted into an analog video signal.
A digital luminance signal and first and second digital chrominance signals.
And a signal conversion matrix circuit for outputting video signals of the standard television system as the analog video signals.
When outputting an image signal, the first and second digital
Multiple time delays used for band limiting color difference signals
A filtering circuit composed of a delay element and a small
Modifying means for modifying the digital luminance signal.
And Bei, non-standard television system as the analog video signal
When outputting a video signal, the time delay of the
A video signal format conversion circuit, wherein the element is used as a delay circuit. 2. The video signal format conversion circuit according to claim 1, wherein said modifying means comprises a first digital color difference signal.
A video signal format conversion circuit characterized in that the video signal format conversion circuit is also modified .