JP2005348069A - Copyright signal detection circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem that a threshold value for discriminating closed caption signals superposed on the 21th and 284th line which are blanking periods of a video signal is set as an average value + 20IRE of pedestal levels of several lines in the blanking periods and applied to the 21th line, however, the threshold value does not become the optimal threshold value when a video signal level of the line on which the closed caption signal is superposed changes and detection precision is deteriorated. <P>SOLUTION: Deterioration of detection ratio is suppressed even in the case of the video signal with unstable signal levels since this copyright signal detection circuit is constituted so as to preliminarily calculate threshold levels which change according to levels of the video signal by a slicer 25 from the video signal from an LPF 21 before passing line memories 12, 13 and to detect the closed caption signal by a CC signal detection circuit 20 using the calculated threshold level, utilizing that the line memories 12, 13 for Y/C separation conventionally in the circuit and an LPF 15 in the post-stages. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention belongs to the field of video signal processing, and more particularly to a copyright signal detection circuit that detects a copyright signal superimposed on a video signal, and more particularly, to a non-standard signal (process in which radio waves propagate). Closed caption signal that is a copyright signal that is superimposed during the blanking period of the video signal in the case of a weak electric field signal or a video signal such as a video signal in which interference has occurred in buildings, mountains, etc. It is related with what made it possible to suppress that the detection accuracy of this falls.

  A closed caption signal is a signal that is transmitted by superimposing various information signals such as a character signal and a control signal with a vertical blanking signal in the vertical blanking period of a television signal, and corresponds to a closed caption signal on the receiving side. By providing such a decoder, it is possible to view the original broadcast while displaying the teletext.

  By the way, in a conventional copyright signal detection circuit such as a closed caption signal, an XDS (Extended Data Service) superimposed on the closed caption signal on the 284th line of the video signal using a data buffer memory and There is one that replaces the first and second fields of a video signal by detecting a special signal called (see, for example, Patent Document 1).

  This is because, for example, in video equipment equipped with a system for changing the synchronization signal called TBC (time base collector), the first and second fields are determined based on the video signal before the synchronization signal is changed. If the detection performance of the XDS signal decreases due to noise or the like, the field may be erroneously determined. As a countermeasure, the field is replaced.

The conventional copyright (closed caption) signal detection circuit will be described below with reference to FIGS. 6, 7, and 8. FIG.
In FIG. 6, this conventional copyright signal detection circuit 50 includes a video signal input terminal T1, an A / D conversion circuit 11, line memories 12 and 13, an adder circuit 130, a logical comb filter 14, and an LPF 1 15 A synchronization separation circuit 16, a line counter 17, a pedestal level detection circuit 18, a slicer 19, a CC (Closed Caption) signal detection circuit 20, and a closed caption signal output terminal T2.

The A / D conversion circuit 11 in the copyright signal detection circuit 50 converts the analog video signal s100 from the video signal input terminal T1 into a digital video signal s101.
The line memories 12 and 13 respectively delay the digital video signal S101 from the A / D conversion circuit 11 by one line,

  The addition circuit 130 adds the video signal s102 output from the line memories 12 and 13 and the video signal s101 output from the A / D conversion circuit 11,

  The logical comb filter 14 is a sum signal of the video signal s102 output from the line memories 12 and 13 and the video signal s101 output from the A / D conversion circuit 11, and is referred to as a luminance signal (hereinafter referred to as “Y signal”). .) And color signal (hereinafter referred to as “C signal”), LPF1 15 is a Y signal including a closed caption signal which is a copyright signal output from the Logical Comb filter 14. The high frequency component of s103 is removed, and the sync separation circuit 16 separates and outputs the horizontal sync signal s130 and the vertical sync signal s134 from the Y signal s104 output from the LPF 115, The counter 17 counts the number of horizontal lines in one frame from the horizontal synchronization signal s130 and the vertical synchronization signal s134 output from the synchronization separation circuit 16.

  The pedestal level detection circuit 18 determines the luminance of the video signal from the Y signal s104 output from the LPF 115, the horizontal synchronization signal s130 output from the synchronization separation circuit 16, and the count value s131 output from the line counter 17. Pedestal level s135, which is the reference potential of the signal and the synchronization signal,

  The slicer 19 calculates a threshold level s133 for discriminating between “1” and “0” of the closed caption signal from the output signal (pedestal level) s135 from the pedestal level detection circuit 18.

  The CC signal detection circuit 20 includes a Y signal s104 output from the LPF 115, a count value s132 indicating the number of horizontal lines output from the line counter 17, and a threshold level s133 of the CC signal output from the slicer 19. The binary closed caption signal s110 superimposed on the 21st and 284th lines of the video signal is detected and output to the CC signal output terminal T2.

The copyright (closed caption) signal detection circuit 50 configured as described above will be described with reference to FIGS.
FIG. 7 shows the waveform of the video signal input from the video signal input terminal T1, and the closed caption signal, which is one of the copyright signals described above, is a vertical blanking period (first) of the video signal. It is superimposed on the 21st line of 1 field and the 24th line of 2nd field. The lower half of FIG. 7 shows an enlarged video signal line on which the closed caption signal shown in the upper half of FIG. 7 is superimposed, and shows the closed caption signal standard.

Next, the operation of the conventional copyright signal detection circuit will be described with reference to FIG.
The analog video signal s100 input from the video signal input terminal T1 is converted into a digital video signal s101 by the A / D conversion circuit 11. The video signal s101 output from the A / D conversion circuit 11 is output as a signal s102 delayed by one line by the line memories 12 and 13, added to the video signal s101 by the addition circuit 130, and then added by the logical comb filter 14. Separated into Y signal s103 and C signal. Among the video signals output from the logical comb filter 14, the Y signal s103 including the closed caption signal is subjected to high-frequency components such as noise being removed by the LPF 115 (see FIG. 8A).

The Y signal s104 output from the LPF 115 is input, and the synchronization separation circuit 16 separates the signal into a horizontal synchronization signal s130 (see FIG. 8B) and a vertical synchronization signal s134. With the horizontal synchronization signal s130 and the vertical synchronization signal s134 output from the synchronization separation circuit 16 as inputs, the line counter 17 outputs a counter value s132 indicating the number of horizontal lines in one frame (see FIG. 8C). Based on the horizontal synchronization signal s130 output from the synchronization separation circuit 16, the horizontal line counter value s131 output from the line counter 17, and the Y signal s104 output from the LPF 115, the pedestal level detection circuit 18 The average value s135 of the pedestal level from the 10th line to the 20th line of the horizontal line is calculated (see FIG. 8D: eb shown here is a calculated value). Using the pedestal level s135 output from the pedestal level detection circuit 18, the slicer 19 calculates a threshold level s133 for discriminating between “1” and “0” of the closed caption signal (see FIG. 8E: here) Ab shown in E is a calculated value). Based on the Y signal s104 from the LPF 115, the counter value s132 from the line counter 17, and the threshold level s133 output from the slicer 19, the CC signal detection circuit 20 detects the closed caption signal s110 (FIG. 8). F), and output from the CC signal output terminal T2.
JP 2002-314955 A (page 2-4, FIG. 7)

  However, in the conventional technology, as a mechanism for calculating a threshold level for detecting a closed caption signal, a threshold value obtained by adding a certain value to the average value of the pedestal levels between the 10th line to the 20th line in the vertical blanking period is used. It is used as a level.

  For this reason, when the video signal level of the line on which the closed caption signal is superimposed is changed, the optimum threshold level is not obtained, and as a result, the detection accuracy of the closed caption signal is lowered.

  The present invention has been made in order to solve the above-described problems of the prior art, and is capable of setting an optimum value for closed caption signal detection and improving the detection accuracy of the closed caption signal. An object of the present invention is to provide a copyright signal detection circuit capable of performing the above.

  In order to solve the above problems, the copyright signal detection circuit according to the present invention has a line memory for delaying the video signal by one line before detecting a closed caption signal, and the closed caption signal detection circuit includes: From the signal before passing through the line memory, using the fact that the LPF located in the previous stage and the LPF incorporated for another function are functionally equivalent and used before the line memory, The threshold level is set by detecting the pedestal level of the line including the closed caption signal in advance, and the threshold level is applied to the video signal delayed by one line.

  That is, a copyright signal detection circuit according to claim 1 of the present invention includes an A / D conversion circuit that converts an analog video signal into a digital video signal (hereinafter referred to as a video signal), and an A / D conversion circuit. A delay memory that delays the video signal by one line; a YC separation filter that separates the video signal from the delay memory into a luminance signal (hereinafter referred to as a Y signal) and a color signal (hereinafter referred to as a C signal); A first filter circuit for removing high-frequency components such as noise from a video signal including a closed caption (hereinafter referred to as CC) signal of either the Y signal or the C signal from the YC separation filter; A second filter circuit that removes a high frequency component of the video signal from the A / D conversion circuit, and a synchronization separation circuit that separates a horizontal synchronization signal and a vertical synchronization signal from the video signal from the second filter circuit; From the sync separation circuit A line counter that counts the number of lines in one frame based on a horizontal synchronizing signal and a vertical synchronizing signal, a video signal from the second filter circuit, and a count value from the line counter based on a CC signal “1”, A threshold level calculation circuit for calculating a threshold (hereinafter referred to as a threshold level) for detecting a “0” signal, a video signal from the first filter circuit, and a threshold level from the threshold level calculation circuit; And a CC signal detection circuit for detecting a CC signal based on the above.

  A copyright signal detection circuit according to claim 2 of the present invention includes an A / D conversion circuit that converts an analog video signal into a digital video signal (hereinafter referred to as a video signal), and an A / D conversion circuit. A delay memory that delays the video signal by one line, a YC separation filter that separates the video signal from the delay memory into a Y signal and a C signal, and either the Y signal or the C signal from the YC separation filter; A first filter circuit for removing high-frequency components such as noise from a video signal including a CC signal, a second filter circuit for removing high-frequency components of the video signal from the A / D conversion circuit, and the second filter circuit. A synchronization separation circuit for separating a horizontal synchronization signal and a vertical synchronization signal from a video signal from the filter circuit, and a line counter for counting the number of lines in one frame based on the horizontal synchronization signal and the vertical synchronization signal from the synchronization separation circuit And said A first threshold level calculation circuit for calculating a threshold level for detecting “1” and “0” of the CC signal based on the video signal from the second filter circuit and the count value from the line counter; and the line Based on the counter value from the counter, the horizontal synchronization signal from the synchronization separation circuit, and the video signal from the second filter circuit, a threshold level for detecting a Clock Run In pulse that is a detection pulse of the CC signal is calculated. A line including a CC signal based on a second threshold level calculation circuit, a video signal from the second filter circuit, a count value from the line counter, and a threshold level from the second threshold level calculation circuit; A CC discriminating circuit for discriminating whether or not there is a video signal from the first filter circuit and the first threshold level; Out it is obtained by a CC signal detection circuit for detecting a CC signal from the corresponding line only when that determines contains CC signal based on the determination result of the threshold level from the circuit from the CC discriminating circuit.

  A copyright signal detection circuit according to claim 3 of the present invention includes an A / D conversion circuit that converts an analog video signal into a digital video signal (hereinafter referred to as a video signal), and a signal from the A / D conversion circuit. A delay memory that delays the video signal by one line, a YC separation filter that separates the video signal from the delay memory into a Y signal and a C signal, and either the Y signal or the C signal from the YC separation filter; A first filter circuit for removing high-frequency components such as noise from a video signal including a CC signal, a second filter circuit for removing high-frequency components of the video signal from the A / D conversion circuit, and the second filter circuit. A synchronization separation circuit that separates a horizontal synchronization signal and a vertical synchronization signal from a video signal from the filter circuit; a line counter that counts the number of lines in one frame from the horizontal synchronization signal and the vertical synchronization signal from the synchronization separation circuit; The second A first threshold level calculating circuit for calculating a threshold level for detecting “1” and “0” of the CC signal based on the video signal from the filter circuit and the count value from the line counter; A weak electric field determination circuit for determining whether or not an input video signal is a weak electric field signal based on the video signal from the filter circuit and the threshold level from the first threshold level calculation circuit; A threshold level conversion circuit for converting a threshold level from the first threshold level calculation circuit in accordance with a determination signal of the first signal, and a dynamics of a video signal from the first filter circuit based on the determination signal from the weak electric field determination circuit A video signal level conversion circuit for converting a range, an output signal from the video signal level conversion circuit, and the slice level conversion circuit; It is obtained by a CC signal detection circuit for detecting a closed caption signal 2 value based on the count value from the output signal and the line counter of the circuit.

  A copyright signal detection circuit according to a fourth aspect of the present invention is the copyright signal detection circuit according to the first or second aspect, wherein either the Y signal or the C signal from the YC separation filter is a CC signal. The video signal including the signal is a Y signal, the video signal output from the second filter circuit, the horizontal synchronization signal output from the synchronization separation circuit, and the horizontal line counter output from the line counter The value and the threshold level output from the first threshold level calculation circuit are input to determine whether the input video signal corresponds to a standard signal, a non-standard signal, or a weak electric field signal, and the determination A status determination circuit for outputting a result and a weak electric field signal level; a determination result from the status determination circuit; a weak electric field signal level; and the Y output from the first filter circuit And a video signal level conversion circuit for converting the dynamic range of the Y signal in the case of a weak electric field signal, and according to the determination result and the weak electric field signal level output from the status determination circuit. The threshold level conversion circuit for converting the threshold level output from one threshold level calculation circuit, and the input video signal from the status determination circuit corresponds to any of a standard signal, a non-standard signal, and a weak electric field signal. And a selector for switching which threshold level of the first threshold level calculation circuit or the video signal level conversion circuit is output according to a determination signal indicating The Y signal from the level conversion circuit, the threshold level output from the selector, and the line count And a counter value output from the data as input is obtained so as to output the closed caption signal of two values.

  The copyright signal detection circuit according to claim 5 of the present invention is the copyright signal detection circuit according to claim 4, wherein the threshold level value for closed caption detection output from the selector group is input, A VB-ID threshold level conversion circuit for converting a threshold level for detecting a VB-ID signal that is a copyright signal that controls reproduction of digital recording superimposed on two predetermined lines that are ranking periods; -VB-ID signal using the threshold level for VB-ID output from the ID threshold level conversion circuit, the Y signal output from the selector group, and the counter value of the number of horizontal lines output from the line counter as inputs. Further, a VB-ID signal detection circuit for detecting a binary signal of the VB-ID signal is generated, thereby generating a threshold level for detecting the VB-ID signal and a closed caption. In the generation of the threshold level for the tone signal detection is obtained so as to share the entire circuit.

  With the above configuration, the copyright signal detection circuit of the present invention minimizes the increase in circuit scale by using the line memory used for Y / C separation and the LPF circuit used for other functions. The threshold level used when detecting closed caption signals can be set to an optimal value, and it is possible to determine whether the line is a line on which closed caption signals are superimposed. Even when the signal is non-standard, the output of an erroneous closed caption signal can be suppressed. Similarly, when the signal is a weak electric field signal, the detection accuracy of the closed caption signal can be improved. Further, by sharing a part of the detection circuit for the VB-ID signal, the efficiency of the circuit can be realized.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(Embodiment 1)
FIG. 1 shows a copyright signal detection circuit according to Embodiment 1 of the present invention. In FIG. 1, T1 is an analog video signal input terminal, 11 is an A / D conversion circuit, 12 and 13 are line memories (delay memory), 130 is an adder circuit, 14 is a logical comb filter (YC separation filter), and 15 is LPF1 (First filter circuit), 21 is LPF2 (second filter circuit), 22 is GCP (gate clamp pulse), 23 is a sync separation circuit, 24 is a line counter, 25 is a slicer (threshold level calculation circuit), 20 Is a CC (Closed Caption) signal detection circuit.

The outline of the operation of the copyright signal detection circuit configured as described above will be described below with reference to FIG.
The analog video signal s100 input from the video signal input terminal T1 is converted into a digital video signal s101 by the A / D conversion circuit 11. The video signal s101 output from the A / D conversion circuit 11 is output as a signal s102 delayed by one line by the line memories 12 and 13, added to the video signal s101 by the addition circuit 130, and then added by the logical comb filter 14. Separated into Y signal s103 and C signal. Among the video signals output from the Logical comb filter 14, the Y signal s103 including the closed caption signal is removed by the LPF 115 from high frequency components such as noise. The LPF 221 is a circuit originally provided for detecting a signal called a gate clamp pulse (GCP) 22, and is an LPF having performance equivalent to that of the LPF 115. Using the signal (see FIG. 9G) s105 output from the LPF 221, the sync separation circuit 23 separates the horizontal sync signal (see FIG. 9H) s106 and the vertical sync signal. With the horizontal synchronization signal s106 and the vertical synchronization signal output from the synchronization separation circuit 23 as inputs, the line counter 24 counts the number of horizontal lines in one frame (see FIG. 9I). A detection signal for detecting a copyright signal from the 21st and 284th lines on which the copyright (closed caption) signal is superimposed by the slicer 25 with the count value s107 from the line counter 24 and the video signal s105 from the LPF 2 as inputs. Clock Run In (see FIG. 7) is detected, and the average value of the maximum and minimum values is output to the CC signal detection circuit 20 as the copyright signal detection threshold level s108 (see FIG. 9J).

Next, the video signal input to the CC signal detection circuit 20 will be described.
The video signal s101 converted into the digital video signal by the A / D conversion circuit 11 is delayed by one line in the line memories 12 and 13, and the video signal s102 output from the line memories 12 and 13 and the A / D Based on the video signal s101 output from the D conversion circuit 11, it is separated into a Y signal s103 and a C signal by the logical comb filter.

  Since the copyright (closed caption) signal described here is superimposed on the Y signal, the Y signal will be described below. The Y signal s103 output from the Logical Comb filter 14 is subjected to removal of a high frequency component such as a noise component by the LPF 115, and a video signal (see FIG. 9K) s104 from which the high frequency component has been removed is used as a CC signal detection circuit 20. Output to.

  CC signal detection circuit using as input the horizontal line count value s109 output from the line counter 24, the closed caption signal threshold level s108 output from the slicer 25, and the Y signal s104 output from the LPF115 The closed caption signal (see FIG. 9L) is detected at 20, but the threshold level for thresholding the Y signal s104 on which the closed caption signal is superimposed is set as the threshold level s108 of the closed caption signal. This is calculated in advance using the video signal of one line before detecting the closed caption signal before passing, and the Y signal s104 output from the LPF1 15 via the line memories 12 and 13 is calculated. By applying the threshold level s108, a line on which a closed caption signal is superimposed Performs detection using the threshold levels al calculation, it outputs a closed caption signal s110 detected from CC signal output terminal T2.

  Therefore, it is possible to change the closed caption signal detection wave sensitivity, which is fixed with respect to the standard signal in the conventional example, according to the threshold level, thereby improving the detection efficiency of the closed caption signal.

  As described above, according to the copyright signal detection circuit of the first embodiment, the A / D conversion circuit that converts an analog signal into a digital signal and the video signal from the A / D conversion circuit are delayed by one line. A line memory, a logial comb filter that separates a luminance signal and a color signal (hereinafter referred to as a Y signal and a C signal) from the video signal output from the line memory, and noise from the video signal from the logical comb filter. LPF1 (Low Pass Filter) that removes high-frequency components, LPF2 that removes high-frequency components of the video signal from the A / D converter, and horizontal and vertical sync signals detected from the video signal from the LPF2 A sync separator, a line counter that counts the number of lines in one frame from the horizontal sync signal and the vertical sync signal from the sync separator, a video signal from the LPF 2 and a count from the line counter. A slicer for calculating a threshold level for detecting a closed caption signal “1” or “0” from the value, a video signal from the LPF 1, a count value from the line counter, and a threshold level from the slicer By configuring the copyright signal detection circuit with the CC (Closed Caption) signal detection circuit that detects the closed caption signal, and using the Y / C separation line memory that was in the original video signal processing circuit, The threshold level is calculated in advance from the line where the closed caption signal is superimposed, so that the closed caption signal can be detected according to the detected fluctuation level of the threshold level. Reduced detection rate of closed caption signal even for recorded video signals , The effect is obtained that it is possible to improve the detection accuracy of the closed caption signal.

(Embodiment 2)
FIG. 2 shows a copyright signal detection circuit according to the second embodiment of the present invention. In FIG. 2, T1 is an analog video signal input terminal, 11 is an A / D converter circuit, 12 and 13 are line memories, 14 is a logical comb filter, 15 is LPF1, 21 is LPF2, 22 is GCP (gate clamp pulse), 23 is a sync separation circuit, 24 is a line counter, 25 is a slicer, 26 is a discrimination slicer (second threshold level calculation circuit), 27 is a closed caption (CC) discrimination circuit, 28 is a selector, 29 is a CC signal detection circuit is there.

  The outline of the operation of the copyright signal detection circuit configured as described above will be described below with reference to FIG. 9, but the description of the same components as those in Embodiment 1 will be omitted.

  2 includes a video signal s105 output from the LPF 221, a count value s107 of the number of lines output from the line counter 24, and a horizontal synchronization signal s106 output from the synchronization separation circuit 23. Is input, and a value obtained by adding a signal amplitude 25IRE (Institute of Radio Engineers; see FIG. 7) to the pedestal level is output as a threshold level s111 used to detect a pulse of Clock Run In. The line count value s107 counted by the line counter 24, the threshold level s108 for detecting the copyright signal from the slicer 25, the threshold level s111 for determining the Clock Run In output from the discrimination slicer 26, and the LPF2 With the video signal s105 output from 21 as an input, the CC discrimination circuit 27 discriminates whether or not the signal superimposed on the video signal is a closed caption signal. The discrimination method is based on whether or not a certain number or more of the Clock Run In pulses superimposed on the 21st and 284th lines are detected with respect to the discrimination threshold level s111 output from the discrimination slicer 26. There is a method of determining whether or not is a line on which a closed caption signal is superimposed and outputting a determination result s112.

  The selector 28 receives the determination result s112 output from the CC determination circuit 27 and the threshold level s108 output from the slicer 25 as input, and the threshold level s108 or the closed caption signal is superimposed based on the determination result s112. Any one of the predetermined values c indicating not being output is output. With the signal s113 output from the selector 28, the count value s107 output from the line counter 24, and the Y signal s104 output from the LPF1, the CC signal detection circuit 29 detects a closed caption signal. Do. At this time, if the signal s113 output from the selector 28 has a predetermined value c, the CC signal detection circuit 29 does not detect the closed caption signal, and the LPF115 output signal s104 is directly output to the CC signal output terminal. Output to T2.

  For this reason, when the input video signal is a non-standard signal, the line counter causes a count error, and a line on which the closed caption signal is originally not superimposed is erroneously determined as a line on which the closed caption signal is superimposed. The CC discriminating circuit 27 superimposes a closed caption signal on whether or not a certain number or more of the Clock Run In pulses superimposed on the 21st and 284th lines are detected with respect to the discrimination threshold level s111. It is possible to prevent it by determining whether or not it is a line that has been processed.

  As described above, according to the copyright signal detection circuit according to the second embodiment, the video signal output from the LPF 2 in the copyright signal detection circuit according to the first embodiment, the count value output from the line counter, A discrimination slicer that detects a threshold level for Clock Run In discrimination from the horizontal synchronization signal output from the sync separation circuit, the video signal output from the LPF 2, the count value output from the line counter, and the slicer CC (Closed Caption) discriminating circuit for discriminating whether the line includes a closed caption signal from the threshold level output from the discriminating slicer and the discrimination threshold level output from the discriminating slicer, and discrimination from the CC discriminating circuit As a result, a selector for selecting whether to output a threshold level from the slicer or a fixed value, and the LP Copyright from the video signal from F1, the threshold level from the slicer, and the CC signal detection circuit that detects the CC signal from the corresponding line only when it is determined that CC is included from the determination result from the CC determination circuit Configured a signal detection circuit so that the line counter malfunctions when a non-standard signal is input and the detection of a closed caption signal from the wrong line can be avoided by detecting the malfunction of the line counter in advance. Therefore, it is possible to suppress the malfunction of the closed caption signal detection function.

(Embodiment 3)
FIG. 3 shows a copyright signal detection circuit according to the third embodiment of the present invention. In FIG. 3, T1 is an analog video signal input terminal, 11 is an A / D conversion circuit, 12 and 13 are line memories, 130 is an adder circuit, 14 is a logical comb filter, 15 is LPF1, 21 is LPF2, and 22 is GCP ( Gate clamp pulse), 23 is a sync separator, 24 is a line counter, 25 is a slicer, 30 is a weak electric field discriminator, 31 is a slice level converter (threshold level converter), 32 is a video signal level converter, and 20 is CC signal detection circuit.

An outline of the operation of the copyright signal detection circuit configured as described above will be described below with reference to FIG. Note that the description of the same components as those in the first and second embodiments is omitted.
The video signal s105 output from the LPF2 21 and the horizontal synchronization signal s106 output from the synchronization separation circuit 23 are input, and the weak electric field determination circuit 30 determines whether or not the input signal is a weak electric field signal. The discrimination result and the weak electric field level s114 are output. The slice level conversion circuit 31 and the video signal level conversion circuit 32 receive the determination result output from the weak electric field determination circuit 30 and the weak electric field level s114, and are output from the LPF 115 from the value of the weak electric field level s114. The Y signal s104 is converted into a Y signal s115 value corresponding to the value of the weak electric field level s114, and a threshold level s116 obtained by converting the dynamic range of the threshold level s108 output from the slicer 25 is output. The CC signal detection circuit 20 receives the Y signal s115 output from the video signal level conversion circuit 32, the threshold level s116 output from the slice level conversion circuit 31, and the line counter s107 output from the line counter 24 as inputs. Detect caption signal and output to CC signal output terminal T2.

  For this reason, since the value of the Y signal can be converted according to the weak electric field level and the dynamic range of the threshold level can be converted, it is possible to prevent the detection accuracy of the closed caption signal from being lowered even if the input video signal is a weak electric field signal. .

  As described above, according to the copyright signal detection circuit according to the third embodiment, the video signal output from the LPF 2 described in the copyright signal detection circuit according to the first embodiment, the threshold level output from the slicer, A weak electric field discriminating circuit that discriminates whether or not the input video signal is a weak electric field signal based on the horizontal synchronizing signal output from the sync separation circuit, and a weak electric field based on the threshold level output from the slicer. Based on the threshold level conversion circuit that converts the threshold level according to the weak electric field level in the case of the electric field signal, the Y signal from the LPF1, the discrimination result output from the weak electric field discrimination circuit, and the weak electric field level, the LPF1 A video signal level conversion circuit that converts the dynamic range of the entire video signal from the video signal, an output signal from the video signal level conversion circuit, and an output from the slice level conversion circuit Since the copyright signal detection circuit is composed of the CC signal detection circuit that detects the closed caption signal from the force signal and the count value from the line counter, the input video signal is a weak electric field signal and the signal level is lowered. Even in this case, it is possible to suppress a decrease in detection accuracy of the closed caption signal by adjusting the dynamic range of the entire video signal according to the level of the weak electric field.

(Embodiment 4)
FIG. 4 shows a copyright signal detection circuit according to the fourth embodiment of the present invention. In FIG. 4, T1 is an analog video signal input terminal, 11 is an A / D conversion circuit, 12 and 13 are line memories, 130 is an adder circuit, 14 is a logical comb filter, 15 is LPF1, 21 is LPF2, and 22 is GCP ( Gate clamp pulse), 23 sync separation circuit, 24 line counter, 25 slicer, 33 status determination circuit, 31 slice level conversion circuit (threshold level conversion circuit), 32 video signal level conversion circuit, 28, 34 , 35 is a selector, and 20 is a CC signal detection circuit.

An outline of the operation of the copyright signal detection circuit configured as described above will be described below with reference to FIG. Note that description of the same components as those in the first, second, and third embodiments is omitted.
The horizontal line counter value s107 output from the line counter 24, the threshold level s108 output from the slicer 25, the horizontal synchronization signal s106 output from the synchronization separation circuit 23, and the LPF222 Based on the received video signal s105, the status signal determination circuit 33 determines whether the input video signal s105 corresponds to a standard signal, a non-standard signal, or a weak electric field signal. As the discrimination method, when the number of lines of the video signal s105 output from the LPF2 21 is the 21st and 284th lines, a Run In Pulse (see FIG. 7) which is a closed caption signal discrimination pulse is detected. It is determined whether it is a standard signal or a non-standard signal, and by comparing the pedestal level of the video signal s105 with the level at the time of the standard signal, it is determined whether it is a weak electric field signal, The discrimination result and the weak electric field level s117 are output.

  When the discrimination result is determined to be a weak electric field signal, the video signal s104 output from the LPF 115, the determination result output from the status determination circuit 33, the weak electric field signal level s117, and the threshold output from the slicer 25 The video signal output from the LPF 115 in the video signal level conversion circuit 32 and the threshold level conversion circuit 31 described in the third embodiment using the level s108, the determination result, and the weak electric field signal level s117 as inputs. Conversion processing of the dynamic range of s104 and the threshold level of the slicer 25 is performed.

  The selector 28 outputs an output value from the slicer 25 when the input video signal s105 is a standard signal, and outputs a predetermined value c when the input video signal s105 is a non-standard signal. The selectors 34 and 35 output a weak electric field signal. If there is, the selector is switched to “1”, otherwise the selector is switched to “0” and output. The CC signal detection circuit 20 detects a closed caption signal using the horizontal line counter value s107 from the line counter 25, the video signal s118 output from the selector 35, and the s119 output from the selector 34 as inputs. The closed caption signal s110 is output from the CC signal output terminal T2.

  For this reason, when the input video signal is a weak electric field signal, the closed caption signal is detected in a state where the value of the Y signal is converted according to the weak electric field level and the dynamic range of the threshold level is converted. In the case of a signal, it becomes possible to perform closed caption signal detection for the Y signal s104 that has passed the LPF1 15 with the threshold level set to a predetermined value, and the input signal is in any of the standard signal, non-standard signal, and weak electric field signals. Accordingly, the closed caption signal can be detected adaptively.

  As described above, according to the copyright signal detection circuit according to the fourth embodiment, the threshold level output from the slicer described in the copyright signal detection circuit according to the third embodiment and the number of horizontal lines output from the line counter. Status determination that determines whether the input signal is a standard signal, non-standard signal, or weak electric field signal, based on the count value, the horizontal sync signal output from the sync separator, and the video signal output from LPF2 A copyright signal detection circuit is configured by adding a circuit and a selector circuit for setting a video signal and a threshold level suitable for each state from the output signal from the status determination circuit, and the input signal is a standard signal. By adding a status discriminating circuit that discriminates either non-standard signal or weak electric field signal, the signal state is automatically discriminated and each Processing corresponding to the state can be performed.

(Embodiment 5)
FIG. 5 shows a copyright signal detection circuit according to the fifth embodiment of the present invention. In FIG. 5, T1 is an analog video signal input terminal, 11 is an A / D conversion circuit, 12 and 13 are line memories, 130 is an adder circuit, 14 is a logical comb filter, 15 is LPF1, 21 is LPF2, and 22 is GCP ( Gate clamp pulse), 23 is a sync separator, 24 is a line counter, 25 is a slicer, 33 is a status discriminator, 31 is a slice level converter, 32 is a video signal level converter, 28, 34 and 35 are selectors, 20 Is a CC signal detection circuit, 36 is a VB-ID threshold level conversion circuit, and 37 is a VB-ID detection circuit.

An outline of the operation of the copyright signal detection circuit configured as described above will be described below with reference to FIG. Note that description of the same components as those in the first, second, third, and fourth embodiments will be omitted.
The VB-ID threshold level conversion circuit 36 receives the closed caption detection threshold level value s119 output from the selector 34 described in the fourth embodiment, and is the video blanking period shown in FIG. , Converted to a threshold level s121 for detecting the VB-ID signal superimposed on the 283rd line.

  Here, the VB-ID signal is a copyright signal that controls duplication when performing digital recording of the digital vision signal superimposed on the 20th and 283rd lines of the video blanking period as described above. The signal is superimposed one line before the closed caption signal. The closed caption signal “1” expressed as a binary signal is represented by a signal amplitude of 50IRE and “0” is represented by an amplitude of 0IRE, whereas the VB-ID signal is represented by a signal amplitude of 70IRE and “0” of the signal amplitude. It is represented by 0IRE.

  The VB-ID threshold level s121 output from the VB-ID threshold level conversion circuit 36, the Y signal s118 output from the selector 35 described in the fourth embodiment, and the horizontal signal output from the line counter 24 Using the counter value s107 for the number of lines as an input, the VB-ID signal detection circuit 37 detects the binary signal s122 of the VB-ID signal and outputs it from the VB-ID signal output terminal T3.

  Therefore, by adding a VB-ID detection circuit and a VB-ID threshold level conversion circuit, the entire circuit can be generated with a threshold level for detecting a closed caption signal and a threshold level for detecting a VB-ID signal. It becomes possible to share.

  As described above, the copyright signal detection circuit according to the fifth embodiment is based on the count value output from the line counter described in the copyright signal detection circuit according to the fourth embodiment and the video signal output from LPF2. In addition, the VB-ID signal, which is copyright information for the purpose of suppressing multiple copies when performing digital recording with NTSC consumer digital video recorders (20, 283 lines) By adding a CC-VBID detection circuit that discriminates the threshold level and a VB-ID threshold level conversion circuit that converts the threshold level for closed caption signal detection to the threshold level for VB-ID signal detection, the rest of the circuit Can be shared to generate a threshold level for detecting a closed caption signal and a threshold level for detecting a VB-ID signal, and the efficiency of the circuit can be realized.

  In the fifth embodiment, a CC-VBID detection circuit and a threshold level conversion circuit are added to the fourth embodiment. However, the CC-VBID detection circuit and the threshold level are also added to the first to third embodiments. A conversion circuit may be added, and the same characteristics as in the fifth embodiment can be provided.

  The copyright signal detection circuit according to the present invention determines a non-standard signal or a weak electric field signal, and takes measures corresponding to each of them, so that not only a standard signal but also a non-standard signal or a weak electric field signal is used. This is useful for suppressing a decrease in detection accuracy of the copyright signal.

1 is a configuration diagram showing a copyright signal detection circuit according to a first embodiment of the present invention. Configuration diagram showing a copyright signal detection circuit according to a second embodiment of the present invention Configuration diagram showing a copyright signal detection circuit according to a third embodiment of the present invention Configuration diagram showing a copyright signal detection circuit according to a fourth embodiment of the present invention. Configuration diagram showing a copyright signal detection circuit according to a fifth embodiment of the present invention Configuration diagram showing a copyright signal detection circuit of a conventional circuit Illustration of closed caption signal (NTSC) The figure which shows the timing chart of the copyright signal detection circuit of the conventional circuit with respect to this invention The figure which shows the timing chart of the copyright signal detection circuit by Embodiment 1, 2 of this invention

Explanation of symbols

T1 Analog video signal input terminal
T2 CC (closed caption) signal output pin
T3 VB-ID signal output pin
11 A / D converter circuit
12, 13 line memory
14 Logical Comb filter
15 LPF (Low Pass Filter) 1
16 Sync separation circuit
17 Line counter
18 Pedestal level detection circuit
19 Slicer
20 CC signal detection circuit
21 LPF2
22 GCP (Gate Clamp Pulse)
23 Sync separation circuit
24 line counter
25 Slicer
26 Discrimination slicer
27 CC discrimination circuit
29 CC signal detection circuit
30 Weak electric field discrimination circuit
31 Slice level conversion circuit
32 Video signal level conversion circuit
33 Status discrimination circuit
36 VB-ID signal threshold level conversion circuit
37 VB-ID signal detection circuit
s100 Analog video signal
s101 Digital video signal
s103 Y signal
s104 Y signal after removing high-frequency components
s106 Horizontal / vertical sync signal
s107 Horizontal line count value
s108 CC signal threshold level
s110 CC signal
s111 CC discrimination threshold level
s112 CC discrimination result
s114 Weak electric field discrimination result and weak electric field level
s117 Status determination result

Claims (5)

An A / D conversion circuit that converts an analog video signal into a digital video signal (hereinafter referred to as a video signal);
A delay memory for delaying the video signal from the A / D converter circuit by one line;
A YC separation filter that separates a video signal from the delay memory into a luminance signal (hereinafter referred to as a Y signal) and a color signal (hereinafter referred to as a C signal);
A first filter circuit for removing high-frequency components such as noise from a video signal including a closed caption (hereinafter referred to as CC) signal of either the Y signal or the C signal from the YC separation filter; ,
A second filter circuit for removing a high frequency component of the video signal from the A / D conversion circuit;
A synchronization separation circuit for separating a horizontal synchronization signal and a vertical synchronization signal from the video signal from the second filter circuit;
A line counter that counts the number of lines in one frame based on the horizontal synchronization signal and the vertical synchronization signal from the synchronization separation circuit;
Based on the video signal from the second filter circuit and the count value from the line counter, a threshold value (hereinafter referred to as a threshold level) for detecting the “1” and “0” signals of the CC signal is calculated. A threshold level calculation circuit to perform,
A CC signal detection circuit for detecting a CC signal based on the video signal from the first filter circuit and the threshold level from the threshold level calculation circuit;
A copyright signal detection circuit. An A / D conversion circuit that converts an analog video signal into a digital video signal (hereinafter referred to as a video signal);
A delay memory for delaying the video signal from the A / D converter circuit by one line;
A YC separation filter for separating the video signal from the delay memory into a Y signal and a C signal;
A first filter circuit for removing a high frequency component such as noise from a video signal including a CC signal of either the Y signal or the C signal from the YC separation filter;
A second filter circuit for removing a high frequency component of the video signal from the A / D conversion circuit;
A synchronization separation circuit for separating a horizontal synchronization signal and a vertical synchronization signal from the video signal from the second filter circuit;
A line counter that counts the number of lines in one frame based on the horizontal synchronization signal and the vertical synchronization signal from the synchronization separation circuit;
A first threshold level calculation circuit for calculating a threshold level for detecting “1” and “0” of the CC signal based on the video signal from the second filter circuit and the count value from the line counter;
Based on the counter value from the line counter, the horizontal sync signal from the sync separation circuit, and the video signal from the second filter circuit, a threshold level for detecting a clock run in pulse that is a CC signal detection pulse is set. A second threshold level calculation circuit for calculating;
CC discrimination for discriminating whether a line includes a CC signal based on the video signal from the second filter circuit, the count value from the line counter, and the threshold level from the second threshold level calculation circuit Circuit,
Only when it is determined that a CC signal is included based on the video signal from the first filter circuit, the threshold level from the first threshold level calculation circuit, and the determination result from the CC determination circuit, the corresponding line is extracted. A CC signal detection circuit for detecting a CC signal;
A copyright signal detection circuit. An A / D conversion circuit that converts an analog video signal into a digital video signal (hereinafter referred to as a video signal);
A delay memory for delaying the video signal from the A / D converter circuit by one line;
A YC separation filter that separates the video signal from the delay memory into a Y signal and a C signal;
A first filter circuit for removing a high frequency component such as noise from a video signal including a CC signal of either the Y signal or the C signal from the YC separation filter;
A second filter circuit for removing a high frequency component of the video signal from the A / D conversion circuit;
A synchronization separation circuit for separating a horizontal synchronization signal and a vertical synchronization signal from the video signal from the second filter circuit;
A line counter that counts the number of lines in one frame from the horizontal synchronization signal and the vertical synchronization signal from the synchronization separation circuit;
A first threshold level calculation circuit for calculating a threshold level for detecting “1” and “0” of the CC signal based on the video signal from the second filter circuit and the count value from the line counter;
A weak electric field discriminating circuit for determining whether or not the input video signal is a weak electric field signal based on the video signal from the second filter circuit and the threshold level from the first threshold level calculating circuit;
A threshold level conversion circuit that converts a threshold level from the first threshold level calculation circuit according to a determination signal from the weak electric field determination circuit;
A video signal level conversion circuit that converts a dynamic range of the video signal from the first filter circuit based on a determination signal from the weak electric field determination circuit;
A CC signal detection circuit for detecting a binary closed caption signal based on an output signal from the video signal level conversion circuit, an output signal from the slice level conversion circuit, and a count value from the line counter;
A copyright signal detection circuit. In the copyright signal detection circuit according to claim 1 or 2,
The video signal including the CC signal of either the Y signal or the C signal from the YC separation filter is a Y signal,
The video signal output from the second filter circuit, the horizontal synchronization signal output from the synchronization separation circuit, the counter value of the number of horizontal lines output from the line counter, and the first threshold level calculation circuit The threshold level output from the input is used to determine whether the input video signal corresponds to a standard signal, non-standard signal, or weak electric field signal, and status determination that outputs the determination result and the weak electric field signal level Circuit,
A video signal level for converting the dynamic range of the Y signal in the case of a weak electric field signal by using the determination result from the status determination circuit and the weak electric field signal level and the Y signal output from the first filter circuit as inputs. A conversion circuit;
A threshold level conversion circuit for converting the threshold level output from the first threshold level calculation circuit according to the determination result and the weak electric field signal level output from the status determination circuit;
The first threshold level calculation circuit and the video signal level conversion according to a determination signal indicating whether the input video signal from the status determination circuit corresponds to a standard signal, a non-standard signal, or a weak electric field signal A selector that switches which threshold level of the circuit is output;
The CC signal detection circuit receives the Y signal from the video signal level conversion circuit, the threshold level output from the selector, and the counter value output from the line counter as inputs, and outputs a binary closed caption signal. Output,
A copyright signal detection circuit. The copyright signal detection circuit according to claim 4,
A VB-ID signal that is a copyright signal that controls reproduction of digital recording superimposed on two predetermined lines that are video blanking periods, using the threshold level value for closed caption detection output from the selector group as an input VB-ID threshold level conversion circuit that converts to a threshold level for detecting
The VB-ID threshold level output from the VB-ID threshold level conversion circuit, the Y signal output from the selector group, and the counter value of the number of horizontal lines output from the line counter are input. By further providing a VB-ID signal detection circuit for detecting a binary signal of the ID signal,
The entire circuit is shared between the generation of the threshold level for detecting the VB-ID signal and the generation of the threshold level for detecting the closed caption signal.
A copyright signal detection circuit.

Images