JP2006135380A - Method and device for determining video signal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To determine the presence or the absence of an input video signal by a composite synchronizing signal generated by compositing the horizontal synchronizing signal and the vertical synchronizing signal of the input video signal. <P>SOLUTION: The number of edges of the composite synchronizing signal of a video signal inputted from an input terminal 1 is counted with an input signal counter 3 for a period (T<SB>1</SB>) set with a period setting part 2. A counter value (X) is outputted. A value (A) which is based on a calculated value of the horizontal synchronizing signal in the period (T<SB>1</SB>) set with a range setting part 5, a value (B) in consideration of a calculated value of the composite synchronizing signal and a noise component caused by a weak electric field, and the counter value (X) are counted with a counter (Y<SB>1</SB>) when it is A≤X≤B, and otherwise counted with a counter (Y<SB>2</SB>) in a counter value comparison processor 4. An up/down counter is subjected to up-processing when the counter value of the (Y<SB>1</SB>) reaches an upper limit value (C) set with an upper limit setting part 7 in an up/down counter 8. When the counter value of the (Y<SB>2</SB>) reaches an upper limit value (D), the up/down counter is subjected to down-processing. The presence or the absence of the input video signal is determined by using an up/down counter value with a signal presence/absence determining part 10. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a video signal processing method and apparatus, and more particularly to a video signal determination method and apparatus for reducing malfunction in determination of a normal video signal due to the influence of noise such as a weak electric field.

  In general, a television screen in the NTSC broadcasting system forms one frame screen by two field signals, and one frame is composed of 525 line signals. A vertical synchronizing signal for synchronizing the screens of the fields and a horizontal synchronizing signal for synchronizing the line signals constituting the frame form a part of the video signal.

  The video signal is also detected in the recording / reproducing apparatus and used in various signal processing blocks. As an example, when a TV broadcast channel is switched, if no sync signal is detected in the video signal input after switching, it is determined that no video signal exists, and no sync signal is detected in a channel without a video signal. By replacing the noise screen with a blue back (BLUE BACK) screen or another reference screen, visual inconvenience due to noise appearing on the screen is improved.

  The conventional video signal detection determination method is based on counting the number of synchronization signals in one field of a video signal and the number of synchronization signals in one frame period, determining whether a video signal is input, and determining the period of the synchronization signal. The presence or absence of was judged. However, there are various types of noise in the video recording / reproducing apparatus, and when these weak electrolysis noise and noise frequency components are similar, the noise may be erroneously determined as a synchronization signal.

  Conventionally, a video signal determination method and apparatus to which the synchronization signal determination method described in Patent Document 1 is applied are known. In the video signal determination method disclosed in Patent Document 1, in the video signal recording / reproducing apparatus, the interval T1 for counting the number of horizontal synchronization signals in the input video signal and the number of vertical synchronization signals are counted. And a minimum value N1 and a maximum value N2 of the number of horizontal synchronization signals detected in the section T1, and a minimum value M1 and a maximum value M2 of the number of vertical synchronization signals detected in the section T2. A step of counting the number of pulses determined as a horizontal synchronization signal in the section T1 to obtain a first counting value, and a number of pulses determined as a vertical synchronization signal in the section T2. The step of obtaining a second counting value and the first counting value correspond to a value between N1 and N2, and the second counting value. It has a configuration in which tag value includes the step of determining a normal synchronization signal in the case that corresponds to a value between the M1, M2 is detected.

Also, the video signal determination device disclosed in Patent Document 1 is a video signal recording / reproducing device, wherein a vertical synchronization signal separation unit for separating a vertical synchronization signal from an input composite synchronization signal, the vertical synchronization signal separation unit A first counting unit for counting the number of vertical synchronizing signals during a predetermined first setting interval to obtain a first counting value, and the first counting value is included in a predetermined first setting range A first comparator for generating a first detection signal, and a second counting unit for counting the number of horizontal synchronizing signals during a predetermined second set interval in the input composite synchronizing signal to obtain a second counting value When the second counting value is included in a predetermined second setting range, the second comparator unit for generating the second detection signal and the first detection signal are generated simultaneously. Having a configuration including a calculation unit for generating a determination signal of the synchronizing signal detection.
Japanese Patent No. 3043307 (paragraph numbers 0007 and 0009 and FIGS. 1 and 2)

  However, in the above-described conventional configuration, since the counter unit counts the number of horizontal sync signals in the input video signal and the counter unit counts the number of vertical sync signals, the horizontal sync signal in the input video signal is provided. Therefore, it is necessary to provide a dedicated circuit for each, and there is a problem that the configuration is complicated and the cost is increased.

  The present invention solves the above-described conventional problems, and a video signal determination method and apparatus for determining the presence or absence of an input video signal by a composite sync signal obtained by combining a horizontal sync signal and a vertical sync signal in the input video signal. The purpose is to provide.

In order to achieve this object, the video signal determination method according to the present invention includes a value A based on a calculated value of the number of rising edges or falling edges in a predetermined period T ₁ of a horizontal synchronization signal in an input video signal, and the input Estimating the number of edges caused by noise based on the calculated value of the number of rising edges or falling edges in the predetermined period T ₁ of the composite synchronizing signal obtained by combining the horizontal synchronizing signal and the vertical synchronizing signal in the video signal A value B based on each value is set, the number X of rising edges or falling edges X in the predetermined period T ₁ of the composite synchronization signal is counted, and the number X of edges of the composite synchronization signal is A ≦ X ≦ It is configured to determine that there is a signal when the condition is B, and that there is no signal when the condition is X <A or X> B.

In addition, the video signal determination device of the present invention counts the number X of rising edges or falling edges X in a predetermined period T ₁ of a composite synchronizing signal obtained by combining a horizontal synchronizing signal and a vertical synchronizing signal in an input video signal. A counter means, a value A based on a calculated value of the number of rising or falling edges in the predetermined period T ₁ of the horizontal synchronizing signal, and an edge of the horizontal synchronizing signal and the vertical synchronizing signal in the predetermined period T ₁ Range setting means for setting and outputting a value B based on a calculated value of each rising edge or rising edge number and an estimated value of the number of edges caused by noise based on a weak electric field, an output X of the input signal counter means, The output values A and B of the range setting means are compared, and it is determined that there is a signal when the output X satisfies the range of A to B. And it outputs the count Y _1, the output X is provided with a counter value comparison processing means for outputting the count Y ₂ determines that no signal is greater than A less than or B.

  According to the configuration of the present invention, since the presence or absence of the input video signal can be determined using the composite synchronization signal, the configuration can be simplified and the cost can be reduced as compared with the conventional configuration in which the horizontal synchronization signal and the vertical synchronization signal are separated. There is an effect.

According to the first and fourth aspects of the present invention, a composite synchronizing signal obtained by combining a horizontal synchronizing signal and a vertical synchronizing signal in an input video signal is expressed as a rising edge of the composite synchronizing signal within a predetermined period T ₁ or The falling edge is counted, the count value is set to X, a predetermined value based on the calculated value of the edge of the horizontal synchronization signal in the predetermined period T ₁ is set to A, and the horizontal synchronization in the predetermined period T ₁ is set to A. A predetermined value based on the calculated value of the edge of the signal and the edge obtained by adding the vertical synchronizing signal and the experimental value in consideration of the weak electric field is defined as B. In the comparator, A ≦ X ≦ B is a signal, and X < A or X> B is based on the configuration of determining that there is no signal, and the edge of the composite sync signal is counted without separating the horizontal sync signal and the vertical sync signal from the input video signal. By comparing a predetermined value, it is possible to accurately determine the presence or absence decision of the video signal with a simple configuration.

The invention according to claim 2 and claim 5 counts the number of times Y ₁ when the condition for determining the presence of the signal continues, compares Y ₁ with a predetermined value C, and if the number is the same, the number increases. An up process is performed on the down counter, the number of times Y ₂ when the condition for determining that there is no signal is continued is counted, Y ₂ is compared with a predetermined value D set in advance, and if the number is the same, the up / down counter is counted. In contrast to the above-described effect, it is possible to determine the presence / absence of a video signal without causing a malfunction with respect to noise.

The invention according to claim 3 and claim 6 compares the count value Z _n (where n is a natural number) of the up / down counter with predetermined values E and 0, and the counter of the up / down counter The gist of the configuration is that the determination according to the value of Z _n is held until the value Z _i (where i is a natural number satisfying i> n) becomes E or 0 again, resulting in a hysteresis circuit and noise. For example, the presence or absence of a video signal can be determined without causing a malfunction.

  Hereinafter, an embodiment of a video signal determination apparatus according to the present invention will be described with reference to FIGS. FIG. 1 is a block diagram showing a configuration of a preferred embodiment of the video signal determination apparatus of the present invention, and FIG. 2 is a flowchart in the embodiment. In FIG. 1, 1 is an input terminal, 2 is a period setting unit, 3 is an input signal counter unit, 4 is a counter value comparison processing unit, 5 is a range setting unit, 6 is a comparison unit, 7 is an upper limit setting unit, and 8 is An up / down counter unit, 9 is a level reference value setting unit, 10 is a signal presence / absence determination unit, and 11 is an output terminal.

The operation of each element in FIG. 1 will be described. A composite synchronizing signal obtained by combining a horizontal synchronizing signal and a vertical synchronizing signal is input to the input terminal 1. The edge (either rising or falling) of the input composite synchronization signal is counted for the period (T ₁ ) set by the period setting unit 2. Assuming that the counter value of the period t by the input signal counter unit 3 is X (t), the counter value comparison processing unit 4 compares the predetermined ranges A and B set by the range setting unit 5 with X (t), The number of consecutive ranges in which X (t) is A or more and B or less is counted as count Y ₁ , and the number in which the other ranges (X (t) is less than A or greater than B) continues is counted as count Y _2. When counting and spanning the range from A to B and the other ranges, the count Y ₁ and the count Y ₂ are reset.

Thus the Y ₁ and Y ₂ obtained, the upper limit D of the upper limit value C and Y ₂ of Y ₁ which were set by the upper limit setting unit 7 compares the comparison unit 6, each of the counter Y ₁ or Y _{When 2} reaches the upper limit value, a signal is output to the up / down counter section 8. If X (t) is in the range from A to B, the up / down counter unit 8 adds 1 to the up / down counter Z _n , and if X (t) is less than A or greater than B, the up / down counter Z _n Subtract 1

When the value of the up / down counter Z _n obtained by the up / down counter unit 8 is equal to the maximum value E set by the level reference value setting unit 9, the signal during the period T ₁ is set to a high level and equal to 0. In this case, the signal is determined to be at a low level, and when it is greater than 0 and less than E, the signal presence / absence determination unit 10 performs signal presence / absence determination to hold the state of T ₁ before the period T ₁ and outputs each signal from the output terminal 11. . The up / down counter Z _n has a maximum value set to E even if the condition that X (t) is A or more and B or less continues (in other words, Y ₁ = C continues). Even if the condition where (t) is less than A or more than B continues (in other words, Y ₂ = D continues), it is set to 0.

  The flow of each process in the video signal determination apparatus of the present embodiment described above will be described with reference to FIG. The flow chart shown in FIG. 2 shows and explains the principle in this embodiment in a series. The loop of X (t) can be eliminated by providing, for example, a shift register in FIG. And the processing speed can be improved.

First, to set the video signal determination period T ₁ in S201. Of the image signal input from the input terminal 1, the number of edges rising or falling of the horizontal sync signals between T ₁ to be set by the range setting unit 5 A, the number of edges rising or falling of the horizontal synchronizing signal and a vertical synchronizing signal and a weak B, which is the sum of the estimated number of rising or falling edges of the noise component caused by the electric field, and the upper limit of the count value Y ₁ where the number of edges X (t) set by the upper limit setting unit 7 continues from A to B. The upper limit value D of the count value Y ₂ where the value C, the number of edges X (t) is less than A or greater than B, and the upper limit value E of the up / down counter Z _n set by the level reference value setting unit 9 are Set in step S202. The number X (t) of edges of the composite synchronizing signal of the video signal input from the input terminal 1 is counted by the input signal counter unit 3 (S203).

The counter value comparison processing unit 4 compares in S204 whether X (t) counted in S203 is A or more and B or less set in S202, or other conditions, and X (t) is A or more and B or less. in the case of the conditions, the conditions by adding 1 to the counter Y ₁ in step S206 as long as continuous S205, becomes the C set in S202 (S208), the up-down counter in the up-down counter unit 8 in S209 Z _n Add 1 to.

On the other hand, the number of edges X (t) is A, or less than B more conditions set in step S202 is continuous with (S210), 1 in the count value Y ₂ at S211 added in the counter value comparison processing unit 4 in S204, in S202 at the set D (S213), 1 is subtracted from the up-down counter Z _n in the up-down counter unit 8 in S214.

In the above flow chart, when the condition where X (t) is A or more and B or less and the condition where X (t) is less than A or B or more are changed in S204, as shown in S207 and S212, Y ₁ and to reset the Y _2. If Y ₁ = C is not satisfied in S208, or if Y ₂ = D is not satisfied in S213, the process returns to S204 where the number of edges X (t) is compared with A and B, and each condition is determined. Repeat the count accordingly.

When the count by the period T ₁ in the input signal counter unit 3, the up-down counter Z _n is equal to E set in S202 (e.g., if the initial value of Z _n to 0, Y ₁ = C condition or E times satisfaction The signal presence / absence determination unit 10 determines that the signal level is high (there is a signal), and Z _n is equal to 0 (for example, _{assuming that} the initial value of Zn is E−1, the condition of Y ₂ = D is E or satisfy) the signal presence determination unit 10 when the determined low level (no signal) times, in other cases if the state (high level in the period T ₁ of the immediately preceding time period T ₁ set in S201 High level state, low level if low level).

  As described above, in the video signal determination in the present embodiment, the horizontal sync signal and the vertical sync signal are separated from the video signal in order to apply the composite sync signal in which the horizontal sync signal and the vertical sync signal are combined. Compared to the conventional configuration in which the horizontal synchronization signal and the vertical synchronization signal are counted independently, it is simpler, so the circuit of the device can be reduced, and the noise component caused by the weak electric field is the nesting signal. The influence on the determination can also be suppressed.

Next, an example to which the above embodiment is applied will be described. Since T ₁ set by the period setting unit 2 is 2 msec and the horizontal synchronization signal is 64 μsec in both the NTSC system and the PAL system, the number of edges is 31, but about 2 edges are removed during the period T _1. In view of this, the lower limit A set by the range setting unit 5 in 31-2 is set to 29. Similarly to the above, the number of edges based on the horizontal sync signal is 31 and the number of edges based on the vertical sync signal is 7 in the NTSC system and 9 in the PAL system, so both are considered 9 and the number of edges due to noise based on the weak electric field. Is set to 60, and the upper limit value B set by the range setting unit 5 is set to 60 at 31 + 9 + 20. Also, C and D set by the upper limit setting unit 7 are set only to determine the continuity, so the minimum value of 2 is set. Further, the reference value E set by the level reference value setting unit 9 is a value for setting retention of hysteresis for interpolating between the presence or absence of a video signal, and is set to 7.

In this embodiment, when setting the lower limit value of the range setting unit 5, the number of missing edges in the horizontal synchronization signal is also taken into consideration, and the period of T ₁ (2 msec) is determined from the number of edges (31) calculated from the horizontal synchronization signal. By subtracting the number (2) and setting the lower limit A, the reduction in the number of edges caused by noise in the vicinity of the horizontal sync signal level often generated in the actual video signal is taken into account. It can be. Further, when setting the upper limit value of the range setting unit 5, the number of edges of the horizontal synchronizing signal is the number of edges (31) determined from the period of T ₁ (2 msec), and the number of edges of the vertical synchronizing signal is the number of edges in the video system. The number of edges (9) based on a method with a large number of edges (PAL method in this embodiment) is adopted, and the estimated number of edges (in this embodiment) caused by a noise component based on a weak electric field that is often found in real video signals. 20) is also taken into account, and the upper limit value B is set, so that the number of edges X (t) including the noise in a predetermined range due to the video system and the weak electric field is included, so that a realistic number of edges can be obtained.

Further, in this embodiment, the count Y ₁ is a cumulative count value in which the number of edges X (t) continuously satisfies the above-mentioned range of A to B, and the count Y ₂ has an edge number X (t) of less than A or B If the condition of the cumulative count value that satisfies a larger condition continuously, and the condition of the number of edges X (t) changes, both the counts Y ₁ and Y ₂ are reset, that is, the continuity is added to the count. Absorption that occurs at the time of a change is absorbed, and only conditions having continuity are counted, so that malfunction can be suppressed.

The upper limit value C of Y _{1 and} the upper limit value D of Y ₂ set in the upper limit setting unit 7 are reset when both the counts Y ₁ and Y ₂ are changed when the condition of X (t) is switched as described above. Since this is the upper limit value of the continuous count value under each condition, even if the minimum number (2) is set as in this embodiment, the continuity is sufficiently ensured and the video signal is determined with high accuracy. be able to.

Further, by comparing the reference values E (7 in this embodiment) and 0 set by the level reference value setting unit 9 with the up / down counter value Z _n, it is determined that there is no video signal if equal to 0, If it is equal to E, it is determined that there is a video signal, and if it is greater than 0 and less than E, the signal presence / absence immediately before the period of T ₁ is set to be weak electrolysis noise or noise similar to a synchronization signal. In contrast, the presence or absence of the input video signal can be determined with high efficiency without causing a malfunction.

  The video signal determination of the present invention can be widely applied to the field of digital recording of video signals, including DVD recorders that are now widely used.

1 is a configuration diagram of a video signal determination device according to an embodiment of the present invention. Flowchart of video signal determination method according to the embodiment

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Input terminal 2 Input signal counter part 3 Period setting part 4 Counter value comparison process part 5 Range setting part 6 Comparison part 7 Upper limit setting part 8 Up / down counter part 9 Level reference value setting part 10 Signal presence determination part 11 Output terminal

Claims (6)

Horizontal synchronizing signal for a predetermined period T based on the calculated value of the number of edges rising or falling edge of the ₁ value A in the input video signal, and a composite of the horizontal synchronizing signal and a vertical synchronizing signal in the input video signal composite A value B based on a calculated value of the number of rising or falling edges of the synchronization signal in the predetermined period T ₁ and an estimated value of the number of edges caused by noise based on a weak electric field is set, respectively, and the composite synchronization signal The number X of rising edges or falling edges in the predetermined period T ₁ is counted. When the number X of edges of the composite synchronizing signal is A ≦ X ≦ B, a signal is present, and X <A or X> B A video signal determination method characterized in that it is determined that there is no signal when the above condition is satisfied. The number of times Y ₁ when the condition for determining the presence of the signal is continued is counted, the Y ₁ is compared with a predetermined value C set in advance, and if the number is the same, an up process is performed on the up / down counter. counting the number of times Y ₂ which determines conditions are continuous, claim 1, wherein comparing the predetermined value D which is set in advance and Y _2, and performs down process to the up-down counter if the same number The video signal determination method described. The count value Z _n of the up / down counter (where n is a natural number) is compared with predetermined values E and 0, and the counter value Z _i of the up / down counter (where i satisfies i> n). until natural number) is E or zero again, the video signal determination method of claim 2, wherein the holding determination according to the value of the Z _n. An input signal counter means for counting the number X of rising edges or falling edges in a predetermined period T ₁ of a composite synchronizing signal obtained by combining a horizontal synchronizing signal and a vertical synchronizing signal in an input video signal;
The value A based on the calculated value of the number of rising edges or falling edges in the predetermined period T ₁ of the horizontal synchronizing signal, and the rising edge or rising edge of the horizontal synchronizing signal and the vertical synchronizing signal in the predetermined period T ₁ . Range setting means for setting and outputting a value B based on a calculated value of each of the number of edges and an estimated value of the number of edges caused by noise based on a weak electric field;
The output X of the input signal counter means is compared with the output values A and B of the range setting means. When the output X satisfies the range of A to B, a signal Y is determined and a count Y ₁ is output. A video signal determination device comprising: a counter value comparison processing unit that determines that there is no signal when the output X is less than A or greater than B, and outputs a count Y ₂ . The upper limit C of the number of consecutive counts Y ₁ output by the counter value comparison processing means and the upper limit value D of the number of consecutive counts Y ₂ output by the counter value comparison processing means are set, and C and D are set. Upper limit setting means to output;
The value of the count Y ₁ or the value of the count Y ₂ output from the counter value comparison processing means is compared with the upper limit value C or D. If Y ₁ is equal to C, the count value Z _n ( Here, n is up to natural number), Y ₂ is according to claim 4, further comprising a comparing means for outputting a signal down the count value Z _n of the up-down counter means if equal to D Video signal determination device. Level reference value setting means for setting and outputting a reference value E of the count value Z _n ;
The count value Z _n is compared with the reference values E and 0 to determine the presence or absence of a signal corresponding to the count value Z _n, and the count value Z _i (where i is a natural number satisfying i> n) video signal determining apparatus according to claim 5, further comprising a signal presence determination means for maintaining the determination in accordance with the count value Z _n until again one of the values of E or zero.

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