JP2006180052A - Video signal processor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a video signal processor performing YC separation accurately, using a sampling clock that does not always synchronize in phase with a chrominance subcarrier. <P>SOLUTION: The video signal processor comprises a DPLL 3 for detecting the instantaneous phase of a chrominance subcarrier, a timing generation circuit 4 for setting the reference point of phase at a predetermined period, based on the instantaneous phase of a chrominance subcarrier detected by the DPLL 3 and detecting the sampling phase, at each sampling point simultaneously with detection of phase difference between the reference point of phase thus set and a sampling clock, and a delay filter 5 for delaying a video signal by a phase difference detected by the timing generation circuit 4, wherein the output from the delay filter 5, i.e. the video signal, is written to a memory and the data read out from the memory are supplied to a YC separation circuit 17. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a video signal processing apparatus having means for separating a composite video signal into a luminance signal and a carrier color signal, and more particularly to a YC separation circuit using a comb filter.

  There are three types of color television standard systems for analog broadcasting: NTSC, PAL, and SECAM. In either method, the video signal is transmitted in the form of a composite video signal in which a luminance signal (hereinafter referred to as “Y signal”) and a carrier color signal (hereinafter referred to as “C signal”) are frequency-multiplexed. For this reason, a process called “YC separation” for separating these two signals is required on the receiver side.

  In YC separation, a comb filter using a line delay and a frame delay is generally used. The comb filter separates the Y signal and the C signal from the composite video signal using a ratio of the color subcarrier frequency, the horizontal frequency, and the vertical frequency of the video signal. For example, in the NTSC system, the color subcarrier frequency is 227.5 times the horizontal frequency, so that the color subcarrier phase is shifted by 180 degrees compared to the previous line (a time point one period before the horizontal period). It will be. Therefore, in an image having no change in the vertical direction, the amplitude of the Y signal is the same as that of the previous line, whereas the amplitude of the C signal is reversed from that of the previous line. In such a case, the Y signal is obtained by dividing the sum of the composite video signal without delay and the composite video signal delayed by one line by 2, and the C signal is obtained by dividing the difference by 2. Hereinafter, a comb filter using a line delay is referred to as a line comb filter. There are various types of line comb filters, not just those that simply add or subtract 1-line delayed signals (see, for example, Patent Document 1).

  In the NTSC system described above, the color subcarrier frequency is 59718.75 times the vertical frequency, so that the color subcarrier phase is 180 degrees compared to the previous two fields (at a time point two cycles before the vertical cycle). That is a shift. Therefore, in a still image that does not move in the time direction, the Y signal and the C signal can be separated by the same operation as the line comb filter using the composite video signal without delay and the composite video signal delayed by two fields. . Since two fields correspond to one frame, a comb filter using a frame delay may be referred to as a frame comb filter. In the following, delays sufficiently larger than one-line delays including odd field delays are collectively referred to as frame delays, and comb filters that use such frame delays are referred to as frame comb filters. As described above, the frame comb filter performs accurate YC separation on a still image, but YC separation performance deteriorates on an image with a lot of motion. For this reason, a YC separation circuit that uses a frame comb filter generally uses a motion detection circuit that detects a temporal change in a video signal using a frame-delayed video signal. The processing such as weakening the function of the frame comb filter is performed as is detected. Examples of the frame comb filter and motion detection circuit include those described in Patent Document 2 as conventional examples.

  In the PAL system, the color subcarrier phase is shifted by 180 degrees for every two lines, and the color subcarrier phase is also shifted by 180 degrees for every two frames, so the line comb filter and the frame comb filter are used as in the NTSC system. YC separation can be performed (for example, Patent Document 3). In the SECAM method, a comb filter is generally not used. However, since the color subcarrier phase is shifted by 180 degrees for every three lines and every field, the line comb filter and the frame comb filter are theoretically applied to YC separation. It is possible.

  In these conventional YC separation circuits, the frequency of the sampling clock is often an integer multiple of the color subcarrier frequency. For example, in the NTSC system, if the sampling frequency is four times the color subcarrier frequency, sampling points where the color subcarrier phase is shifted 180 degrees every 910 clocks and every 477750 clocks can be obtained. In order to generate a clock that is phase-synchronized with the color subcarrier in this way, it is common to control the oscillation frequency of the crystal resonator using an analog PLL (phase-locked loop). Hereinafter, a clock phase-synchronized with the color subcarrier is called a burst lock clock.

  On the other hand, there is a method of performing YC separation using a sampling clock that is not necessarily phase-synchronized with the color subcarrier. In particular, when a fixed frequency sampling clock is used, there is an advantage that an analog PLL is not required. However, if the sampling clock is not a burst lock clock, there is no correlation between the sampling interval and the color subcarrier period, so there is no sampling point corresponding to exactly one line before or one frame before a certain sampling point. there is a possibility. For example, in the NTSC YC separation circuit, consider a case where the sampling frequency is 100 ppm higher than four times the color subcarrier frequency. At this time, one line delay corresponds to 909.909 clock delay, and the video signal exactly one line before a certain sampling point exists between the sampling points before 909 clock and before 910 clock. Similarly, one frame delay corresponds to 477702.225 clock delay, and a video signal exactly one frame before a certain sampling point exists between 477702 clocks and 477703 clocks before. When the sampling clock is not a burst lock clock as described above, some device is required to accurately obtain a video signal with one line delay and one frame delay.

  Patent Document 4 is an example of a video signal processing apparatus that performs YC separation using a sampling clock having a fixed frequency. In this method, after sampling a composite video signal with a 27 MHz clock, the sampling rate is converted to a frequency four times the color subcarrier frequency. Since the converted video signal is equivalent to the video signal sampled by the burst lock clock, the video signal before one line or one frame can be obtained accurately by delaying this video signal by one line or one frame. Can do.

  On the other hand, Patent Document 5 shows an example of a video signal processing apparatus that performs YC separation without changing the sampling rate. In this case, the distortion of the video signal accompanying the sampling rate conversion is reduced. In this method, the video signal is delayed by about one frame in a sampling clock unit of a fixed frequency, and the delayed video signal is further passed through an interpolation filter to generate a video signal between two sampling points. The video signal one frame before is obtained. The same applies to the case where a two-frame delay is realized. By preparing another interpolation filter, a video signal two frames before can be accurately obtained.

Japanese Patent No. 3299810 (pages 25-29, Fig. 1) Japanese Patent No. 3464291 (page 4-5, FIG. 16) US Pat. No. 4,833,526 (pages 5-7, FIG. 1) Japanese Patent Laid-Open No. 2002-315018 (page 4-7, FIG. 1) JP 2004-007247 A (page 4-9, FIG. 1)

  However, in Patent Document 5 described above, it is assumed that only two types of video signals in total, that is, one frame delay and two frame delays are obtained. In order to use the line comb filter, it is necessary to obtain a video signal with an accurate line delay, but this means is not shown. Further, as the input of the frame comb filter, there is a case where a frame-delayed video signal further delayed by one line or more is used. However, in this case as well, no means for obtaining an accurately delayed video signal is shown. . If the idea of Patent Document 5 is expanded and interpolation filters are prepared for the types of video signal delays, the number of interpolation filters increases and the circuit scale increases.

  In addition, among video signals, there are non-standard signals such as VTR reproduction signals whose color subcarrier frequency, horizontal frequency, and vertical frequency ratios are not in compliance with the NTSC, PAL, and SECAM standards. With regard to the NTSC system, the case where the color subcarrier frequency is shifted from 227.5 times the horizontal frequency corresponds to the non-standard signal. In such a case, since it is difficult to correctly perform YC separation using a frame comb filter, it is necessary to perform non-standard signal detection to stop the operation of the frame comb filter. No means for performing non-standard signal detection is shown in FIG.

  The present invention has been made to solve the above problems, and in a video signal processing apparatus that performs YC separation using a sampling clock that is not necessarily phase-synchronized with a color subcarrier, line delay and accuracy can be accurately achieved with a small circuit scale. An object is to obtain a frame-delayed video signal and to obtain a non-standard signal detection circuit with a small number of additional circuits.

This invention was made in order to solve the problems as described above.
In a video signal processing apparatus that separates a luminance signal and a carrier color signal from a video signal sampled by a clock signal,
Color subcarrier phase detection means for detecting a value corresponding to the instantaneous phase of the color subcarrier used to generate the carrier color signal;
Reference point generating means for generating a reference point for the color subcarrier phase every predetermined period based on the detection result of the color subcarrier phase detecting means;
Phase difference detection means for detecting a phase difference between the reference point generated by the reference point generation means and the clock signal in units of less than one clock cycle;
Delay means for delaying a video signal at each sampling point based on the phase difference detected by the phase difference detection means;
Sampling phase detection means for detecting the sampling phase of the video signal delayed by the delay means based on the detection result of the color subcarrier phase detection means;
Storage means for storing the video signal delayed by the delay means;
Memory control means for controlling writing and reading of video signals to and from the storage means based on the sampling phase detected by the sampling phase detection means;
There is provided a video signal processing apparatus comprising YC separation means for generating a luminance signal and a carrier color signal using at least a video signal read from the storage means.

  In the present invention, since the delay means for delaying the video signal based on the phase difference between the reference point of the color subcarrier phase and the clock signal is arranged in the previous stage of the storage means, a clock that is not necessarily phase-synchronized with the color subcarrier is used. Even in such a case, it is possible to obtain a video signal with a line delay and a frame delay accurately from the storage means, and there is an effect that YC separation can be performed with high accuracy using a line comb filter and a frame comb filter.

Embodiment 1 FIG.
FIG. 1 is a diagram showing the configuration of a video signal processing apparatus according to Embodiment 1 of the present invention.

  The illustrated video signal processing circuit receives a digital composite video signal supplied to the input terminal 1 and processes it. The synchronous separation circuit 2, a digital PLL (hereinafter referred to as “DPLL”) 3, The timing generation circuit 4, the delay filter 5, the frame memory controller 6, the first to third frame memories 7, 8, and 9, the line memory controller 10, and the first to sixth line memories 11 to 16. And a YC separation circuit 17. These circuits handle digital signals and operate at a predetermined clock frequency unless otherwise specified.

A digital composite video signal is input from the input terminal 1. This digital composite video signal is obtained by sampling an analog composite video signal at a predetermined sampling frequency. This sampling frequency is synchronized with the frequency of the clock used for the operation of the circuits shown in FIG.
The synchronization separation circuit 2 separates the horizontal synchronization signal and the vertical synchronization signal from the video signal input from the input terminal 1. The DPLL 3 is a signal indicating the reference of the color subcarrier phase superimposed in the horizontal blanking interval of the video signal using the video signal input from the input terminal 1 and the horizontal synchronization signal separated by the synchronization separation circuit 2. And the instantaneous phase of the color subcarrier at each sampling point is detected. In the NTSC and PAL systems, the color burst signal is a signal indicating the color subcarrier phase reference, and in the SECAM system, the unmodulated color subcarrier signal is a signal indicating the color subcarrier phase reference. The internal configuration of DPLL 3 will be described later.

The timing generation circuit 4 sets a reference point of the color subcarrier phase at a predetermined cycle based on the instantaneous phase of the color subcarrier detected by the DPLL 3, and sets the reference point of the set color subcarrier phase and the sampling clock. The phase difference is detected in units of less than one cycle of the sampling clock, and at the same time, the sampling phase at each sampling point is detected based on the instantaneous phase of the color subcarrier detected by DPLL3.
Details of the timing generation circuit 4 will be described later.
The delay filter 5 is used as delay means for delaying the video signal based on the phase difference between the reference point of the color subcarrier phase detected by the timing generation circuit 4 and the sampling clock.

The frame memory controller 6 writes and reads video signals to and from the first frame memory 7, the second frame memory 8, and the third frame memory 9 based on the sampling phase of each sampling point detected by the timing generation circuit 4. Control.
The frame memory controller 6 writes the video signal delayed by the delay filter 5 in any one of the first frame memory 7, the second frame memory 8, and the third frame memory 9. The video signal is read out from the remaining two frame memories that are not written. If the frame memory to be written for each frame is switched, video signals with 1-frame delay and 2-frame delay can be read from two frame memories that have not been written. The 1-frame delay and 2-frame delay video signals read from the frame memory are output to the line memory controller 10 via the frame memory controller 6.

The line memory controller 10 includes a first line memory 11, a second line memory memory 12, a third line memory 13, and a fourth line memory based on the sampling phase of each sampling point detected by the timing generation circuit 4. Control of writing and reading of video signals to the memory 14, the fifth line memory 15, and the sixth line memory memory 16 is performed. A video signal delayed by the delay filter 5 is written into the first line memory 11, the second line memory 12, and the third line memory 13 via the line memory controller 9. On the other hand, in the fourth line memory 14, the fifth line memory 15, and the sixth line memory 16, a one-frame delayed video signal output from the frame memory controller 6 is written. The line memory controller 10 uses the three line memories of the first line memory 11, the second line memory 12, and the third line memory 13 to delay one line by the same control as the frame memory controller 6 described above. And a two-line delayed video signal are obtained. In addition, a video signal (hereinafter, referred to as a video signal obtained by further delaying a one-frame delayed video signal by one line using the three line memories of the fourth line memory 14, the fifth line memory 15, and the sixth line memory 16). "1 frame + 1 line delayed video signal") and a video signal delayed by 2 lines (hereinafter referred to as "1 frame + 2 line delayed video signal") are obtained.
Thus, the frame memories 7 to 9 and the line memories 11 to 16 are used as storage means for storing the video signal delayed by the delay filter 5.
The 2-frame delayed video signal output from the frame memory controller 6 is output to the YC separation circuit 16 via the line memory controller 9. The video signal output from the line memory controller 9 to the YC separation circuit 16 is a total of 0 line delay, 1 line delay, 2 line delay, 1 frame delay, 1 frame + 1 line delay, 1 frame + 2 line delay, and 2 frame delay. There are seven types of video signals.

  The YC separation circuit 16 generates a Y signal and a C signal using these seven kinds of video signals, and outputs them from the output terminal 17 and the output terminal 18, respectively.

  Next, the internal configuration of the DPLL 3 will be described with reference to FIG.

  The burst gate 22 is a color burst signal (or an unmodulated color subcarrier superimposed on the horizontal blanking period of the video signal input from the input terminal 20 based on the horizontal synchronization signal input from the input terminal 21. Signal). The phase comparator 23 detects a phase error between the output signal of the burst gate 22 and the sine wave output from the sine wave ROM 26 and outputs it to the loop filter 24. The loop filter 24 smoothes the phase error detected by the phase comparator 23 and generates a control value for the phase accumulator 25. The phase accumulator 25 adds a constant value corresponding to the free-running oscillation frequency of the DPLL 3 to the control value generated by the loop filter 24 and adds up every clock to generate a phase value from 0 degrees to 360 degrees. To do.

  For example, it is assumed that the phase value that is the output of the phase accumulator 25 is 250 degrees at a certain time. If the control value that is the output of the loop filter 24 is constant at 1 degree and the constant value added by the phase accumulator 25 is 45 degrees, the output of the phase accumulator 25 after 1 clock becomes 296 degrees and 2 clocks After 342 degrees, after 3 clocks it will be 28 degrees, after 4 clocks it will be 74 degrees, etc.

  The phase value output from the phase accumulator 25 is output to the sine wave ROM 26 and the output terminal 27. The sine wave ROM 26 is a circuit that outputs sin (w) with respect to the input value w.

  Here, it is indicated that the phase value output from the output terminal 27 is a value corresponding to the instantaneous phase of the color subcarrier. When the phase error detected by the phase comparator 23 is constantly 0, it is considered that the color burst signal (or unmodulated color subcarrier signal) and the sine wave oscillation generated by the sine wave ROM 26 are in phase synchronization. It is done. Accordingly, at this time, the phase value input to the sine wave ROM 26 is considered to be equal to the instantaneous phase of the color burst signal (or unmodulated color subcarrier signal). Since the color burst signal is a signal indicating the reference phase of the color subcarrier signal, the phase value output from the output terminal 27 is also considered to be a value corresponding to the color subcarrier phase. Strictly speaking, the phase value output from the output terminal 27 may have a constant phase error with respect to the color subcarrier phase, but in reality, this phase error does not cause a problem in the operation of the circuit. Therefore, in the following, the phase value output from the output terminal 27 is treated as the instantaneous phase of the color subcarrier itself.

  In this way, the DPLL 3 constitutes a color subcarrier phase detection means for detecting a value (FIG. 4B) corresponding to the instantaneous phase of the color subcarrier used for generating the carrier color signal (C).

  In the case of the PAL system, the phase of the color burst signal is not constant unlike the NTSC system, and changes alternately by +90 degrees or -90 degrees for each line. Therefore, in the PAL system, the phase error detected by the phase comparator 23 alternates between +45 degrees and −45 degrees for each line, and the color burst signal and the sine wave oscillation generated by the sine wave ROM 26 are phase-synchronized. You can think that it is in a state.

  In the case of the SECAM system, two types of color subcarriers having different frequencies are switched for each line. In this case, for example, one DPLL can be used for one type of color subcarrier. In the SECAM system, the color subcarrier is inverted 180 degrees every three lines. Therefore, in order to synchronize the DPLL with the color subcarrier, it is desirable to perform line discrimination and correct the inverted color subcarrier phase.

  Further, the internal configuration of the timing generation circuit 4 will be described with reference to FIG.

The instantaneous phase of the color subcarrier detected by the DPLL 3 is input to the phase difference detection circuit 29, the reference point generation circuit 30, and the first counter 31 via the input terminal 28.
The reference point generation circuit 30 generates a reference point for the color subcarrier phase at a predetermined cycle (almost constant cycle) based on the instantaneous phase of the color subcarrier (the detection result of the color subcarrier phase detection means (3)). Or used as reference point generation means for setting. The reference point generation circuit 30 outputs a timing pulse to the first counter 31 and the phase difference detection circuit 29 each time a new reference point is set.
The first counter 31 receives the sampling clock at the count input terminal C, increments by 1 every clock, receives the timing pulse from the reference point generation circuit 30 at the reset input terminal R, and outputs the timing pulse every time the timing pulse is output. This circuit resets the count value. The count value in the first counter 31 is output from the output terminal Q.
The phase difference detection circuit 29 is based on the phase difference between the color subcarrier phase when the timing pulse is output and the color subcarrier phase at the sampling point appearing simultaneously with the reference point or immediately after the reference point. This is a circuit for calculating the delay amount of the video signal used in. As will be described later, the phase difference detection circuit 29 detects the phase difference between the reference point generated by the reference point generation circuit 3 and the sampling clock signal in units of less than one clock cycle.
The delay amount calculated by the phase difference detection circuit 29 is output to the delay filter 5 via the output terminal 32. The count value of the first counter 31 is output to the line memory controller 10 and the frame memory controller 6 via the output terminal 33. In the line memory controller 10 and the frame memory controller 6, the count value of the first counter 31 is used as a value indicating the sampling phase of the video signal.

  The first counter 31 detects the sampling phase of the video signal delayed by the delay filter 5 based on the instantaneous phase of the color subcarrier detected by the DPLL 3 (the detection result of the color subcarrier phase detection means (3)). It is used as means for performing (sampling phase detection means).

  Hereinafter, the operation of the video signal processing apparatus according to the first embodiment will be specifically described with reference to the drawings.

  In the description, the sampling clock frequency is fs, the color subcarrier frequency is fsc, the horizontal frequency is fh, and the vertical frequency is fv. In the first embodiment, a case where a standard NTSC video signal in which fs = 27 MHz, fsc = 227.5 × fh, and fh = 262.5 × fv is processed will be considered.

  In the NTSC system, fsc = 3.579545 MHz is a standard value, and at this time, fs = 1716 × fh holds. Therefore, it can be seen that in the standard NTSC video signal, sampling points where the color subcarrier phase shifts by 180 degrees are found every 1716 clocks. However, in an actual video signal, the relationship of fs = 1716 × fh does not always hold. Therefore, the reference point set by the reference point generation circuit 30 is a point where 1712 clocks or more have elapsed from the previously set reference point, and the color subcarrier phase is shifted by 180 degrees with respect to the previously set reference point. Suppose there is. Furthermore, the instantaneous phase of the color subcarrier at the reference point is assumed to be either 0 degrees or 180 degrees. Under this condition, even if fs is slightly deviated from 27 MHz or fsc is slightly deviated from the standard value of the NTSC system, as long as fs <8 × fsc is satisfied, 1712 clocks or more and 1720 clocks from the previously set reference point. It is always possible to set a new reference point during the passage of less. Since the point where the instantaneous phase of the color subcarrier is 0 degree or 180 degrees does not always coincide with the sampling point, the reference point usually exists between two sampling points.

  Here, the operation of the timing generation circuit 4 will be described with reference to FIG. 4A is a sampling clock, FIG. 4B is data representing the instantaneous phase of the color subcarrier inputted from the input terminal 28, FIG. 4C is the most significant bit of data representing the instantaneous phase, and FIG. (D) is the count value of the first counter 31, FIG. 4 (e) is the value of the lower 11 bits (T) of the count value, FIG. 4 (f) is the most significant bit (B) of the count value, 4 (g) shows the delay amount of the video signal calculated by the phase difference detection circuit 29, and FIG. 4 (h) shows the timing pulse output from the reference point generation circuit 30.

  Assume that the instantaneous phase of the color subcarrier input from the input terminal 28 is represented by 10 bits, and the 10-bit value 512 is converted to a phase and corresponds to 180 degrees. In the reference point generation circuit 30, the value of the lower 11 bits of the count value of the first counter 31 is 1712 or more, and the value of the most significant bit of the instantaneous phase of the color subcarrier input from the input terminal 28 has changed. Suppose that sometimes a timing pulse is output. This corresponds to the timing at which the reference point is set. The first counter 31 is a 12-bit counter, and increments by 1 every clock, and resets the count value every time the reference point generation circuit 30 generates a timing pulse. It is assumed that the reset value is 2048 when the count value when the timing pulse is generated is less than 2048, and 0 when it is greater than 2048. The phase difference detection circuit 29 multiplies the value of the lower 9 bits of the instantaneous phase of the color subcarrier when the timing pulse is output by a value corresponding to (fs / fsc), and further divides the value by 16 as a delay filter. 5 is output through the output terminal 32 as the delay amount used in the step 5.

  In FIG. 4, the instantaneous phase of the color subcarrier is always increased by 136 per clock. This corresponds to a case where the color subcarrier frequency is 136 times 1024 of the sampling clock frequency, that is, 3.585375 MHz. Furthermore, it is assumed that the instantaneous phase of the color subcarrier is 0 in the initial state, and the first reference point is set at this time, and the count value of the first counter 31 is 3761 at this time.

  When the initial state is as described above, the count value of the first counter 31 is reset to 0 by a timing pulse one clock after the first reference point is set, and becomes 1712 after 1712 clocks. At this time, the instantaneous phase of the color subcarrier is 520, and the most significant bit of the instantaneous phase of the color subcarrier represented by 10 bits changes from 0 to 1. Therefore, when the count value reaches 1712, the reference point generation circuit 30 generates a timing pulse. In this way, the second reference point is detected between when the count value of the first counter 31 is 1711 and when it is 1712.

  In the next clock cycle, the count value of the first counter 31 is reset to 2048 in response to the timing pulse. Similarly, the phase difference detection circuit 29 multiplies 8 which is the lower 9 bits of the 10-bit value of 520 by (fs / fsc) and divides the result by 16. Since (fs / fsc) = (1024/136) from the initial assumption, the output value of the phase detection circuit 29 is 3 (rounded down to the nearest decimal point). This indicates that the phase difference between the second reference point and the rising edge of the sampling clock is approximately 3/64 clocks in terms of the sampling clock period. The ratio of fsc and fs may be a value obtained by detecting both frequencies by some means, but may be a constant determined in advance. For example, even if calculation is always performed using (NTS standard value) as (fs / fsc) = (27 / 3.579545), the calculation accuracy is not adversely affected.

  In response to the delay amount calculated by the phase difference detection circuit 29, the delay filter 5 converts the video signal at each sampling point into 64 minutes from when the second reference point is detected until the third reference point is detected. Are delayed by three clocks. The delay filter is a kind of interpolation filter, and is considered to be a filter that creates a video signal between clocks by interpolation. In general, when a sampling function or a higher-order polynomial is used, accurate interpolation can be performed, but linear interpolation or the like may be used together.

  Similarly, the count value of the first counter 31 is 3760 after the generation of the timing pulse indicating that the second reference point has been detected, and the instantaneous phase of the color subcarrier is 16. At this time, the lower 11 bits of the count value is 1712, and the most significant bit of the instantaneous phase of the color subcarrier changes from 1 to 0. Therefore, at this timing, the reference point generation circuit 30 detects the third reference point. A timing pulse is generated to indicate that this has occurred. The third reference point is between the time when the count value of the first counter 31 is 3759 and 3760, and the phase difference from the sampling clock that appears immediately after that is converted into a 10-bit color subcarrier phase. Will be 16. The delay amount at this time is 7/64 clocks in terms of the sampling clock period by the above-described calculation method. The delay filter 5 delays the video signal at each sampling point by 7/64 clocks from the detection of the third reference point to the detection of the fourth reference point. The count value of the first counter 31 is reset to 0 at the next clock that generates the timing pulse.

  In the same manner, the fourth and subsequent reference points are detected.

Next, the operation of the line memory controller 10 will be described with reference to FIGS. 5 and 6 are two-dimensional representations of sampling points arranged in time series using the X and Y coordinates. The X coordinate takes an integer value from 0 to 1715, and the Y coordinate takes an integer value of 0 or more.
Each sampling point after the delay corresponds to a lattice point in the figure and can be identified by the X coordinate and the Y coordinate. The delayed sampling point at coordinates (X, Y) = (x, y) is the sampling point after (x + y × 1716) clocks of the delayed sampling point at (X, Y) = (0, 0). (When (x + y × 1716) clocks have elapsed from the sampling point at (X, Y) = (0, 0)). The number on the upper right of each grid point is the count value of the first counter 31 and is a value indicating the sampling phase of the video signal delayed by the delay filter 5. In the figure, in order to simplify the following description, the value of the most significant bit of the sampling phase, which is a 12-bit value, is shown in parentheses, and the value of the remaining lower 11 bits is shown on the left side of the most significant bit. Hereinafter, the most significant bit of the sampling phase is referred to as a reference phase and is represented by the symbol B. The lower 11 bits of the sampling phase are called phase offset and are represented by the symbol T. A symbol Dn at the lower right of each lattice point indicates a delay amount used by the delay filter 5 after the nth reference point is detected and the (n + 1) th reference point is detected.
Further, white circles are actual sampling points (sampling points before delay), and arrows from the white circles are sampling points where the video signal that was at the position of the white circle by the delay filter 5 is at the tip of the arrow. In other words, the delay filter 5 obtains the sample value of the video signal at the position of the white circle (and the instantaneous value of the video signal at the sampling point at the end of the arrow based on the sample value in the vicinity thereof by delay or interpolation. Note that the instantaneous value of the video signal obtained by delay or interpolation in this way is also called a sample value, and the point at which this sample value is obtained is called a sampling point.
For example, the video signal at the upper left point A in FIG. 5 appears at the sampling point where (X, Y) = (1, 1) by the delay filter 5. (In order to make the figure easier to see, description of sampling phase, delay amount, etc. is omitted at some lattice points.

  In the operation of the timing generation circuit 4 described above, there is a delay of one clock from when the reference point is detected until the count value of the first counter 31 is reset. Since the delay of 1 clock does not become a problem, in the following figure, the position of the reference point is shifted by 1 clock, and the counter value is immediately after the reference point is detected (in the same clock period, not after the lapse of 1 clock period). It is described to be reset. There is a one-clock delay from the detection of the reference point until the delay amount used by the delay filter 5 is calculated. In the following figures, the delay amount is calculated immediately after the reference point is detected for the same reason. It is described as such.

  First, the case where fs = 1716 × fh holds will be described with reference to FIG. Since the first embodiment assumes that fsc = 227.5 fh holds, the first reference point is between (X, Y) = (3, 0) and (X, Y) = (4, 0). If detected, the second and subsequent reference points are also detected between 3 and 4 in the X coordinate. That is, all the reference points are detected on a straight line indicated by P in the figure. When the straight line P is expressed as X = p (3 <p <4), Dn = 4-p holds for an arbitrary n. That is, it can be seen that the same delay amount is used at all sampling points. In addition, the phase offset T of the sampling points where X = 4 is all 0 by the operation of the first counter 31 described above. Therefore, T = 1716−X at sampling points where X is less than 4, and T = X−4 at sampling points where X is 4 or more. Considering the video signal delayed by the delay filter 5, the instantaneous phase of the color subcarrier at the sampling point where the reference phase is B and the phase offset is T is given by (B × 180 degrees + T × fsc ÷ fs × 360 degrees). Therefore, the instantaneous phases of the color subcarriers at two sampling points where T and B are both equal are the same, and the instantaneous phases of the color subcarriers at two sampling points where T is equal and only B is different are 180 degrees different from each other. become. Therefore, the line memory controller 10 uses the value of T as a read / write address for the line memory, and controls the line memory to be read / written every time the value of B changes, so that the YC separation circuit 17 uses it. A video signal with 1-line delay and 2-line delay is obtained.

  Next, let us consider a case where the line memory controller 10 further delays the one-frame delayed video signal output from the frame memory controller 6 by one line and two lines. Assume that the frame memory controller 6 outputs a video signal with a delay of one frame in which the color subcarrier phase is correctly shifted by 180 degrees. That is, it is assumed that a video signal having the same T and different only B is obtained at an arbitrary (X, Y) as a video signal delayed by one frame. At this time, since the arrangement of the video signal with one frame delay corresponds to the case where the value of B in FIG. 5 is replaced with 0 and 1, the value of T is set to the fourth line memory 14, the fifth line memory 15, and the 6 is used as the read / write address of the line memory 16 and is controlled so that the line memory to be read / written is switched every time the value of B is changed. , And a video signal with a delay of 1 frame + 2 lines can be obtained.

  The operation of the frame memory controller 6 for the first frame memory 7, the fifth frame memory 8, and the sixth frame memory 9 is substantially the same as the operation of the line memory controller 10. Among the video signals delayed by the delay filter 5, between the (n + 1) th reference point and the (n + 1) th reference point, ((n mod 525) × 1716 + T) is used as the read / write address for the three frame memories, If the control is performed so that the frame memory to be read / written is switched every time the reference point is detected 525 times, a 1-frame delayed video signal and a 2-frame delayed video signal can be obtained.

  Next, the case where fs = 1716 × fh does not hold will be described with reference to FIG. In FIG. 6, it is assumed that fs = 1716.25 fh, and the first reference point is detected at a sampling point where (X, Y) = (2, 0). At this time, the values of T, B, and Dn are as shown in the figure. D0 = 0, D1 = 16, D2 = 32, D3 = 48, D4 = 0, D5 = 16, D6 = 32, and D7 = 48 (64 corresponds to one clock delay). In the figure, the reference point of the color subcarrier phase is indicated by a straight line P as in FIG. As can be seen from the figure, a straight line parallel to the straight line P can be obtained by connecting white circles corresponding to sampling points having the same T. Note that since the X coordinate can only take values from 0 to 1715, strictly speaking, a line connecting white circles corresponding to sampling points having the same T is a collection of line segments of a finite length. , Y) = (x, y) is the same point as (X, Y) = (x-1716, y + 1), and it is considered that a straight line can be drawn without being cut halfway. In the figure, a straight line connecting points coincident with sampling points where T = 3 by the delay filter 5 is indicated by P3. The straight line P3 is represented by Y = 4 × (X-5). When Y = 6844, X = 1716, but as described above, (X, Y) = (1716, 6844) is considered to point to the point (X, Y) = (0, 6845). Considering the video signal before being delayed by the delay filter 5, the color subcarrier phase at the point (X, Y) = (x, y) is determined from the point (p, y) on the straight line P with the same Y coordinate. ((X−p) × fsc ÷ fs × 360 degrees). That is, it can be seen that the instantaneous phases of the color subcarriers at the points on the straight line parallel to the straight line P are all equal. Therefore, considering the video signal delayed by the delay filter 5, the color subcarrier phases at two sampling points having the same value of T are either equal to each other or different from each other by 180 degrees. This is exactly the same as in the case of FIG. 5, and the video signal of the line delay and frame delay used in the YC separation circuit 17 is obtained by the read / write control of the line memory and the frame memory as described above.

  As described above, in the video signal processing apparatus according to the first embodiment, only one delay filter is used, and 0 line delay, 1 line delay, 2 line delay, 1 frame delay, 1 frame + 1 line delay used in the YC separation circuit 13 are used. It is possible to generate a total of seven types of video signals of 1 frame + 2 line delay and 2 frame delay. Even when the line delay and frame delay data further increase, the number of delay filters is only one. Even when a video signal having a field delay (for example, 262 line delay) is required, it can be seen that a video signal having a field delay can be obtained in almost the same manner by replacing the frame memory with a field memory.

  Although only the NTSC system has been described in the first embodiment, the PAL system can be handled with the same configuration. For example, in the PAL-I system used in the UK, fsc = (1135 ÷ 4 + 1 ÷ 625) × fh, fh = 312.5 × fv, and when fs = 27 MHz, fs = 1728 × fh. In the PAL system, the color subcarrier phase is shifted by 180 degrees approximately every two lines. Therefore, in the NTSC system, if the reference point setting period of 1752 clocks or more is set to 3452 or more, the PAL-I system YC separation is performed in the same manner. A video signal with a line delay and a frame delay used in the above is obtained. Further, in the case where a video signal in which the color subcarrier phase after about one line is shifted by 270 degrees is also necessary in the PAL-I system, it is at a point that is more than 1724 clocks and less than 1732 clocks from the previously set reference point. First, a point where the instantaneous phase of the color subcarrier is 90 degrees or 270 degrees may be searched.

  In the SECAM system, fh = 312.5 × fv, and fsc is switched to fsc = 282 × fh and fsc = 272 × fh for each line. When fs = 27 MHz, fs = 1728 × fh, and there is a point where the color subcarrier phase is shifted by 180 degrees either before 3456 clocks or after 3456 clocks. It may be set to 3452 or more corresponding to two lines.

Embodiment 2. FIG.
The second embodiment is an example having a timing generation circuit 4 having an internal configuration different from that of the first embodiment.

  FIG. 7 is a diagram showing the configuration of the timing generation circuit 4 according to the second embodiment of the present invention. In FIG. 7, the same reference numerals as those in FIG. 3 denote blocks having the same configuration, and the description thereof is omitted.

  The timing generation circuit of FIG. 7 is generally the same as that shown in FIG. 3 except that a shift register 35 and a second counter 36 are added. The first counter 31 is the same as the counter 31 of FIG. 3, but its output terminal Q is connected to the shift register 35 (not the output terminal 33 as in FIG. 3). Similarly, the phase detection circuit 29 is the same as the phase detection circuit 29 of FIG. 3, but its output is connected to the shift register 35 (not the output terminal 32). Similarly, the reference point generation circuit 30 is the same as the reference point generation circuit 30 of FIG. 3, but its output is also connected to the shift register 35.

  As shown in FIG. 8, the shift register 35 includes five stages of registers 35a to 35e, a selection circuit 35f that receives and outputs one of the outputs of the registers 35a to 35e, and a subtraction circuit 35g. . The subtraction circuit receives the lower 11 bits of the count value of the first counter 31, subtracts the lower 11 bits of the count value of the first counter 31 from “1716”, and outputs the subtraction result. The first-stage register 35a receives the output (Sn) of the subtraction circuit 35 and the output (delay amount Dn) of the phase difference detection circuit 29. The second to fifth stage registers 35b to 35e receive the outputs of the first to fourth stage registers 35a to 35d, respectively. The first to fifth stage registers 35 a to 35 e perform a shift operation according to the timing pulse output from the reference point generation circuit 30. The timing pulse output from the reference point generation circuit 30 is supplied to the selection circuit 35f together with the horizontal synchronization signal input from the input terminal 34.

  The shift register 35 outputs a 6-bit delay amount Dn, which is an output of the phase difference detection circuit 29, and “when a timing pulse indicating that the nth reference point is detected in the reference point generation circuit 30 is output. The value obtained by subtracting the lower 11 bits of the count value of the first counter 31 (hereinafter referred to as “increment value” and written as Sn) is stored in the first-stage register 35a and The values stored in the registers 35a to 35d in the first to fourth stages are moved to the registers 35b to 35f in the next stage. The selection circuit 35f initially selects (in the initial state) the third-stage register 35c, and every time a timing pulse is output from the reference point generation circuit 30, the selection circuit 35f is one stage later than the previously selected register. Select a register, read and output the value stored in the selected register, and select the previous register every time the reference edge of the horizontal sync signal input from the input terminal 34 is detected. Reads and outputs the value stored in the selected register. When the timing pulse and the reference edge of the horizontal synchronizing signal are detected at the same time, a register at the same stage as that selected so far is selected, and the value stored in the selected register is read and output. Since the value of each register is shifted backward by one stage when a timing pulse is generated, the read value itself does not change even if the register one stage behind is read out by the timing pulse. When the timing pulse and the reference edge of the horizontal synchronizing signal are detected at the same time, the register value of the same stage is read, but the value stored in the register of each stage is moved to the next register. Therefore, the read value itself is a different value. Among the read values, the delay amount Dn is output to the delay filter 5 via the output terminal 32, and the increment value Sn is output to the second counter 36.

The second counter 36 is a 12-bit counter that receives a sampling clock at its count input terminal C and counts up by one every clock. However, in the second counter 36, the next count value of 1715 is 2048, and the next count value of 3763 is 0.
The second counter 36 receives the increment value Sn output from the shift register 35 at its addition input terminal A, receives the horizontal synchronization signal at the control input terminal B, and detects the reference edge of the horizontal synchronization signal. Each time, the increment value Sn output from the shift register 35 is added to the current count value. Here, “addition” means setting to a value equal to the count value that appears after the same number of clocks as the value to be added are input. For example, when Sn = 3 is added when the current count values are 0, 1714, and 3762, the next values are 3, 2049, and 1, respectively. When the increment value Sn is a negative value, instead of subtracting the absolute value of Sn from the count value, the count is stopped only for the clock cycle corresponding to the value obtained by adding 1 to the absolute value of Sn. For example, when Sn = −2, the count is stopped for 3 clocks. The count value of the second counter 36 is output from the output terminal Q, and is output to the frame memory controller 6 and the line memory controller 10 via the output terminal 33 of the timing generation circuit 4. The count value of the second counter 36 indicates the sampling phase of the video signal delayed by the delay filter 5.

  The first to fifth stage registers 35a to 35e are used as phase difference holding means for holding the phase difference detected by the phase difference detection circuit 29 in time series, and the selection circuit 35f is outside the effective video period. Is used as phase difference selection means for updating the phase difference read from the phase difference holding means (35a to 35e), for example, at the reference edge of the horizontal synchronizing signal.

  By configuring the timing generation circuit 4 as described above, it is possible to perform accurate YC separation even for non-standard signals in which the relationship between fsc, fh, and fv is not in accordance with the standard. This will be described below.

  Looking at FIG. 6 of the first embodiment, there is a point (X, Y) = (3, 5) where only one value of T is 1716. In order to use the line comb filter, at least two sampling points having the same value of T are required. However, there is no point having the same T in (X, Y) = (3, 5). Therefore, the line comb filter cannot be used. Therefore, only in the vicinity of (X, Y) = (3, 5), the accuracy of YC separation is degraded.

  In the first embodiment, however, a standard NTSC video signal satisfying fsc = 227.5 × fh and fh = 262.5 × fv is processed. In this case, FIG. The straight line P connecting the reference points shown and the straight line connecting the appearance positions of the reference edges of the horizontal synchronization signal (hereinafter referred to as “straight line H”) are always parallel. Therefore, it is possible to make the reference point always appear within the horizontal blanking period and prevent the point (X, Y) = (3, 5) in FIG. 6 from appearing on the display screen.

  However, in a non-standard signal where fsc = 227.5 × fh does not hold, the straight line P and the straight line H may not be parallel, and (X, Y) = (3, 5) in FIG. Such a point cannot always appear within the horizontal blanking interval.

  On the other hand, in the second embodiment, the point at which the count value of the second counter 36 representing the sampling phase becomes discontinuous becomes the reference edge of the horizontal synchronizing signal, so that the line comb filter is always used in the effective video period. Will be able to.

  Now, suppose fs = 1715.75 × fh = 27 MHz, and fs = (1716 + 1 ÷ 3) ÷ 227.5 × fsc = 10298 ÷ 1365 × fsc. At this time, the reference edge of the horizontal synchronizing signal appears every 1715.75 clocks, and the point where the instantaneous phase of the color subcarrier shifts by 180 degrees appears every 1716.333 clocks. Further, here, it is assumed that the first reference point is detected at (X, Y) = (3, 0), and the reference edge of the first horizontal synchronizing signal is detected at (X, Y) = (5, 0). Assume that the number of stages of the shift register 35 is five, and the output of the shift register 35 when the reference edge of the horizontal synchronizing signal is first detected is the value of the third stage.

  9 shows the XY coordinates of the sampling point appearing on or immediately after the straight line H, the values of the increment value Sn and the delay amount Dn detected at that time, the values stored in the respective stages of the shift register 35, A register stage serving as an output of the shift register 35 is shown. However, the values Sn and Dn stored in the respective stages of the shift register 35 are substituted with the value n in order to avoid complication. Also, the register stage where the value is not yet stored is left blank.

  FIG. 10 shows the values of T and B at each sampling point, as well as FIGS. 5 and 6 of the first embodiment, and the value of Dn used in the delay filter 5 to generate the video signal at each sampling point. Is shown. However, unlike the first embodiment, the values of T and B are sampling phases generated by the second counter 36, and the value of Dn is a value output by the shift register 35. In FIG. 10, it is assumed that the count value of the second counter 36 is 0 at (X, Y) = (5, 2). The first reference point is detected at (X, Y) = (3, 0), and a point where the instantaneous phase of the color subcarrier shifts by 180 degrees appears every approximately 1716.333 clocks. The possible straight line P is a straight line represented by Y = 3 × (X−3) in the drawing. Similarly, since the reference edge of the first horizontal synchronization signal is detected at (X, Y) = (5, 0) and appears every 1715.75 clocks, a straight line obtained by connecting the reference edges of the horizontal synchronization signal. H is a straight line represented by Y = −4 × (X−5) in the drawing.

  Hereinafter, the operation of the timing generation circuit 4 in FIG. 7 will be described with reference to FIGS. 9 and 10. By the operation described in the first embodiment, the value of the lower 11 bits of the first counter 31 is reset to 0 every time the reference point appears. In the second embodiment, since the most significant bit of the first counter 31 is not referred to by any circuit, the value of the lower 11 bits of the first counter 31 is simply written as the count value of the first counter 31 here. The count value of the first counter 31 becomes 0 when (X, Y) = (3, 0) where the first reference point appears. At this time, since the reference point is on the sampling point, the value of D1 is zero. Since the value of S1 cannot be determined because the count value of the first counter 31 immediately before (X, Y) = (3, 0) is not defined, it is assumed here that S1 = 0.

  As shown in FIG. 10, the second reference point appears at a point between (X, Y) = (3, 1) and (X, Y) = (4, 1). ) = (3, 1), the count value of the first counter 31 should be incremented by 1 per clock and should be 1716. Further, when (X, Y) = (4, 1), it is reset to 0, and S2 = 1716-1716 = 0 is detected. D2 corresponds to two-thirds of the clock, and D2 = 64 ÷ 3 × 2 = 42 (rounded down after the decimal point).

  Similarly, the third reference point appears at a point between (X, Y) = (3, 2) and (X, Y) = (4, 2), and (X, Y) = (3 , 2), the count value of the first counter 31 is 1715, so S3 = 1716-1715 = 1, and D3 = 64 ÷ 3 = 21 corresponding to one-third clock is detected as D3. .

  The reference edge of the third horizontal synchronization signal is detected at a point between (X, Y) = (4, 2) and (X, Y) = (5, 2). At this time, the reference edge and the horizontal synchronization are detected. Since the same number of reference edges are detected, the output of the shift register 35 is a third-stage register, and D0 = 0 is a delay amount given to the delay filter 5 as shown in FIG. Therefore, the delay filter passes the video signal without delay until the reference edge of the fourth horizontal synchronizing signal is detected. Since the second counter 36 is not reset, the count value cannot be determined from the position of the reference point like the count value of the first counter 31. Therefore, as described above, in FIG. 10, the count value of the second counter 36 at (X, Y) = (5, 2) is determined to be zero.

  Since the fourth reference point coincides with (X, Y) = (4, 3) and the count value of the first counter 31 at (X, Y) = (3, 3) is 1715, S4 = 1716− 1715 = 1 and D4 = 0 is detected.

  Similarly, the reference edge of the fourth horizontal synchronizing signal is detected at a point between (X, Y) = (4, 3) and (X, Y) = (5, 3), and the shift register 35 at this time is detected. 9 is the third-stage register from FIG. 9, S2 = 0 is output as the increment value, and D2 = 42 is output as the delay amount. Since the count value of the second counter 36 at (X, Y) = (4, 3) is 1715, S2 is added to the count value of the second counter 36 at (X, Y) = (5, 3). After that, it becomes 1715. Between the reference edge of the fourth horizontal synchronization signal and the reference edge of the fifth horizontal synchronization signal, D2 = 42 (corresponding to about two-thirds clock delay) is used as the delay amount of the delay filter 5. Since the next count value of 1715 in the second counter 36 is 2048, the count value of the second counter 36 in (X, Y) = (6, 3) is 2048.

  Hereinafter, the sampling phases T and B, the increment value Sn, and the delay amount Dn can be similarly determined for the fifth and subsequent reference points and the reference edge of the horizontal synchronization signal.

  Here, consider a straight line P0 connecting points that coincide with the sampling point where T = 0 by the delay filter 5. As shown in FIG. 10, since the straight line P0 is parallel to the straight line P, it can be seen that the color subcarrier phase at the point coincident with the sampling point where T = 0 by the delay filter 5 is at least within the range shown. On the other hand, it can be seen that the line is cut before and after Y = 6 in P1713 that connects points that coincide with the sampling point where T = 1713 by the delay filter 5. This means that the color subcarrier phase of the point on P1713 is different before and after Y = 6, and the line comb filter cannot be applied to the point on P1713 before and after Y = 6. However, since the point on P1713 around Y = 6 is a point in the vicinity of the horizontal synchronizing signal and corresponds to a position outside the effective video period, it usually does not appear on the display screen, and the YC separation accuracy deteriorates. It does not lead to deterioration of the display screen.

  As described above, in the second embodiment, the point at which the delay amount Dn is updated and the point at which the sampling phase changes discontinuously by the increment value Sn are used as the position of the reference edge of the horizontal synchronization signal. The line comb filter is always available during the period.

  In the second embodiment, the delay amount Dn is updated and the increment value Sn changes at the reference edge of the horizontal synchronization signal. However, a timing pulse generated by appropriately delaying the horizontal synchronization signal may be used. That is, the update of the delay amount Dn (that is, the phase difference) and the change of the increment value Sn may occur other than the reference edge of the horizontal synchronization signal. However, it is desirable to perform it outside the effective video period.

  In the second embodiment, an example of the NTSC method has been described. In the case of the PAL method or the SECAM method, the delay amount Dn and the increment value Sn are updated at the reference edge of the horizontal synchronization signal only once every two lines. do it.

  Furthermore, in the second embodiment, the number of stages of the shift register 35 is five, but any number of stages may be used. The larger the number of stages of the shift register 35, the larger the circuit scale, but the larger the shift from the standard signal of fsc, fh, fv can be dealt with. If fsc and fh are not in accordance with the standard, as shown in FIG. 9, the register stage serving as the output of the shift register 35 shifts indefinitely from the third stage in the initial state. The register stage that is the output of the shift register 35 may be reset to the third stage in the vertical blanking period once per frame.

Embodiment 3 FIG.
The third embodiment is an example in which non-standard signal detecting means for detecting a non-standard signal as shown in FIG. 10 is provided.

  FIG. 11 is a diagram showing a configuration of a video signal processing apparatus according to Embodiment 3 of the present invention. In FIG. 11, the same reference numerals as those in FIG. 1 denote blocks having the same functions, and the description thereof is omitted. The timing generation circuit 4 may be the same as the timing generation circuit 4 of FIG. 3 described in the first embodiment, or the same as the timing generation circuit 4 of FIG. 7 described in the second embodiment. FIG. 11 is different from the first and second embodiments in that a non-standard signal detection circuit 37 is provided. Further, the frame memory controller 38 performs an operation different from that of the frame memory controller 6 of the first and second embodiments for detecting the non-standard signal.

  The non-standard signal detection circuit 37 includes a horizontal synchronization signal and a vertical synchronization signal output from the synchronization separation circuit 2, a sampling phase detected by the timing generation circuit 4, a 1-frame delay and a 2-frame delay output from the frame memory controller 6. A non-standard signal is detected using the data, and the detection result is output to the YC separation circuit 17. The YC separation circuit 17 changes the method for generating the luminance signal and the carrier color signal according to the detection result of the non-standard signal detection circuit 37. For example, when a non-standard signal is detected by the non-standard signal detection circuit 37, the YC separation circuit 17 stops the operation of the frame comb filter and separates the Y signal and the C signal using a filter other than the frame comb filter. To do. The frame memory controller 38 obtains the position information on the display screen of each sampling point from the non-standard signal detection circuit 37 and the first frame memory 7 and the second frame together with the video signal delayed by the delay filter 5. Write to the frame memory 8 and the third frame memory 9.

  FIG. 12 is a diagram showing an internal configuration of the non-standard signal detection circuit 37 according to the third embodiment of the present invention. In the figure, the horizontal synchronization signal separated by the synchronization separation circuit 2 is supplied to a horizontal counter 42, a vertical counter 43, and a first non-standard signal detection circuit 44 via an input terminal 39, respectively. Similarly, the vertical synchronization signal separated by the synchronization separation circuit 2 is supplied to the vertical counter 43 and the first non-standard signal detection circuit 44 via the input terminal 40, respectively. The sampling phase detected by the timing generation circuit 4 is supplied to the first nonstandard signal detection circuit 44 via the input terminal 41.

As shown in FIG. 13, for example, the first non-standard signal detection circuit 44 includes an inversion detection circuit 44a, a vertical synchronization signal counter 44b, an up / down counter 44c, and a determination circuit 44d.
The inversion detection circuit 44a receives the most significant bit B of the sampling phase output from the timing generation circuit 4, and outputs a pulse (inversion detection pulse) every time it is inverted.
The vertical synchronization signal counter 44b receives the vertical synchronization signal output from the synchronization separation circuit 2 at its count input terminal C, counts the reference edge of the vertical synchronization signal, and when the count value becomes 16 (that is, the vertical synchronization signal). When the reference edge is detected 16 times), a detection pulse is output.
The up / down counter 44c receives the horizontal synchronization signal output from the synchronization separation circuit 2 at its up-count input terminal U, counts up by 1 every time the reference edge is detected, and outputs the pulse output from the inversion detection circuit 44a. (Inverted detection pulse) is received at the downcount input terminal D, and every time this pulse is input, it is decremented by one, the detection pulse output from the vertical synchronization signal counter 44b is received at the reset input terminal R, and the detection pulse is received. Then, the count value is reset to zero. The count value of the up / down counter 44c is output from the output terminal Q and input to the determination circuit 44d.
The determination circuit 44d determines that a non-standard signal has been detected when the count value of the up / down counter 44c is 2 or more or -2 or less, and outputs this determination result. The output of the determination circuit 44d is output to the YC separation circuit 17 via the output terminal 47 as a detection result (first nonstandard signal detection result) by the first nonstandard signal detection circuit 44.

The horizontal counter 42 receives a sampling clock at its count input terminal C, counts up by 1 every clock, receives a horizontal synchronization signal at its reset input terminal R, and counts every time a reference edge of the horizontal synchronization signal is input. Reset the value to zero. The count value of the horizontal counter 42 is a value corresponding to the horizontal display position on the display screen. The count value of the horizontal counter 42 is output from its output terminal Q, and is output to the frame memory controller 38 via the output terminal 45 of the non-standard signal detection circuit 37.
The vertical counter 43 receives the horizontal synchronization signal at its count input terminal C, increments by one each time the reference edge of the horizontal synchronization signal is input, receives the vertical synchronization signal at its reset input terminal R, and receives the vertical synchronization signal Each time a reference edge is input, the count value is reset to zero. The count value of the vertical counter 43 is a value corresponding to the vertical display position on the display screen. The count value of the vertical counter 43 is output from its output terminal Q and is also output to the frame memory controller 38 via the output terminal 46 of the non-standard signal detection circuit 37.

  The valid video period generation circuit 48 generates a 1-bit signal indicating the horizontal blanking period based on the value of the horizontal counter 42, and outputs it to the frame memory controller 38 via the output terminal 49. Further, a 1-bit signal indicating an effective video period is generated based on the value of the horizontal counter 42 and is output to the second non-standard signal detection circuit 52. The horizontal blanking period and the effective video period set by the effective video period generation circuit 48 are periods that do not overlap each other, and the horizontal blanking period is a part or all of the period other than the effective video period.

  Thus, the horizontal counter 42 and the effective video period generation circuit 48 constitute position information generating means for outputting a binary signal representing the effective video period as position information. And a position information generating means for outputting, as position information, a multilevel signal representing the position on the display screen generated based on the horizontal synchronizing signal and the vertical synchronizing signal. The position information generating means configured by the combination of 48 and the position information generating means configured by the combination of the horizontal counter 42 and the vertical counter 43 are configured to generate position information of each sampling point based on at least the horizontal synchronization signal. It is common.

  The second non-standard signal detection circuit 52 includes a horizontal blanking period for a one-frame delayed video signal input from the input terminal 45 and a horizontal blanking for a two-frame delayed video signal input from the input terminal 46. When the period overlaps the effective video period set by the effective video period generation circuit 48 in time, it is determined that a non-standard signal has been detected, and this determination result is used as a second non-standard signal detection result. To the YC separation circuit 17. In the horizontal blanking period of the video signal with 1 frame delay and the video signal with 2 frame delay, information on the horizontal blanking period set by the effective video period generation circuit 48 is sent to the first frame via the frame memory controller 38. It is obtained by writing to the memory 7, the second frame memory 8, and the third frame memory 9. In order to write the horizontal blanking period information into these three frame memories, a 1-bit signal indicating the horizontal blanking period may be written together with the video signal at each sampling point, or the horizontal blanking period may be erased. Using the fact that the video signal in the period does not appear on the display screen, the value of the video signal in this period may be replaced with a unique value indicating the horizontal blanking interval.

  The third non-standard signal detection circuit 54 displays the horizontal / vertical display position of the 1-frame delayed video signal input from the input terminal 45 and the horizontal / vertical display of the 2-frame delayed video signal input from the input terminal 46. It is determined that the non-standard signal has been detected when the position deviates from the horizontal / vertical display position generated by the horizontal counter 42 and the vertical counter 43 by a certain value or more, and this determination result is determined as the third non-standard signal detection result To the YC separation circuit 17 via the output terminal 55. The horizontal / vertical display positions of the 1-frame delayed video signal and the 2-frame delayed video signal are obtained by using the horizontal / vertical display position information generated by the horizontal counter 42 and the vertical counter 43 via the frame memory controller 6. It is obtained by writing to the frame memory 7, the second frame memory 8, and the third frame memory 9. In order to write the horizontal / vertical display position information to these three frame memories, a signal representing the horizontal / vertical display position may be written together with the video signal at each sampling point, or the video signal in the horizontal blanking period may be written. By utilizing the fact that it does not appear on the display screen, the value of the video signal during this period may be replaced with a value representing the horizontal / vertical display position.

  Thus, the non-standard signal detection circuit 37 has three non-standard signal detection circuits. The YC separation circuit 17 is assumed to stop the operation of the frame comb filter when any one of the three nonstandard signal detection circuits detects a nonstandard signal.

  In the following, it will be described that the three non-standard signal detection circuits can detect a non-standard signal in which fsc and fh are not in a relationship as specified.

As seen in FIG. 10, in the non-standard signal, the straight line H indicating the reference edge of the horizontal synchronizing signal and the straight line P indicating the reference point of the color subcarrier phase are not parallel to each other. This means that the horizontal period and the period in which the reference point appears are different. Therefore, if the difference between the number of reference edges of the horizontal synchronizing signal and the number of reference points within a certain period is not equal, the input signal can be said to be a non-standard signal. In the first non-standard signal detection circuit 44, the most significant bit representing the reference phase B is inverted when the new reference point is set. Therefore, the count value of the up / down counter is 2 or more or − The value of 2 or less is a case where the reference point is detected twice or more during one horizontal period, or the reference edge of the horizontal synchronization signal is detected twice or more between two reference points. . Therefore, it can be seen that the non-standard signal can be detected by the count value of the up / down counter built in the first non-standard signal detection circuit 44.
As described above, the first non-standard signal detection circuit 44 outputs the non-standard signal based on the difference between the predetermined period determined based on the horizontal synchronization signal and the period at which the reference point generation circuit 30 generates the reference point. Detected.

  Further, the sampling point (X, Y) = (4, 3) in FIG. 10 is a point in the vicinity of the straight line H, which is a point existing in the horizontal blanking interval. (X, Y) = (4, 3) is also a point on the straight line P. The XY coordinates on the straight line P after this sampling point are Y = 3 × (until the straight line P and the straight line H intersect each other. X-3). Accordingly, the video signal that appears after the reference point is set 525 times from (X, Y) = (4, 3) is (X, Y) = (179, 528). Similarly, the straight line H can be expressed as Y = −4 × (X−5), and the point on the straight line H that appears immediately before (X, Y) = (179, 528) is (X, Y) = ( -127, 528). Therefore, the horizontal display position of (X, Y) = (179, 528) is 179 − (− 127) = 306. The horizontal blanking period in the NTSC system is normally about 10.9 microseconds including the horizontal front porch and is less than 300 clocks in terms of 27 MHz clock, so (X, Y) = (179,528) Is a sampling point in the effective video period. Since the sampling point (X, Y) = (4, 3) on the same straight line P one frame before is a sampling point existing in the horizontal blanking interval, the second non-standard signal detection circuit 52 performs the processing shown in FIG. It can be seen that the state corresponds to a non-standard signal.

  As described above, the second non-standard signal detection circuit 52 has the timing (represented by the output of the effective video period generation circuit 48) and the storage means (the output of the video signal within the effective video period) from the delay filter 5. 7-9, 11-19) the time from when the video signal within the effective video period is read (detected from the 1-frame delayed video signal and 2-frame delayed video signal supplied via the terminals 50, 51) It can also be said that the non-standard signal is detected based on the difference.

  Similarly, in (X, Y) = (4, 3) and (X, Y) = (179, 528), the vertical display position is the same, but the horizontal display position differs by 300 clocks or more. If determined appropriately, it can be seen that the non-standard signal can also be detected by the third non-standard signal detection circuit 54 due to the difference between the horizontal and vertical display positions.

As described above, the third non-standard signal detection circuit 54 includes the position information (represented by the outputs of the horizontal counter 42 and the vertical counter 43) of the video signal delayed by the delay filter 5 and the storage means (7 to 7). 9, 11 to 16), the non-standard signal is detected based on the difference in position information (obtained from the 1-frame delayed video signal and 2-frame delayed video signal supplied via the terminals 50 and 51). It can also be said.
The second non-standard signal detection circuit 52 and the third non-standard signal detection circuit 54 have positional information associated with the video signal delayed by the delay filter 5 (the outputs of the horizontal counter 42 and the vertical counter 43, or the effective video). Common in that the non-standard signal is detected based on the comparison result between the output of the period generation circuit 48) and the position information associated with the video signal read from the storage means (7-9, 11-16). ing.

  Although the value of the X coordinate of the sampling point (X, Y) = (− 127, 528) on the straight line H is a negative value, as described in the first embodiment, (X, Y) = Since (x, y) and (X, Y) = (x-1716, y + 1) are considered to be the same point, (X, Y) = (− 127, 528) is exactly (X, Y). = (1589,527).

  As described above, in Embodiment 3, three different non-standard signal detection circuits are used. However, any one of the three may be used, or any two may be used in combination.

  In the third embodiment, the effective video period generation circuit 48 outputs a signal representing the horizontal blanking period to the frame memory controller 38, and outputs a signal representing the effective video period to the second non-standard signal detection circuit 52. However, conversely, a signal indicating the effective video period may be output to the frame memory controller 38 and a signal indicating the horizontal blanking interval may be output to the second non-standard signal detection circuit 52.

  The third embodiment includes a non-standard signal detection circuit that detects a non-standard signal in which the values of the color subcarrier frequency, the horizontal frequency, and the vertical frequency are not in a predetermined ratio, and accordingly, according to the non-standard signal detection result. By changing the operation of the YC separation means, YC separation can be performed with high accuracy even for non-standard signals.

Embodiment 4 FIG.
In the first and second embodiments, the frame memory controller 6 determines the read / write address of the frame memory based on the sampling phase, but in the fourth embodiment, the read / write address of the frame memory is determined based on the horizontal synchronizing signal and the vertical synchronizing signal. An example of determining a write address is shown.

  FIG. 14 is a diagram showing a configuration of a video signal processing apparatus according to Embodiment 4 of the present invention. In FIG. 14, the same reference numerals as those in FIG. 1 are blocks having the same functions, and description thereof is omitted.

  In FIG. 14, an SDRAM (synchronous DRAM) 59 is used as a frame memory. The 1-frame delay and 2-frame delay data are stored in different storage areas in the SDRAM 59.

  The write timing controller 56 sets an effective video period based on the horizontal synchronization signal and the vertical synchronization signal output from the synchronization separation circuit 2, and delays the write enable signal that is enabled in the effective video period in the delay filter 5. It outputs to SDRAM controller 58 with the made video signal. Further, the value of the video signal in a part of the effective video period is replaced with the value of the sampling phase output from the timing generation circuit 4.

  The read timing controller 57 includes a horizontal synchronization signal and a vertical synchronization signal output from the synchronization separation circuit 2, a sampling phase detected by the timing generation circuit 4, and a 1-frame delay video signal and 2-frame delay output from the SDRAM controller 58. The first read enable signal for reading out the video signal with 1 frame delay and the second read enable signal for reading out the video signal with 2 frame delay are generated based on the sampling phase information included in the video signal of Through this, the video signal with 1 frame delay and the video signal with 2 frame delay are read out from the SDRAM 59.

  Based on the write enable signal output from the write timing controller 56, the SDRAM controller 58 writes a video signal (partially replaced with a sampling phase) existing in the effective video period to the SDRAM 59. Further, every time the first read enable signal output from the read timing controller 57 is enabled, the video signal of 1 frame delay is read from the SDRAM 59 in the order in which it is written, and the second read enable signal is enabled. Each time, the video signals with a delay of 2 frames are read out from the SDRAM 59 in the order in which they were written, and output to the read timing controller 57, respectively.

In the fourth embodiment, the SDRAM 59 is used as storage means for storing the video signal delayed by the delay filter 5 and the sampling phase detected by the sampling phase detection means (31).
The write timing controller 56 and the SDRAM controller 58 are used as write control means for controlling the writing of the video signal and the sampling phase to the SDRAM 59 based on the horizontal synchronization signal and the vertical synchronization signal.
The read timing controller 57 and the SDRAM controller 58 read the sampling phase from the SDRAM 59 based on the horizontal synchronizing signal and the vertical synchronizing signal, and the sampling phase read from the SDRAM 59 and detected by the sampling phase detecting means (31). It is used as a read control means for determining the timing for reading a video signal from the SDRAM 59 based on the comparison result with the sampling phase.

  The non-standard signal detection circuit 60 obtains information related to the read timing of the 1-frame delayed video signal and the 2-frame delayed video signal from the read timing controller 57 and detects the non-standard signal. The detection result of the non-standard signal is output to the YC separation circuit 17, and the YC separation circuit 17 stops the operation of the frame comb filter when the non-standard signal is detected.

  The operation of the video signal processing apparatus according to the fourth embodiment will be described below.

  The write timing controller 56 detects the horizontal display position and the vertical display position of each sampling point from the reference edge of the horizontal synchronization signal and the vertical synchronization signal, and sets the effective video period. The horizontal display position represents the number of clocks that have elapsed since the reference edge of the horizontal synchronizing signal was detected, and the vertical display position represents the number of reference edges of the horizontal synchronizing signal that were detected after the reference edge of the vertical synchronizing signal was detected. Value. Hereinafter, when the horizontal display position of each sampling point is H and the vertical display position is V, the coordinates of the point are represented by (H, V). The write timing controller 56 assumes that sampling points that exist within a period in which the HV coordinates are 200 ≦ H <1680 and 18 ≦ V <260 are sampling points within the effective video period. The write timing controller 56 outputs the value of the video signal to the SDRAM controller 58 by replacing the value of the video signal with the values of T and B at the sampling point where H = 200 for the sampling points where 200 ≦ H ≦ 201. If the video signal is represented by a 10-bit value, T is 11 bits and B is a 1-bit value. Therefore, in order to write T and B to the SDRAM 59, it is necessary to replace the video signals at at least two sampling points. . As a result, the first two words of each line of the video signal stored in the SDRAM 59 represent sampling phase information.

  On the other hand, the read timing controller 57 enables the first read enable signal for two clocks at the position (H, V) = (200, 17). As a result of the operation of the write timing controller 56 described above, the SDRAM controller 58 outputs T and 1 at the position of (H, V) = (200, 18) one frame before in response to the first read enable signal. The value of B. Hereinafter, the values of T and B of one frame delay obtained from the SDRAM controller 58 are written as T1 and B1. Similarly, in order to distinguish from T1 and B1, the values of T and B output from the timing generation circuit 4 to the read timing controller 57 are written as T0 and B0. The read timing controller 57 detects the timing when T0 and T1 are equal and B0 and B1 become different values, and then enables the first read enable signal for 1480 clocks. The last two clocks of 1480 clocks are for reading the values of T1 and B1 at (H, V) = (200, 19). Similarly, the values of T0, T1, B0, and B1 are compared, and a first read enable signal is generated based on the comparison result.

  The same applies to the generation method of the second read enable signal. However, when the values of T and B of the two-frame delay are written as T2 and B2, the timing when T0 and T2 are equal and B0 and B2 are equal is set. Only the point of detection is different from the method of generating the first read enable signal.

  With the above operation, when the input video signal is a standard signal, accurate 1-frame delay and 2-frame delay data can be obtained. This will be described with reference to FIGS. In the description, it is assumed that the timing generation circuit 4 has the configuration described in FIG. 7 of the second embodiment.

  15 and 16 consider a case where fsc = 227.5 × fh, fh = 262.5 × fv, and fs = 1716.25 × fh. FIGS. 15 and 16 are similar to FIG. 6, but HV coordinates are shown instead of the delay amount Dn at the lower right of the lattice points. 15 and 16, the values of T and B in (X, Y) = (6, 2) are T = 2 and B = 0, and the HV coordinates are (H, V) = (0, 16). The straight line P is Y = 4 × (X−2), and the straight line H is Y = 4 × (X−5). At this time, the straight line P3 connecting the points coincident with the sampling point where T = 3 by the delay filter 5 becomes Y = 4 × (X−7) +2. At a sampling point between (X, Y) = (6, 2) and (X, Y) = (5, 3), D1 = 0 detected at (X, Y) = (2, 0) is used. Is done. Similarly, from the operation (X, Y) = (6, 3) described in the second embodiment, D2 = 16 (1/4 clock detected from (X, Y) = (3, 1)). Equivalent), S2 = 0 is used. Therefore, the sampling phase of (X, Y) = (6, 3) is T = 1 and B = 1. The same applies hereinafter.

  FIG. 16 shows the range of 131 ≦ X ≦ 140, 525 ≦ Y ≦ 531, and shows the state of sampling points corresponding to the timing about one frame after FIG. Hereinafter, the point (X, Y) = (8, 6) on the straight line P3 is defined as a point C. Further, since the straight line P3 is Y = 4 × (X−7) +2, T = 3 in (X, Y) = (139, 530). Hereinafter, let (X, Y) = (139, 530) be the point F. Since B = 0 at the point C, B = 0 also at the point F that appears after 524 reference points that are even numbers are detected. Further, since the straight line H is Y = 4 × (X−5) and passes through (X, Y) = (137.5, 530), the H coordinate of the point F is 1. Further, at point C, V = 20, and at point F that appears after the detection of the reference edges of 524 horizontal synchronization signals, two vertical synchronization signals are detected while the reference edges of 525 horizontal synchronization signals are detected. V = 19 in consideration of the detection of the reference edge. Similarly, the values of T, B, H, and V at each sampling point shown in FIG.

  The write timing controller 56 writes the sampling points existing in the period in which the HV coordinates are 200 ≦ H <1680 and 18 ≦ V <260 to the SDRAM 59. Among the sampling points in the region shown in FIG. The write enable is initially enabled at a point where (H, V) = (200, 18), and (X, Y) = (206, 4) corresponds to this point. At this time, since T = 201 and B = 0, the video signal at the sampling points (X, Y) = (206, 4) and (X, Y) = (207, 4) is replaced by T as described above. = 207, B = 0 is written to the SDRAM 59.

  On the other hand, in the read timing controller 57, the first read enable signal is first enabled at the position of (H, V) = (200, 17). The point at which (H, V) = (200, 17) at the sampling points in the area shown in FIG. 16 is (X, Y) = (337, 528). Thus, values of T = 201 and B = 0 are read out. The point where T = 201 and B = 1 first after (X, Y) = (337, 528) is (X, Y) = (337, 529) after 1716 clocks. Since the HV coordinates of this point are (H, V) = (199, 18), the writing to the SDRAM 59 is almost equal to the HV coordinates of (X, Y) = (206, 4), and the color subcarrier phase is It can be seen that a 1-frame delayed video signal shifted by 180 degrees is read from the SDRAM 59. The same applies to the case where a video signal with a delay of 2 frames is read using the second read enable signal.

  Next, the operation when a non-standard signal is input will be described with reference to FIGS. In FIGS. 17 and 18, similarly to FIG. 10 of the second embodiment, it is assumed that fs = 1715.75 × fh = 27 MHz and fs = 10298 ÷ 1365 × fsc. 17 and 18, the values of T and B in (X, Y) = (5, 2) are T = 0 and B = 0, and the HV coordinates are (H, V) = (0, 16). The straight line P is Y = 3 × (X−3), and the straight line H is Y = −4 × (X−5). In FIG. 17, a straight line P0 connecting points coincident with sampling points where T = 0 by the delay filter 5 is Y = 3 × (X−5) +2. Similarly, although not shown in FIG. 17, a straight line P1407 connecting points coincident with the sampling point where T = 1407 by the delay filter 5 is Y = 3 × (X−1412) +2.

  FIG. 18 shows the state of the sampling points corresponding to the timing about one frame after FIG. Using the straight line P1407 in the figure as a reference, the values of T and B at each sampling point can be found as in the case of FIG. Similarly, the HV coordinates of each sampling point are known with reference to the straight line H.

  Of the sampling points in the region shown in FIG. 17, the point corresponding to (H, V) = (200, 18) where the write enable is first enabled is (X, Y) = (204, 4). is there. At this time, T = 198 and B = 0, and the above-described operation causes T instead of the video signal at the sampling points of (X, Y) = (204, 4) and (X, Y) = (205, 4). = 198, B = 0 is written to the SDRAM 59.

  On the other hand, the point where (H, V) = (200, 17) at the sampling points in the region shown in FIG. 18 is (X, Y) = (73, 528). Through 58, the values T = 198 and B = 0 are read. The point where T = 198 and B = 1 first after (X, Y) = (73, 528) is (X, Y) = (279, 529) after 1922 clocks. Since the HV coordinate of this point is (H, V) = (406, 18), there is a difference of 200 or more from the HV coordinate of (X, Y) = (204, 4) when writing to the SDRAM 59 is started. It shows that the point where the subcarrier phase is shifted by 180 degrees is a point further delayed by 200 clocks or more from one frame delay.

  As seen in FIGS. 15 and 16, in the standard signal, a point where T is equal and B is different after about 1716 clocks from the point where (H, V) = (200, 17) is found. In the non-standard signal as shown in FIG. 18, a point where T is equal and B is different at a timing greatly deviated from 1922 clock and 1716 clock is found.

  In this way, the non-standard signal detection circuit 60 determines the number of clocks from when the read timing controller 57 reads T1 and B1 through the SDRAM controller 58 until the next time the read enable signal is enabled. By obtaining from 57, a non-standard signal can be detected. That is, when the time until a point where T0 and T1 are equal and B0 and B1 are different is found is deviated by a certain number or more from 1716 clocks with respect to the point where (H, V) = (200, 17). The video signal is determined to be a non-standard signal. Similarly, with reference to the point where (H, V) = (200, 17), the time until a point where T0 and T2 are equal and B0 and B2 are equal is also deviated from a certain number of times by 1716 clocks. It is determined that the input video signal is a non-standard signal.

  As described above, the non-standard signal detection circuit 60 according to the present embodiment has the sampling phase detected by the sampling phase detection unit 31 (in the timing generation circuit 4) and the sampling phase read from the storage unit (SDRAM 59). A non-standard signal is detected based on the comparison result.

  In the fourth embodiment, since only the video signal within the effective video period is written into the SDRAM 59, the capacity of the frame memory can be reduced compared to the first and second embodiments.

1 is a block diagram showing an overall configuration of a video signal processing apparatus according to Embodiment 1 of the present invention. It is a block diagram which shows the internal structure of DPLL3 used in Embodiment 1 of this invention. It is a block diagram which shows the internal structure of the timing generation circuit 4 used in Embodiment 1 of this invention. FIG. 6 is a waveform diagram showing signal waveforms generated by the timing generation circuit 4. It is a figure which shows operation | movement of the video signal processing apparatus which is Embodiment 1 of this invention when a sampling clock frequency is equal to 1716 times the horizontal frequency. It is a figure which shows operation | movement of the video signal processing apparatus which is Embodiment 1 of this invention when a sampling clock frequency is not equal to 1716 times of a horizontal frequency. It is a block diagram which shows the internal structure of the timing generation circuit 4 used in Embodiment 2 of this invention. It is a block diagram which shows the internal structure of the shift register 35 in the timing generation circuit 4 of FIG. It is a block diagram which shows operation | movement of the shift register 35 used in Embodiment 2 of this invention. It is a figure which shows operation | movement of the video signal processing apparatus which is Embodiment 2 of this invention. It is a block diagram which shows the whole structure of the video signal processing apparatus which is Embodiment 3 of this invention. 4 is a block diagram showing an internal configuration of a non-standard signal detection circuit 37. FIG. 3 is a block diagram showing an internal configuration of a first non-standard signal detection circuit 44. FIG. It is a block diagram which shows the whole structure of the video signal processing apparatus which is Embodiment 4 of this invention. It is a figure which shows the operation | movement at the time of the standard signal input of the video signal processing apparatus which is Embodiment 4 of this invention. It is a figure which shows the operation | movement at the time of the standard signal input of the video signal processing apparatus which is Embodiment 4 of this invention. It is a figure which shows the operation | movement at the time of the nonstandard signal input of the video signal processing apparatus which is Embodiment 4 of this invention. It is a figure which shows the operation | movement at the time of the nonstandard signal input of the video signal processing apparatus which is Embodiment 4 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Input terminal, 2 Synchronous separation circuit, 3 DPLL, 4 Timing generation circuit, 5 Delay filter, 6 Frame memory controller, 7 1st frame memory, 8 2nd frame memory, 9 3rd frame memory, 10 Line memory Controller 11 first line memory 12 second line memory 13 third line memory 14 fourth line memory 15 fifth line memory 16 sixth line memory 17 YC separation circuit 18 , 19 output terminal, 20, 21 input terminal, 22 burst gate, 23 phase comparator, 24 loop filter, 25 phase accumulator, 26 sine wave ROM, 27 output terminal, 28 input terminal, 29 phase difference detection circuit, 30 reference point Generation circuit, 31 first counter, 32, 33 output terminal, 34 Input terminal, 35 shift register, 36 second counter, 37 non-standard signal detection circuit, 38 frame memory controller, 39, 40, 41 input terminal, 42 horizontal counter, 43 vertical counter, 44 first non-standard signal detection circuit 45, 46, 47 output terminal, 48 effective video period generation circuit, 49 output terminal, 50, 51 input terminal, 52 second non-standard signal detection circuit, 53 output terminal, 54 third non-standard signal detection circuit, 55 output terminal, 56 write timing controller, 57 read timing controller, 58 SDRAM controller, 59 SDRAM, 60 non-standard signal detection circuit.

Claims (8)

In a video signal processing apparatus that separates a luminance signal and a carrier color signal from a video signal sampled by a clock signal,
Color subcarrier phase detection means for detecting a value corresponding to the instantaneous phase of the color subcarrier used to generate the carrier color signal;
Reference point generating means for generating a reference point for the color subcarrier phase every predetermined period based on the detection result of the color subcarrier phase detecting means;
Phase difference detection means for detecting a phase difference between the reference point generated by the reference point generation means and the clock signal in units of less than one clock cycle;
Delay means for delaying a video signal at each sampling point based on the phase difference detected by the phase difference detection means;
Sampling phase detection means for detecting the sampling phase of the video signal delayed by the delay means based on the detection result of the color subcarrier phase detection means;
Storage means for storing the video signal delayed by the delay means;
Memory control means for controlling writing and reading of video signals to and from the storage means based on the sampling phase detected by the sampling phase detection means;
A video signal processing apparatus comprising: YC separation means for generating a luminance signal and a carrier color signal using at least a video signal read from the storage means. In a video signal processing apparatus that separates a luminance signal and a carrier color signal from a video signal sampled by a clock signal,
Color subcarrier phase detection means for detecting a value corresponding to the instantaneous phase of the color subcarrier used to generate the carrier color signal;
Reference point generating means for generating a reference point for the color subcarrier phase every predetermined period based on the detection result of the color subcarrier phase detecting means;
Phase difference detection means for detecting a phase difference between the reference point generated by the reference point generation means and the clock signal in units of less than one clock cycle;
Delay means for delaying a video signal at each sampling point based on the phase difference detected by the phase difference detection means;
Sampling phase detection means for detecting the sampling phase of the video signal delayed by the delay means based on the detection result of the color subcarrier phase detection means;
Storage means for storing the video signal delayed by the delay means and the sampling phase detected by the sampling phase detection means;
Write control means for controlling writing of a video signal and a sampling phase to the storage means based on a horizontal synchronization signal and a vertical synchronization signal;
A sampling phase is read from the storage means based on the horizontal synchronization signal and the vertical synchronization signal, and based on a comparison result between the sampling phase read from the storage means and the sampling phase detected by the sampling phase detection means. Read control means for determining the timing for reading the video signal from the storage means;
A video signal processing apparatus comprising: YC separation means for generating a luminance signal and a carrier color signal using at least a video signal read from the storage means. Phase difference holding means for holding the phase difference detected by the phase difference detecting means in time series; and
Phase difference selecting means for updating the phase difference read from the phase difference holding means at a predetermined timing outside the effective video period,
The video signal processing apparatus according to claim 1, wherein the delay unit delays the video signal at each sampling point based on the phase difference selected by the phase difference selection unit. Non-standard signal detection means for detecting a non-standard signal based on a difference between a predetermined period determined based on a horizontal synchronization signal and a period at which a reference point is generated by the reference point generation means,
4. The video signal processing apparatus according to claim 1, wherein the YC separation unit changes a method of generating a luminance signal and a carrier color signal in accordance with a detection result of the non-standard signal detection unit. Non-standard signal detection means for detecting a non-standard signal based on a comparison result between the sampling phase detected by the sampling phase detection means and the sampling phase read from the storage means,
The video signal processing apparatus according to claim 2, wherein the YC separation unit changes a method of generating a luminance signal and a carrier color signal according to a detection result of the non-standard signal detection unit. Position information generating means for generating position information of each sampling point based on at least a horizontal synchronization signal;
Non-standard signal detection for detecting a non-standard signal based on a comparison result between the position information associated with the video signal delayed by the delay means and the position information associated with the video signal read from the storage means Means and
4. The video signal processing apparatus according to claim 1, wherein the YC separation unit changes a method of generating a luminance signal and a carrier color signal in accordance with a detection result of the non-standard signal detection unit. The position information generated by the position information generating means is a binary signal representing an effective video period,
The non-standard signal detection means is based on a time lag between a timing at which a video signal within an effective video period is output from the delay means and a timing at which a video signal within an effective video period is read from the storage means. The video signal processing apparatus according to claim 6, wherein a standard signal is detected. The position information generated by the position information generating means is a multi-value signal representing a position on the display screen generated based on a horizontal synchronization signal and a vertical synchronization signal,
The storage means stores the position information generated by the position information generation means together with the video signal delayed by the delay means,
The non-standard signal detection unit detects the non-standard signal based on a difference between the position information of the video signal delayed by the delay unit and the position information read from the storage unit. The video signal processing apparatus described.

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