JP2009267793A - Video signal processor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a video signal processor in which a cycle of a reading vertical synchronizing signal can follow a deviation of the cycle of the vertical synchronizing signal of an input video signal in a wide range. <P>SOLUTION: This video signal processor 1 comprises: a vertical synchronizing cycle measuring part 4 for measuring a cycle of an input vertical synchronizing signal; a horizontal synchronizing cycle computing part 5 for computing a cycle of a horizontal synchronizing signal based on the cycle of the measured input vertical synchronizing signal; and a synchronizing signal generating part 3a for generating an output horizontal synchronizing signal and an output vertical synchronizing signal based on the cycle of the computed horizontal synchronizing signal and the input vertical synchronizing signal. Further, the synchronizing signal generating part 3a comprises: a vertical synchronizing signal detecting part 6 for detecting the input vertical synchronizing signal, thereby detecting a cycle of the output vertical synchronizing signal; and a vertical-horizontal synchronizing signal generating part 9 for generating the output vertical synchronizing signal and the output horizontal synchronizing signal based on the cycle of the detected output vertical synchronizing signal and the cycle of the computed horizontal synchronizing signal. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a video signal processing device that converts an input video signal into a video signal suitable for a display device.

  There are various standards for video signals, and the number of pixels for each scanning line, the number of scanning lines, and the frequency differ depending on each standard. In this way, when video signals having different numbers of pixels, scanning lines, and frequencies are supplied to the video display device to display a desired video, the number of pixels, the number of scanning lines, and the frequency for each scanning line of the video signal Must be converted to fit the display device.

  FIG. 6 is a block diagram showing a general configuration of a video signal processing device 20 that converts such an input video signal into a video signal suitable for a display device. In FIG. 6, a video signal processing device 20 includes a noise removal unit 22 that removes noise from input video signal data, an IP conversion unit 23 that performs IP conversion, and a signal processing device (display device or the like) connected to a subsequent stage. The horizontal / vertical pixel number conversion unit 24 for converting the horizontal / vertical pixel number, the image quality adjustment unit 25 for adjusting the image quality, the pixel number conversion from the input video signal, An output synchronization signal generation unit 21 that generates an output synchronization signal that defines the number of lines is provided. Here, the conversion from the input video signal to the video signal suitable for the display device is performed by temporarily writing the input video signal to the storage device (frame buffer) with reference to the synchronization signal of the input video signal, and at a desired frequency. This is done by reading the video signal based on the output synchronization signal.

  In order to prevent the input image and the output image from interfering with each other when the input video signal is converted to the output video signal, the vertical sync signal for writing the input video signal (hereinafter referred to as the input vertical sync signal) And the period of the vertical synchronizing signal for reading (hereinafter referred to as output vertical synchronizing signal) must be matched. That is, when there is a deviation in the period of the input vertical synchronization signal of the input video signal, it is necessary to change the period of the output vertical synchronization signal following the deviation. Here, when the input vertical synchronization signal of the input video signal is used as the output vertical synchronization signal as it is, the problem of deviation of the period of the input vertical synchronization signal does not occur. However, in such a case, when the input vertical synchronization signal is interrupted, data cannot be output to the subsequent video signal processing device, and nothing is displayed on the display device (blackout). Not suitable.

  Therefore, the video signal processing device 20 operates so that the readout synchronization signal is generated independently of the input synchronization signal, and the generated output vertical synchronization signal is matched with the input vertical synchronization signal. FIG. 7 is a diagram illustrating a conventional method for adjusting the period of the output vertical synchronization signal when there is a deviation in the period of the input vertical synchronization signal. The cycle of the output horizontal synchronizing signal is set by a register based on the specifications of the video display device. Specifically, it is determined by the number of scanning lines of the video display device. The period of the output vertical synchronization signal is a value obtained by counting the output horizontal synchronization signal by the number of scanning lines. Next, when there is a deviation in the cycle of the input vertical synchronization signal, the phases of the input vertical synchronization signal and the output vertical synchronization signal are compared in order to match the cycle of the output vertical synchronization signal with the cycle of the input vertical synchronization signal. Depending on the detected phase difference, the period of the output horizontal synchronization signal in the vertical front porch part of the output vertical synchronization signal that does not affect the output video signal is shortened or lengthened, and the period of the output vertical synchronization signal is input vertically Follow the period deviation of the sync signal. Here, the front porch portion is a scanning line region outside the effective display region of the video display device, and is a period until the output vertical synchronizing signal rises from the next line where the vertical enable signal is negated. In the example shown, a maximum of 3 lines can be adjusted.

  In the conventional video signal processing apparatus, the period of the output horizontal synchronization signal of the readout synchronization signal is set in advance by a register, and the output vertical synchronization signal is generated based on the value. Also, the phase deviation of the output vertical sync signal is adjusted by comparing the phase of the input vertical sync signal and the output vertical sync signal and changing the cycle of the output horizontal sync signal of the vertical front porch according to the phase difference. ing.

  Here, the fluctuation amount of the cycle of the output horizontal synchronizing signal of the vertical front porch unit is a value obtained by dividing the deviation of the cycle of the output vertical synchronizing signal by the number of scanning lines of the vertical front porch unit. However, since the number of scanning lines in the vertical front porch part is usually only a few to a dozen lines, the conventional method for adjusting the period of the vertical synchronizing signal by changing the period of the output horizontal synchronizing signal in the vertical front porch part is acceptable. The amount of fluctuation in the period of the output horizontal synchronization signal may be smaller than the amount of fluctuation obtained by the above calculation. Since the video display device is higher definition and larger than the conventional one, the ratio of the number of scanning lines in the vertical front porch part to the number of scanning lines in the effective display area is reduced, and the video display device consumes less power. Since the reduction of the area including the vertical front porch part outside the effective display area is required due to the demand for electric power, it is clear that the conventional method cannot cope with the deviation of the period of the output vertical synchronization signal. became.

  Accordingly, the present invention has been made to solve such a problem, and the video signal processing that allows the period of the vertical synchronizing signal for reading to follow a wider range with respect to the deviation of the period of the vertical synchronizing signal of the input video signal. The object is to obtain a device.

  A video signal processing apparatus according to an embodiment of the present invention includes a vertical synchronization period measuring unit that measures a period of an input vertical synchronization signal of an input video signal, and an output video signal based on the measured period of the input vertical synchronization signal. A horizontal synchronization period calculation unit that calculates a period of a horizontal synchronization signal so that the number of scanning lines is constant, and an output horizontal synchronization signal and an output vertical based on the calculated horizontal synchronization signal period and the input vertical synchronization signal A synchronization signal generation unit that generates the synchronization signal. In addition, the synchronization signal generation unit detects a period of the output vertical synchronization signal by detecting the input vertical synchronization signal, a period of the detected output vertical synchronization signal and the calculated horizontal synchronization signal A vertical / horizontal synchronization signal generating unit that generates an output vertical synchronization signal and an output horizontal synchronization signal based on the period;

  With this configuration, the input vertical synchronization signal at each timing is selected between the period of the input vertical synchronization signal at an arbitrary timing T1 to be processed by the video signal processing apparatus and the period of the input vertical synchronization signal at the timing T2 subsequent to T1. The idea is that the deviation between the periods of the input vertical synchronization signal at each timing is small enough to be acceptable, regardless of the deviation from the period of the reference output vertical synchronization signal set by the register. Is based.

  According to another embodiment of the present invention, a video signal processing apparatus outputs a vertical synchronization period measuring unit that measures a period of an input vertical synchronization signal of an input video signal and a period of the measured input vertical synchronization signal. A horizontal synchronization period calculation unit that calculates a period of the horizontal synchronization signal so that the number of scanning lines of the video signal is constant, and based on the calculated horizontal synchronization signal period and the input vertical synchronization signal, the output horizontal synchronization signal and A synchronization signal generation unit that generates an output vertical synchronization signal. In addition, the synchronization signal generation unit generates a vertical / horizontal synchronization signal generation unit that generates an output vertical synchronization signal and an output horizontal synchronization signal based on the calculated period of the horizontal synchronization signal, and the generated output vertical synchronization signal and input A phase comparator for detecting a phase difference from the vertical synchronization signal. In addition, the vertical / horizontal synchronization signal generation unit includes a horizontal cycle adjustment unit that adjusts the cycle of the horizontal synchronization signal in the vertical front porch unit of the output vertical synchronization signal based on the detected phase difference.

  In this configuration, in addition to the idea of the previous embodiment, it is assumed that the deviation between the period of the input vertical synchronization signal at timing T1 and the period of the input vertical synchronization signal at timing T2 exceeds an allowable level. However, this is based on the idea that the fluctuation amount of the period of the horizontal synchronizing signal with respect to each scanning line of the vertical front porch is as small as possible.

  According to an embodiment of the present invention, the period of the output vertical synchronization signal can follow a wider range of the deviation of the period of the input vertical synchronization signal while keeping the number of vertical lines of the output video signal constant. The writing / reading timing to the frame buffer can be matched. Therefore, even when the cycle of the input vertical synchronization signal is changed, the display range can be expanded without disturbing the image.

  According to another embodiment of the present invention, the number of vertical lines of the output synchronization signal is adjusted in accordance with the period deviation of the input vertical synchronization signal while adjusting the period of the horizontal synchronization signal of the vertical front porch unit. It is possible to operate by switching to the period of the output horizontal synchronizing signal which is kept constant. Therefore, the period of the output vertical synchronization signal can follow the deviation of the period of the input vertical synchronization signal over a wider range, and even if the period of the input vertical synchronization signal changes, the image is displayed without being disturbed. The possible range can be expanded.

<Embodiment 1>
FIG. 1 is a diagram showing a configuration of a video signal processing apparatus 1 according to the present invention. The horizontal synchronization signal and the vertical synchronization signal of the video signal are input to the video signal processing device 1 as an input horizontal synchronization signal and an input vertical synchronization signal, and an output horizontal synchronization signal and output suitable for the video display device are output by the output synchronization signal generation unit 2. It is converted into a vertical synchronizing signal and supplied to the video display device together with the video signal. The conversion from the input video signal to the output video signal is performed by writing the input video signal to the storage means (hereinafter referred to as a frame buffer) using the input synchronization signal and using the output synchronization signal of the desired frequency to output the video from the frame buffer. This is done by reading the signal. Here, the signal processing A is signal processing performed by the noise removal unit, the IP conversion unit, and the like shown in FIG. Similarly, signal processing B is signal processing performed by a horizontal / vertical pixel conversion unit, and signal processing C is signal processing performed by an image quality adjustment unit or the like.

  The output synchronization signal generation unit 2 makes the number of scanning lines of the output video signal constant based on the vertical synchronization period measurement unit 4 that measures the period of the input vertical synchronization signal and the measured period of the input vertical synchronization signal. A horizontal synchronization period calculation unit 5 that calculates a period of a horizontal synchronization signal, and a synchronization signal generation that generates an output horizontal synchronization signal and an output vertical synchronization signal based on the calculated period of the horizontal synchronization signal and the input vertical synchronization signal Part 3.

  FIG. 2 is a diagram showing a configuration of the synchronization signal generation unit 3a (corresponding to the synchronization signal generation unit 3 shown in FIG. 1) in the present embodiment. The synchronization signal generation unit 3a detects the input vertical synchronization signal to detect the period of the output vertical synchronization signal, and the horizontal signal calculated based on the detected timing of the input vertical synchronization signal. A horizontal synchronization period capturing unit 7 that captures the period of the synchronization signal, a horizontal synchronization period storage unit 8 that stores the period of the captured horizontal synchronization signal, and a period of the stored horizontal synchronization signal are input as the period of the output horizontal synchronization signal. And a vertical / horizontal synchronization signal generator 9 for generating an output vertical synchronization signal and an output horizontal synchronization signal based on the detected period of the output vertical synchronization signal and the period of the input output horizontal synchronization signal.

  FIG. 3 is a diagram illustrating a method of adjusting the period of the vertical synchronization signal of the video signal processing apparatus 1 according to the present embodiment when a deviation occurs in the period of the input vertical synchronization signal. Hereinafter, the operation of the video signal processing apparatus 1 will be described with reference to FIGS. When a deviation occurs in the cycle of the input vertical synchronization signal (in FIG. 3, the cycle of the input vertical synchronization signal changes from 639600 clk to 560000 clk with respect to the output signal basic clock), the horizontal synchronization cycle calculation unit 5 The period of the horizontal synchronizing signal is calculated (700 clk) so that the number of scanning lines (number of vertical lines) is constant (800 lines in this embodiment). The calculated period of the horizontal synchronization signal is temporarily stored in the horizontal synchronization period storage unit 8 and input to the vertical / horizontal synchronization signal generation unit 9 as the period of the output horizontal synchronization signal. The period of the output vertical synchronization signal is a period (560000clk) from when the vertical synchronization signal detector 6 detects the input vertical synchronization signal until the next input vertical synchronization signal is detected, and the vertical / horizontal synchronization signal generator 9 is input. The vertical / horizontal synchronization signal generator 9 generates an output vertical synchronization signal and an output horizontal synchronization signal based on the period of the output vertical synchronization signal (560000clk) and the period of the output horizontal synchronization signal (700clk).

  As described above, according to the video signal processing apparatus 1 in the present embodiment, the cycle of the output vertical synchronization signal is wider than the deviation of the cycle of the input vertical synchronization signal while keeping the number of vertical lines of the output video signal constant. Therefore, the write / read timing to the frame buffer can be matched. Therefore, even when the cycle of the input vertical synchronization signal is changed, the display range can be expanded without disturbing the image.

<Embodiment 2>
In the first embodiment, as shown in FIG. 3, since the cycle of the output horizontal synchronization signal is switched from the next cycle (B period) after the cycle of the output vertical synchronization signal is switched, immediately before the cycle of the output horizontal synchronization signal is switched. There is a problem that the number of output lines in the period (period A) cannot be guaranteed. For example, in FIG. 3, the number of vertical lines in the cycle (period A) in which the cycle of the output vertical synchronization signal is changed varies from 800 lines to 700 lines. Therefore, the video signal processing apparatus according to the present embodiment aims to keep the number of vertical lines of the output synchronization signal constant even when the cycle of the output vertical synchronization signal is switched. Further, when the period of the output vertical synchronizing signal in the period B has a deviation from the period of the output synchronizing signal in the period A, there is a problem that the deviation cannot be followed.

  FIG. 4 is a diagram showing a configuration of the synchronization signal generation unit 3b (corresponding to the synchronization signal generation unit 3 shown in FIG. 1) in the present embodiment. The other configuration of the video signal processing apparatus 10 in the present embodiment is the same as that in FIG. The synchronization signal generating unit 3b includes a horizontal synchronization period capturing unit 11 that captures the calculated period of the horizontal synchronization signal based on the timing of the output vertical synchronization signal, and a horizontal synchronization period storage unit that stores the period of the captured horizontal synchronization signal. 12 and the cycle of the stored horizontal synchronization signal are input as the cycle of the output horizontal synchronization signal, and an output horizontal synchronization signal is generated based on the cycle of the input output horizontal synchronization signal. A vertical / horizontal synchronization signal generation unit 13 that generates an output vertical synchronization signal from the counted value, and a phase comparison unit 15 that compares the phases of the input vertical synchronization signal and the output vertical synchronization signal are provided. The vertical / horizontal synchronization signal generation unit 13 includes a horizontal synchronization cycle adjustment unit 14 and adjusts the horizontal cycle of the vertical front porch unit based on the timing of the vertical data enable signal according to the result of the phase comparison unit 15.

  FIG. 5 is a diagram illustrating a method of adjusting the period of the vertical synchronization signal of the video signal processing apparatus 10 according to the present embodiment when a deviation occurs in the period of the input vertical synchronization signal. Hereinafter, the operation of the video signal processing apparatus 10 will be described with reference to FIGS. First, when there is no deviation in the input vertical synchronization signal (in FIG. 5, the period of the input vertical synchronization signal is constant 639600 clk with respect to the output signal basic clock), the horizontal synchronization period calculation unit 5 scans the output video signal scanning line. The period of the horizontal synchronizing signal is calculated (800 clk) so that the number (the number of vertical lines) is constant (800 lines in this embodiment). The calculated period of the horizontal synchronization signal is temporarily stored in the horizontal synchronization period storage unit 12 and input to the vertical / horizontal synchronization signal generation unit 13 as the period of the output horizontal synchronization signal. The vertical / horizontal synchronization signal generation unit 13 generates an output horizontal synchronization signal based on the cycle (800clk) of the input output horizontal synchronization signal, and outputs the output horizontal synchronization signal from a value counted by the number of lines (800 lines). A vertical synchronization signal is generated. The phase comparison unit 15 compares the phases of the generated output vertical synchronization signal and the input vertical synchronization signal, and the horizontal synchronization cycle adjustment unit 14 adjusts the cycle of the output horizontal synchronization signal in the vertical front porch unit according to the phase difference. To do.

  Next, when a deviation occurs in the input vertical synchronization signal (in FIG. 5, the period of the input vertical synchronization signal changes from 639600 clk to 560000 clk with respect to the output signal basic clock), the horizontal synchronization period calculation unit 5 The period of the horizontal synchronization signal is calculated (700 clk) so that the number of scanning lines (number of vertical lines) is constant (800 lines in this embodiment). The calculated period of the horizontal synchronization signal is temporarily stored in the horizontal synchronization period storage unit 12 and input to the vertical / horizontal synchronization signal generation unit 13 as the period of the output horizontal synchronization signal. The vertical / horizontal synchronization signal generation unit 13 generates an output vertical synchronization signal and an output horizontal synchronization signal based on the period of the input output horizontal synchronization signal.

  Here, immediately after the vertical cycle is switched (period A), the vertical / horizontal synchronization signal generation unit 13 generates an output horizontal synchronization signal based on the cycle (800 clk) of the output horizontal synchronization signal immediately before the cycle is switched. An output vertical synchronizing signal is generated from a value obtained by counting the output horizontal synchronizing signal by the number of lines (800 lines). The phase comparison unit 15 compares the phases of the generated output vertical synchronization signal and the input vertical synchronization signal and outputs the result to the horizontal synchronization period adjustment unit 14. The horizontal synchronization period adjustment unit 14 adjusts the period of the output horizontal synchronization signal in the vertical front porch unit according to the phase difference, and follows the deviation of the period of the input vertical synchronization signal.

  In the next cycle (B period) after the vertical cycle is switched, the vertical / horizontal synchronization signal generation unit 13 generates an output horizontal synchronization signal based on the cycle (700clk) of the output horizontal synchronization signal immediately after the cycle is switched. Then, an output vertical synchronization signal is generated from a value obtained by counting this output horizontal synchronization signal by the number of lines (800 lines). The phase comparison unit 15 compares the phases of the generated output vertical synchronization signal and the input vertical synchronization signal and outputs the result to the horizontal synchronization period adjustment unit 14. The horizontal synchronization period adjustment unit 14 adjusts the period of the output horizontal synchronization signal in the vertical front porch unit according to the phase difference, and follows the deviation of the period of the input vertical synchronization signal.

  As described above, according to the video signal processing apparatus 10 of the present embodiment, the vertical synchronization of the output synchronization signal is adjusted in accordance with the period deviation of the input vertical synchronization signal while adjusting the period of the horizontal synchronization signal of the vertical front porch unit. It is possible to operate by switching to the period of the horizontal synchronizing signal that keeps the number of lines constant. Therefore, the period of the output vertical synchronization signal can follow the deviation of the period of the input vertical synchronization signal over a wider range, and even if the period of the input vertical synchronization signal changes, the image is displayed without being disturbed. The possible range can be expanded.

  In addition, the deviation of the input vertical synchronization signal between the A period and the B period is small, and it is not necessary to adjust the period of the output horizontal synchronization signal as a whole period, but it can be adjusted by adjusting the period of the horizontal synchronization signal of the vertical front porch There may be some degree of deviation. In such a case, the synchronization signal generation unit 3b may further include a horizontal synchronization cycle comparison unit 16 that compares the cycle of the output horizontal synchronization signal and the calculated cycle of the horizontal synchronization signal before the horizontal synchronization signal capturing unit 11. . The horizontal synchronization period comparison unit 16 can set an update threshold value, and when the difference value between the output horizontal synchronization signal period and the calculated horizontal synchronization signal period exceeds the threshold value, The period of the synchronization signal may be output to the horizontal synchronization period capturing unit 11.

  In addition, the horizontal synchronization period comparison unit 16 can set the maximum period value and the minimum period value of the horizontal synchronization signal, and when the calculated horizontal synchronization signal period is within a predetermined range, The period is output to the horizontal synchronization period capturing unit 11, and the horizontal synchronization signal period is controlled so as not to deviate from the input range of the output destination device.

  As described above, the calculated horizontal synchronization signal cycle is not unconditionally updated, and the value is updated only when the difference value from the current output horizontal synchronization signal cycle exceeds the threshold value. Hysteresis is provided in the period of the vertical synchronizing signal, and the period of the output vertical synchronizing signal can be prevented from being frequently updated.

  Further, at the time of update, the maximum period and the minimum period of the output synchronization signal can be ensured by clipping the period of the horizontal synchronization signal with the maximum value and the minimum value.

It is the figure which showed the structure of the video signal processing apparatus of this invention. It is the figure which showed the structure of the synchronizing signal generation part in Embodiment 1 of this invention. It is the figure which showed the period adjustment method of the vertical synchronizing signal in Embodiment 1 of this invention. It is the figure which showed the structure of the synchronizing signal generation part in Embodiment 2 of this invention. It is the figure which showed the period adjustment method of the vertical synchronizing signal in Embodiment 2 of this invention. It is the figure which showed the structure of the conventional video signal processing apparatus. It is the figure which showed the period adjustment method of the conventional vertical synchronizing signal.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1,10,20 Video signal processing apparatus, 2,21 Output synchronous signal production | generation part, 3 Synchronization signal production | generation part, 4 Vertical synchronization period measurement part, 5 Horizontal synchronization period calculation part, 6 Vertical synchronization signal detection part, 7, 11 Horizontal Synchronization period capture unit, 8, 12 Horizontal synchronization period storage unit, 9, 13 Vertical / horizontal synchronization signal generation unit, 14 Horizontal synchronization period adjustment unit, 15 Phase comparison unit, 16 Horizontal synchronization period comparison unit, 22 Noise removal unit, 23 IP conversion unit, 24 horizontal / vertical pixel number conversion unit, 25 pixel adjustment unit.

Claims (6)

A video signal processing device for converting an input video signal into a video signal suitable for a display device by writing the input video signal into a storage means and reading the video signal with an output synchronization signal of a desired frequency. ,
A vertical synchronization period measurement unit that measures the period of the input vertical synchronization signal of the input video signal;
Based on the measured period of the input vertical synchronization signal, a horizontal synchronization period calculation unit that calculates the period of the horizontal synchronization signal so that the number of scanning lines of the output video signal is constant;
A synchronization signal generating unit that generates an output horizontal synchronization signal and an output vertical synchronization signal based on the calculated period of the horizontal synchronization signal and the input vertical synchronization signal;
The synchronization signal generator is
A vertical synchronization signal detector that detects the period of the output vertical synchronization signal by detecting the input vertical synchronization signal;
Video signal processing comprising: a vertical / horizontal synchronization signal generating unit that generates an output vertical synchronization signal and an output horizontal synchronization signal based on the detected period of the output vertical synchronization signal and the calculated period of the horizontal synchronization signal apparatus. The synchronization signal generator is
Based on the detected timing of the input vertical synchronization signal, a horizontal synchronization period capturing unit that captures the calculated period of the horizontal synchronization signal;
A horizontal synchronization cycle storage unit that stores a cycle of the horizontal synchronization signal that has been captured, and
The vertical / horizontal synchronization signal generation unit inputs a cycle of the horizontal synchronization signal stored in the horizontal cycle storage unit as a cycle of an output horizontal synchronization signal, and inputs the detected cycle of the output vertical synchronization signal and The video signal processing apparatus according to claim 1, wherein an output vertical synchronization signal and an output horizontal synchronization signal are generated based on a period of the output horizontal synchronization signal. A video signal processing device for converting an input video signal into a video signal suitable for a display device by writing the input video signal into a storage means and reading the video signal with an output synchronization signal of a desired frequency. ,
A vertical synchronization period measurement unit that measures the period of the input vertical synchronization signal of the input video signal;
Based on the measured period of the input vertical synchronization signal, a horizontal synchronization period calculation unit that calculates the period of the horizontal synchronization signal so that the number of scanning lines of the output video signal is constant;
A synchronization signal generating unit that generates an output horizontal synchronization signal and an output vertical synchronization signal based on the calculated period of the horizontal synchronization signal and the input vertical synchronization signal;
The synchronization signal generator is
A vertical / horizontal synchronization signal generating unit that generates an output vertical synchronization signal and an output horizontal synchronization signal based on the calculated period of the horizontal synchronization signal;
A phase comparison unit that detects a phase difference between the generated output vertical synchronization signal and the input vertical synchronization signal;
The vertical / horizontal synchronization signal generation unit includes a horizontal cycle adjustment unit that adjusts a cycle of the horizontal synchronization signal in a vertical front porch unit of the output vertical synchronization signal based on the detected phase difference. apparatus. The synchronization signal generator is
A horizontal synchronization period capturing unit that captures the calculated period of the horizontal synchronization signal based on the timing of the output vertical synchronization signal;
A horizontal synchronization cycle storage unit that stores a cycle of the horizontal synchronization signal that has been captured, and
The vertical / horizontal synchronization signal generation unit inputs a cycle of the horizontal synchronization signal stored in the horizontal synchronization cycle storage unit as a cycle of an output horizontal synchronization signal, and is based on the cycle of the input output horizontal synchronization signal 4. The video signal processing apparatus according to claim 3, wherein the output vertical synchronization signal and the output horizontal synchronization signal are generated. The synchronization signal generation unit further includes a horizontal synchronization cycle comparison unit that calculates a difference between the cycle of the output horizontal synchronization signal and the calculated cycle of the horizontal synchronization signal in a previous stage of the horizontal synchronization cycle capturing device,
5. The horizontal synchronization cycle comparison unit according to claim 4, wherein the horizontal synchronization cycle comparison unit outputs the cycle of the horizontal synchronization signal calculated when the calculated difference exceeds a predetermined threshold value to the horizontal synchronization cycle capturing unit. Video signal processing device.   5. The horizontal synchronization signal comparison unit outputs the calculated horizontal synchronization signal cycle to the horizontal synchronization cycle capturing unit when the calculated cycle of the horizontal synchronization signal is within a predetermined range. 5. The video signal processing apparatus according to 5.

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