JPH0630376A - Video signal processor - Google Patents

Abstract

PURPOSE:To record and reproduce a vertical high frequency signal onto a VTR or an LD with excellent S/N by controlling the vertical high frequency signal to an optimum level before recording and restoring the level to the original level after reproduction. CONSTITUTION:A gain of a vertical high frequency signal in a video signal obtained at an output of a gain control circuit 11 is kept to be an optimum constant value, the video signal is frequency-modulated by an FM modulation circuit 13 and recorded on a medium by a recording means 14 Then the signal reproduced by a reproduction means 15 is demodulated by an FM demodulation circuit 16. Since the signal is subjected direct FM modulation, a burst signal is added even to a scanning line on which the vertical high frequency signal is sent. Thus, when a burst level detection circuit 17 detects a burst level, a gain changed properly at the gain control circuit 11 is discriminated. Then a control circuit 18 is controlled by an output of the level detection circuit 17 to keep the burst level constant, then the gain of the vertical high frequency signal is restored.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal processing apparatus for recording / reproducing a video signal called a wide television having an aspect ratio of 16: 9 on a disc or a VTR.

[0002]

2. Description of the Related Art In recent years, a wide television standard has been proposed, and a demand for a wide television signal recording / reproducing apparatus is increasing.

Hereinafter, a method of transmitting a video signal of a wide television will be described with reference to FIG. (a) represents an original signal having an aspect ratio of 16: 9. In this example, the number of scanning lines is 576. Next, the scanning lines of this original signal are thinned out to 432 lines to form the main signal (b). At this time, the vertical high frequency band is lost due to thinning, so the high frequency band is extracted by the vertical filter at the same time that the main signal in (b) is obtained.
As (c), the remaining 144 scanning lines are used for transmission. And
As shown in (d), 77 vertical high-frequency signals are arranged above and below the main signal for transmission. If this signal is displayed on a conventional television with an aspect ratio of 4: 3, vertical high frequency signals can be received at the top and bottom, and 16: 9 main signals can be received at the central 432 lines, which is compatible. In addition, the vertical high frequency signal is transmitted as a signal (e) whose amplitude is suppressed centering on the black level in order to make it inconspicuous when displayed on a conventional television.

[0004]

However, if such a signal is recorded as it is on a conventional VTR or a laser disk (LD), the S / N becomes low because the level of the vertical high frequency signal is low, and the signal is wide TV. Even if the vertical high frequency signal is returned to the original state and the vertical resolution is restored, there is a disadvantage in that it looks as a disturbance.

The present invention solves the above-mentioned conventional problems, and provides a video signal processing apparatus having a good S / N by appropriately changing the gain of a scanning line through which a vertical high frequency signal is transmitted. To aim.

Further, the present invention is directed to a direct F such as an LD.
An object of the present invention is to provide a video signal processing device that can be used for both an M-modulation recording device and a VTR-like low-frequency conversion recording device.

[0007]

In order to achieve this object, in the video signal processing apparatus of the present invention, n (n is an integer) scanning lines are thinned out to m (m is an integer) and thinned out. Detecting the gain of the video signal having the aspect ratio of 16: 9 in which the vertical high frequency components which are lost due to being transmitted in the thinned nm scanning lines are detected during the thinned nm scanning lines. And a first gain control circuit in which the gain of the (n−m) scanning line periods is controlled by the gain detection circuit.
An FM modulation circuit that FM-modulates the output of the first gain control circuit, a recording unit that records the output of the FM modulation circuit on a recording medium, a reproducing unit that reproduces the recording medium, and an output of the reproducing unit. An FM demodulation circuit for performing FM demodulation;
A burst level detection circuit that detects the level of the burst signal of the video signal output from the M demodulation circuit, and the n-th output of the FM demodulation circuit that is the output of the burst level detection circuit.
and a second gain control circuit for controlling the gain in the period of m scanning lines.

[0008]

According to the present invention, when the recorded / reproduced signal is restored to the vertical high frequency signal by the wide television to restore the vertical resolution, a video signal having a good S / N can be obtained.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the arrangement of a video signal processing apparatus according to the first embodiment of the present invention. In FIG. 1, the input video signal is input to the gain control circuit 11. The video signal is a wide television signal in which the vertical high frequency signal described above is fitted in the scanning lines at the top and bottom of the screen. The gain of the vertical high-frequency signal of this video signal is detected by the gain detection circuit 10, and the gain control circuit 11 keeps the gain constant.
To control. Further, the timing generation circuit 12 generates timing for the vertical high frequency signal period and supplies it to the gain detection circuit 10 and the gain control circuit 11. In the video signal thus obtained at the output of the gain control circuit 11, the gain of the vertical high frequency signal is kept at an optimum constant value. This video signal is FM-modulated by the FM modulation circuit 13 and recorded on the medium by the recording means 14.
In this embodiment, as the recording medium, the LD is suitable because the signal is directly FM-modulated.

Next, the signal reproduced from the medium by the reproducing means 15 is FM demodulated by the FM demodulation circuit 16. Since the signal is subjected to direct FM modulation, the burst signal is also added to the scanning line through which the vertical high frequency signal is transmitted. Therefore, if the burst level is detected by the burst level detection circuit 17, the gain appropriately changed by the gain control circuit 11 can be known. Therefore, the gain of the vertical high frequency signal can be restored by controlling the gain control circuit 18 with the output of the burst level detection circuit 17 so that the burst level becomes constant. The timing of the scanning line to which the vertical high frequency signal is transmitted is generated by the timing generation circuit 19. In this way, it is possible to record and reproduce vertical high frequency signals at the optimum level,
The S / N ratio of the vertical high frequency signal can be improved.

In the above description, the gain control is explained by the feedforward control from the gain detection circuit 10 to the gain control circuit 11 and from the burst level detection circuit 17 to the gain control circuit 18, but it can also be realized by feedback control. .

Next, a second embodiment of the present invention will be described with reference to FIG. The present embodiment is an example suitable for a device for low-frequency converting and recording a color signal such as a home VTR. The input wide-screen video signal is separated into a luminance signal and a chrominance signal by the YC separation circuit 40. However, the line through which the vertical high frequency signal is transmitted is directly output to the luminance signal output. The gain of the vertical high frequency signal sent to the luminance signal output is detected by the gain detection circuit 41, and is controlled to the optimum level by the gain control circuit 42. The vertical high frequency signal having the optimum level is finally FM-modulated by the FM modulation circuit 46 and recorded in the luminance signal channel. However, if the gain change is not recorded at the same time, the original high-frequency signal is reproduced. I can't put it back. One method is to leave only the burst signal on the transmission line for the vertical high frequency signal, and to restore the original signal by controlling the gain with the burst level as a reference during reproduction as in the first embodiment. Although this method is simple, it has a drawback that a high frequency burst cannot be recorded in a luminance signal channel in a VHS system VTR having a narrow transmission band. Therefore, in this embodiment, the information of the gain change changed by the gain control circuit 42 is generated by the pilot signal generation circuit 44 and the switch circuit 45 is generated during the horizontal synchronization period.
The method of switching and adding with is adopted. An example of the addition method is shown in FIG. FIG. 3A is a vertical high frequency signal, and signals to which a pilot signal is added are (b) and (c). (b)
Is to add a DC value according to the gain, and (c) is to add a burst signal having a relatively low frequency that can be recorded in the luminance signal channel.

In this way, the video signal to which the pilot signal has been added is FM-modulated by the FM modulator circuit 46, and mixed with the color signal converted to the low frequency band by the frequency conversion circuit 29.
It is mixed in 7 and recorded on the recording medium by the recording means 48. Next, the video signal reproduced from the recording medium by the reproducing means 50 is separated into a luminance signal and a chrominance signal by the high-pass filter 51 and the low-pass filter 55, respectively. The brightness signal is F
The M demodulation circuit 52 performs FM demodulation, the pilot signal separation circuit 53 separates the pilot signal, and the gain control circuit 54 controls the gain according to the level. as a result,
The vertical high frequency signal returns to the gain before recording. The line for transmitting the vertical high frequency signal is designated by the timing generation circuit 57 to the gain control circuit 54. On the other hand, the chrominance signal is converted into a high frequency band by the frequency converter 56, which is opposite to that at the time of recording, and is mixed with the luminance signal by the mixing means 58 and output as a wide television signal.

[0015]

As described above, according to the present invention, the vertical high frequency signal is controlled to the optimum level before recording, and is returned to the original level after the reproduction, so that the vertical high frequency signal is transferred to the VTR or the LD. There is an effect that recording and reproducing can be performed well.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a video signal processing device according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a video signal processing device according to a second embodiment of the present invention.

FIG. 3 is a waveform diagram showing a waveform of a vertical high frequency signal to which a pilot signal according to the present invention is added.

FIG. 4 is a schematic diagram showing a transmission method of a wide television signal.

[Explanation of symbols]

 10 gain detection circuit 11, 18 gain control circuit 17 burst level detection circuit 44 pilot signal generation circuit 45 switch circuit 29, 56 frequency converter 53 pilot signal separation circuit 54 gain control circuit

Claims (2)

[Claims] 1. N-m scan lines in which n (n is an integer) scan lines are thinned out to m (m is an integer) and vertical high frequency components lost due to thinning are thinned out. Transmitted at 16:
The thinned nm of the video signal having an aspect ratio of 9
A gain detection circuit for detecting a gain in one scanning line period, a first gain control circuit in which a gain in the (n−m) scanning line periods is controlled by the gain detection circuit, and a first gain control circuit An FM modulation circuit that FM-modulates the output of the recording medium, a recording unit that records the output of the FM modulation circuit on a recording medium, a reproduction unit that reproduces the recording medium, and an FM demodulation circuit that FM-demodulates the output of the reproduction unit. A burst level detection circuit for detecting the level of the burst signal of the video signal output from the FM demodulation circuit; and a gain of the output of the FM level demodulation circuit in the nm scan line periods of the output of the FM demodulation circuit. And a second gain control circuit for controlling the video signal. 2. N (m is an integer) scan lines are thinned out to m (m is an integer) lines, and mn scan lines are obtained by thinning out vertical high frequency components which are thinned out and lost. Transmitted at 16:
And a YC separation circuit for separating a color signal and a luminance signal during the thinned m scanning line periods and passing the image signal having an aspect ratio of 9 during the n-m periods and outputting the luminance signal output. A gain detection circuit for detecting the gain of the thinned mn scanning line periods of the luminance signal output output from the YC separation circuit; and a gain detection circuit for gaining the mn scanning line periods. A controlled first gain control circuit, a gain information addition circuit for adding the gain information obtained by the first gain control circuit to a luminance signal, and an FM modulation circuit for FM-modulating the output of the gain information addition circuit A first frequency converter for frequency-converting the color signal output of the YC separation circuit to a low frequency band; a recording for adding the output of the FM modulation circuit and the output of the first frequency converter and recording them on a recording medium. Means and from said medium Reproducing means for reproducing, a filter circuit for extracting the FM-modulated luminance signal and frequency-converted color signal of the output of the reproducing means, and an FM for FM demodulating the luminance signal of the output of the filter circuit.
A demodulation circuit, a second frequency converter for frequency-converting a color signal into a high frequency band, and n according to gain information of an output of the FM demodulation circuit.
A video signal processing device, comprising: a second gain control circuit in which the gain in the period of m scanning lines is controlled.