JPH0385975A - Video signal processing unit - Google Patents

Abstract

PURPOSE:To ensure the processing such as clamping a pedestal level and horizontal synchronization and to attain excellent reduction of a video in the horizontal direction by switching a video signal for a horizontal blanking period into a video signal not compressed timewise. CONSTITUTION:A video signal is read based on a readout clock signal of a 2nd frequency higher than a write clock signal is read from a storage means 2 and the video signal is a video signal resulting from an input video signal subject to timewise compression, the video is reduced in the horizontal direction and displayed. Moreover, two different fixed signals are inputted to a fixed signal changeover means 5 and the fixed signal from the fixed signal changeover means 5 and the video signal from the storage means 2 are inputted to a video signal changeover means 4 and they are outputted switchingly. Thus, the horizontal synchronization of the video and the pedestal level clamp to be implemented during the horizontal blanking period are implemented accurately and the compression of the video in the horizontal direction is attained in an excellent way.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is suitably implemented in cases where a video signal having an aspect ratio different from the aspect ratio is input to a video display device having a unique aspect ratio. The present invention relates to a video signal processing device.

[Conventional technology]

Generally, when a video signal having a horizontal aspect ratio smaller than its own aspect ratio is input to a video display device, the video is expanded in the horizontal direction and displayed. For example, aspect ratio 4:3 (horizontal width: vertical width)
As shown in FIG. 4(a), in a video display device, the ratio of the horizontal width WHI to the vertical width Wvl of the display area is 4.
:3, and when a video signal with an aspect ratio of 4:3 representing a circular figure is input to a video display device with an aspect ratio of 16:9, the horizontal width Wl( 2 and the vertical width WV2 is 16:9. Therefore, an elliptical figure expanded in the horizontal direction is displayed in the display area where the ratio of 2 and the vertical width WV2 is 16:9. Therefore, a video signal with an aspect ratio of 4:3 is converted into a video signal with an aspect ratio of 16:3. When inputting the video to the video display device No. 9, the video is input horizontally in order to display the video in an area where the horizontal direction WH3 is 4/3 times the vertical direction WV2, as shown in FIG. 4(C). It must be reduced, and the video signal must be processed for this purpose.

A typical prior art technique for processing such video signals is shown in FIG. For example, this video signal processing device converts a video signal with an aspect ratio of 4:3 into an aspect ratio of 1.
It is used when inputting to a 6:9 video display device.

A video signal with an aspect ratio of 4:3 from input terminal TN is sent to analog/digital converter 1 (rA, /D converter 1
A line memory 2 that stores digital video signals for one horizontal scanning period after being converted into digital video signals by
given to. This line memory 2 takes in and stores therein the digital video signal from the A/D converter 1 in accordance with the write clock signal CKI having a frequency of "1".

The digital video signal stored in this line memory 2 is
The readout digital video signal is read out based on the readout clock signal GK2 having a frequency r□ higher than the frequency f1, and the readout digital video signal is converted into an analog signal by a digital/analog converter 3 (hereinafter referred to as rD/A converter 3). The signal is converted into a video signal and output to the output terminal OUT. This output terminal O
A video display device (not shown) having an aspect ratio of 16:9 is connected to the UT.

The frequency f of the read clock CK2! is, r, -(
4/3) ・f.

Therefore, the video signal for one horizontal scanning period is
It will be read out from the line memory 2 in a time of 74. At this time, the video signal (
That is, the video signal other than the horizontal blanking period) is read out in such a way that the video is positioned at the center of the display area. This allows the input terminal IN to be
) When the video signal shown in ) is input, a video signal having the waveform shown in FIG. That is, after a period Δl has elapsed since the compressed video signal corresponding to the human-powered video signal in the horizontal blanking period ΔB is derived in the period ΔB1, the input video signal in the scanning period ΔH is converted to (3/4) ΔH. A video signal compressed to a period of length ΔH1 is derived.

As a result, in a video display device with an aspect ratio of 16:9, the video is compressed by 3/4 times in the horizontal direction and displayed in the center of the display area, so the display of the video with an aspect ratio of 483 is improved. It will be carried out.

[Problems to be Solved by the Invention] However, in the above configuration, the video signal of the horizontal blanking period ΔB as well as the video signal of the scanning period ΔH is
Because of this, the video signal is compressed to four times as long as the video signal.
There is a problem in that the horizontal synchronization of the video and the clamping of the pedestal level, which should be performed during the horizontal blanking period, may not be performed accurately.

The purpose of this invention is the above-mentioned technical! ! ! [Means for Solving the Problems] A video signal processing device according to the present invention processes a human input signal based on a write clock signal of a first frequency. and the first
a first fixed signal from a first fixed signal generation circuit; and a second fixed signal generation circuit. a second fixed signal from the horizontal blanking period, outputs the first fixed signal during the horizontal synchronization signal period of the horizontal blanking period, and outputs the second fixed signal during the remaining period of the horizontal blanking period. and a fixed signal switching means, the video signal is switched so that the fixed signal output from the fixed signal switching means is output during the horizontal blanking period, and the video signal output from the storage means is output during the remaining period. It is designed so that it can be switched by means.

[Effect]

According to the video signal processing device of the present invention, since the video signal is read from the storage means based on the read clock signal having a second frequency higher than the first frequency of the write clock signal, the read video signal becomes a video signal obtained by temporally compressing the input video signal. Therefore, when this video signal is input to a video display device, the video is displayed reduced in the horizontal direction.

Further, two different fixed signals are input to the fixed signal switching means, and the fixed signal switching means creates a horizontal blanking period signal that is not compressed in time by switching and outputting the two different fixed signals. .

The fixed signal from the fixed signal switching means and the video signal from the storage means are input to the video signal switching means, and the video signal switching means switches between the video signal from the storage means and the fixed signal from the fixed signal switching means. Output. That is, the fixed signal from the fixed signal switching means is output during the horizontal blanking period, and the video signal from the storage means is output during the remaining period.

As a result, the video signal during the horizontal blanking period is a signal that is not subjected to the above-mentioned temporal compression processing. Therefore, in a video display device, the horizontal synchronization and pedestal level of the video that should be performed during the horizontal blanking period are obtained. Processing such as clamping can be performed reliably.

〔Example〕

FIG. 1 is a block diagram showing the basic configuration of an embodiment of the present invention. In FIG. 1, parts corresponding to those shown in FIG. 5 described above are designated by the same reference numerals.

This video signal processing device receives an input signal from an input terminal IN.
The video signal converted into a digital signal by the /D converter l is read out by a clock signal C having a first frequency f1.
read based on KI and write clock signal GK2 having a second frequency f2 higher than said first frequency;
A line memory 2 is provided as a storage means from which the stored video signal is read out based on. The output of this line memory 2 is applied to a D/A converter 3, converted into an analog signal, and then applied to one individual contact 4b of a video signal switching circuit 4.

A first fixed signal generation circuit 6 that generates a horizontal synchronization signal value
The first fixed signal from is applied to one individual contact 5a of the fixed signal switching circuit 5.

The second fixed signal from the second fixed signal generation circuit 7 that generates the pedestal level value is transferred to the fixed signal switching circuit 5.
is applied to the other individual contact 5b.

This fixed signal switching circuit 5 connects its common contact 5c to its individual contact 5a during the horizontal synchronizing signal period of the horizontal blanking period.
and is connected to the individual contact 5b during the remaining period of the horizontal blanking period. Then, the fixed signal led out to the common contact 5c is transferred to the other individual contact 4 of the video signal switching circuit 4.
given to a.

This video signal switching circuit 4 connects its common contact 4C to the individual contact 4a during the horizontal blanking period, and to the individual contact 4b during the remaining period. And the common contact 4.
The video signal derived from C is given to the output terminal OUT,
The signal is input from this output terminal OUT to a video display device (not shown).

In this embodiment, when a video signal with an aspect ratio of 4:3 is input to a video display device with an aspect ratio of 16:9, the relationship between the first frequency f and the second frequency f8 is f, -( 4/3) ・It is assumed that r self.

A/D converter 1, line memory 2. and D/A converter 3
performs the same operation as the configuration shown in FIG. 5, and therefore has an aspect ratio of 4 shown in FIG.
:3, the video signal applied from the D/A converter 3 to the individual contact 4b of the video signal switching circuit 4 becomes the video signal shown in FIG. 2(b).

The value of the first fixed signal from the first fixed signal generation circuit 6 is set as the level HL of the horizontal synchronization signal of the input video signal, and the value of the second fixed signal from the second fixed signal generation circuit 7 is set as the level HL of the horizontal synchronization signal of the input video signal. Assuming that the signal pedestal level is CL, the fixed signal switching circuit 5 connects the common contact 5C to the individual contact 5a during the horizontal synchronization signal period of the horizontal blanking period as described above, and connects the common contact 5C to the individual contact 5a during the horizontal blanking period. For the remaining period, the common contact point 5
As a result of connecting c to the m-separate contact 5b, the fixed signal applied to the individual contact 4a of the video signal switching circuit 4 becomes a signal equivalent to the video signal during the horizontal blanking period of the input signal.

Therefore, as described above, the video signal switching circuit 4 connects the common contact 4c to the individual contact 4a during the horizontal blanking period, and connects the common contact 4c to the individual contact 4a during the remaining period.
As a result of connecting to b, the output terminal OUT is as shown in Fig. 2(c).
The video signal shown in will be derived.

That is, only the video signal of the scanning period ΔH is compressed, and the video signal of the horizontal blanking period ΔB is not subjected to temporal compression processing and is supplied from the output terminal OUT to the video signal display device. Become. This allows the video signal display device to perform the following operations during the horizontal blanking period:
It is possible to reliably perform horizontal synchronization of images and clamping of the pedestal level. Moreover, the video signal with the scanning period ΔB of the input video signal is compressed into a period Δ)fl that is 3/4 times as long as the input video signal, so the video is reduced horizontally by 3/4 times and is displayed at the center of the 8N display area. will be displayed. In this way, reduction of the image in the horizontal direction can be performed satisfactorily while ensuring horizontal synchronization and pedestal clamping.

FIG. 3 is a block diagram showing the basic configuration of another embodiment of the invention. In FIG. 3, parts corresponding to those shown in FIG. 1 described above are designated by the same numbers. In this embodiment, a video signal switching circuit 8 is provided between the line memory 2 and the D/Am converter 3, and the video signal switching circuit 8 converts the first digital signal from the first fixed signal generation circuit 10. Fixed signal and second fixed signal generation circuit 1
A digital fixed signal obtained by switching a second digital fixed signal from 1 with a fixed signal switching circuit 9;
The digital mole signal from the line memory 2 is switched and fed to the D/A converter 3. The video signal switching circuit 8 connects its common contact 8C to the individual contact 8a connected to the fixed signal switching circuit 9 during the horizontal blanking period, and during the remaining period, connects the common contact 8C to the individual contact 8a connected to the line memory 2. Connect to contact 8b. With such a configuration as well, it is possible to achieve the same functions and effects as described in connection with the first embodiment.

〔Effect of the invention〕

As described above, according to the video signal processing device of the present invention, the video signal during the horizontal blanking period can be made into a video signal that is not temporally compressed. While ensuring that processing such as horizontal synchronization of the video and clamping of the pedestal level that should be performed during the erasing period is performed, the reduction in the horizontal direction of the video can be performed satisfactorily.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the basic configuration of a video signal processing device in an embodiment of the present invention, FIG. 2 is a waveform diagram for explaining the operations of FIGS. 1 and 5, and FIG. A block diagram showing the basic configuration of another embodiment of the present invention, FIG. 4 is an explanatory diagram showing a simplified display mode in a video display device, and FIG. 5 is a block diagram showing the basic configuration of the prior art. It is. 2...Line memory (storage means), 4.8...
. . . Video signal switching circuit, 5.9 . . . Fixed signal switching circuit, 6. 7.10.11...
・Fixed signal generation circuit.

Claims (1)

[Claims] storage means for reading an input signal based on a write clock signal having a first frequency and outputting the read video signal based on a read clock signal having a second frequency higher than the first frequency; A first fixed signal from a fixed signal generation circuit and a second fixed signal from a second fixed signal generation circuit are given, and the first fixed signal is output during the horizontal synchronization signal period of the horizontal blanking period. However, during the remaining period of the horizontal blanking period, a fixed signal switching means for outputting the second fixed signal, a fixed signal from the fixed signal switching means, and a video signal from the storage means are applied, A video signal processing device comprising video signal switching means for outputting a fixed signal from the fixed signal switching means during a horizontal blanking period and outputting a video signal from the storage means for the remaining period.