JPH01205695A - Video signal band control system - Google Patents

Abstract

PURPOSE:To decrease S/N deterioration occurring due to the expansion of a reproduction band by switching to a low-pass filter in a lower band when few or no prescribed high-band component exists in program software. CONSTITUTION:The output of a luminance signal tandem filter circuit 32 is inputted to first and second low-pass filter circuits 37 and 38. The low-pass filter circuit 37 is the broad-band low-pass filter of a cut-off frequency, which is about 6MHz, and the low-pass filter circuit 38 is the low-pass filter of another cut-off frequency, which is about 3MHz. The output of a correction delay line 39 and the low-pass filter 38 is selected by a control signal from a control signal generating circuit 36 at a selecting circuit 40, a transmission band becomes narrower when few or no high-band component is included in an input NTSC video signal, and consequently, the S/N deterioration at the time of reproduction can be decreased.

Description

Detailed Description of the Invention (Industrial Field of Application) The video signal band control system of the present invention relates to a recording/reproducing signal system used in video disc players, VTRs, etc. An index that displays the luminance signal band during playback in the case of the dye reflex 1-color process that directly modulates the signal without low-frequency conversion and records the high-frequency component of the input NTSC video signal inserted during recording. The present invention relates to a signal system that performs band control based on a signal and, as a result, improves the S and /N of demodulated video signals 8.

(Prior Art) When recording a wider band video signal on a video disc player, VTR, etc., an appropriate frequency modulation band is selected and both recording and playback are made wider. ? It is necessary to use an f-band video signal low-pass filter.

When the video signal band is made into a broadband tri, generally the S/
N deteriorates, but in order to save this S/N deterioration, the amplitude is small by 1%'! Noise reduction called coring, which removes i-range components, is often performed.

(A problem solved by the invention) Conventional video signal band control methods usually have the following problems: 1. As the low-pass filter during playback is made wider, the S/N ratio deteriorates. In this case, the filter band remains wide even without the high-frequency components included in ProGuera's low-quality software, so S/N degradation occurs in the same way. Coring technology can improve the S/N, but this coring eliminates the high-frequency components of small signals, resulting in a decrease in resolution, so it is not possible to improve the S/N sufficiently. There is a problem.

(Means for solving the problem) In order to solve the above-mentioned problem, the present invention
;- band control method includes a luminance signal filter that extracts the old 11 signals from the input video signal by using the line correlation of the input video signal during recording, and a luminance signal filter that extracts the old 11 signals from the input video signal using line correlation of the input video signal, and a detection circuit that detects that the residual color signal component is constant and is greater than or equal to BEL and outputs a display signal; 4: A gate circuit that outputs a high-frequency component of the luminance signal 8 having a predetermined frequency or higher in a period excluding the interval, and when the high-frequency component of the luminance signal from this gate circuit is above a certain level, A waveform shaping circuit that envelope-detects the high-frequency component and shapes the waveform, and a detection that outputs a detection signal created by calculating the number, duration, etc. of pulses in one field or one frame output from this waveform shaping circuit. circuit, and generates an index signal according to the absence of the high frequency component of the luminance signal in field or frame units at a time corresponding to a predetermined directivity planning interval 191 based on the detection signal from the detection circuit. an index signal generating circuit for generating an output video by superimposing the index signal within a vertical planning period of a video signal obtained by delaying the input video signal by one field or one frame; 6Q index F3 from the reproduced demodulated video signal corresponding to the output video Y4 during playback.
A control signal is generated that outputs a control signal that is generated in response to the above-mentioned index signal "I" from this separation circuit and switches to the field or frame A (Q) during the vertical blanking period. circuit, and a luminance signal separated from the reproduced demodulated video signal is supplied.
first and second low-pass filter circuits having different off-frequencies, and the luminance signals output from the first and second low-pass filter circuits depending on the presence or absence of the index signal; It is characterized by using a selection circuit for selective output and a reproduction side signal processing system with six outputs.

(Example) In the case of video signals from program software such as regular movies, there are not always high frequency components, and there are many scenes that consist only of quite low frequency components in the sequel, and in this case, playback By detecting high-frequency components on the side and switching the low-pass filter band, or by switching and using multiple low-pass filters with different transmission bands, the S/N of the demodulated video (-i signal can be improved. Monkey.

There are 121 methods for detecting 11-range components in playback n:'i, but there are 121 methods that are completely competitive with the conventional circuit format, but the second step of the playback mechanism is 1~up, and the detection. This method can be said to be disadvantageous, especially in relation to video disc players that do not take self-recording into consideration.

If the high-frequency component of the video image is detected during recording and an index is inserted and recorded, the playback side C can create a control signal in the cylinder just by detecting this index signal. This can be said to be advantageous compared to high frequency component detection on the playback side.

The present invention aims to improve the S and /N of demodulated video signals by x+r I211 in the video (ρ! NTSC included in the CDV with additional recording of
A method of controlling a luminance signal band in a video signal direct-color one-field or frame period will be described in detail with reference to the drawings.

FIG. 1 is a block diagram of a recording side signal processing system showing an example of the video band control method according to the present invention.

As shown in the figure, the input NTS input to input terminal 1
C video signal H34, 1 line delay line 2.3.58MHz
The signal is input to the bandpass filter circuit 3.

Then, the video signal delayed by 1 line by the 1-line delay line 2 is separated into 3.58 MH components by the band filter circuit 4, which is the same as the band filter circuit 3.
By adding the output of the bandpass filter circuit 3 to the 3.58 MH component inverted by the inverting amplifier circuit 6, a color signal comb filter is constructed.

In addition, the input NTSC video signal y3 is passed through a bandpass filter circuit 3, /
N T' S
A luminance signal comb-shaped filter using C-e@Shingsuki line correlation is constructed.

It should be noted that the configuration of the comb-shaped filter does not need to be adopted as this example, and it goes without saying that other commonly known methods may be used.

A high-frequency component of 3M82 or more is separated from the output of the luminance signal comb filter (output of the cylinder circuit 8) by the high-pass filter circuit 9. , a 3.58MHz color signal component that was not separated by the luminance signal comb filter is included.In order to remove the influence of this color signal component, a narrow 3.58MHz band is extracted from the 111 output of the luminance IC signal comb filter. Filter circuit 10T: 'Takes out the color signal component, detects it in the detection circuit 11, and then shapes the components below a preset level to use as a display signal of the residual color signal.

Historically, the input N T S Clllli image signal is input to the synchronization separation circuit 12, where the synchronization signal is separated, and the blanking pulse generation circuit 13 generates a blanking signal. Of course, it is also possible to use an external synchronized blanking signal without a synchronization separation circuit. The blanking gate circuit 14 outputs 3M)12 or more high frequency components of the luminance signal excluding the blanking portion. The blanking gate circuit 14 uses the horizontal domei signal to control the 3M synchronization signal during the horizontal blanking period.
H, and other components are removed, and the envelope detection circuit 15
This is a circuit to remove the influence of the synchronization signal.

In addition, in this Brann-Young gate circuit 14, the same 1r, 1
1~ is also performed by the residual color signal display signal,
The output of the high-pass filter circuit 9 does not contain any color signal components, but consists purely of high-frequency components of the luminance signal.

High-frequency components of 3MH or more of the blanked luminance signal are detected by an envelope detection circuit 15, and if there is a component higher than a predetermined level, it is converted into a rectangular wave by a waveform shaping circuit 16. .

The detection circuit 17 is a detection circuit for detecting the number, distribution state, density, continuity, etc. of the shaped rectangular wave within the field or frame, and is realized by, for example, performing arithmetic processing with a microcomputer or the like. can. The index signal generation circuit 18 for selecting different U degree signal bands is determined by the calculation result of the detection circuit 17.
Generates an index signal representing a high frequency component in the middle of a field or frame.

Furthermore, the input NTSC video signal is converted into a digital signal by one A/D conversion circuit, delayed by one field or one frame by a relay circuit 28, and then converted into an analog signal by a D/A conversion circuit 21'C. is converted to

This NTSC video signal delayed by one field or one frame is supplied to the Chihiro circuit 22, where the output of the index signal generation circuit 18 is inserted into this video signal.
It is output from the output terminal 23.

FIGS. 2(a) to 2(d) are diagrams showing examples of insertion positions and forms of the index signals shown in FIG. 1.

FIG. 6(a) shows a vertical synchronization signal in an NTSC video signal, and here the index signal is inserted immediately after the vertical synchronization signal. This location was chosen because it is in the cylinder for generating the Goo1 signal, and may be any location during the vertical blanking period.

FIG. 5B is a diagram showing one form of the index signal, which is inserted in the form of a pulse at a constant level. The amplitude of the pulse is determined by considering the S/N of the detection signal, the shadow theme on the monitor, etc., and 75 [R] is appropriate. In the same figure (C), go to Off-Sera 1 as well.
This figure shows a case where a fixed digit frequency is used as an index signal.It has the feature that the detection S/N can be improved even when the S/N during reproduction is poor. Figure 1(d) is a 1J diagram showing the case where the index signal to be inserted is made up of multiple bits.-As an example, high acid component detection during recording is performed at multiple frequencies, and this index signal is used to By displaying how many MH2 or more P the component is, it becomes possible to switch and use a plurality of low-pass filters, which are groups of bands, on the reproduction side.

FIG. 3 is a block diagram of a reproduction side signal processing system showing an embodiment of the video signal band control method according to the present invention.

As shown in the figure, a reproduced demodulated NTSC video signal is input to an input terminal 31. 32 is a luminance signal comb filter circuit, which may be the luminance signal comb filter shown in FIG. 1 described above or a comb filter having a square configuration.

NTSCfl! l! The image signal is synchronously separated in a sync signal separation circuit 33, and a gate pulse generation circuit 34 generates a goo-1 pulse for gating after the vertical sync signal ia, as described above. Of course, when an index signal is inserted at a different location during recording, it goes without saying that a gate pulse is generated to erase that location.

The index gate circuit (separation circuit) 35 has an input N T
The index signal is divided M=J from the S CIPXi image signal by the Goo1~pulse. 1 for filter switching
, II III The signal generating circuit 36 generates the Zll till signal depending on the presence or absence of the above-mentioned index signal and switches in the vertical blanking period in units of fields or frames.
A signal is created. The output of the luminance signal comb filter circuit 32 is input to first and second low-pass filter circuits 37 and 38. The low-pass filter circuit 37 is a wide-band low-pass filter with a cutoff frequency of about 6 MH2, and the low-pass filter circuit 38 is a low-pass filter with a cutoff frequency of about 3 MH2. The supplementary iE delay line 39t is a delay line for correcting the delay between both outputs of the low-pass filter circuit 3.7.38. The outputs of the three correction delay lines and the low-pass filter circuit 38 are selected by the selection circuit 44 according to the control signal from the control signal generation circuit 36, and are transmitted when there are no or few high-frequency components contained in the input NTSC video signal. The band becomes narrower, and therefore S/N deterioration during reproduction can be reduced.

In other words, when a control signal is output from the control signal generation circuit 36 in accordance with the presence of the index signal, compared with the cut-off frequency of the second low-pass filter circuit 38,
The brightness jα signal output from the first low-pass filter circuit 37 having a high cutoff frequency is selectively output via the correction delay line 39 within the vertical blanking period.

Further, the color signal output from the comb filter circuit 32 passes through a delay line 41 for time alignment with the Terutei signal (Y).
The superimposition circuit 42 selects the ! from the selected selection circuit 40 ! !
It is added to the i degree signal and output from the output terminal 43 as an NTSC video signal. In addition, the luminance signal,
It is also possible to output the color signals from the terminals 44 and 45 while being separated from each other.

In the reproduction-side signal processing system described above, switching between the two types of low-pass filter circuits 37 and 38 has been described, but basically the same procedure can be applied even if the number of low-pass filters to be switched is increased.

By increasing the number, finer control becomes possible, but the circuit configuration naturally becomes more complex.

Also, here, the cutoff frequencies of two types of low-pass filter circuits 37°38 are 6 M)lz and 3 MHz.
However, the present invention is not limited to this, and it is possible to select an appropriate frequency in accordance with the spirit of the present invention.

Further, in the above embodiment, for convenience of explanation, NTSC video signal processing was explained using an analog circuit, but after A/D conversion of the input NTSC video signal, various memories, filters, Chikanobu correction, etc. are performed by digital processing. Of course, this is also possible, and in reality digital processing is easier to implement.

(Effects of the Invention) As described above, the video signal band control method of the present invention is compatible with playback circuits used in existing VTRs, video disc players, etc. Since it switches to a low-pass filter with a lower band when there are no or few components, it is possible to reduce S/N deterioration caused by widening the reproduction band.Also, it has the feature that it is possible to reduce the S/N deterioration caused by the widening of the reproduction band. By setting the switching timing in units of fields or frames, there is an effect that switching can be performed without visually unnatural feeling.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a recording side signal processing system showing an embodiment of the video signal band control method according to the present invention, and FIG.
) to (d) are diagrams showing examples of the inserting position and form of the index signal shown in FIG. 1, and FIG. 3 is a block diagram of a reproduction side signal processing system showing an embodiment of the video signal control method according to the present invention. FIG. 7... Complementary a delay line, 8... Addition circuit, 11... Detection circuit, 14... Blanking goo 1~ circuit, 16... Waveform shaping circuit, 17... Detection circuit, 18 ... index signal generation circuit, 35 ... index gate circuit (separation circuit), 36 ... control signal generation circuit, 37 ... first low-pass filter circuit, 38 ... second low-pass Filter circuit, 40... selection circuit.

Claims (1)

[Scope of Claims] A luminance signal filter that extracts a luminance signal from the input video signal by utilizing line correlation of the input video signal during recording; and a residual color signal component in the luminance signal output from the luminance signal filter. a detection circuit that detects that the signal is above a certain level and outputs a display signal; and the display signal from this detection circuit is supplied, and the frequency exceeds a predetermined frequency during a period excluding the period in which the display signal exists and the horizontal blanking period. a gate circuit that outputs a high-frequency component of the luminance signal from the gate circuit; and a waveform shaping circuit that envelope-detects the high-frequency component and shapes the waveform when the high-frequency component of the luminance signal from the gate circuit is at a certain level or higher. , a detection circuit that outputs a detection signal created by calculating the number, duration, etc. of pulses in one field or one frame output from this waveform shaping circuit; an index signal generation circuit that generates an index signal according to the presence or absence of the high frequency component of the luminance signal in units of frames at a time corresponding to a predetermined vertical blanking period; and a circuit that delays the input video signal by one field or one frame. a recording side signal processing system having a superimposing circuit that superimposes the index signal to produce an output video signal within a vertical blanking period of the output video signal; a separation circuit that separates the index signal; a control signal generation circuit that outputs a control signal that is generated depending on the presence or absence of the index signal from the separation circuit and switches in a vertical blanking period in units of fields or frames; and the regeneration demodulation circuit. first and second low-pass filter circuits to which a luminance signal separated from the video signal is supplied and have different cutoff frequencies;
A video signal band control system comprising: a reproduction side signal processing system having a selection circuit for selectively outputting the luminance signal outputted from a low-pass filter circuit within vertical blanking feedback.