JPH0681333B2 - Video signal processor - Google Patents

Description

Description: INDUSTRIAL APPLICABILITY The present invention can be applied to a recording / reproducing device such as a VTR and a video signal transmitting device, and is effective for obtaining good high frequency characteristics of a luminance signal and characteristics of a color signal. Is.

Conventional technology The VTR currently used for broadcasting has a tape width of 1
Inches and 2 inches are the mainstream, and as the video signal recording method, the composite video signal is directly frequency-modulated. During this recording / reproducing process, fluctuations in the time axis occur due to uneven rotation of the head, uneven running of the tape, and the like. This fluctuation is corrected by the time axis corrector (TBC) at the time of reproduction by using the horizontal synchronizing signal and the burst signal in the reproduced video signal. However, in this system, in the case of the NTSC system, the chrominance signal is quadrature two-phase modulated with a 3.58 MHz subcarrier and is superimposed on the luminance signal. The characteristic noise is not sufficiently reduced, and the color subcarrier has a phase variation corresponding to the residual jitter of TBC, which serves as a phase nozzle and the convergence of the color vector is not sufficient.

From this point of view, two components of the color signal are used as one recording method for improving the S / N in the amplitude and phase directions of the color signal and improving the convergence as can be extended to Japanese Patent Application No. 59-163155. There is also a method of frequency-modulating and recording, and correcting the time axis at the time of reproduction, and then modulating (encoding) with a reference subcarrier to add to the luminance signal in order to form a composite video signal. According to this method, since the color signal (component signal) is also FM recorded in the baseband, it is reproduced well with S / N and encoded with the reference subcarrier, so there is no phase noise and it is good. It is possible to obtain various reproduced color signals.

An example of this system will be described with reference to FIG. In FIG. 3, 1, 2, and 3 are luminance signals Y, RY signals, and BY, respectively.
Signal input terminal, 25 is a synchronizing signal generator, 5 is a time axis compressor, 4 and 6 are frequency modulators, 7 and 8 are heads, 9 and 10 are frequency demodulators, 11 and 12 are TBC, and 14 is a reference signal. An input terminal, 15 is a sync generator, 16 is an encoder, and 18, 19, 20, and 21 are Y, RY, BY signals, and a composite video signal output terminal, respectively.
The Y signal applied to the terminal 1 is modulated by the frequency modulator 4 and recorded on the tape by the head 7. On the other hand, the two color signal components RY signal and BY signal applied to terminals 2 and 3 are
A synchronizing signal generated by the synchronizing signal generator 25 is added to the RY signal from the horizontal synchronizing signal in the Y signal by the adder 26, and the time axis compressor 5 halves the time axis by one line. Is So one signal Represents the RY signal compressed into 1/2 line), is modulated by the frequency modulator 6, and is recorded on the tape by the head 8. The luminance signal and the color signal are sent to the head 7 and the head 8.
Separate tracks are formed and recorded on the tape. During reproduction, the Y signal reproduced by the head 7 is demodulated by the frequency demodulator 9 and then corrected in time axis by the TBC 11. The color signal reproduced by the head 8 is demodulated by the frequency demodulator 10 and then corrected on the time axis by the TBC 12 and expanded to the original time axis. TBC11 and 12 are
The signal is written to the memory by the write clock created from the horizontal sync signal in the reproduced and demodulated signal, and the signal is read from the memory by the read clocks 22 and 23 created by the sync generator 15 from the reference signal applied to the terminal 14. By reading out, time axis correction and expansion operations are performed. Also, here, the sync signal is removed, and Y
The reference synchronization signal 24 created by the sync generator 15 is added to the signal by the adder 13. In this way
It is replaced with a noise-free synchronizing signal, and reproduced Y, RY, BY signals are obtained at terminals 18, 19, 20. On the other hand, the output R of TBC12
The -Y, B-Y signals are encoded by the encoder 16 by the reference subcarrier 27 created by the sync generator 15, added by the adder 17 with the Y signals, and a reproduced composite video signal is obtained at the terminal 21.

In this method, Y, RY, BY signals are input, so when recording a composite video signal, a Y, RY, B
After separating to -Y, it is led to the input terminals 1, 2, and 3.
At the time of this separation, in order to widen the band of the luminance signal and the color signal,
Generally, a comb filter using line correlation is used.

Problems to be Solved by the Invention In separation of a luminance signal and a chrominance signal using a comb filter, a chrominance signal is mixed with a luminance signal and a chrominance signal is mixed with a luminance signal in a portion having no correlation. Color signal components RY, BY
The signal is recorded / reproduced, then modulated again by the encoder to be a carrier color signal, and then added to the reproduced luminance signal, but is a carrier color signal before being demodulated into RY and BY during modulation. When the signals are modulated with the carrier wave of the same phase as and are added in the same phase as the color signal mixed with the luminance signal, the components mixed with each other are restored to the original state. With this configuration, the high frequency component of the luminance signal is mixed with the color signal and transmitted, and is added again to the signal transmitted in the luminance signal band in the correct phase, so that a good signal can be obtained. In addition, the color signal is also restored to the original state, and is obtained as a good signal with no color shift or change in saturation. However, in general, the phase of the color subcarrier of the output signal of the VTR is freely adjusted with respect to the phase of the color subcarrier of the reference signal from the input terminal 14 at the TBC in order to adjust the delay with other video signal systems. Made to change. Also, the phase of the color subcarrier of the input composite video signal at the time of recording is the same in four fields in the case of the NTSC signal, but the phase relationship between the reproduced signal and the reference input signal is often only the odd-even field discrimination. . In such a case, RY, B
The phase of the color subcarrier modulated with the -Y signal and the phase of the original composite video signal are not fixed. When originally modulated with opposite phases, the color of the uncorrelated portion disappears and the high frequency band of the luminance signal disappears. Also, if the phases are not perfectly matched, they appear as high frequencies of the luminance signal and distortion of the color signal.

This phenomenon causes some difference in quantity even when a low-pass filter or a bandpass filter is used instead of a comb filter for separating a luminance signal and a chrominance signal.

The present invention provides a means for removing such high band of luminance signal and distortion of chrominance signal to obtain a good reproduction or transmission signal.

Means for Solving the Problems To solve the above problems, the present invention provides a first signal having the same frequency as the color subcarrier of the input composite video signal together with either the luminance signal or the two chrominance signal components. The phase of a color subcarrier (second signal) modulated (encoded) with two color signal components recorded or transmitted and reproduced or transmitted is compared with the phase of the first signal, and an input composite image is obtained. It has means for controlling the phase relationship between these signals so that the phase of the color carrier contained in the signals and the phase of the second signal become the same or closest to each other.

By using the above means, the signal reproduced or transmitted, encoded again, and returned to the composite video signal has the same high frequency range as the luminance signal and the same phase as the chrominance signal as the original input signal, or distortion. The resolution is good because there is no correlation, and there is little or no color shift, resulting in a high-quality signal.

Embodiment FIG. 1 shows a block diagram of an embodiment of the present invention, and a method of reading the first signal prior to the blanking period will be described. In FIG. 1, the same numbers as those in FIG. 3 represent the same items and perform the same operations. 28 is a composite video signal input terminal, 29
Is a reference phase signal generator, 36 is a decoder, 30 is an adder, 31
Is a video signal phase adjustment signal input terminal, 32 is a color subcarrier phase adjustment signal input terminal, 33 is a reference phase signal extractor, 34 is a phase comparator, and 35 is a phase shifter. The composite video signal applied to the terminal 28 is separated by the decoder 36 into Y, RY and BY signals. At this time, in the portion having no correlation, the color signal component remains in the Y signal and the Y signal component remains in the RY and BY signals. The recording process of the RY and BY signals is the same as in FIG. On the other hand, the Y signal is a reference phase signal generated by the reference phase signal generator 29 from the color subcarrier (created from the burst signal, VIR signal, etc.) in the input composite video signal (same frequency as the color subcarrier or synchronized with this). Signal, the same frequency as the color subcarrier in the following description [3.58MHz for NTSC signal]
Is treated as a line in the vertical blanking, such as vertical blanking and burst signal position in the following description) by the adder 30 and recorded on the tape in the same manner as in FIG. To be done. At the time of reproduction as well as in FIG. 3, a reproduction Y signal is obtained at the output of TBC11 and a reproduction RY, BY signal is obtained at the output of TBC12, and reproduction Y, RY,
A BY composite signal is obtained at the terminal 21 as a reproduced composite video signal.

Here, the color subcarrier 27 created by the sync generator 15 is synchronized with the signal when the signal is applied to the reference signal input terminal 14, and is free-running when the signal is not applied. Further, the phase relationship with the input signal of the terminal 14 can be arbitrarily adjusted by the signal from the color subcarrier phase adjustment signal input terminal 32. Furthermore, when the phase shifter 35 is bypassed, TBC1
Read signals 1 and 12 (clock and horizontal and vertical reference signals) 22AB and 23AB are arbitrarily moved by the signal from the video signal phase adjustment signal input terminal, and output video signals (Y, R-
The phase of Y, BY and the composite video signal) is changed. Therefore, in the example of FIG. 3, the phase of the TBC output signal and the color subcarrier 2
The phase relationship of 7 is not fixed, and the above-mentioned problem occurs.
Further, the following inconvenience also occurs in a device having a simple configuration in which the phase of the output video signal and the phase of the color subcarrier are not changed. That is, the VTR having the configuration shown in FIGS. 1 and 3 is
In order to obtain continuity of the sync signal at the time of editing, servo control is performed so that the reference signal applied to the terminal 14 or the internal sync signal of the sync generator and the odd-even field of the signal reproduced from the tape are matched. However, in the case of the NTSC signal, the relationship between the phase of the color subcarrier and the field is the same in four fields. That is, the first, third or second, fourth
In the field, the sync signals are the same, but the color subcarriers are inverted. In the servo control described above, the output color subcarrier 27 of the sync generator 15 and the first, third, second, and fourth fields of the signal reproduced from the tape can be distinguished, but the first and third fields can be distinguished. Also, the second and fourth fields cannot be distinguished. Therefore, even if the reproduction signal and the color subcarrier are internally matched in phase with each other in the reproduction signal in one state, the phase is reversed in the reproduction in the opposite state, which is the worst state. This can be solved by performing servo control that can distinguish the first to fourth fields (known color frame servo), but the circuit becomes complicated,
It has the drawback that the pull-in time during editing becomes long. Further, even if this is done, it is invalid for the device controlling the terminals 31 and 32.

From the above points, according to the present invention, as shown in the embodiment of FIG. 1, the reference phase signal added at the time of recording is extracted from the output Y signal of the TBC 11 by, for example, one line ahead of the original position to extract the reference phase signal. Extractor 33 and sync generator 15
The output reference color subcarrier 27 is compared with the phase by the phase comparator 34, the error signal is guided to the phase shifter 35, and the phases of the TBC read signals 22A and 23B output from the sync generator 15 are controlled. Further, the blanking signal 37A is guided from the sync generator 15 to the phase shifter 35, and the phase control at that timing is prohibited. Output signals 22B and 23B from TBC11,12, Y, R
Read out -Y, BY signals. After this, the blanking circuit 3
In step 7, the preceding read signal is blanked based on the blanking signal 37A. In this way, the read timing of the signal from the TBC is controlled, and the output of the TBC is always Y, R-Y with the residual color subcarrier in the input video signal of the same phase as or closest to the color subcarrier 27. , BY signal is obtained, and a good composite video signal is obtained at the terminal 21.

Furthermore, since the first signal at the original position is read out again with the phase shift control applied, even if the component signal output of terminals 18, 19, 20 is dubbed to another VTR,
Since the relative relationship between the first signal and the color subcarrier in the input composite video signal included in the component signal is not broken, a good composite video signal can be obtained even in the encoder inside another VTR.

Here, the operation of performing phase control by reading the first signal one line ahead of the other will be described with reference to FIG.

A waveform 38 is an output waveform from the TBC 11 when the phase shifter 35 is not operating in FIG. The waveform on the n-th line is the first signal. 38-a is an extraction of only the carrier component, and 38-b, 38-c, 38-d below are the read points from the TBC 11 shifted every 90 ° of the sub-carrier. Further, the waveform 39 is a subcarrier in the encoder. According to the present invention, it is preferable that the subcarrier 39 and the first signal have the closest phase, and the waveform 38-b is controlled so as to be read from the TBC 11. To be done. This kind of control of the read phase controls the read start address phase from the memory inside the TBC for each horizontal scanning line, so at least one horizontal line is required until the correct phase is detected after the phase error is detected. It takes a scanning period. In this sense, the phase of the first signal superimposed on the n-th line does not match the phase of the video signal after the (n + 1) th line, and if the component dubbing is performed as it is, the same effect as the present invention can be obtained with the dubbed signal. I can't.

Therefore, as shown in the waveform 40, the first signal originally appearing on the n-th line is read out from the memory in advance, for example, in the (n-1) th line before the first line, and the first signal read out in advance is used. Therefore, if the phase error is detected, and the phase control is performed based on the phase error while reading the first signal originally read on the n-th line on the n-th line, the first signal on the n-th line and n + 1 Since the phase shift of the video signal after the line becomes the same, the same effect as that of the present invention can be obtained even in the signal subjected to the component dubbing.

It is important to note here that when the NTSC subcarrier is used as the first signal, the phase is one horizontal scan line before.
Since it is inverted by 180 °, in detecting the phase error on the (n-1) th line, if the phase of the waveform 40-b which is the phase inverted by 180 ° with respect to the subcarrier 39 in FIG. 2 is selected,
The phase of the subcarrier 39 and the first signal of the nth line match.

Further, in the above embodiment, the two color signal components are explained as RY and BY signals, but I, Q signals or signals of any other axes may be used. The method of recording the two color signal components is not limited to the time base compression, and any method such as frequency modulation and multiplexing may be used. Furthermore, a method of recording the luminance signal and the two color signal components on the time axis into one signal and recording with one pair of heads, and a method of recording the two color signal components line-sequentially (two pairs of heads or one pair of heads) Head) and various other methods. Further, it goes without saying that the present invention can be used not only for recording / reproducing video signals but also for all processing of video signals such as transmission.

As described above, the present invention records or transmits the first signal representing the phase of the color subcarrier of the input composite video signal together with either the luminance signal or the two color signal components, and reproduces or transmits the two colors. The phase of the color subcarrier (second signal) modulated (encoded) by the signal component is compared with the phase of the first signal in the previous term, and the color subcarrier included in the input composite video signal and the second signal are compared. Means for controlling the phase relationship of these signals so that the phases of these signals match or are closest to each other.

As the first signal transmitted with either the luminance signal or the two chrominance signal components, the VIR signal added to the vertical blanking of the input composite video signal may be used as it is, or a new luminance signal or A signal having a constant phase (the frequency may be the same as or synchronized with the color subcarrier) may be added to the vertical blanking of the two color signal components, or a burst signal in the input composite video signal. May be used as it is, or a new burst signal (the frequency may be the same as or synchronized with the burst signal) may be used by replacing it with either the luminance signal or the two chrominance signal components. The means for controlling the phase of the color subcarrier included in the reproduced or transmitted input composite video signal and the phase of the color subcarrier modulated by the two color signal components to be the same or closest to each other is read from the TBC. There are a method of controlling the timing, a method of controlling the timing of writing to the TBC, and a method of controlling the amount of the reproduced or transmitted luminance signal and two color signals delayed by the variable delay line.

Regardless of the above phase control means, the phase error detection means compares the phase of the color subcarrier at the encoder with the phase of the color subcarrier contained in the input composite video signal. It is necessary to perform phase comparison immediately before setting. If the phase comparison means and the phase control means are closed loop, the stability of the control system cannot be obtained. Therefore, in the present invention, the control system is an open loop, and the first signal as the phase reference of the input composite video signal is Disable phase control.

That is, as a method of obtaining the first signal to be applied to the phase comparison means, a method of applying from a system that does not have phase control different from the luminance signal to be inputted to the encoder or a first signal is obtained from the luminance signal to be inputted to the encoder. In this case, the method of prohibiting the phase control only when the first signal is used, or the first signal serving as the phase reference is read out from the storage device (memory) prior to the blanking period of the video signal to detect the phase error. There is a method of obtaining in advance.

On the other hand, from the viewpoint of VTR function, it is necessary to dubb the component signal as it is, and it is preferable that the first signal is also effective for the dubbed signal. From this point of view, the method of reading and controlling the first signal in advance and the method of obtaining the first signal from another system that does not use phase control do not break the phase relationship between the component signal and the first signal. As for the dubbed signal, there is an advantage that the first signal is effective.

As another method, as a reference phase signal, a color frame (first, second, third, and fourth field distinction is detected from the input composite video signal, superimposed as a pulse signal, and reproduced as a reference color subcarrier. There is also a method of controlling the delay amount of the reproduction signal so that it matches the color frame, but in this method, the phase of the sync signal of the input composite video signal and the color subcarrier are not completely in accordance with the standard, and there is a slight deviation. The color subcarrier at the time of encoding does not match the residual color subcarrier of the video signal, and the phase of the output video signal cannot be controlled by external control.

As described above, according to the present invention, when the composite video signal is separated into the luminance signal and the two color signal components, and the composite video signal is obtained again after processing such as recording / reproducing or transmission, A good signal can be obtained with no or minimal distortion of the gamut and color signals.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a signal waveform diagram for explaining the operation of the present invention, and FIG.
It is a block diagram of the conventional video signal recording / reproducing apparatus. 16 …… Encoder, 29 …… Reference phase signal generator, 30 ……
Adder, 33 ... reference phase signal extractor, 34 ... phase comparator, 35 ... phase shifter, 36 ... decoder.

Claims (8)

[Claims] 1. When a composite video signal is separated into a luminance signal and two color signal components, and recorded / reproduced or transmitted, the two color signal components are modulated again and superimposed on the luminance signal to obtain a composite video signal. A luminance signal to be recorded or transmitted, and at least one of two color signal components, and a first signal having the same frequency as the color subcarrier in the original composite video signal is superimposed and transmitted, and the first signal And a phase of a color subcarrier (second signal) modulated by the reproduced or transmitted two color signal components to detect a phase error, and a reproduced or transmitted luminance signal according to the obtained phase error amount. A video signal processing device characterized by controlling the phases of two color signal components. 2. The video signal processing device according to claim 1, wherein the first signal is recorded or transmitted by being superimposed on a luminance signal separated from the composite video signal. 3. The phase of the reproduced or transmitted luminance signal and the two color signal components is controlled by controlling the amount of delay of the reproduced or transmitted luminance signal and the two color signal components. The video signal processing device according to claim 1. 4. A reproduced or transmitted luminance signal and two chrominance signal components are applied to a delay means capable of varying a delay amount, and at least the phases are compared in comparing the phases of the first signal and the color subcarrier. The video signal processing according to claim 1, wherein the delay amount of the delay means is fixed and the phase error amount is derived only when the delay amount is varied, and the delay amount is varied according to the phase error amount. apparatus. 5. A first system obtained by applying a reproduced or transmitted luminance signal and two chrominance signal components to a delay means whose delay amount can be varied and not passing through said delay means.
2. The video signal processing device according to claim 1, wherein the phase error amount is derived by comparing the phase of the signal of FIG. 3 and the phase of the color subcarrier, and the delay amount is varied according to the phase error amount. . 6. A reproduced or transmitted luminance signal and two chrominance signal components are applied to a delay means capable of varying the delay amount, and only the first signal is fixed to an arbitrary blanking interval of the video signal. The phase error amount is derived by reading it out before the delay means and comparing the phase with the color subcarrier, and the delay amount is varied according to this phase error amount to obtain the phase of all video signal parts including the first signal. The video signal processing device according to claim 1, wherein the video signal processing device controls the video signal processing device. 7. A reproduced or transmitted luminance signal and two chrominance signal components are temporarily stored in a storage device, and the delay amount is controlled at the time of reading to store the reproduced or transmitted luminance signal and two chrominance signal components. The video signal processing device according to claim 3, wherein the phase of the color signal component is controlled. 8. When a reproduced or transmitted luminance signal and two chrominance signal components are temporarily stored in a storage device and read out to eliminate fluctuations in the time axis of these signals, the delay amount is controlled, 8. The video signal processing device according to claim 7, wherein the reproduced or transmitted luminance signal and the phases of two color signal components are controlled.