JPS6113436B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a method for selecting and reproducing an arbitrary recording track of a recording medium in which an interlaced scanning video signal such as a VTR is recorded so that one recording track is formed for each signal of one field. The present invention relates to a video signal processing device suitable for application to a video signal reproducing device that obtains a reproduced video signal by performing reproduction an arbitrary number of times.

In current VTRs, a magnetic tape TP as shown in FIG. 1 is wound around a magnetic tape guide drum having a rotating magnetic head and guided so that recording tracks RT are formed, for example, diagonally with respect to the longitudinal direction of the magnetic tape TP. It is common practice to record one field of signals to form one recording track. As shown in the figure, field signals of the first to fourth fields _F1 to _F4 are sequentially recorded on this recording track RT. Fa indicates the first frame, and Fb indicates the second frame, each consisting of first and second fields F ₁ , F ₂ and third and fourth fields F ₃ , F ₄ .

Magnetic tape with video signals recorded in this way
In normal playback, the magnetic tape TP is run at a predetermined speed and the recording tracks RT are sequentially played back by the rotating magnetic head, so there is no problem with normal playback, but slow playback, still playback, or high-speed playback poses no problem. In the case of irregular mode playback such as, the same recorded track may be repeatedly played back two or more times, or each recorded track RT may be played back every other or every second track. In the case of irregular mode reproduction as described above, when reproducing one field of a video signal, the rotating magnetic head does not necessarily scan only the same recording track RT, but may scan across adjacent recording tracks RT. In some cases, crosstalk and guard band noise occur. Therefore, play in an irregular mode like this
In VTRs, various means are used to cause the rotating magnetic head to scan only a desired recording track without scanning adjacent recording tracks. Second
The figure is a diagram showing one means, and 1 is, for example, 1
This is one of the rotating magnetic heads of the pair, and numeral 3 is a rotating base to which the rotating magnetic head 1 is attached. Then, this rotating magnetic head 1 is attached to an electrostrictive element such as a bimorph 2, this bimorph 2 is attached to a rotating base 3, and this bimorph 2 is attached to an electrostrictive element such as a bimorph 2.
A control signal is supplied to the bimorph 2 to bend the bimorph 2 in either the up or down direction in the case of irregular mode reproduction, so that the tracking of the rotating magnetic head 1 is reliably performed.

By the way, as shown in Figure 3, in an NTSC color television signal (color video signal), between an odd field and an even field, there is a main part of the vertical blanking period when the vertical direction on the playback screen is taken as a reference. However, the difference is 0.5H (H indicates the horizontal period), so if the odd and even fields are not played alternately in the irregular mode playback described above, even if the synthesized synchronization signal of the playback color video signal is Even if the replacement is performed in accordance with the reference composite synchronization signal, the image will move up and down on the playback screen. When the video signal is a black-and-white video signal, the characteristics of the video signal are different in the odd and even fields, but in the case of a color video signal, in addition to this, the characteristics of the color subcarrier signal in each field are different. The phases are different, and taking this into consideration, in the case of a color video signal, the characteristics of the video signal are repeated with a period of 4 fields, ie, 2 frames.

To explain further, when color subcarrier signals are considered in the same field, a certain signal and a signal having a phase difference of one horizontal period from that signal are opposite in phase. Further, when comparing the first field _F1 and the second field _F2 , the phases of the color subcarrier signals corresponding to the corresponding positions in the vertical direction of the screen are opposite to each other, and the second field _F2 and the third field F ₃ are in the same phase, and the third field
Field _F3 and fourth field _F4 have opposite phases. Therefore, in the case of irregular mode reproduction of a color video signal, the first to fourth fields F ₁ to F ₄
If the order of the images is out of order, there is a possibility that significant color disturbance will occur on the screen due to the vertical movement of the screen.

An object of the present invention is to provide a reproduction screen that can be reproduced even when the video signal to be reproduced is a color video signal, even if not only the odd and even fields but also the phases of the color subcarrier signals are different from those of the reference composite synchronization signal. The present invention aims to propose a video signal processing device that eliminates vertical movement of images and does not cause color interference.

The present invention and one embodiment thereof will be described in detail below with reference to FIG. The embodiment shown in FIG. 4 is a case where the present invention is applied to the NTSC color television signal as shown in FIG. 3 above. The present invention selects an arbitrary recording track of a recording medium on which an interlaced scanning video signal is recorded so that one recording track is formed for each field signal, and reproduces the reproduced video signal an arbitrary number of times using a reproducing means. Although it can be applied to a video signal reproducing device designed to obtain
This is a case where the present invention is applied to a VTR (video tape recorder, magnetic recording and reproducing device). In FIG. 4, 10 is a reproducing circuit. In this regeneration circuit,
As is well known, the FM-modulated luminance signal of the reproduced signal reproduced from a rotating magnetic head is FM demodulated, and the low-frequency conversion carrier color signal is converted to the original carrier color signal, resulting in NTSC color. The video signal includes horizontal and vertical synchronization signals and burst signals, but since the composite color synchronization signal output from a VTR generally has a distorted waveform, the horizontal and vertical synchronization signals and burst signals from the reference composite color synchronization signal are generally distorted. It is common to exchange using a color burst signal. Reference numeral 11 denotes a time base error correction circuit (time base collector), and an input terminal 12 is supplied with an NTSC color video signal obtained from the above-described reproduction circuit 10. In the time axis error correction circuit 11, the color video signal from the input terminal 12 is supplied to the A/D conversion circuit 13 to be converted into a digital signal. The color video signal converted into a digital signal is then supplied to and written into the main memory device 14, which is made up of a charge transfer device such as a BBD or CCD. 17 is a synchronization separation circuit to which the color video signal from the input terminal 12 is supplied and the horizontal and vertical synchronization signals and burst signals are separated. Reference numeral 19 denotes a write clock signal generation circuit which generates a write clock signal of, for example, three times or four times the color subcarrier frequency from the burst signal and horizontal synchronization signal from the synchronization separation circuit 17, and converts the write clock signal from this from A to D. circuit 1
3 and is also supplied to the main storage device 14 via the control circuit 18 to write the digital color video signal from the A/D conversion circuit 13 with its write clock signal. Therefore, if there is a time axis error in the color video signal supplied to the input terminal 12,
The write clock signal will also have a corresponding time base error. The control circuit 18 is supplied with the write clock signal from the write clock signal generation circuit 19 described above, as well as a vertical synchronization signal or other synchronization signals from the synchronization separation circuit 17.

The digital color video signal stored in the main memory device 14 is read out by supplying the read clock signal from the read clock signal generation circuit 20 to the main memory device 14 via the control circuit 18. The signal is supplied to the conversion circuit 15. This read clock signal is also supplied to the DA converter circuit 15. The readout clock signal generated by the readout clock signal generation circuit 20 is generated from the reference color subcarrier signal and the reference horizontal synchronization signal from the reference composite color synchronization signal generation circuit 21, and its frequency is adjusted to match the frequency of the write clock signal. For example, the frequency is selected to be three or four times the carrier wave frequency. Further, the reference vertical synchronization signal or other synchronization signal from the reference composite color synchronization signal generation circuit 21 is supplied to the control circuit 18. Note that a burst signal is also output from the reference composite color synchronization signal generation circuit 21.

First, in the present invention, an arbitrary recording track of a magnetic medium (magnetic tape) on which an interlaced scanning color video signal is recorded so that one recording track is formed for each signal of one field is selected and the recording track is transferred to a rotating magnetic head or the like. Whether or not the field oddness of the reproduced color video signal obtained by reproducing an arbitrary number of times by the reproduction means and the reference composite color synchronization signal from the reference composite color synchronization signal generation circuit 21 matches, and the color subcarrier signal of the field. A field comparison circuit 25 is provided which compares whether the phases of the signals match or are distorted. Then, the horizontal and vertical synchronizing signals from the synchronization separation circuit 17 are supplied to a field odd-even discrimination circuit 26, and the discrimination output thereof is supplied to a field comparison circuit 25. Further, the burst signal from the synchronization separation circuit 17 is supplied to a field color subcarrier signal phase discrimination circuit 27, and its discrimination output is supplied to a field comparison circuit 25.

Furthermore, the reference horizontal and vertical synchronizing signals from the reference composite color synchronizing signal generating circuit 21 are supplied to a field odd/even discriminating circuit 28, and the discriminating output thereof is supplied to the field comparing circuit 25. Furthermore, the color subcarrier signal from the reference composite color synchronization signal generation circuit 21 is passed to the field color subcarrier signal phase determination circuit 29.
and its discrimination output is supplied to the field comparison circuit 25. Then, a control signal is output from the output terminal 25A to determine whether or not the fields of the reproduced color video signal and the reference composite color synchronization signal match in odd-even, and further from the output terminal 25B, the phase of the color subcarrier signal of the field is Outputs a control signal indicating whether or not the condition is met.

Reference numeral 30 denotes a luminance/chromaticity separation circuit to which the color video signal whose time axis error has been corrected is outputted from the output terminal 16 of the time axis error correction circuit 11.
This is supplied to a luminance/chromaticity separation circuit 30, and a luminance signal and a carrier color signal are outputted to output terminals 30A and 30B, respectively.

31 is a first arithmetic circuit which supplies a reproduced luminance signal in a reproduced color video signal and obtains a first arithmetic mean signal of that signal and a signal having a phase different from that signal by one horizontal period. This first arithmetic circuit 31
supplies the luminance signal from the output terminal 30A directly to the synthesizer (adder) 33, and the delay amount is 1H.
(H is a horizontal period) is supplied to a synthesizer 33 through a delay circuit 32, and these signals are added. The addition output from the synthesizer 33 has a damping ratio of 1/2.
is supplied to the first attenuator 34 from which the first
is configured to obtain an arithmetic average signal of. 3
5 is a first switch circuit for switching and selecting the reproduced luminance signal and the first arithmetic mean signal from the first arithmetic circuit 31, which includes a movable contact m and fixed contacts a,
It has b. Then, the reproduced luminance signal is supplied as is to the fixed contact a, and the first arithmetic average signal from the first arithmetic circuit 31 is supplied to the fixed contact b.

36 supplies the reproduced carrier color signal in the reproduced video signal and obtains a second arithmetic average signal of that signal and a signal having a phase difference of one horizontal period from that signal with and without phase inversion. This is a second arithmetic circuit. This second arithmetic circuit 36 has an output terminal 30B.
The carrier color signal is directly supplied to a combiner (subtractor) 38, and is also supplied to a combiner 38 through a delay circuit 37 with a delay amount of 1H, and the delayed signal is subtracted from the undelayed signal. still,
The combiner 38 may be an adder, and the output of the delay circuit 37 may be supplied to the combiner 38 through an inverter circuit. The subtracted signal from the synthesizer 38 is then supplied to an attenuator 39 with an attenuation ratio of 1/2, and the second arithmetic mean signal is obtained from the attenuator 39. Reference numeral 40 designates a second switch circuit for switching and selecting between the reproduced carrier color signal and the second arithmetic mean signal from the second arithmetic circuit 36. This second switch circuit 40 has a movable contact m and fixed contacts a and b, and the carrier color signal from the output terminal 30B is directly supplied to the fixed contact a, and the second phase signal from the second arithmetic circuit 36 is supplied directly to the fixed contact a. The average signal is supplied to fixed contact b.

These first and second switch circuits 3
5 and 40 are switched and controlled by the odd/even match/mismatch control signal from the output terminal 25A of the field comparison circuit 25 mentioned above. When the fields of the reproduced color video signal and the reference composite color synchronization signal match in odd-even, each movable contact m changes to a fixed contact a.
If they do not match, the fixed contact b is switched to the fixed contact b.

42 is a third switch circuit for switching and selecting whether the output of the second switch circuit 40 is phase-inverted or not.
This is a switch circuit. That is, the output from the movable contact m of the second switch circuit 40 is supplied to the inverter circuit 41. The third switch circuit 42 has a movable contact m and fixed contacts c and d. Then, the output from the inverter circuit 41 is supplied to the fixed contact c, and the output from the movable contact m of the second switch circuit 40 is directly supplied to the fixed contact d. A switching output is obtained from the movable contact m. This third switch circuit 42 is operated by a control signal from the output terminal 25B of the field comparison circuit 25 that determines whether or not the phase of the carrier color signal of the field of the reproduced color video signal and the reference composite color synchronization signal matches. If they match, the movable contact m is switched to the fixed contact d, and if they do not match, the fixed contact c is switched.
It is designed so that it can be switched to

43 is a combiner, and the first switch circuit 3
5 and the output of the third switch circuit 42 are combined and added, and the reference composite color synchronization signal 21
The horizontal and vertical synchronization signals and burst signals are also combined and added. In this case, in the above-described time axis error correction circuit, it is assumed that the horizontal, vertical, and burst signals are removed to correct the time axis error.

Note that if the reproduced color video signal is not corrected for time axis errors and has horizontal and vertical synchronization signals and burst signals, the signals are distorted and each synchronization from the reference composite color synchronization signal 21 is shall be replaced by the signal. 44
is an output terminal from the synthesizer 43, from which a signal-processed color video signal is obtained.

The operation of this video signal processing device will be explained below. In the first arithmetic circuit 31 and the first switch circuit 35, if the field of the reference composite color synchronization signal is an odd number, and the field of the reproduced color video signal is an even number, the n- The signals of the first line and the n-th line that coincide in the vertical direction on the screen are arithmetic averaged, and this is used as the video signal of the n-th line of the odd field. Conversely, if the field of the reference composite color synchronization signal is an even number and the field of the reproduced color video signal is an odd number, the signals of the nth line and the signal of the n+1th line of the reproduced color video signal are similarly arithmetic averaged. , to the n-th line signal of the even field.

Further, in the second arithmetic circuit 36 and the second switch circuit 40, substantially the same thing as described above is performed, but in this case, a certain signal and a signal having a phase different from that signal by one horizontal period are processed. Since the color subcarrier signals have inverted phases, one signal is inverted and both signals are arithmetic averaged.

In this way, when the fields do not match, an arithmetic average signal is created and signal interpolation is performed according to the field oddness of the reference composite color synchronization signal. Since the phases of the color subcarrier signals are different as shown in FIG.
6, the third switch circuit 42 is switched so that the phase of the carrier color signal output from the second switch circuit 40 matches the phase of the reference composite color synchronization signal. It is something to do.

All cases of operation of this video signal processing device are shown in a table in FIG. FIG. 5 shows that when the fields of the reproduced video signal are the first field _F1 to the fourth field _F4 , the field of the reference composite color synchronization signal corresponds to the fourth field.
F ₄ ~ 3rd field F ₃ or 2nd field F ₂ ~
1st field F ₁ or 3rd field F ₃ ~ 2nd
This shows the presence or absence of interpolation signal processing of the field _F2 and the presence or absence of color inversion of the carrier color signal.

In the above description, the inverter circuit 41 and the third
This is a case where the switch circuit 42 is provided after the second switch circuit 40, but the second arithmetic circuit 36
It may be provided on the input side.

According to the above-mentioned video signal processing device of the present invention, an arbitrary recording track of a recording medium on which an interlaced scanning color video signal is recorded so that one recording track is formed for each field signal is selected, and the reproducing means selects the arbitrary recording track. Even if a reproduced signal obtained by reproducing the signal an arbitrary number of times is reproduced on a monitor receiver, there is no shift in the vertical direction of the screen, and color interference does not occur. Therefore, image deterioration during playback in variable speed modes such as slow playback, still playback, and high speed playback can be suppressed.

[Brief explanation of the drawing]

Figure 1 shows the pattern of the magnetic tape, Figure 2 shows the pattern of the magnetic tape.
The figure shows a rotating magnetic head and its surrounding parts.
FIG. 3 is a waveform diagram around the vertical blanking period of an NTSC color video signal, FIG. 4 is a block diagram showing an embodiment of the present invention, and FIG. 5 is a chart for explaining the operation. TP is recording medium, RT is recording track, F ₁ to _{F 4}
are the first to fourth fields, Fa and Fb are the first and second frames, 1 is a rotating magnetic head as a reproduction means, 10 is a reproduction circuit, 11 is a time axis error correction circuit, and 21 is a reference composite color synchronization signal generation circuit, 2
5 is a field comparison circuit; 26 is a field odd/even discrimination circuit; 27 is a field color subcarrier signal phase discrimination circuit; 28 is a field odd/even discrimination circuit; 29 is a field color subcarrier signal phase discrimination circuit; 32 is a delay circuit, 33 is a combiner, 34 is an attenuation circuit, 35 is a first
36 is a second arithmetic circuit, 37 is a delay circuit, 38 is a combiner, 39 is an attenuator, 40 is a second switch circuit, 41 is an inverter circuit, 4
2 is a third switch circuit, and 43 is a synthesizer.

Claims (1)

[Claims] 1. A reproduced color image obtained by selecting an arbitrary recording track of a recording medium in which an interlaced scanning color image signal is recorded so that one recording track is formed for each field signal, and reproducing it an arbitrary number of times using a reproducing means. A field comparison circuit that compares whether the signal and the reference composite color synchronization signal from the reference composite color synchronization signal generation circuit match whether the odd-even field of the field matches and whether the phase of the color subcarrier signal of the field matches. and a first arithmetic circuit that supplies a reproduced luminance signal in the reproduced color video signal and obtains a first arithmetic mean signal of that signal and a signal that differs in phase by one horizontal period from that signal; a first switch circuit for switching and selecting the reproduced luminance signal and the first arithmetic mean signal from the first arithmetic circuit; a second arithmetic circuit that obtains a second arithmetic mean signal of a phase-inverted signal having a phase difference of one horizontal period with respect to the signal; and a third switch circuit that switches and selects the output of the second switch circuit and the phase-inverted version of this output, When the first, second, and third switch circuits are switched and controlled by the comparison signal of the field comparison circuit, and the odd-even of the field of the reproduced luminance signal matches the odd-even of the field of the reference composite color synchronization signal, The reproduced luminance signal is obtained from the first switch circuit, and when they do not match, the first arithmetic average signal is obtained, and the odd-even of the field of the reproduced carrier color signal is the same as the field of the reference composite color synchronization signal. When they match, the reproduced carrier color signal is obtained from the second switch circuit, and when they do not match, the second arithmetic average signal is obtained, and the color sub-field of the reproduced carrier color signal is obtained from the second switch circuit. When the phase of the carrier wave signal matches the phase of the color subcarrier signal of the field of the reference composite color synchronization signal, the output of the second switch circuit is obtained from the third switch circuit, and when they do not match, the output of the second switch circuit is obtained from the third switch circuit. A video signal processing device characterized in that a signal is obtained by inverting the phase of the output of the switch circuit.