JPS6374390A - Signal processing system for y/c separation video signal - Google Patents

Abstract

PURPOSE:To reduce deterioration of picture quality even when dubbing is made many times by detecting phase difference between horizontal synchronizing signals extracted from reproduced luminance signals and chroma signals and forming vertical synchronization information for chroma signals. CONSTITUTION:Saw tooth wave SS of a saw tooth wave generator 12 is sampled by a sampling pulse M3that indicates nearly middle point of horizontal synchronizing signals H(C). The sampling voltage shows phase accuracy of a pair of rotary heads. Phase errors ERR obtained from a sampling hold circuit 13 are evened off by a smoothing circuit 16, and selected by switches S1,S2 for each A recording track and B track, and held by capacitors C1, C2. Thereby, it becomes possible to eliminate the problem of writing in different address even when phase error becomes large by dubbing of several times.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention provides a method for correcting the phase relationship between the luminance signal and the chrominance signal when reproducing a tape in which the luminance signal and the chrominance signal are recorded on separate recording tracks. It concerns a signal processing method.

[Summary of the invention]

In the signal processing method of Y/C separated video signals of the present invention, in order to record and reproduce high-quality video signals, the luminance signal and color signal components are recorded on separate tracks, and are simultaneously processed using two pairs of rotating heads. In a device configured to reproduce the luminance signal, the phase of the horizontal synchronization signal of the reproduced luminance signal and the horizontal synchronization signal component of the color signal component are compared, and the frame synchronization information of the color signal component is determined based on the obtained phase difference information. This method is useful as a method for compensating for Y/C phase errors that occur when dubbing component color video signals.

[Conventional technology]

A device that records and plays back a color video signal (VTR) generally converts the video signal into a luminance signal Y and a color signal component (
After separating into color difference signals (color difference signals) C, these signals are subjected to signal processing and recorded in a superimposed manner on the same recording track.
In TR, a method (Y/C separate recording) is adopted in which the luminance signal and color signal components are recorded on separate recording tracks.

FIG. 5 shows a tape recording pattern according to this recording method, where Y^, YB are recording tracks of luminance signals for 1 field, and C^, CB are recording tracks of chroma signals corresponding to Y^, YB. be.

On the chroma signal tracks CA and CB, the color difference signals R-Y and B-Y for one field are recorded with their time axes compressed into stations, and a horizontal synchronization signal synchronized with the luminance signal is also added. has been done.

However, track C^ of chroma signal.

Normally, a vertical synchronizing signal component is not added to the CO, and the vertical synchronizing signal of the reproduced luminance signal is used as a reference for signal processing.

[Problem that the invention seeks to solve]

By the way, in this recording method, the recording track Y of the luminance signal
A rotating head corresponding to the recording track C^, B of the chroma signal and the recording track C^, B is required, but if there is an error in the relative position of these two pairs of rotating heads, the phase of the luminance signal and chroma signal will change on the tape during recording. There is a problem in that even if the data is recorded in the correct phase during reproduction, a phase error will occur in each reproduced output.

In other words, now the relative speed of the head and tape is 7 m.
/ sec, the recording length of 1 water period recorded on the tape is 7X10-6/30X525:444gm/H,
Even if the relative error between the two pairs of rotating heads is ±10 microns, ±10 p m ・fli3.5/444 = ±1.4
A phase error of 4JLs occurs.

Therefore, as shown in FIG. 6, the reproduced luminance signal Y
When dubbing is performed by supplying ^ and chroma signal CA from the VTR of machine A to the VTR of machine B (dubbing in Y/C separated format causes less signal deterioration), the Since a phase error is added to , the phase of the luminance signal Y and the phase of the chroma signal C become
: There is a possibility of a deviation of 2.88 ps.

Then, when dubbing is performed several times on such a reproduced signal, 3. A phase error of up to %H (H is 1 water period) occurs, which becomes a problem when converting this dubbed signal into a composite video signal via, for example, a TBC (time base correction device).

That is, each TBC that corrects the time axis of the luminance signal and chroma signal requires a vertical synchronization signal that serves as a reference for one field, but as mentioned above, the vertical synchronization signal is not added to the chroma signal. Therefore, conventionally, a synchronization signal separated from the luminance signal was supplied to the TBC for the chroma signal.

However, as mentioned above, when the phase error becomes large, it becomes impossible to determine the line address of the chroma signal based on the vertical synchronization signal of the luminance signal, and the horizontal line of the luminance signal and chroma signal after time axis correction is There is a possibility of deviation.

The present invention was made to solve this problem by forming vertical synchronization information for a chroma signal corresponding to a phase error from a vertical synchronization signal for a luminance signal. It provides a signal processing method.

[Means for solving problems]

FIG. 1 shows a schematic explanatory diagram of the basic signal processing method of the present invention, where l is the horizontal synchronization signal HD (Y) of the reproduced luminance signal and the horizontal synchronization signal HD (C
), and 2 is a phase control unit that shifts the phase of the vertical synchronization signal of the luminance signal based on the phase difference information output from the phase detection unit l.

Note that 3 indicated by a dotted line indicates the TBC 14 for the luminance signal and the TBC for the chroma signal. A signal processing circuit is shown in which the data storage position in the memory is designated as a reference and the time axis is corrected.

[Effect]

By comparing the phase between the reproduced luminance signal and the horizontal synchronization signal extracted from the chroma signal and detecting the phase difference, the relative phase error between the luminance signal and chroma signal recorded on the tape is detected. Therefore, when the phase of vertical synchronization added to the luminance signal is controlled by the phase control section 2 based on this relative phase error, vertical synchronization information for the chroma signal is formed. Therefore, when the write clock of TE01 for chroma is generated based on this vertical synchronization information, the luminance signal obtained from TE01 for luminance signal and the chroma signal obtained from TE01 for chroma signal are always on the same horizontal line. This makes it possible to reduce deterioration in image quality even when dubbing is performed many times.

〔Example〕

Fig. 2 shows a circuit showing an embodiment of the signal processing system for Y/C separated video signals of the present invention, and Fig. 3 shows its operating wavefront. A monostable multivibrator is supplied with the extracted horizontal synchronization signal H(Y), 12 is a sawtooth wave generator, 13 is a sampling hold circuit, and 14.15 is a horizontal synchronization signal extracted from the reproduced chroma signal. This is a monostable multivibrator that performs H (C) signal processing and generates the sampling pulse M3 for the sampling and hold circuit 13.

16 is a smoothing circuit that smooths the sample voltage over one field period, and 17 is a waveform (ADV SW) that changes the phase of the switching pulse SW of the rotary head.
) shows an edge trigger generation circuit that outputs edge pulses from switches Sl and S2.
By alternately closing the capacitors cl and c2, the sampling voltage (phase error) for each field is held in the capacitors cl and c2.

Reference numeral 18 indicates a buffer amplifier, and the output pulse width of the monostable multivibrator 19 to which the vertical synchronization signal v (y) of the luminance signal is input is made variable according to its output current, and the vertical synchronization information V (C) of the chroma signal is made variable. It forms the

The signal processing method for a Y/C separated video signal of the present invention is capable of obtaining vertical synchronization information of a chroma signal from a vertical synchronization signal of a luminance signal using the circuit described above. This will be explained with reference to the waveform diagram in FIG.

The sawtooth wave generator 12 is reset by the output pulse Ml indicating the falling point of the horizontal synchronization signal H(Y) of the luminance signal input to the monostable multivibrator 11,
The sawtooth wave SS is sampled by a sampling pulse M3 indicating approximately the midpoint of the horizontal synchronization signal H(C) extracted from the chroma signal.

This sampling voltage is indicated by an O mark on the A recording track and a Δ mark on the B recording track, and as mentioned above, the luminance signal Y (^, B) and chroma signal C recorded on the tape
It shows the phase error of (^, B), that is, the stirrup accuracy of the pair of rotating heads.

Although the sampling pulse M3 is formed by the two monostable multivibrators 14 and 15, it may be formed by other waveform processing.

Phase error E obtained from sampling hold circuit 13
, RR are averaged by the smoothing circuit 16, and A
Switches s, s2 for each recording track and B track
However, since the phase error immediately after track switching has a large noise component N as seen in the ERRI waveform, smoothing circuit 1
After passing through 6, the phase error E is generated by the output pulse P l * P 2 with the phase of the switching pulse SW shifted.
RR2 is sampled again and held in capacitors CI and C2.

Then, A and B held in these capacitors c, , c2
The track phase error signal (O·Δ) is again formed into a single phase error signal ERR3 by the switching pulse SW, and is used as a signal for modulating the output pulse width of the monostable multivibrator 19.

The vertical synchronization V (Y) of the luminance signal is input to the trigger terminal T of this monostable multivibrator 19;
As shown in the waveform diagram in the figure, this vertical synchronizing signal v (y)
The pulse width t of the output pulse M4 of the monostable multivibrator triggered by is determined by the phase error signal ERR3. Therefore, if the falling point of the output pulse M4 forms the vertical synchronization information V (C) of the chroma signal, , v (y) and V (C) are the luminance signal (Y^, e ) and chroma signal (C
A, B) corresponds to the phase error.

Therefore, if these synchronization signals v(y) and v(C) are supplied as lock signals for the TBC of the luminance signal and the TBC of the chroma signal, even when the phase error becomes large due to several dubbings, both It becomes possible to solve the problem that, for example, the 10th signal on a horizontal line is written to a different address.

Note that the circuit configuration described above shows an example for signal processing of the Y/C separated video signal of the present invention, and the specific circuit configuration for detecting the phase error (ERR) is the same as that of the signal processing of the present invention. Other circuit means may be employed as long as they achieve the desired processing scheme.

〔Effect of the invention〕

As explained above, the signal processing method of the Y/C separated video signal of the present invention converts the phase error between the luminance signal and chroma signal caused by the mechanical precision of the VTR and several dubbings into the horizontal synchronization signal of the luminance signal. Since the horizontal synchronization signal of the chroma signal is detected and the vertical synchronization information of the chroma signal is formed from this phase error, signals such as TBC, etc., which are required to synthesize Y/C separated video signals, can be used. This has the effect of preventing incorrect processing from being performed.

[Brief explanation of the drawing]

FIG. 1 is a basic block diagram of the present invention, FIG. 2 is a block diagram showing an embodiment according to the present invention, FIG. 3 is a waveform diagram of the main part of FIG. 2, and FIG. 4 is a vertical synchronization information V FIG. 5 is a waveform diagram for explaining (C), FIG. 5 is a tape pattern diagram of the Y/C separation recording method, and FIG. 6 is a waveform diagram of a luminance signal and a chroma signal. In the figure, 1 is a phase detection section, 2 is a phase control section, HD (Y),
V (Y) is the horizontal synchronization signal and vertical synchronization signal of the luminance signal,
HD (C) and V (Y) indicate the horizontal synchronization signal and vertical synchronization information of the chroma signal.

Claims (1)

[Claims] a phase detection unit that detects a phase difference between a horizontal synchronization signal of the luminance signal and a horizontal synchronization signal of the color signal component reproduced when the luminance signal and the color signal component are reproduced from separate recording tracks; and the phase detection unit A phase control section is provided for shifting the phase of the vertical synchronization signal of the luminance signal by a phase difference signal output from the Y, and vertical synchronization information of the color signal component is obtained from the phase control section. /C signal processing method for separated video signals.