JPS62171295A - Video signal recording method - Google Patents

Abstract

PURPOSE:To obtain a stable output signal without being affected by reproducing noise and residual jitter by setting a location of a synchronizing signal where the phase of a horizontal synchronizing signal and the phase information of chrominance subcarrier included in a recorded video signal have a prescribed relation in advance at the recording. CONSTITUTION:A burst signal separated by a burst gate 3 from a composite video signal fed to a terminal 1 is led to a PLL 6, a continuous wave in 14. 3MHz in synchronism with the burst signal is obtained and the continuous wave is frequency-divided and synthesized by a synchronizing generator 7 to obtain a composite synchronizing signal 22 having a prescribed phase relation with the burst signal. In this case, the location of the horizontal and vertical synchronizing signal of the composite synchronizing signal 22 is set from the horizontal synchronizing signal and vertical synchronizing signal separated by the horizontal synchronizing signal separator 4 and a vertical synchronizing signal separator 5 from the input signal. On the other hand, the synchronizing signal is eliminated from the input composite video signal by a synchronizing signal eliminating device 2 and the synchronizing signal 22 having a prescribed phase relation with the burst signal is added newly by an adder 8 and a signal is obtained always at the output of the adder 8 where the synchronizing signal is made constant.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention can be used in video signal recording and reproducing devices such as VTRs, and is particularly useful for obtaining high-quality reproduced images with VTRs for broadcasting, business use, etc. This is effective for editing performance.

Conventional technology In conventional broadcasting VTRs, the input composite video signal is frequency-modulated and recorded as it is (dai-ref) (FM).
is widely used. Time axis fluctuations (jitter) occur in the playback signal of a VTR, but this is caused by a time axis corrector (jitter).
TBC). Usually, a digital TBC is used, which converts the video signal into a digital signal with a clock synchronized with the burst signal in the reproduced signal, writes it into the memory, reads it from the memory with a fixed stability lock, and returns it to the signal. By doing this, jitter is removed.At this time, the synchronization signal and burst signal are also replaced.When adding the synchronization signal to the output video signal, the synchronization signal of the recorded composite video signal and the video signal are If they are added in exactly the same positional relationship as the input and output video signals, the left and right positions of the input video signal and the output video signal will be exactly the same on the monitor.Also, the phase of the added burst signal and the color subsignal in the output video signal will be the same. The hue is determined by the phase relationship of the carrier waves.

However, the added synchronization signal and burst signal are
The synchronization signal is generated by a synchronization signal generator inside the TBC, or is generated based on a reference signal added externally. Therefore, the position of the TBC output video signal is adjusted so that the desired hue is obtained using this burst signal. If the phase relationship (seH) between the added synchronization signal and the burst signal is exactly the same as that of the input composite video signal, the left and right positions of the output signal will be the same as the input signal, but if they are different, they will be shifted.

In the NTSC signal, as shown in FIG. 3, four color fields (color frames) are defined by the phase relationship (SCH) between the burst signal and the synchronization signal. The allowable range of SCH is within ±40°. When editing two video signals with a VTR and connecting them, the SCH of both video signals
If they match perfectly and the color frames at the editing point are continuous, no horizontal shift of the image at the editing point will occur when a constant synchronization signal and burst are added during playback and output. However, the reality is that S and CH of current NTSC signals are not accurately managed.

If the SCH is different, the position of the video signal is shifted so that the hue is correct with the added reference burst signal, resulting in a left-right shift at the editing point.

Also, if the continuity of the color frame is lost at the edit point (
For example, in Fig. 3, the color frame person is followed by the color frame person (K), and the added burst signal has continuity in the color frame.
To match the hue, the video signal is shifted to the left or right by half a cycle of the color subcarrier, ie, 140 nsea. These operations are performed at the TBC.

Apart from the above-mentioned direct FM method, in recent years, as a method of obtaining high-quality playback signals in a compact size, video signals are combined with luminance signals.
Separate the luminance signal into two color signal components, frequency modulate the luminance signal,
The two color signal components are time-base compression multiplexed into a single signal and then frequency modulated, or the two color signal components are each frequency modulated and then frequency multiplexed and recorded. component method). In this case, when a composite video signal is separated into a luminance signal and two color signal components, recorded and reproduced, and then encoded again to obtain a composite video signal, the composite video signal is generated based on the phase of the color subcarrier at the time of encoding. If the phase is the same as that of the color subcarrier in the middle, the color signal component remaining in the luminance signal during separation and the high-frequency component of the luminance signal remaining in the color signal will be combined as before, and the original Although a similar composite video signal can be obtained, if the two phases do not match, color shift and high-frequency distortion of the luminance signal will occur.

For this reason, there is a method in which the color subcarrier components included in the original composite video signal are recorded in a superimposed manner even after separation, and based on this, the phase relationship between the phase of the color subcarrier used for encoding and the phase of the original color subcarrier is controlled. is proposed in Japanese Patent Application No. 19451/1983.

Problems to be Solved by the Invention In the FM system, a write clock of pTBc is created using a burst signal. The frequency of the write and read clocks is usually 4 fsc or 3 fsa (/s
c: color subcarrier frequency) K is set. 4f5G
The clock has a horizontal frequency fH and 'f sc =91O
f) The relationship is an integral multiple of I, and the phases of each line are aligned.

Therefore, this signal does not have information on the polarity of the color subcarrier. Therefore, the horizontal positional relationship between writing and reading is determined from the phase of the burst signal added at the time of output and the phase information of the burst signal recorded and reproduced, and machine control is performed to obtain the correct hue. In this way, T.B.
C becomes complicated to control the horizontal position. Furthermore, since it is necessary to immediately follow phase discontinuities at the editing point, it is not possible to provide a time constant due to integration, etc., and it has the disadvantage that it is easily affected by noise during playback.

Also in the component method, patent application 1986-1945
As stated in Specification No. 1, the horizontal position at the time of readout is determined by comparing the phase of the color subcarrier information in the original composite video signal recorded additionally to the component signal with the phase of the color subcarrier at the time of encoding. control, it is susceptible to noise and residual jitter in the reproduced original color subcarrier information, which can be a source of instability. Furthermore, since an immediate response must be made at the editing point, a time constant cannot be provided.

Means for Solving the Problems In order to solve the problems above, in the present invention, the phase information of the color subcarrier included in the video signal to be recorded and the phase of the horizontal synchronization signal are in a fixed relationship in advance during recording. The position of the synchronization signal is set as follows.

In this way, it is useful to record while keeping the SCH constant, but during playback, the horizontal position can be finely controlled based on the phase relationship between the reproduced burst signal and the burst signal added to the output signal (direct FM), and the added There is no need to control the horizontal position by phase comparison between the color subcarrier information included in the recorded input composite video signal and the encoded color subcarrier (component recording); simply write using a clock synchronized with the playback signal and read using the reference clock. In particular, by simply configuring pTBc and performing burst addition and encoding so that the color frames of the recorded and reproduced video signal and the output video signal have a predetermined relationship, it is possible to always obtain the correct hue, and also to can be encoded with the same color subcarrier phase. In this way, since there is no need to perform complicated control in the reproduction system, a stable output signal can be obtained without being affected by reproduction noise or residual jitter.

Embodiment FIG. 1 shows a block diagram of an embodiment of the present invention, and will be described. In FIG. 1, 1 is a composite video signal input terminal, 2 is a sync signal remover, 3 is a burst gate, 4 and 10 are horizontal sync signal separators, 5 is a vertical sync signal separator, and 6 is a PIJ
L, 7 is a sync generator, 9 is a decoder, 11 is a horizontal synchronization signal/burst generator, 17 is a time axis compressor, 1
8.19 is a frequency modulator, and 20.21 is a head.

A burst signal separated by the burst gate 3 from the composite video signal applied to the terminal 1 is guided to the PLL 6,
14.3MH2 (=41..) synchronized with burst signal
A continuous wave is obtained, and the sync generator 7 divides and combines the continuous waves to obtain a composite synchronization signal 22 having a constant phase relationship with the burst signal. At this time,
The positions of the horizontal and vertical synchronizing signals of the composite synchronizing signal 22 are set by the input signal and the horizontal synchronizing signal and vertical synchronizing signal separated by the horizontal synchronizing signal separator 4 and the vertical synchronizing signal separator 5. On the other hand, the synchronizing signal remover 2 removes the synchronizing signal from the input composite video signal, and then the adder 8 adds a new synchronizing signal 22 having a constant phase relationship with the burst signal. In this way, a signal in which the KSCH is always kept constant is obtained at the output of the adder 8,
The signal is guided to the decoder 9. In the decoder 9, the composite video signal is converted into a luminance signal Y and two color difference signals RY and BY. Horizontal synchronization signal/burst generator 1 from the horizontal synchronization signal separated from the Y signal by horizontal synchronization signal separator 10
According to 1, a horizontal synchronization signal and a burst signal used for removing jitter during playback are created, and 2.2 is used for the Y signal.
5MH2 (=143fH) is added to the adder 12. The horizontal synchronizing signal is added to the R-Y signal by the adder 13.
．． A burst signal of 125 MHz (=□f□) is added to the adder 14. Also, the B-Y signal has 1.12
A burst signal of 5M)-1z is added by the adder 15. Furthermore, for vertical blanking of the B-Y signal, color frame information 23 created by the sync generator 7 is used.
(eg, a pulse signal indicating the first field of a color field) is added by an adder 16. Adder 14
The output R-Y signal of the adder 16 and the output B-Y signal of the adder 16 are guided to the time axis compressor 17, where they are compressed to the dedicated time, and the R-Y signal is placed before A in one line, and the B-Y signal is sent after A. -Y signals are multiplexed into one signal. The output Y signal of the adder 12 and the output compressed color signal of the time-base compressor 17 are each modulated by frequency modulators 113 and 19, and are output to the head 2.
0.21, separate tracks are formed and recorded on the tape.

Next, a block diagram of an embodiment of processing for reproducing signals recorded in this manner is shown in FIG. 2, and will be described. In FIG. 2, 24 and 26 are frequency demodulators, 26 is a color frame signal separator, 27 is a TBC, 2B is a sync generator, and 29 is an encoder. head 2o
The signal reproduced by the head 21 and demodulated by the frequency demodulator 24 and the compressed color signal reproduced by the head 21 and demodulated by the frequency demodulator 25 are guided to the TBC 27, where jitter is removed and the color signal is The axis is elongated,
It is separated into the RY signal and the BY signal.

TBC read clock 34 is sync generator 2
Created in 8. The TBC output R-Y signal and B-Y signal are guided to the encoder 29 and encoded by the color subcarrier 36 created by the sync generator 28, and the TBC output R-Y signal and B-Y signal are
It is added to the C output Y signal by an adder 30. Further, in the sync generator 28, the reference synchronization signal and the burst signal 3
6 is also created and added to the output signal of the adder 3o by the adder 31, and an output composite video signal is obtained at the terminal 33.

The sync generator 2 generates a TBC readout clock 34 that has a certain relationship based on the reference video signal applied to the terminal 32 (runs freely when no reference video signal is applied).
, a color subcarrier for encoding 35, and a reference synchronization signal/burst signal 36. Therefore, the timing of signal readout of the TBC and the phase relationship between the encoded color subcarrier and the additional synchronization signal/burst signal are always constant. Also, the timing of writing to the TBC is set by the burst signal (signal added during recording) in the playback signal (
The write clock is also created as a burst signal). The burst signal added during recording is created in synchronization with the horizontal synchronization signal of the Y signal, and this horizontal synchronization signal is set to have a certain phase relationship with the color subcarrier of the original input composite video signal. Therefore, if the color frames match, the phase relationship between the encoded color subcarrier and the color subcarrier in the original input composite video signal is always constant. Here, in order to match the color frames of the reproduced signal and the output signal, the color frame information superimposed on the B-Y signal,
The signal is separated by a color frame signal separator 26 and supplied to a servo circuit, which performs servo control so that the output color frame of the sync generator 28 and the reproduced color frame match. In this way, the phases of the original color subcarrier and the encoded color subcarrier can always be matched. In addition, even in a method that does not perform servo to match color frames, the color frame information separated from the reproduced B-Y signal and the sync generator 2 that is added to the output
The phases of both color subcarriers can be matched by comparing the output color frame with the color frame of No. 8, and if they match, they are encoded as is, and if they are opposite, the readout timing is shifted by half a cycle of the color subcarrier. In this case as well, the control is not fine control using reproduced color subcarrier information as in the conventional example, but simply control of whether to shift by half a cycle or not, and the determination can be made by extracting the pulse signal, so it is stable. can be done.

Furthermore, not only the method of recording color frame information by superimposing it on a video signal as in the above embodiment, but also the method of recording it by superimposing it on a control signal is also effective.

The same can be applied to the FM system as well by omitting the areas around the decoder and encoder in FIGS. 1 and 2.

Effects of the Invention As described above, according to the present invention, hue matching and color subcarriers in the same phase as the original color subcarriers can be achieved by simple processing during recording without performing complicated control in the reproduction system. It is possible to realize encoding with , simplifying the circuit and improving stability.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a block diagram showing an embodiment of a method for reproducing a video signal recorded by the method shown in FIG. 1, and FIG. FIG. 3 is a waveform diagram showing a phase relationship between a synchronization signal and a color subcarrier. 2... Synchronization signal remover, 3... Burst gate, 4... Horizontal synchronization signal separator, 5...
...Vertical synchronization signal separator, 6...PLL,
7...Sync generator, 9...Decoder, 11...Horizontal synchronization signal/burst creator, 8, 12, 13, 14, 15° 16...・Adder.

Claims (3)

[Claims] (1) When processing and recording an input composite video signal, set the position of the synchronization signal so that the phase information of the color subcarrier included in the recorded video signal and the phase of the horizontal synchronization signal have a constant relationship. A video signal recording method characterized by: (2) When separating and recording an input composite video signal into a luminance signal and two color signal components, the color subcarrier in the original input video signal is included in the recorded luminance signal and two color signal components. The position of the synchronization signal is set so that the phase information of the luminance signal and the horizontal synchronization signal of the luminance signal have a constant relationship, and a signal representing the timing with the luminance signal is added to at least one of the two color signal components to be recorded. A video signal recording method according to claim 1, characterized in that: (3) The video signal recording method according to claim 1 or 2, characterized in that color frame information of the input composite video signal is superimposed and recorded on a part of the video signal.