JP2002218492A - Color signal demodulator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a color signal demodulator that can demodulate a color signal with high accuracy even from a color video signal obtained by a VTR or the like. SOLUTION: A Y/C separate circuit 3 separates Y and C signals from a signal resulting from a sampled video signal subjected to line delay processing. A switch circuit 5 selects a color burst signal of the digital video signal not subjected to the line delay processing or a chrominance carrier signal subjected to the line delay processing and a color signal demodulator 6 demodulates the selected color signal according to a phase angle of a color sub carrier. A phase detector 10 detects the phase of the color burst from demodulated U, V signals and a correction circuit 11 corrects an offset of a color subcarrier phase for each sample of a current line from the color burst phase of a preceding line and the current line. A phase angle generator 9 obtains a phase angle of the subcarrier from the corrected phase.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color signal demodulation device, and more particularly to a video signal such as a VTR (video tape recorder) for separating a Y / C (lightness / chromaticity signal) from a composite video signal and demodulating the color signal. The present invention relates to a color signal demodulation device for performing color demodulation with high performance.

[0002]

2. Description of the Related Art A video signal in a color television or the like is transmitted by synthesizing a luminance signal (Y) and a chrominance signal (C). The synthesized video (color television) signal is
In the case of high-efficiency compression-encoding transmission, it is important to accurately demodulate a chrominance signal at the time of demodulation by a receiver. The color signal demodulation method generally performs demodulation using the relationship between the color subcarrier (color subcarrier) frequency fsc of the color television signal and the horizontal synchronization frequency fh. NTS
In the case of the color television of the C system, fsc = 455/2
There is a relationship of × fh, and also in the case where Y / C separation and color signal demodulation are performed by digital signal processing, color signal demodulation is performed using these relationships.

[0003] In a normal television (TV) signal, the above relationship is maintained, but the NTR signal reproduced from the VTR is used.
This relationship may not always be maintained in the SC color television signal. When compressing and encoding a video signal, the TV signal is sampled (sampled) using a sampling clock synchronized with the horizontal synchronization signal in order to encode the video signal with high efficiency using the frame correlation of the TV signal. There is a need. Therefore, when the VTR signal is sampled by a sampling clock synchronized with the horizontal synchronization frequency, the phase of the color subcarrier sampled for each line is shifted. In other words, the frequency of the color subcarrier fluctuates with respect to the horizontal synchronization frequency.

The frequency shift does not abruptly shift for each line, but shifts little by little continuously, so that the phase at the head of the line and the phase at the end of the line are shifted. Therefore, if the phase of the color subcarrier is determined from the color burst at the beginning of the line, the phase of the subcarrier is shifted at the end of the line. There has been a problem that color signals cannot be demodulated correctly and color shift or color unevenness occurs. Furthermore, if the color signal cannot be demodulated correctly, there is a problem that the predictive coding efficiency of the compression coding decreases.

[0005] As a prior art of the color signal demodulation method, there is, for example, a "video signal processing circuit" (hereinafter referred to as a first prior art) of Japanese Patent Application Laid-Open No. 04-96595, and its configuration is shown in a block diagram in FIG. That is, the synchronization signal separation circuit 111, PL
L (phase locked loop) circuit 112, A / D (analog / digital) conversion circuit 113, video data line memory 114, color subcarrier signal reproduction circuit 115, color subcarrier line memory 116, timing generation circuit 117, digital comb filter 118 and a color signal demodulation circuit 119.

This video signal processing circuit operates as follows. The A / D conversion circuit 113 digitizes the video signal with a sampling clock synchronized with an integer multiple of the horizontal synchronization signal.
The color subcarrier signal reproduction circuit 115 obtains the phase difference Q and the amplitude CC of the color burst from the two successive burst signal values using the sampling theorem. Based on this, a digital color subcarrier signal for one line is generated and stored in the color subcarrier line memory 116. Color signal demodulation circuit 11
Reference numeral 9 color-demodulates the color signal (C) data separated by the digital comb filter 118 using the color subcarrier supplied from the color subcarrier line memory 116.

[0007] Since the main purpose of this processing circuit configuration is to demodulate a standard TV signal, it is assumed that fsc and fh satisfy the relationship described above and that the phase of the color subcarrier is constant at the beginning and end. , And a color subcarrier. For this reason, a signal such as a VTR has a disadvantage that color signals cannot be correctly demodulated near the end of a line. Further, in this processing circuit configuration, the chrominance subcarrier signal reproduction circuit 115 and the chrominance signal demodulation circuit 119 are separate, so that the circuit scale becomes large.

Japanese Patent Application Laid-Open No. 8-331592 discloses a "hue correction video signal decoder" (hereinafter, referred to as a second prior art). FIG. 7 is a block diagram showing the configuration. The decoder (demodulator) includes multipliers 71 and 73, low-pass filters (LPF) 72 and 74, sin, cos
It comprises a (sine, cosine) table 75, a phase difference detector 76, a hue correction amount register 77, a digital oscillator 78, and an adder 79. The phase difference detector 75 detects a phase difference from the demodulated U signal and V signal of the burst signal. The digital transmitter 76 generates a phase of the color subcarrier having the same phase as the color burst from the detected phase difference. The hue correction amount register 78 is set with the hue correction amount, and the correction amount is added to the phase of the subcarrier.

[0009]

In the above-mentioned second prior art decoder, the circuit for obtaining the color subcarrier signal and the color demodulation circuit are constituted by one demodulation circuit. If applied to the prior art, the configuration would be simplified. However, since the phase difference is determined at the beginning of the line, the problem or defect that the color signal cannot be correctly demodulated near the end of the line cannot be improved in the video signal such as the VTR described in the first related art.

[0010]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a color signal demodulation apparatus capable of accurately demodulating a color signal even when demodulating a color television signal such as a VTR.

[0011]

According to the present invention, there is provided a color signal demodulating apparatus comprising: a line delay circuit for line-delaying a video signal sampled by a sampling clock having an integral multiple of a horizontal synchronization frequency;
A Y / C separation circuit for separating a luminance signal (Y) and a carrier chrominance signal (C) from a line-delayed signal, and a return path selection of a digital video signal color burst signal without line delay and a line-delayed carrier color signal. A switch circuit;
A color signal demodulation circuit for demodulating the color signal selected by the switch circuit using the phase angle of the color subcarrier, and a phase detection for detecting the phase angle of the color burst from the two demodulated color difference signals (U, V) And a correction circuit for correcting a shift between the previous line and the current line, and a phase angle generator for obtaining a subcarrier phase angle from the phase corrected by the correction circuit.

According to a preferred embodiment of the color signal demodulation device of the present invention, the Y / C separation circuit has a separation filter characteristic using a comb filter and a band-pass filter characteristic, and is provided between the lines of the color burst signal. Is adaptively determined using the correlation in the above, and when the correlation is strong, the comb filter Y
/ C separation is performed, and when the correlation is weak in a video signal such as a VTR, Y / C separation is performed by a band-pass filter. The line delay circuit and the comb filter delay circuit are shared. As a phase detector, the phase angle is roughly determined from the two color difference signals,
Means for determining whether the state is the initial state or the retracted state, means for setting a coarse phase value to the integral initial value in the initial state, and integrating means for integrating a value obtained by multiplying the V signal by a predetermined coefficient in the retracted state. Judging from the line correlation of the color burst, the coefficient value is increased when the color burst phase greatly changes in a video signal such as a VTR, and the coefficient value is decreased when the color burst phase of a broadcast signal or the like is stable.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The construction and operation of a preferred embodiment of a color signal demodulation device according to the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram showing the configuration of a preferred embodiment of a color signal demodulation device according to the present invention. This color signal demodulation device includes an A / D converter 1, a line delay circuit 2, an adaptive Y / C separation circuit 3, a PLL circuit 4, a switch (SW) circuit 5, a color signal demodulator 6, a synchronization separation circuit 7, It comprises a circuit 8, a phase angle generator 9, a phase detector 10 and a correction circuit 11.

Next, the function of each component constituting the color signal demodulator shown in FIG. 1 will be described. The synchronization separation circuit 7 separates a horizontal synchronization signal from an input video (or image) signal,
Supply to L circuit 2. The PLL circuit 2 generates a sampling clock having a frequency equal to N times the frequency fh of the horizontal synchronization signal. As the sampling frequency used in the MPEG2 method of the video compression code, there is 13.5 MHz as a sampling frequency suitable for the PAL signal and the NTSC signal. In this case,
N = 858. The control circuit 8 outputs a signal indicating a head of a line, a color burst section, and other control signals, and supplies them to the SW circuit 5, the phase angle generator 9, and the correction circuit 11. In order to correct the delay of the adaptive Y / C separation circuit 3, the signal from the output of the A / D converter 1 to the SW circuit 5 is
Although it is necessary to delay by the delay time, it is omitted to simplify the description.

The A / D converter 1 samples a video signal to obtain a digital video signal. The digital video signal is supplied to the line delay circuit 2 and the SW circuit 5. The line delay circuit 2 delays the digital signal by one line. The line-delayed video signal is supplied to the adaptive Y / C separation circuit 3. In order to form a comb filter, a signal without line delay is also supplied to the adaptive Y / C separation circuit 3 at the same time. The adaptive Y / C separation circuit 3 has a two-line comb filter and band-pass filter characteristics, and has a comb filter characteristic when the line correlation is high. When the line correlation is low, the digital video signal is separated into a luminance signal (Y) and a carrier chrominance signal (C) by bandpass filter characteristics, and the separated carrier chrominance signal (C) is supplied to the SW circuit 5.

The SW circuit 5 selects and outputs the color burst signal of the portion of the digital video signal which is not delayed during the period of the burst flag according to the control signal from the control circuit 8, and in the other periods, the one line cycle. And selects and outputs the separated separated carrier color signal (C). Compared to the carrier chrominance signal (C), the signal in the color burst section is output one line ahead of the signal. The color signal demodulator 6 generates sin (sine) and cos (cosine) values corresponding to the phase angle of the color subcarrier from the phase angle signal. Then, by multiplying the chrominance signal and passing through an LPF (low-pass filter), the carrier chrominance signal or the color burst signal is demodulated to obtain two color difference signals (U, V).

The phase detector 10 detects the phase of a color burst from the two color difference signals U and V, and outputs a correct phase. In the NTSC signal, the color burst is in the minus direction (180 °) of the U axis (BY axis).
It is. Therefore, if the subcarriers are in phase,
The U (BY) signal during the color burst period has a negative value, V
(RY) should be approximately zero. Color difference signals U, V
Tan (θ) = V / U from the relationship between the trigonometric function and the sample value. If a conversion table for obtaining θ from the color difference signals U and V is provided, the phase value can be obtained from the U and V values.

The correction circuit 11 corrects the reference phase shift when the phase of the color burst gradually changes line by line when a video signal such as a VTR is input. If the color subcarriers of the next line are calculated based only on the phase of the color burst detected at the head of the line, the phase of the color burst becomes discontinuous for each line. Therefore, instead of resetting the value of the color burst at the beginning of each line, the intermediate phase of the line is corrected from the phase of the color burst before and after the line. Phase correction is performed linearly in the middle of one line section so that the phase gradually changes for each sample. As the phase of the color burst, the phase value of the k-th line is α01
When the phase value of the (k + 1) th line is α02, 1
The amount of change between lines (N samples) is (α02
−α01), so (α02−α01)
/ N is corrected. Therefore, the corrected phase αi of the i-th sample is αi = α01 + i (α02−α01) / N
Is output.

The phase angle generator 9 generates a phase angle of a subcarrier. In the phase angle generator 9, the phase angle of each sample of the subcarrier is added to the corrected phase of the color burst to obtain the phase angle θi of each sample. From the subcarrier frequency fsc = 455/2 × fh and the sampling frequency fs = N × fh, the angular velocity ω is ω = 2π × fsc /
fs. Therefore, the subcarrier phase angle θi at the ith sample point is given by the following equation. θi = αi + (π × 455 / N) × i Since the phase is corrected by the operation of the correction circuit 11,
Even for a video signal such as a VTR, the carrier color signal (C) can be demodulated with high quality without color shift.

FIG. 2 is a diagram for explaining the operation of detecting the color burst phase. The signal supplied from the SW circuit 5 is a color signal CB of a synchronization section (burst flag section) including a carrier color signal (C) of a video section and a color verse signal.
However, the order is changed and multiplexed. As shown in FIG. 2, the carrier chrominance signal C (k-
1), color burst signal BF of the (k + 1) th line
(K + 1), the carrier color signal C (k) of the k-th line, the (k)
+2) line color burst BF (k + 2), ...
It becomes the order of. The color burst phase of the k-th line is α01
And the phase of the color burst of the (k + 1) th line is α02
Is detected, the correction circuit 11 corrects the phase for demodulating the carrier color signal (C) of the k-th line with the correction phase αt.

FIG. 3 is a block diagram showing a detailed configuration example of the color signal demodulator 6 in FIG. The color signal demodulator 6 includes multipliers 30, 32, LPFs 31, 33, cos
(Cosine) table 34 and sin (sine) table 3
5. The color burst signal and the color signal of the carrier color signal (C) supplied to the color signal demodulator 6 are supplied to multipliers 30 and 32. The signal of the subcarrier phase angle is represented by a sin table 35 and a cos table 3
4 is supplied. The sine table 35 stores the input phase angle θ
Is a conversion table of sin (θ) with respect to, and the output is supplied to the multiplier 32. The cos table 34 is a conversion table of cos (θ) with respect to the input phase angle θ, and the output is supplied to the multiplier 30. The multiplier 30 converts the multiplication result into an LPF
31. The LPF 31 has a low-pass digital filter characteristic, blocks high frequencies, and has a baseband U (B
-Y) is output. Similarly, the multiplier 32
The multiplication result is supplied to the LPF 33, and the high frequency is blocked by the LPF 33, and a V (RY) color difference signal is output.

FIG. 4 is a block diagram showing a detailed configuration of the line delay circuit 2 and the adaptive Y / C separation circuit 3. 1H line memories 41, 47, coefficients 40, 42, 4
8, an adder 43, a SW circuit 44, an adaptive control circuit 49, a band-pass filter (BPF) circuit 45, and a subtractor 46. In this embodiment, the comb filter is 2
An example of a configuration that is an H-shaped comb filter is shown. Normally, the color signal output from the comb filter is further band-limited by a BPF to obtain a carrier color signal (C). Since a video signal such as a VTR has no line correlation, the color signal (C) is separated only by the BPF.

The line memories 41 and 47 delay the input signal by 1H and output it. Coefficient units 40, 42 and 48
Has coefficients k0, k1, and k2, respectively, and multiplies each input by each coefficient and outputs the result. The coefficients k0, k1, and k2 of the 2H-type comb filter are -−１, 、 ２, respectively.
And −−１. The adder 43 is provided for each coefficient unit 4
The outputs from 0, 42 and 48 are added and output. In a normal NTSC signal, the phase of the color subcarrier is
Invert every line. The coefficients are-／, 2/4 and-
In the case of ４, the signal of the frequency component of the color subcarrier, that is, the signal (C) of the carrier color signal component passed through the comb filter is output to the output of the adder 43.

The SW circuit 44 and the adaptive control circuit 49 are supplied with a 1H delay NTSC signal and a carrier color signal (C). The adaptive control circuit 49 compares the difference between the color burst signals in the burst flag section. The difference between the two is obtained, and if the difference is larger than a certain ratio (preset value) of the size of the color burst,
It is determined that there is no line correlation in the color burst, and the control signal w for switching is supplied to the SW circuit 44 so that the color signal is obtained not by using the comb filter but by the BPF circuit 45.

The SW circuit 44 selects based on the control signal w and supplies it to the BPF circuit 45. BPF circuit 4
Reference numeral 5 denotes a band-pass filter that passes near the subcarrier frequency, and passes the carrier chrominance signal (C). Carrier color signal C
Is supplied to the subtractor 46 and the next stage circuit. The subtracter 46 subtracts the carrier chrominance signal (C) from the NTSC signal, and outputs a luminance signal (Y) at the output. As another example, a configuration may be adopted in which two characteristics are prepared for the BPF circuit 45 instead of one, and switching is performed between a case where a comb filter is used and a case where a comb filter is not used. The filter characteristics are set so that the pass band is wide in the case of a comb filter and narrow in the case of only a BPF. The comb filter has the configuration of 2H, but in FIG. 4, the line memory 47 and the coefficient 48 are deleted, and the coefficient values k0, k0,
By setting k1 to -1/2 and 1/2, respectively, a 1H-type comb filter can be formed. In this case, the separation characteristics of the comb filter are slightly reduced, but the circuit scale can be reduced.

Next, FIG. 5 shows the phase detector 1 shown in FIG.
0 shows a detailed configuration. If a circuit for obtaining the phase θ from the values of the color difference signals U and V is configured by a conversion table, the U signal becomes 8
Assuming that the bit and the V signal are 8 bits and the precision of θ is 8 bits, a conversion table for obtaining an 8-bit output for an input signal of 8 + 8 = 16 bits is required. The number increases. This configuration,
RO of 8 bit size instead of 16 bit size
This is an example that can be simplified with M.

The phase detector 10 includes a conversion table 5
1, a coefficient unit 52, an adder 53, a SW circuit 54, and a register 55. In the conversion table 51,
Upper four-bit signals U4 and V4 of the U and V signals are input. The conversion table 51 has a conversion characteristic of obtaining a phase θ from a 4-bit U signal and a 4-bit V signal, and outputs the phase θ with respect to the input U4 and V4 signals with, for example, 8-bit accuracy. It is supplied to the SW circuit 54. Also, S
A control signal S for controlling the W circuit 54 is also output. Input U
When the signal is negative and the V signal is in the range of -8 to 7, if U4 is negative and V4 is -1 or 0, the pull-in state is set to S.
= 0 is set as an initialization state in other cases, and a signal of S = 1 is output and supplied to the SW circuit 54. The V signal is supplied to the coefficient unit 52, the magnitude is multiplied by k (for example, 倍), and supplied to the adder 53. A separate determination circuit is required. However, when the amplitude of the color subcarrier is small and when it is desired to converge to the 180 ° phase quickly, the value of k is increased.

The adder 53 adds the output of the coefficient unit 52 and the output of the register 55 and supplies the result to the SW circuit 54. S
When the control signal S is in the pull-in state S = 0, the W circuit 54 selects and outputs the signal from the adder 53 and supplies it to the register 55. When the control signal is the initialization S = 1,
The value of the phase θ supplied from the conversion table 51 is selected and output, and supplied to the register 55. Therefore, the control signal S
Is S = 1, the initialization state is set and the register 55
, The phase θ determined from U4 and V4 is set and output. When the control signal S is S = 0, a value obtained by multiplying the value of the V signal by k as a pull-in state is integrated by an integrator including the adder 53 and the register 55. Integral is 1
Perform with 0-bit precision. The value of the 10-bit phase is 36
It is shown normalized to 0 °.

The register 55 operates according to a control signal from the control circuit 8 during a color burst period, holds a signal from the SW circuit 54 as a sampling clock, and outputs it. The output of the register 55 is output as a phase signal. If the signal U is negative and the signal V is positive, the phase of the color burst is between 90 ° and 180 °,
When the value (positive) of the signal V is integrated, the phase increases and the phase of the integrated value approaches 180 °. At 180 °, the phase of the color burst changes by 1 to the phase of the color subcarrier.
At 80 °, the value of the signal V becomes 0, the integrated value does not change, and the phase maintains the position of 180 °.

Since there are about 10 color burst cycles, first, U and V roughly determine the phase using the signal values of the upper 4 bits, and if the initial value is set,
From then on, the chrominance signal will be demodulated from the roughly correct burst phase. Then, the values of the signals U and V are values determined to be in the retracted state. When the control signal S outputs the retracted state, the process of the retracted state is performed from the next time. That is, the correction is performed in the integration process, and the value obtained by multiplying the value of the signal V by the coefficient unit 52 by k is stored in the register 5.
The value is added to the value of 5, and is sequentially corrected. By the end of the color burst section, the phase has converged to the correct phase. With the control signal from the control circuit 8, the integration processing stops at the end of the burst section, and the obtained phase value is held until the next line. Is done.

When the correlation is high, since the phase hardly changes for each line, the value of k is set sufficiently smaller than 1. In a video signal such as a VTR, when the phase of a color burst greatly changes for each line, the value of k is set to a value similar to 1. If the value of k is adaptively switched based on the inter-line correlation or phase correlation of the color burst signal, more accurate color signal demodulation is possible. Whether or not the signal of the color burst has a strong correlation between the lines can be determined by whether or not the value of the phase detected by the phase detector 10 greatly changes for each line. Using this determination result, the switching of the adaptive Y / C separation circuit 3 can be controlled.

In the configuration shown in FIG. 5, the cycle of the color burst is 10 cycles, but the phase detector 10 forms a loop, and there is a delay due to the LPF, the response due to the correction is delayed, and in the state of the pull-in process. When the length of the color burst is short, the pull-in time is insufficient, and when the amplitude is small, the correction value is small and the correction cannot be performed within the time. Therefore, the amplitude of the color burst (for example, the signal U
Is detected). When the amplitude is small, the value of the signal V also decreases. Therefore, if the switching control is performed so as to increase the value of the coefficient k so as to increase the correction amount, the pull-in can be performed quickly, and the color burst can be reduced. The correct phase can be detected sooner near the center but not near the rear end.

The configuration and operation of the preferred embodiment of the color signal demodulation circuit according to the present invention have been described above in detail. However, it should be noted that such an embodiment is merely an example of the present invention and does not limit the present invention in any way. It will be readily apparent to those skilled in the art that various modifications can be made in accordance with the particular application without departing from the spirit of the invention.

[0035]

As will be understood from the above description, the color signal demodulation circuit according to the present invention has the following remarkable practical effects. First, by providing a correction circuit, V
Even a video signal such as a TR can accurately demodulate a color signal.
The carrier chrominance signal (C) separated and demodulated with high accuracy can be coded and transmitted efficiently even when coded and transmitted. The circuit configuration can be simplified by switching between the line-delayed carrier chrominance signal (C) and the non-delayed color burst signal and demodulating the chrominance signal. By obtaining the initial value of the phase roughly and then correcting it sequentially by integration, the size of the conversion table can be reduced as compared with the case where the phase is obtained directly by the conversion table.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a preferred embodiment of a color signal demodulation device according to the present invention.

FIG. 2 is a diagram illustrating multiplexing and correction of a carrier chrominance signal and a burst signal.

FIG. 3 is a block diagram showing a detailed configuration of a color signal demodulator shown in FIG.

FIG. 4 is a block diagram showing a detailed configuration of an adaptive Y / C separation circuit shown in FIG. 1;

FIG. 5 is a block diagram showing a detailed configuration of a phase detector shown in FIG.

FIG. 6 is a block diagram showing a configuration of a conventional phase synchronization device.

FIG. 7 is a block diagram showing a configuration of a conventional phase-locked clock generator.

[Explanation of symbols]

 Reference Signs List 1 A / D converter 2 Line delay circuit 3 Adaptive Y / C separation circuit 4 PLL circuit 5, 44, 54 SW circuit 6 Color signal demodulator 7 Synchronization separation circuit 8 Control circuit 9 Phase angle generator 10 Phase detector 11 Correction Circuits 30, 32 Multipliers 31, 33 LPF 34 Cos conversion table 35 Sin conversion table 40, 42, 48 Coefficient unit 41, 47 Line memory 43, 53 Adder 49 Adaptive control circuit 45 BPF (bandpass filter) 46 Subtractor 51 Conversion table 52 Coefficient unit 55 Register

Continued on the front page F term (reference) 5C055 AA01 BA01 DA01 EA01 EA04 EA08 GA00 GA16 HA08 HA12 HA31 HA35 5C066 AA03 AA06 BA02 CA03 CA05 DB07 DC01 EB08 EB11 EF15 GA02 GA03 GA04 GA05 GA15 GA16 GA20 GA27 HA01 HA03 KA13 JA03 KB KB05 KC04 KC06 KC11 KD03 KD06 KE03 KE05 KE09 KE18 KE24 KF03 KG01 KP02 KP03

Claims (5)

[Claims] 1. A line delay circuit for line-delaying a video signal sampled by a sampling clock having an integral multiple of a horizontal synchronization frequency, and a luminance signal (Y) from the line-delayed signal.
And a Y / C separation circuit for separating the carrier color signal (C), a color burst signal of a digital video signal without line delay and a switch circuit for switching and selecting the line-delayed carrier color signal, and a switch circuit selected by the switch circuit. A color signal demodulation circuit for demodulating a color signal using a phase angle of a color subcarrier, a phase detector for detecting a phase of a color burst from two demodulated color difference signals (U, V), a previous line and a current line A correction circuit for correcting a shift of the color subcarrier phase for each sample of the current line from the color burst phase, and a phase angle generator for obtaining a subcarrier phase angle from the phase corrected by the correction circuit. Color signal demodulation device. 2. The Y / C separation circuit has a separation filter characteristic using a comb filter and a band-pass filter characteristic, and adaptively determines using a correlation between lines of a color burst signal. 2. The color signal according to claim 1, wherein the Y / C separation is performed by the comb filter when the correlation is strong, and the Y / C separation is performed by the bandpass filter when the correlation is weak in a video signal such as a VTR. Demodulator. 3. The color signal demodulator according to claim 1, wherein the line delay circuit and the comb filter delay circuit are shared. 4. A means for determining a phase roughly from the two color difference signals as the phase detector and determining whether the phase is an initialization state or a pull-in state. In the initialization state, the coarse phase value is converted to an integral initial value. 2. The color signal demodulation device according to claim 1, further comprising: a setting unit; and an integrating unit configured to integrate a value obtained by multiplying the V signal by a predetermined coefficient in the pulled-in state. 5. When the color burst phase changes greatly in a video signal such as a VTR, the coefficient value is increased, and the color burst phase of a broadcast signal or the like is stabilized when the color burst phase is determined by the correlation between the lines of the color burst. 5. The color signal demodulation device according to claim 4, wherein the coefficient value is reduced when the color signal demodulation is performed.