JP2001352561A - Video signal processor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the situations that a malfunction is generated in a burst detector by the ASB of color stripe signals, accurate color difference signals can not be obtained and reproducing image quality is degraded at the time of performing conversion to the color difference signals in a decoder. SOLUTION: At a timing including at least a part of the first burst signal of modulation chroma signals including mixed burst signals composed of the first burst signal provided with a first phase component and a second burst signal provided with a second phase component which is the phase discontinuous to the first phase component, a timing pulse generation circuit 8 performs the oscillation phase control of the decoder 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal which carries out good decoding of a modulated chroma signal on which an inverted burst signal such as copyright protection information is superimposed, and which also has a circuit for detecting the copyright protection information. The present invention relates to a processing device.

[0002]

2. Description of the Related Art Currently, digital signal processing of video signals is performed in order to record and reproduce video signals with high image quality. Japanese Patent Application Laid-Open No. H11-308631 introduces, as an example of processing a chroma signal, a decoder that applies a digital PLL to a digitally modulated chroma signal and converts it into a baseband color difference signal. Description will be made with reference to FIG. 6 in a form close to this case. The modulated chroma signal supplied to the input terminal 31 is passed through the band-pass filter 46 to the multiplier 3.
4, 40. By supplying the sine and cosine waves from the carrier generators 39 and 44 as one input of each of the multipliers 34 and 40, the chrominance signals are decoded from the multipliers 34 and 40 and the high-frequency signals generated by the multiplication are further decoded. The color difference signals Cr / Cb can be extracted by removing the band components by the low-pass filters 35 and 41. Further, the signals from the low-pass filters 35 and 41 are used as a burst phase detection circuit 3.
7, 42. The timing of the phase control is performed by a burst period pulse generated from the sync separation circuit. The frequency of the sine wave and cosine wave oscillated from the carrier generation circuits 39 and 44 is feedback-controlled by the burst phase.

[0003] In accordance with these techniques, various copyright protection signals for protecting copyright are inserted into digital broadcast terminals and digital video discs (DVDs).

As an example superimposed on a modulated chroma signal,
There is a color stripe method from Macrovision. NT
Taking the SC method as an example, as shown in FIG. 7, two cycles are added to the color burst signal (A) having nine cycles of the chrominance subcarrier: fsc (3.58 Mhz), and the phase of the preceding 5.5 cycles is added. Turn it over. This inverted phase is referred to as ASB (Adv
anced Split Burst). This A
As shown in FIG. 8, ten or more SB insertion periods are arranged continuously for two or four lines in one field every 17 or 21 lines. The ASB causes color reversal, degrades the image quality to a level that cannot withstand actual operation, and uses it as a copyright protection signal.

[0005]

As described above, the modulated chroma signal includes only a normal burst signal and a burst signal in which an ASB is inserted in the normal burst. Normal VT
The time constant of the R APC (AutoPhase Control) circuit is configured to be able to follow each line.
On the other hand, a television receiver (abbreviated to TV) is controlled by a large time constant that does not follow several lines, so that the difference causes the VTR to be recorded as a signal whose hue is disturbed. Has no effect.

Here, as a method for improving the image quality of the modulated chroma signal, for example, there is a method of converting the modulated chroma signal into a color difference signal and performing digital processing such as time axis correction and edge emphasis. The high-quality color difference signal is output as it is, or is encoded and output as a modulated chroma signal.
Is input to Therefore, it is essential that the high image quality processing unit performs processing using the correctly decoded color difference signal, and that the output burst signal has the same characteristics as the input.

However, when the phase is detected during the entire burst period during the conversion into the color difference signal, the burst detector malfunctions due to the ASB of the color stripe signal. As a result, an accurate color difference signal cannot be obtained, and when a signal output from the high image quality processing unit is output to a TV or the like, the image quality deteriorates to a level that cannot be used in actual operation.

When encoding a color difference signal of high image quality into a modulated chroma signal again, the input signal on which the color stripe signal is superimposed is returned to a normal burst signal in order to replace the burst signal. As a result, copyright protection is not applied to the output to the VTR. Therefore, it is necessary to detect the presence or absence of the superposition of the color stripe signal, and to add the same type of color stripe signal as the input signal to the modulated chroma signal of high image quality.

An object of the present invention is to provide a video signal processing apparatus having a color stripe signal detecting circuit, which can solve the above problem and realize a decoder which does not depend on the color stripe signal to obtain a reproduced signal with high image quality. To provide.

[0010]

The above object is achieved by, as a first means, a first burst signal having a first phase component;
A decoder for converting a modulated chroma signal including a hybrid burst signal including a second burst signal having a second phase component having a discontinuous phase with the first phase component into a color difference signal; And a synchronization separation circuit for extracting information, wherein the decoder further comprises an oscillator for oscillating the decoder at a first timing including at least a part of the first burst signal generated from the synchronization signal information. This is achieved by a video signal processing device characterized by including an oscillation phase control means for performing phase control as a component.

As a second means, the decoder includes first and second multipliers, first and second low-pass filters, first and second oscillation phase control means,
Two systems are arranged in the order of first and second local oscillators, and the modulated chroma signal is supplied to one of the first and second multipliers, and the other of the first and second local oscillators is provided to the first and second local oscillators. An output is supplied, and the oscillation phase control is performed at the first timing, thereby achieving the video signal processing apparatus according to the first means.

As a third means, the first and second phase components of the hybrid burst signal include copyright protection information, and further include a first color difference phase component of the color difference signal at the first timing. And a copyright information detection circuit for detecting copyright protection information from a second color difference phase component at a second timing different from the first timing. Is achieved by the video signal processing device.

As a fourth means, an automatic chroma level control circuit for controlling a burst signal level of a modulated chroma signal to be substantially constant is disposed at a preceding stage of the decoder. This is achieved by a video signal processing device according to the means.

As a fifth means, the oscillation phase control means further comprises a burst detection circuit for detecting a phase of a burst signal, and a low-pass filter capable of switching frequency characteristics at a subsequent stage. This is achieved by the video signal processing device according to the first means and the second means.

As a sixth means, the frequency characteristic of the low-pass filter according to the fifth means is changed between a first period including the hybrid burst signal and a second period not including the hybrid burst signal. This is achieved by a video signal processing device provided with switching control means for performing switching control.

As a seventh means, the frequency characteristic of the low-pass filter according to the fifth means is determined by changing the frequency characteristic of the low-pass filter to a third period not including the vertical synchronization signal generated from the synchronization separation circuit, In the fourth period including the above, the switching is controlled by the video signal processing apparatus.

As an eighth means, the frequency characteristic of the low-pass filter according to the fifth means is controlled by switching the time constant to be large during the first period and to be small during the second period. This is achieved by a video signal processing device characterized in that:

As a ninth means, the frequency characteristic of the low-pass filter according to the fifth means is controlled by switching the time constant to be large during the third period and to be small during the fourth period. This is achieved by a video signal processing device characterized in that:

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIG. FIG. 1 is a block diagram showing an embodiment of a video signal processing apparatus according to the present invention, which is configured to decode a modulated chroma signal included in a composite video signal into a color difference signal to improve image quality. First, a composite video signal is input to the input terminal 1. The composite video signal is converted into, for example, 10-bit digital data by an analog-to-digital converter 2 (hereinafter abbreviated as ADC). The digitized composite video signal is separated by a three-dimensional processing circuit 3 into a digital luminance signal and a digitally modulated chroma signal, and after the noise is removed, the luminance signal is supplied to a clamp circuit 4 to generate a timing pulse, which will be described later. After feedback control is performed so that the pedestal and sync tip levels become substantially constant at the timing generated from the circuit 8, the luminance signal processing circuit 5 performs necessary signal processing such as time axis correction and image quality correction. And output from the output terminal 6.

The output of the clamp circuit 4 is supplied to a sync separation circuit 8
It also generates timing pulses such as a horizontal synchronizing pulse (hereinafter abbreviated as hd), a vertical synchronizing pulse (hereinafter abbreviated as vd), and a field information signal (hereinafter abbreviated as odd).

An output signal from the synchronization separation circuit 7 is supplied to a timing pulse generation circuit 8 and supplied as one of control signals for the clamp circuit 4 and a decoder 10 described later.

The digitally modulated chroma signal has an ACC (Automatic Chroma- le) for controlling the level.
After the level fluctuation of the burst signal is suppressed by the vel control circuit 9, the ry signal (hereinafter abbreviated as Cr signal) and the by signal (Cb) of the color difference signal are converted by the decoder 10 for converting to a baseband. (Abbreviated as signal). The color difference signal is output from output terminals 12 and 13 after the response characteristic of the edge component is improved in the color signal processing circuit 11 or the time axis is corrected. As another output of the ACC circuit 9, a modulated chroma signal whose burst signal level is adjusted is output from the output terminal 14. With this configuration, a modulated chroma signal and a high-quality color difference signal can be obtained as outputs.

FIG. 2 is a block diagram showing the configuration of the decoder 10 shown in FIG. 1. Components having the same function are denoted by the same reference numerals and their description is omitted.

A modulated chroma signal from the ACC circuit 9 is input to an input terminal 31 and supplied to multipliers 34 and 40. The carrier generators 39 and 44 are supplied as one inputs of the multipliers 34 and 40, respectively, and the color difference signals are output from the multipliers 34 and 40, and the low-pass filters 35 and 41 are provided.
The high-frequency component can be removed to extract the color difference signal Cr / Cb. Up to this point, the same processing as in the known example is performed.

The signals from the low-pass filters 35 and 41 are supplied to burst phase detection circuits 37 and 42. The timing of the phase control is performed by a pulse generated from the timing pulse generation circuit 8 of the input terminal 33. FIG. 3 is a characteristic diagram showing one embodiment of a pulse inputted to the input terminal 33, and shows the features of the present invention. From the hd signal input to the timing pulse generation circuit 8, the input terminal 31
A pulse bgp (t1 to t6) having a timing covering the burst of the digitally modulated chroma signal input to the controller is generated. The bgp width is, for example, 64 clocks (4.48 μsec) as a system clock (4 fsc sampling) of about 70 nsec. In the figure, (C) is a trigger pulse for capturing a color difference signal within bgp, and its minimum variable width tg1-tg1 'is about 280 nsec (4
Clock) can be set in increments. (E) in the figure shows the Cb component when the color stripe signal is superimposed. As can be seen, the period from t2 to t4 corresponds to the superposition period of the inverted burst signal, and the Cb component fluctuates to a positive level. Therefore, by setting the trigger pulse tg1 between t4 and t5 when the color stripe signal is not superimposed, it is possible to always perform stable phase detection. This tg1 corresponds to the pulse of the input terminal 33. As another example, a line counter that clears the hd signal and increments by the system clock may be configured to directly generate a trigger pulse in the section from t4 to t5.

The output of detecting the burst phase component is supplied to second low-pass filters 38 and 43. Carrier generators 39 and 44 by low-pass filters 38 and 43
The oscillating frequency of the sine wave and cosine wave generated from is adjusted. Here, switching the frequency characteristics of the low-pass filters 39 and 44 and performing feedback control is a second embodiment of the present invention. Normally, the time constant of the APC circuit of the VTR is configured to be able to follow each line, whereas the television receiver is controlled by a large time constant that does not follow several lines. Came. Therefore, paying attention to the fact that the period in which the color stripe signal is superimposed is determined according to the specifications of Macrovision, and the timing pulse generator 8 uses a (1 to 23) as shown in FIG. Line) or a region where the color stripe signal of c (lines 238 to 262) is not superimposed, b
A switching pulse indicating a superimposed line area shown in (24 to 237 lines) is generated. And a low-pass filter 38,
The time constant of 43 is set small when the switching pulse “0” indicates the period without superimposition, and is large when the switching pulse “1” indicates the period with superposition. This feedback control switching slows down the response during the color stripe signal superimposition period, thereby reducing the effect.
As a specific switching value of the time constant, the cutoff frequency is changed by several tens of Hz.

Next, an embodiment in which the trigger pulse is used for detecting a color stripe signal will be described with reference to FIG. Those indicating the same functions are denoted by the same symbols, and the description is omitted.

Based on the color difference signal from the decoder 10 and the signal supplied from the timing pulse generator 8, the color stripe detection circuit 20 detects the signal and outputs it from the output terminal 21. Next, the detection principle will be described. As described above, in the range from t2 to t4 in FIG. 3, the polarity of Cb differs as shown in (D) and (E) depending on whether or not the color stripe signal is superimposed. Therefore, the trigger pulse tg2 similar to tg1 is output from the timing pulse generator 8.
Is provided in the region from t2 to t4. By calculating the output of the decoder 10 in an offset binary format, the most significant bit indicating the polarity of the color difference signal is taken in for each line. As a judgment, Cb with a color stripe is tg1: Cb
= 0, tg2: Cb = 1, and Cb at no time is tg
1: Cb = 0, tg2: Cb = 0, and detection becomes possible. By calculating the continuity of the detection result, the type of the inserted color stripe can be determined.

The output is, for example, "00" for no color stripe signal superimposition, "01" for a two-line continuous color stripe signal, "10" for a four-line continuous color stripe signal, and "11" for a four-line continuous color stripe signal. Even if the data is compressed to 2-bit data, a counter may be provided as another output, and the number of color stripe signals inserted and the insertion interval itself may be used.

The determination result is transmitted to, for example, a microcomputer (not shown) or the like, and when the color signal processor 11 changes the burst signal, the original color stripe signal is added after the encoder processing (not shown). . This makes it possible to obtain a modulated chroma signal on which the same color stripe signal as that at the time of input is superimposed.

Although the description has been made on the assumption that the number of trigger pulses for taking in the decoder 10 is two, more than two trigger pulses may be used.

As described above, in this embodiment, the digital signal processing is L
It has been described as an example in the state of SI,
The present invention is not limited to one using an LSI.

[0033]

As described above, according to the present invention,
In a video signal processing for decoding a color difference signal from a modulated chroma signal, a video signal processing device that realizes a decoder that does not depend on a color stripe signal and can obtain good reproduction image quality is provided. Furthermore, a video signal processing device provided with the decoder and a color stripe signal detection circuit is provided.

[Brief description of the drawings]

FIG. 1 is a block diagram of a video signal processing apparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram of a decoder according to one embodiment of the present invention.

FIG. 3 is a characteristic diagram of an NTSC type burst signal according to one embodiment of the present invention.

FIG. 4 is a characteristic diagram showing field information according to an embodiment of the present invention.

FIG. 5 is a block diagram of a video signal processing apparatus according to an embodiment of the present invention.

FIG. 6 is a block diagram showing a conventional decoder.

FIG. 7 is a characteristic diagram showing characteristics of an NTSC color stripe signal.

FIG. 8 is a characteristic diagram showing an insertion period of an NTSC color stripe signal.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Input terminal, 2 ... ADC, 3 ... Three-dimensional processing circuit, 4 ...
Clamp circuit, 5 ... luminance signal processing circuit, 6, 12, 1
3, 14 output terminals, 7 synchronization separation circuit, 8 timing pulse generation circuit, 9 automatic chroma level control circuit, 1
0: decoder, 11: color signal processing circuit, 15: video signal processing device

Continued on the front page (72) Inventor Eiji Moro 1410 Inada, Hitachinaka City, Ibaraki Prefecture Inside Digital Media Products Division, Hitachi, Ltd. Product Division (72) Inventor Hiroyuki Hori 1410 Inada, Hitachinaka City, Ibaraki Pref. Digital Media Product Division, Hitachi, Ltd. F-term (reference) 5C055 AA03 CA15 DA01 EA01 EA02 EA03 EA04 EA08 GA39 HA09 HA12 HA15 HA31 HA35 5C066 AA03 AA06 CA11 CA15 DB06 EG01 GA16 GB12 HA03 JA06 KA06 KA09 KB05 KC02 KD03 KE19 KE20

Claims (9)

[Claims] 1. A hybrid burst signal comprising a first burst signal having a first phase component and a second burst signal having a second phase component having a discontinuous phase with the first phase component. In a video signal processing device having a decoder for converting a modulated chroma signal into a color difference signal including: and a sync separation circuit for extracting sync signal information from a luminance signal, the video signal processor includes a decoder for converting the first burst signal generated from the sync signal information. A video signal processing device, comprising: oscillation phase control means for controlling the oscillation phase of the decoder at a first timing including at least a part. 2. The decoder according to claim 1, wherein said decoder includes first and second multipliers, first and second low-pass filters, and first and second multipliers.
The oscillation phase control means and first and second local oscillators are sequentially arranged in two systems, and the modulated chroma signal is supplied to one of the first and second multipliers and the first is supplied to the other. And the output of a second local oscillator is provided,
2. The video signal processing device according to claim 1, wherein the oscillation phase control is performed at the timing of: 3. The first and second phase components of the hybrid burst signal include copyright protection information, and further include the first and second phase components.
A copyright information detection circuit that detects copyright protection information from a first color difference phase component of the color difference signal at the timing of (i) and a second color difference phase component at a second timing different from the first timing. The video signal processing apparatus according to claim 1, wherein 4. A video signal processing apparatus according to claim 1, further comprising an automatic chroma level control circuit for controlling a burst signal level of the modulated chroma signal to be substantially constant before said decoder. apparatus. 5. The oscillation phase control means according to claim 1, further comprising a burst detection circuit for detecting a phase of the burst signal, and a low-pass filter in a subsequent stage capable of switching frequency characteristics. Alternatively, the video signal processing device according to claim 2. 6. A switching control means for switching a frequency characteristic of the low-pass filter between a first period including the hybrid burst signal and a second period not including the hybrid burst signal. 6. The video signal processing device according to claim 5, wherein: 7. The frequency characteristic of the low-pass filter is switched between a third period not including the vertical synchronization signal generated from the synchronization separation circuit and a fourth period including the vertical synchronization signal. 6. The video signal processing device according to claim 5, wherein the video signal processing device performs control. 8. The frequency characteristic of the low-pass filter is controlled by switching a time constant to be large in the first period and to a small time constant in the second period.
The video signal processing device according to claim 1. 9. The frequency characteristic of the low-pass filter is controlled by switching a time constant to be large in the third period and to a small time constant in the fourth period.
The video signal processing device according to claim 1.