JP2006311481A - Field synchronization device and field synchronization method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect correct color field information without transmitting or storing special color field information or the like, when a composite video signal is converted into a component signal and thereafter the component signal is combined back into a composite video signal. <P>SOLUTION: The device comprises a bandpass filter 1 for extracting a subcarrier-band signal from a Y signal of the component signals, a B-Y signal demodulator 2 for demodulating the extracted signal into a plurality of color difference signals using a plurality of subcarriers, a subtractor 5 for obtaining a plurality of difference values between each B-Y signal of a plurality of the B-Y signals and the B-Y signal of the component signals, and a comparator 6 for comparing the plurality of difference values with one another and outputting, as the color field information, the phase information of a subcarrier having a smaller absolute difference value. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a process for converting a component signal into a composite video signal and a field synchronization apparatus and method used in the apparatus.

  MPEG2 (Moving Picture Experts Group Phase 2), which is adopted as an encoding method for terrestrial digital broadcasting and DVD (Digital Versatile Disk) video, is a composite signal such as NTSC (National Television System Committee) composite signal. (Composite signal)) is encoded and transmitted, the input signal is separated into a luminance signal and a color signal (Y / C separation) as a pre-encoding process, and the color signal is a color subcarrier (subcarrier). Since it has been modulated, it is necessary to further demodulate the color and to encode the two color difference signals of the RY signal and the BY signal. On the decoding device side, the decoded video signal is modulated with a subcarrier for the color signal, and the modulated color signal is multiplexed with the luminance signal and output as a composite video signal.

An NTSC composite video signal has a field frequency of fV, a horizontal synchronization frequency of fH, and a subcarrier (SC) frequency of fSC.
fSC = 455 × fH / 2 (Formula 1)
fH = 525 × fV / 2 (Formula 2)
It is decided. From the relationship between the subcarrier frequency fSC: 3.58 [MHz] and the horizontal synchronization frequency fH: 15.734 [kHz] in Equation 1, each horizontal scanning line from the first field to the fourth field is horizontal in each field in FIG. When the relationship is as shown in the scanning lines [61] to [64], the phase of the subcarrier waveform is shifted (inverted) by exactly 180 degrees for each horizontal scanning line (line) ( (See waveforms [71] to [74] of each line in each field in FIG. 9). Further, from Equation 2, the phase of the subcarrier waveform of each line is inverted in two fields (one frame) (the waveforms [71] and [73] of each line of the odd field in FIG. (See waveforms [72] and [74]), the same phase is obtained in 4 fields (2 frames). This relationship is called a four-field sequence (here, one frame is composed of two fields).

Y / C separation performed when a composite video signal is converted into a component signal (Component signal) is generally performed by forming a two-dimensional or three-dimensional filter using the phase relationship of the subcarriers. . After decoding on the MPEG2 reception side, the NTSC composite video signal is reproduced by adding the color signal modulation signal and the luminance signal (Y signal) from the component signal.
Japanese Patent Publication No. 10-000979

  In the process of once converting the NTSC composite video signal into a component signal after performing Y / C separation, the performance of Y / C separation is greatly affected by the image quality. However, it is difficult to completely Y / C separate the NTSC composite video signal. Depending on the signal, leakage of the Y signal to the C signal and leakage of the C signal to the Y signal occur. If the decoding apparatus side can reproduce a four-field sequence that matches the encoding apparatus side, these leaked signals are almost restored to their original state, and image quality is hardly deteriorated. However, if the 4-field sequence does not match the encoding device side and cannot be reproduced, these leakage signals become interference signals, leading to a large deterioration in image quality. Since television signals and the like are operated by switching a plurality of signal sources (programs), the continuity of the field sequence is often not maintained. Therefore, when the field sequence on the decoding apparatus side is not controlled in accordance with the field sequence on the encoding apparatus side, there arises a problem that the image quality changes depending on the program.

  In the prior art, the odd field (first field, third field) and the even field (second field, fourth field) can be easily determined. The first and third fields, and the second and fourth fields of the input NTSC composite video signal are not determined. Further, in the MPEG2 standard, it is possible to transmit a four-field sequence with a field sequence in a picture encoding extension, but these syntaxes (four-field sequence related to subcarrier phase) are fully supported. There are very few encoding / decoding LSIs, and even if they are supported, they must be supported on both the encoding side and the decoding side, and cannot be realized only on the decoding side. was there.

  Furthermore, as shown in FIG. 10, a technique for transmitting a color frame signal and thereby controlling the phase of the color subcarrier has been proposed. In this way, deterioration of image quality can be prevented, but special information needs to be transmitted. In any case, since it is necessary to perform the same process on the encoding side and the decoding side, the problem cannot be solved only on the decoding side.

  In order to solve the above problems, a field synchronization apparatus according to the present invention includes a first signal having a frequency band of a color subcarrier of a composite video signal from a signal of a luminance signal in a component signal separated from the composite video signal. An extraction unit that extracts a signal, and a detection unit that detects color field information related to phase information of subcarriers in a component signal from first phase information included in the first signal. Furthermore, in the field synchronization apparatus according to the present invention, the detection unit uses a plurality of subcarriers to demodulate the first signal, the first demodulation unit that demodulates the plurality of color difference signals, and each color difference signal in the plurality of color difference signals. The first subtraction unit that obtains a plurality of difference values between the first color difference signal that is the color difference signal in the component signal and the difference value in the plurality of difference values is compared, and the absolute value of the difference value is smaller And a first comparison unit that outputs the phase information of the subcarriers as color field information.

  Also, the field synchronization method according to the present invention extracts a first signal having a frequency band of a color subcarrier of a composite video signal from a signal in a signal band of a luminance signal in a component signal separated from the composite video signal. And a second step of detecting color field information related to the phase information in the component signal from the first phase information of the subcarriers included in the first signal. Further, in the field synchronization method according to the present invention, the second step includes a fourth step of demodulating a plurality of color difference signals using the first signal and a plurality of subcarriers, and each color difference in the plurality of color difference signals. The fifth step of obtaining a plurality of difference values between the signal and the first color difference signal that is the color difference signal of the component is compared with each difference value in the plurality of difference values, and the absolute value of the difference value is smaller. And a sixth step of outputting the subcarrier phase information as color field information.

  Furthermore, the field synchronization method according to the present invention is a process for separating a composite video signal into a luminance signal and a color signal, remodulating and synthesizing a component signal obtained by color demodulation, and returning it to a composite video signal. In this field synchronization method, color field information is detected from information included in an effective video signal of a component signal without referring to the color field information of the original composite video signal.

  In the present invention, when the composite video signal is converted into the component signal and then synthesized again, the correct color field information can be detected without transmitting and recording special color field information or the like. The color signal remaining in the luminance signal or the luminance signal leaking into the color signal can be modulated and synthesized with the correct phase, thereby preventing characteristic deterioration associated with Y / C separation and color decoder. it can.

(A) First Embodiment Next, an embodiment of a field synchronization apparatus and method according to the present invention will be described in detail with reference to the accompanying drawings. The present invention determines the color field information of the video signal input to the encoding device side using the luminance signal and the color signal of the component signal decoded on the decoding device side, and synchronizes with the input signal. The generated color field information is generated.

(A-1) Configuration of First Embodiment The configuration of the first embodiment is shown in FIG. The input signal is processed with the component signal of the Y signal as the luminance signal, the BY signal as the chrominance signal, and the RY signal as in the MPEG decoding apparatus, and then the composite video signal (composite signal) by the NTSC encoder. This is an example implemented in a device for outputting, and is an example in which color field information of an input signal can correspond to a signal compliant with the RS-170A standard.

  A band pass filter (BPF: Band Pass Filter) [1] is a 3.58 [MHz] band pass filter that is a frequency band of a color subcarrier, and a Y signal is input to the band pass filter (3.58 [MHz] band). Output a signal.

  The BY signal demodulator [2] includes a first BY signal demodulator [2-1] and a second BY signal demodulator [2-2]. The first BY signal demodulator [2-1] receives the 3.58 [MHz] band signal output from the bandpass filter [1] and demodulates the first BY signal. Output. The first BY signal demodulator [2-1] has a first color subcarrier (first subcarrier (1) having first phase information output from a subcarrier generator [3] described later. + SC)), the first BY signal is demodulated and output. The second BY signal demodulator [2-2] has a configuration equivalent to that of the first BY signal demodulator [2-1]. The second BY signal demodulator [2-2] receives the 3.58 [MHz] band signal output from the bandpass filter [1] and demodulates the second BY signal. Output. The second BY signal demodulator [2-2] outputs a second color subcarrier (second subcarrier (2) having second phase information output from a subcarrier generator [3] described later. -SC)), the second BY signal (second BY signal) is demodulated and output.

  The delay unit [4] receives the third BY signal and outputs a fourth BY signal obtained by delaying the third BY signal by a predetermined time. Here, the predetermined time is the time required to match the phase information of the fourth BY signal and the phase information of the first BY signal (phase information of the second BY signal). It is.

  The subtraction unit [5] includes a first subtraction unit [5-1] and a second subtraction unit [5-2]. The first subtraction unit [5-1] outputs the first BY signal output from the first BY signal demodulation unit [2-1] and the fourth output from the delay unit [4]. The BY signal is input, and a first difference value between the first BY signal and the fourth BY signal is calculated and output. The second subtraction unit [5-2] has a configuration equivalent to that of the first subtraction unit [5-1]. The second subtraction unit [5-2] outputs the second BY signal output from the second BY signal demodulation unit [2-2] and the fourth output from the delay unit [4]. The second BY signal is input, and the second difference value between the second BY signal and the fourth BY signal is calculated and output.

  The comparison unit [6] includes a first comparison unit [6-1]. The first comparison unit [6-1] receives the first BY signal output from the first BY signal demodulation unit [2-1] and the first subtraction unit [5-1]. The output first difference value and the second difference value output from the second subtraction unit [5-2] are input and output as a comparison result. Here, the comparison result is that the first difference value is compared with the second difference value in a region where the BY signal component (BY signal component) extracted from the first BY signal exists. Then, the smaller absolute value of the difference value is detected, and the detection result is used as the comparison result.

  The timing signal / subcarrier generation unit [7] inputs horizontal synchronization and vertical synchronization timing signals and outputs them as signals for color subcarriers (subcarriers (SC)) synchronized with the timing signals. The timing signal / subcarrier generation unit [7] receives the synchronization signal, and generates and outputs a composite synchronization signal used for the NTSC composite video signal (hereinafter referred to as composite video signal). Here, the composite sync signal is a sync signal (: horizontal sync signal, vertical sync signal, color burst signal, equivalent pulse) related to a signal compliant with RS-170A in the composite video signal is output in accordance with the regulations of RS-170A. To do.

  The subcarrier generation unit [3] includes a first subcarrier generation unit [3-1] and a second subcarrier generation unit [3-2]. The first subcarrier generation unit [3-1] receives the subcarrier signal output from the timing signal / subcarrier generation unit [7] and receives the first subcarrier having the first phase information. (+ SC) is output to the first BY signal demodulator [2-1]. The first phase information includes phase information in which the phase of the first subcarrier is the same as the phase information of the subcarrier waveform (FIG. 9: [75]) of the first field and the first line. is there. The second subcarrier generation unit [3-2] receives the subcarrier signal output from the timing signal / subcarrier generation unit [7] and receives the second subcarrier having the second phase information. (-SC) is output to the second BY signal demodulator [2-2]. The second phase information includes phase information in which the phase of the second subcarrier is the same as the phase information of the waveform of the subcarrier in the third field, the first line (FIG. 7: [76]). There is a timing at which the phase of the second subcarrier (−SC) differs from the phase of the first subcarrier (+ SC) by 180 degrees.

  The selection unit [8] includes a first selection unit [8-1]. The first selection unit [8-1] includes the first subcarrier (+ SC) output from the first subcarrier generation unit [3-1] and the second subcarrier generation unit [3-2]. The output second subcarrier (−SC) and the comparison result output from the comparison unit [6] are input, and based on the comparison result, the first subcarrier (+ SC) or the second subcarrier ( -SC) is selected and output as the third subcarrier.

  The phase shift unit [9] receives the third subcarrier output from the selection unit [8], and outputs a fourth subcarrier phase-shifted by +90 [degrees] from the third subcarrier.

  The color signal modulation unit [10] includes a third subcarrier output from the selection unit [8], a fourth subcarrier output from the phase shift unit [9], a third BY signal, and a first RY signal is input, and the signal obtained by modulating the third BY signal with the third subcarrier and the signal obtained by modulating the first RY signal with the fourth subcarrier are added. Then, it is encoded and output as a composite color signal.

  The adder [11] inputs the Y signal, the composite sync signal output from the timing signal / subcarrier generator [7], and the composite color signal output from the color signal modulator [10]. The synchronization signal and composite color signal are added and output as a composite video signal.

(A-2) Operation of the First Embodiment The operation of the first embodiment will be described with reference to FIGS.

[Step S1: Extraction Process (FIG. 2)]
The bandpass filter [1] extracts a signal in the subcarrier frequency band as a color subcarrier from the input Y signal as a luminance signal by a 3.58 [MHz] bandpass filter.

[Step S2: Demodulation Process (FIG. 2)]
Next, the first BY signal demodulator [2-1] receives the 3.58 [MHz] band signal output from the bandpass filter [1], and this 3.58 [MHz]. The B-Y signal is demodulated from the band signal based on the first subcarrier (+ SC), and the first B-Y signal is output [Step S2-1: First Demodulation Process (FIG. 2)]. .

  The second BY signal demodulator [2-2] receives the 3.58 [MHz] band signal output from the bandpass filter [1], and the 3.58 [MHz] band signal. To demodulate the BY signal based on the second subcarrier (−SC) that is 180 degrees different from the phase of the first subcarrier (+ SC), and output the second BY signal [step] S2-2: Second demodulation process (FIG. 2)].

[Step S3: Delay Processing (FIG. 2)]
The delay unit [4] converts the phase information of the third BY signal, which is the BY signal of the component signal, into the phase information of the first BY signal (phase information of the second BY signal). The delayed signal is output as a fourth BY signal.

[Step S4: Subtraction Processing (FIG. 2)]
The first subtraction unit [5-1] calculates and outputs a first difference value between the first BY signal and the fourth BY signal [Step S4-1: First Subtraction Processing] (FIG. 2)].

  The second subtracting unit [5-2] calculates and outputs the second difference value between the second BY signal and the fourth BY signal [Step S4-2: First subtraction processing]. (FIG. 2)].

  Here, if a color difference signal component remains in the Y signal, the first BY signal demodulating unit [2-1] and the second BY signal demodulating unit [2-2] receive the BY signal. Is taken out. If the subcarrier phase information regarding the extracted BY signal matches, the absolute value of the difference value is necessarily small, so that correct color field information can be obtained by selecting the subcarrier with the matching phase information. It becomes possible.

[Step S5: Comparison Process (FIG. 2)]
The first comparison unit [6-1] detects a region where the BY signal component is present from the first BY signal, and compares the first difference value and the second difference value in the region. The one with the smaller absolute value is detected. Thereby, correct color field information is determined. Also, if the input signal is a continuous signal, the color field information will not be discontinuous, so the majority is processed in the field, and the result is stabilized by performing majority processing in several fields. . The output of the first comparator [6-1] is either the subcarrier output of the first subcarrier generator [3-1] or the subcarrier output of the second subcarrier generator [3-2]. It is a signal for controlling whether to use [Step S5-1: First comparison processing (FIG. 2)].

[Step S6: Selection Process (FIG. 2)]
The first selection unit [8-1] selects a subcarrier having correct phase information and passes the subcarrier to the color signal modulation unit [10] [step S6-1: first selection process (FIG. 2)].

[Step S7: Modulation Process (FIG. 2)]
The color signal modulation unit [10] includes a third subcarrier output from the first selection unit [8-1], a fourth subcarrier output from the phase shift unit [9], and a third B- The Y signal and the first RY signal are input, encoded into a composite color signal, and output.

[Step S8: Addition Processing (FIG. 2)]
The adder [11] adds the Y signal, the composite sync signal output from the timing signal / subcarrier generator [7], and the composite color signal output from the color signal modulator [10] to obtain a composite video signal. Output.

(A-3) Effect of First Embodiment As described above, according to the first embodiment, after converting a composite video signal into a component signal, a special video signal is synthesized again. Since correct color field information can be detected without transmitting or recording color field information or the like, the color signal remaining in the Y signal or the Y signal leaking into the color signal can be detected with the correct phase. Modulation and synthesis can be performed, and characteristic deterioration due to Y / C separation and color decoder can be prevented.

(B) Second Embodiment Next, a field synchronization device and method according to a second embodiment will be described in detail with reference to the accompanying drawings.

(B-1) Configuration of Second Embodiment The configuration of the second embodiment is shown in FIG. In the second embodiment, color field information of a component signal serving as an input signal can be adapted to a signal that does not comply with the RS-170A standard.

  The band-pass filter (BPF) [1] is a 3.58 [MHz] band-pass filter that is a frequency band of the color subcarrier. Is output.

  The BY signal demodulator [2] includes a third BY signal demodulator [2-3]. The third BY signal demodulator [2-3] receives the 3.58 [MHz] band signal output from the bandpass filter [1] and outputs a plurality of fifth BY signals. Demodulate and output. The third BY signal demodulator [2-3] has a plurality of fifth BY signals based on a plurality of subcarriers having different phase information output from the subcarrier generator [3]. Is demodulated and output. Here, the subcarriers having different phase information are switched by the selection unit [8] for each field and output.

  The delay unit [4] receives the third BY signal and outputs a fourth BY signal obtained by delaying the third BY signal by a predetermined time. Here, in the second embodiment, the predetermined time is a time required to match the phase information of the fourth BY signal and the phase information of the fifth BY signal.

  The subtraction unit [5] includes a third subtraction unit [5-3]. The third subtractor [5-3] is output from each of the fifth BY signals output from the third BY signal demodulator [2-3] and the delay unit [4]. The fourth BY signal is input, and a difference value between each of the fifth BY signal and the fourth BY signal is calculated and output.

  The comparison unit [6] includes a second comparison unit [6-2]. The second comparison unit [6-2] uses the fifth BY signal (for example, the third subcarrier (SC1)) output from the third BY signal demodulation unit [2-3]. The demodulated fifth BY signal) and each difference value output from the third subtracting unit [5-3] are input and output as a comparison result. Here, the comparison result includes the BY signal component extracted from the fifth BY signal (for example, the fifth BY signal demodulated by the third subcarrier (SC1)). In the area, each difference value is compared, the one having the smaller absolute value of the difference value is detected, and the detection result is used as the comparison result.

  The timing signal / subcarrier generation unit [7] receives horizontal synchronization and vertical synchronization timing signals and outputs the signals as subcarrier (SC) signals synchronized with the timing signals. The timing signal / subcarrier generation unit [7] receives the synchronization signal, and generates and outputs a composite synchronization signal used for the NTSC composite video signal. Here, the composite sync signal is a sync signal (: horizontal sync signal, vertical sync signal, color burst signal, equivalent pulse) related to a signal compliant with RS-170A in the composite video signal is output in accordance with the regulations of RS-170A. To do.

  The subcarrier generation unit [3] uses 0 [degree], +45 [degree], +90 [degree], +135 [degree], based on the phase of the subcarrier generated by the timing signal / subcarrier generation section [7]. Eight types of +180 [degree], +225 [degree] (-135 [degree]), +270 [degree] (-90 [degree]), +315 [degree] (-[45 degree]) are prepared. The phase information between the subcarriers is shifted by 45 [degrees] obtained by equally dividing 360 [degrees] into eight.

  The subcarrier generation unit [3] includes a third subcarrier generation unit [3-3] to a tenth subcarrier generation unit [3-10]. The third subcarrier generation unit [3-3] receives the subcarrier signal output from the timing signal / subcarrier generation unit [7] and receives a reference third subcarrier (SC1) ( FIG. 4: [41]) occurs. Similarly, the fourth subcarrier generation unit [3-4] to the tenth subcarrier generation unit [3-10] receive the subcarrier signal and receive the third subcarrier (SC1), respectively. Fourth subcarrier (SC2) (FIG. 4: [42]) to tenth subcarrier (SC8) having respective phase information with reference to (FIG. 4: [41]) (FIG. 4: [48] ).

  The selection unit [8] includes a second selection unit [8-2]. The second selection unit [8-2] is from the third subcarrier (SC1) to the tenth subcarrier generation unit [3-10] output from the third subcarrier generation unit [3-3]. The output tenth subcarrier (SC8) is appropriately selected, and the selected subcarrier is output to the third BY signal demodulator [2-3]. The selection unit [8] also receives the comparison result output from the comparison unit [6] and, based on the comparison result, out of the third subcarrier (SC1) to the tenth subcarrier (SC8). One is selected and output as a third subcarrier.

  The phase shift unit [9] receives the third subcarrier output from the selection unit [8], and outputs a fourth subcarrier phase-shifted by +90 [degrees] from the third subcarrier.

  The color signal modulation unit [10] includes a third subcarrier output from the selection unit [8], a fourth subcarrier output from the phase shift unit [9], a third BY signal, and a first The RY signal is input, encoded into a composite color signal and output.

  The phase shift unit [12] inputs the composite synchronization signal output from the timing signal / subcarrier generation unit [7] and the comparison result output from the comparison unit [6], and based on the comparison result, The phase of the composite synchronizing signal is shifted (corrected).

  The adder [11] receives the luminance signal (Y signal), the timing signal, the composite sync signal output from the phase shift unit [12], and the composite color signal output from the color signal modulator [10]. The signal, composite sync signal, and composite color signal are added and output as a composite video signal.

(B-2) Operation of Second Embodiment The operation of the second embodiment will be described with reference to FIGS. Here, the subcarrier generation unit [3] in FIG. 3 prepares subcarriers having eight types of phase information, and performs switching by the selection unit [8] about each field for each phase information. The comparison unit [6-2] obtains a subcarrier related to the third BY signal and a subcarrier that is the minimum phase information. Then, using the determined subcarrier, the color signal modulation unit [10] performs modulation processing, and the phase shift unit [12] corrects the phase of the composite synchronization signal to generate a composite video signal.

[Step S1: Extraction Process (FIG. 5)]
The bandpass filter [1] extracts a signal in the subcarrier frequency band as a color subcarrier from the input Y signal as a luminance signal by a 3.58 [MHz] bandpass filter.

[Step S2: Demodulation Process (FIG. 5)]
Next, the third BY signal demodulator [2-3] receives the 3.58 [MHz] band signal output from the bandpass filter [1], and this 3.58 [MHz]. Each of the BY signals based on the third to tenth subcarriers is demodulated from the band signal, and a plurality of fifth BY signals are output [Step S2-3: Third Demodulation] Processing (FIG. 5)].

[Step S3: Delay Processing (FIG. 5)]
The delay unit [4] delays the phase information of the third BY signal, which is the BY signal of the component signal, so as to coincide with the phase information of the fifth BY signal, and delays the signal. Is output as a fourth BY signal.

[Step S4: Subtraction Processing (FIG. 5)]
The third subtraction unit [5-3] calculates and outputs a difference value between each of the fifth BY signal and the fourth BY signal [Step S4-3: Third Subtraction Processing ( FIG. 5)].

  Here, if the color difference signal component remains in the Y signal, the BY signal is extracted from the third BY signal demodulator [2-3]. Since the absolute value of the difference value is always small for the subcarrier phase closest to the extracted BY signal, correct color field information can be obtained by selecting such a subcarrier. .

[Step S5: Comparison Process (FIG. 5)]
The second comparison unit [6-2] detects a region where the BY signal component exists from the output of the third BY demodulation unit [2-3], and performs a third subtraction in the region. Each difference value output from the unit [5-3] is compared, and a subcarrier having a smaller absolute value is detected. This determines the most correct color field. Since the color field information does not become discontinuous if the input signal is continuous, the majority is processed in the field, and the result is further stabilized by, for example, majority processing in several fields [step S5-2: Second comparison process (FIG. 5)].

[Step S6: Selection Process (FIG. 5)]
A subcarrier having correct phase information is selected by the second selection unit [8-2] and passed to the color signal modulation unit [10] [step S6-2: second selection process (FIG. 5)].

[Step S7: Modulation Process (FIG. 5)]
The color signal modulation unit [10] includes a third subcarrier output from the second selection unit [8-2], a fourth subcarrier output from the phase shift unit [9], and a third B- The Y signal and the first RY signal are input, encoded into a composite color signal, and output.

[Step S9: Phase Shift Processing (FIG. 5)]
The phase shift unit [12] shifts (corrects) the phase of the composite synchronization signal based on the comparison result output from the comparison unit [6].

[Step S8: Addition Processing (FIG. 5)]
The adder [11] adds the Y signal, the composite sync signal output from the phase shift unit [12], and the composite color signal output from the color signal modulator [10], and outputs the result as a composite video signal.

(B-3) Effects of the Second Embodiment As described above, according to the second embodiment, even if the original composite video signal is not compliant with a standard such as RS-170A, When the composite video signal is converted into a component signal and then synthesized into an NTSC composite video signal, the optimum color field information and subcarrier phase information are transmitted without transmitting and recording special color field information. Since it can be detected, the color signal remaining in the Y signal or the Y signal leaking into the color signal can be modulated and synthesized with the correct phase, which is accompanied by Y / C separation and color decoder. Characteristic deterioration can be prevented. Furthermore, the phase shift unit [12] of the horizontal synchronization signal can output SCH = 0 [degree] as a signal compliant with RS-170A (SCH: SubCarrier phase to Horizon, horizontal synchronization signal and subcarrier SCH = 0 [degree] represents a phase relationship, where x = 0 when the subcarrier waveform is sin (x) (one or more waveforms with x = 0 [degree] to 360 [degree]). (Refers to a phase relationship that crosses the position of 50 [%] of the fall of the waveform of the horizontal synchronizing signal at the position of [degree] or x = 180 [degree]).

(C) Third Embodiment Next, a field synchronization apparatus and method according to a third embodiment will be described in detail with reference to the accompanying drawings. In the present embodiment, the color field of the video signal input to the encoding device side is determined using the luminance signal and color signal characteristics of the component signal decoded on the decoding device side, and is synchronized with the input signal. A color field signal is generated.

(C-1) Configuration of Third Embodiment The configuration of the third embodiment is shown in FIG. In the third embodiment, an input signal is processed with component signals of Y signal, BY signal, and RY signal, and then output as a composite video signal (composite signal) by an NTSC encoder as in an MPEG decoding apparatus. It is the example implemented to the apparatus to do.

  The bandpass filter (BPF) [1] is a 3.58 [MHz] band-pass filter that is a frequency band of the color subcarrier, and extracts a band with a color signal of the input luminance signal. Then, the luminance signal / residual color signal separation / extraction unit [15-1] separates and extracts the high frequency component and the residual color signal component of the luminance signal. Further, the first BY signal demodulator [2-1] and the second BY signal demodulator [2-2] extract the BY signal from the color signal.

  Furthermore, the delay element [16] is an element that corrects the delay time of the bandpass filter [1]. The residual luminance signal separation and extraction unit [15-2] has the same configuration as the luminance signal / residual color signal separation and extraction unit [15-1], and the BY signal and the residual luminance are input from the input BY signal. Separate and extract from the signal. The delay element [17] and the delay element [18] correct the delay time of the first BY signal demodulator [2-1] and the second BY signal demodulator [2-2]. It is an element to do.

  The comparison unit [6] compares the luminance signal wide-area component and the residual BY signal, and the BY signal and the residual luminance component, and the phase of the subcarrier of the BY signal demodulation unit [2] is the phase on the transmission side. It is determined whether or not they match. The timing signal / subcarrier generation unit [7] generates a subcarrier and a composite synchronization signal for color modulation from the input synchronization signal.

  The first subcarrier generation unit [3-1] and the second subcarrier generation unit [3-2] perform normal rotation and inversion of the phase of the subcarrier, and perform the first subcarrier (+ SC) and second Subcarriers (-SC) are output. Then, the selection unit [8] uses the comparison result of the comparison unit [6] to output the first subcarrier (+ SC) or the second subcarrier generation unit that is the output of the first subcarrier generation unit [3-1]. One of the second subcarriers (-SC), which is the output of [3-2], is selected and output as the third subcarrier.

  The phase shift unit [9] receives the third subcarrier output from the selection unit [8], shifts the phase of the third subcarrier by +90 [degrees], and modulates the RY signal. Output as the fourth subcarrier. The color signal modulator [10] is an NTSC encoder that performs quadrature two-phase modulation on the BY signal and the RY signal using the third subcarrier and the fourth subcarrier. The adder [11] combines the Y signal, the composite color signal, and the composite synchronization signal.

(C-2) Operation of the Third Embodiment The operation of the third embodiment will be described.

  The bandpass filter [1] extracts a signal in the subcarrier frequency band as a color subcarrier from the input Y signal as a luminance signal by a 3.58 [MHz] bandpass filter. The signal includes a band component in the vicinity of 3.58 [MHz] of the Y signal and a color signal component remaining in the Y signal separated by the Y / C separation unit on the transmission side.

  Next, the signal is input to the luminance signal / residual color signal separation / extraction unit [15-1], and the luminance signal / residual color signal separation / extraction unit [15-1] generally performs Y / C separation from the NTSC signal. It has the same configuration as the two-dimensional comb filter used when performing the above.

As described in the “Background Art” section, an NTSC composite video signal has a horizontal synchronization frequency fH and a subcarrier frequency fSC when the horizontal synchronization frequency as the line frequency is fH and the subcarrier (SC) frequency is fSC. The relationship with
fSC = 455 × fH / 2 (Formula 1)
It has become.

  Based on the relationship shown in Equation 1, the principle of the comb filter is to separate the luminance signal and the color signal by utilizing the fact that the phase of the subcarrier is inverted between one line. Furthermore, using this, the high frequency component of the luminance signal and the residual color signal can be separated and extracted from the input signal on the same principle as the Y / C separation that separates the input signal into the luminance signal and the color signal. .

Then, the high frequency component of the luminance signal separated and extracted is input to the first BY signal demodulator [2-1]. Here, the first BY signal demodulator [2-1] outputs the first subcarrier (the subcarrier signal for color modulation, which is the output of the first subcarrier generator [3-1]). + SC), the color demodulation of the high frequency component of the luminance signal is performed with the same phase as the first subcarrier (+ SC). Note that the Y _H signal as the first BY signal output from the first BY signal demodulator [2-1] is converted into a Y signal remaining in the color signal by Y / C separation on the transmission side. The Y ′ _H signal remaining in the BY signal generated by performing color demodulation of the BY signal is a signal subjected to the same processing.

  The second BY signal demodulator [2-2] converts the BY signal into the residual color signal extracted from the luminance signal / residual color signal separation and extraction unit [15-1] which is a comb filter. The color demodulation is performed, and the extracted C′b signal is a BY signal component remaining in the Y signal.

  Next, the input BY signal is input to the residual luminance signal separation and extraction unit [15-2] via the delay element [16] for matching the delay time with the Y signal. Similar to the luminance signal / residual color signal separation and extraction unit [15-1], the residual luminance signal separation and extraction unit [15-2] is a comb filter.

Here, since the Y signal component remaining in the BY signal is usually not in a phase relationship like a color signal, the phase of the output after color demodulation on the transmission side is inverted for each line. Further, since the BY signal is a demodulated signal, the phases of the lines are the same. Therefore, as for the output of the second BY signal demodulator [2-2], the BY signal component is input to the delay element [17] and the remaining Y _H signal component is input to the delay element [18]. The Note that the delay element [17] and the delay element [17] are delayed from the demodulation circuit of the first BY signal demodulation unit [2-1] and the second BY signal demodulation unit [2-2]. It is an element for time adjustment. The outputs of the delay element [17] and the delay element [17] are Cb and Y ′ _H , respectively.

  Then, the comparison unit [6] performs the following processing, and the subcarriers used in the first BY signal demodulation unit [2-1] and the second BY signal demodulation unit [2-2] It is determined whether the phase matches the phase on the transmission side or is inverted.

Here, if Y / C separation on the transmission side is completely performed, there is no residual color signal component in the Y signal, and similarly there is no residual Y signal component in the BY signal. . Therefore, when the residual component has a certain value, the phase of the subcarrier is determined. First,
| Y ′ _H |> α and sgn (Y ′ _H ) = sgn (Y _H )
If so, it is determined that the phase of the subcarrier matches the phase on the transmission side. Also,
| Y ′ _H |> α and sgn (Y ′ _H ) ≠ sgn (Y _H )
If so, it is determined that the phase of the subcarrier is inverted to the phase on the transmission side.

Similarly,
| C′b |> β and sgn (C′b) = sgn (Cb)
If so, it is determined that the phase of the subcarrier matches the phase on the transmission side. Also,
| C′b |> β and sgn (C′b) ≠ sgn (Cb)
If so, it is determined that the phase of the subcarrier is inverted to the phase on the transmission side.

Α and β are threshold values for determining that there is a mixed signal. Another purpose is to prevent malfunction due to noise or the like. Furthermore, sgn (Y _H ), sgn (Cb), sgn (Y ′ _H ), and sgn (C′b) indicate the signs of Y _H , Cb, Y ′ _H and C′b, respectively.

  Since the phase of the subcarrier is continuous as long as the input signal is not discontinuous, it is usually fixed to either coincident or inverted. Therefore, the determination result can be stabilized by performing a majority process in the field or performing a majority process in several frames.

  The output of the comparison unit [6] is the output of the first subcarrier (+ SC) that is the output of the first subcarrier generation unit [3-1] or the output of the second subcarrier generation unit [3-2]. This is a signal for controlling which of the second subcarriers (-SC) is used by the selection unit [8]. Here, although the first subcarrier (+ SC) and the second subcarrier (−SC) are described as separate inputs, only the first subcarrier (+ SC) is input to the selection unit [8]. It is also possible to create a phase inversion signal inside the selection unit [8].

  The color signal modulator [10] performs quadrature two-phase modulation processing on the input BY and RY signals with the phase of the selected subcarrier. Then, the addition unit [11] combines the luminance signal, the color signal, and the synchronization signal, and outputs the resultant signal as an NTSC composite video signal.

(C-3) Effects of the Third Embodiment As described above, according to the third embodiment, after the composite video signal is converted into the component signal, when the composite video signal is synthesized again, there is a special effect. Since correct color field information can be detected with higher accuracy without transmitting or recording color field information or the like, a color signal remaining in the Y signal or a Y signal leaking into the color signal can be detected. , Modulation with the correct phase can be performed, and Y / C separation and characteristic deterioration associated with the color decoder can be prevented.

(D) Fourth Embodiment Next, a field synchronization apparatus and method according to a fourth embodiment will be described in detail with reference to the accompanying drawings. In the present embodiment, a color frame of a component signal serving as an input signal can correspond to a signal that does not conform to the RS-170A standard.

(D-1) Configuration of Fourth Embodiment The configuration of the fourth embodiment is shown in FIG. Here, only differences from the third embodiment will be described.

  In the fourth embodiment, the third subcarrier generation unit [3-3] to the sixth subcarrier generation unit [3-6] have subcarrier phases of 0 [degree], +45 [degree], Four types of +90 [degree] and +135 [degree] are prepared, and the third subcarrier (SC1) to the sixth subcarrier (SC4) are generated.

  Then, the selection unit [8] includes the third subcarrier (SC1) to the sixth subcarrier output from the third subcarrier generation unit [3-3] to the sixth subcarrier generation unit [3-6]. One of the subcarriers (SC4) is sequentially selected and output to the first BY signal demodulator [2-1] and the second BY signal demodulator [2-2].

  The comparison unit [6] selects the one with the phase closest to the subcarrier on the transmission side from the third subcarrier (SC1) to the sixth subcarrier (SC4). The phase shift unit [12] corrects the phase of the synchronization signal in accordance with the phase of the selected subcarrier.

(D-2) Operation of Fourth Embodiment The operation of the fourth embodiment will be described.

In the fourth embodiment, the subcarrier phase is
Phase SC1 = 0 [degrees] of the first subcarrier (SC1), phase SC2 of the second subcarrier (SC2) = + 45 [degrees], phase SC3 of the third subcarrier (SC3) = + 90 [degrees] The phase SC4 of the fourth subcarrier (SC4) = + 135 [degrees]
4 types are prepared. Then, each phase is switched by the selection unit [8], for example, about every frame, and the first BY signal demodulation unit [2-1] and the second BY signal demodulation unit [2-2]. To enter.

  The comparison unit [6] determines the subcarrier phase as in the third embodiment. In the present embodiment, in addition to this, the following comparison is performed.

  First, when the phase of the selected subcarrier is SC1 = 0 [degree], for example, within one frame, the number of pixels that satisfy the following conditions, ΣYp1, ΣYn1, ΣCp1, and ΣCn1 are counted.

Number of pixels satisfying | Y ′ _H |> α and sgn (Y ′ _H ) = sgn (Y _H ): ΣYp1
Number of pixels satisfying | Y ′ _H |> α and sgn (Y ′ _H ) ≠ sgn (Y _H ): ΣYn1
Number of pixels satisfying | C′b |> β and sgn (C′b) = sgn (Cb): ΣCp1
Number of pixels satisfying | C′b |> β and sgn (C′b) ≠ sgn (Cb): ΣCn1
Similarly, in the next frame, the number of pixels, ΣYp2, ΣYn2, ΣCp2, and ΣCn2 when the subcarrier phase is SC2 = + 45 [degrees] is counted.

Number of pixels satisfying | Y ′ _H |> α and sgn (Y ′ _H ) = sgn (Y _H ): ΣYp2
Number of pixels satisfying | Y ′ _H |> α and sgn (Y ′ _H ) ≠ sgn (Y _H ): ΣYn2
Number of pixels satisfying | C′b |> β and sgn (C′b) = sgn (Cb): ΣCp2
Number of pixels satisfying | C′b |> β and sgn (C′b) ≠ sgn (Cb): ΣCn2
Similarly, in the next frame, the number of pixels, ΣYp3, ΣYn3, ΣCp3, and ΣCn3, when the phase of the subcarrier is SC3 = + 90 [degrees] is counted.

Number of pixels satisfying | Y ′ _H |> α and sgn (Y ′ _H ) = sgn (Y _H ): ΣYp3
Number of pixels satisfying | Y ′ _H |> α and sgn (Y ′ _H ) ≠ sgn (Y _H ): ΣYn3
Number of pixels satisfying | C′b |> β and sgn (C′b) = sgn (Cb): ΣCp3
Number of pixels satisfying | C′b |> β and sgn (C′b) ≠ sgn (Cb): ΣCn3
Similarly, in the next frame, the number of pixels, ΣYp4, ΣYn4, ΣCp4 and ΣCn4 when the subcarrier phase is SC4 = + 135 [degrees] is counted.

Number of pixels satisfying | Y ′ _H |> α and sgn (Y ′ _H ) = sgn (Y _H ): ΣYp4
Number of pixels satisfying | Y ′ _H |> α and sgn (Y ′ _H ) ≠ sgn (Y _H ): ΣYn4
Number of pixels satisfying | C′b |> β and sgn (C′b) = sgn (Cb): ΣCp4
Number of pixels satisfying | C′b |> β and sgn (C′b) ≠ sgn (Cb): ΣCn4
Then, each counted Σ value is held, and after all Σ values are counted, each Σ value is compared. Using the result, logical determination is performed as follows.

  When ΣYp1 or ΣCp1 is the maximum value, SC1 is selected as the subcarrier phase.

  When ΣYp2 or ΣCp2 is the maximum value, SC2 is selected as the subcarrier phase.

  When ΣYp3 or ΣCp3 is the maximum value, SC3 is selected as the subcarrier phase.

  When ΣYp4 or ΣCp4 is the maximum value, SC4 is selected as the subcarrier phase.

  When ΣYn1 or ΣCn1 is the maximum value, SC1 inversion is selected as the subcarrier phase.

  When ΣYn2 or ΣCn2 is the maximum value, the inversion of SC2 is selected as the phase of the subcarrier.

  When ΣYn3 or ΣCn3 is the maximum value, SC3 inversion is selected as the subcarrier phase.

  When ΣYn4 or ΣCn4 is the maximum value, SC4 inversion is selected as the subcarrier phase.

  This makes it possible to select a subcarrier having a phase closest to the phase of the subcarrier on the transmission side.

  Then, the phase shift unit [12] sets the SCH phase of the output signal to 0 [degrees] when the phase of the subcarrier selected in this way is other than 0 [degrees] and +180 [degrees]. Processing for complying with the rules of 170A is performed.

(D-3) Effect of Fourth Embodiment As described above, according to the fourth embodiment, even if the original composite video signal is a signal that does not conform to the standard such as RS-170A, When the composite video signal is converted into a component signal and then synthesized again, the optimum color field information can be detected without transmitting and recording special color field information or the like. Therefore, the color signal remaining in the luminance signal or the luminance signal leaking into the color signal can be modulated and synthesized with the correct phase, and characteristic deterioration associated with Y / C separation and color decoder can be prevented. be able to.

  Further, the phase shift unit [12] of the horizontal synchronization signal can output SCH = 0 as a signal conforming to RS-170A.

(E) Other forms of use The present invention can be applied to all processes for converting an NTSC composite video signal into a component signal and then returning it to an NTSC composite video signal again. In addition to the MPEG2 codec apparatus shown in the first to fourth embodiments, it can be incorporated into NTSC encoder processing such as a DVD recording / reproducing apparatus and a component recording type VTR (Video Tape Recorder).

  Since a color field can be detected without requiring special color field information, it does not depend on a processing method of an NTSC decoder that uses an NTSC composite video signal as a component signal. Therefore, an effect can be acquired by incorporating it uniquely in the NTSC encoder process.

  Further, since the process compensates for the deterioration of the Y / C separation characteristic in the NTSC decoder process, complicated processes such as a two-dimensional filter and a three-dimensional filter are not required in the decoder.

  In the present embodiment, the NTSC composite video signal has been described. However, the same effect can be obtained with a PAL (Phase Alternation Line) composite video signal by substantially the same configuration and operation.

It is a figure which shows an example of a structure of the 1st Embodiment of this invention. It is a figure which shows an example of the operation | movement flow of the 1st Embodiment of this invention. It is a figure which shows an example of a structure of the 2nd Embodiment of this invention. It is a figure which shows an example of the subcarrier used in 2nd Embodiment. It is a figure which shows an example of the operation | movement flow of the 2nd Embodiment of this invention. It is a figure which shows an example of a structure of the 3rd Embodiment of this invention. It is a figure which shows an example of a structure of the 4th Embodiment of this invention. It is a figure which shows an example of a prior art (horizontal scanning line). It is a figure which shows an example of a prior art (waveform of a subcarrier). It is a figure which shows an example of a structure of a prior art.

Explanation of symbols

  1: band pass filter (BPF), 2: BY signal demodulator, 2-1: first BY signal demodulator, 2-2: second BY signal, 2-3: second B-Y signal, 3: subcarrier generation unit, 3-1: first subcarrier generation unit, 3-2: second subcarrier generation unit, 3-3: third subcarrier generation unit, 3 -4: fourth subcarrier generation unit, 3-5: fifth subcarrier generation unit, 3-6: sixth subcarrier generation unit, 3-7: seventh subcarrier generation unit, 3-8 : 8th subcarrier generation unit, 3-9: 1st subcarrier generation unit, 3-10: 10th subcarrier generation unit, 4: delay unit, 5: subtraction unit, 5-1: first Subtraction unit, 5-2: second subtraction unit, 5-3: third subtraction unit, 6: comparison unit, 6-1: first comparison unit, 6-2: second comparison unit, 7: Taimin Signal / subcarrier generation unit, 8: selection unit, 8-1: first selection unit, 8-2: second selection unit, 9: phase shift unit, 10: color signal modulation unit, 11: addition unit, 12: Phase shift unit, 15-1: Luminance signal / residual color signal separation / extraction unit, 15-2: Residual luminance signal separation / extraction unit, 16-18: Delay element.

Claims (24)

An extraction unit for extracting a first signal having a frequency band of a color subcarrier of the composite video signal from a signal in a signal band of a luminance signal in a component signal separated from the composite video signal;
A field synchronization apparatus comprising: a detection unit configured to detect color field information related to phase information of subcarriers in the component signal from first phase information included in the first signal.   The field synchronization device according to claim 1, wherein the extraction unit includes a filter unit that extracts the first signal from the luminance signal by a band pass filter. The detector is
A first demodulator that demodulates a plurality of color difference signals using a plurality of subcarriers for the first signal;
A first subtraction unit that obtains a plurality of difference values between each color difference signal in the plurality of color difference signals and a first color difference signal that is a color difference signal in the component signal;
A first comparison unit that compares each difference value in the plurality of difference values and outputs phase information of a subcarrier according to a smaller absolute value of the difference values as the color field information. The field synchronizer described. The first demodulator includes:
A first demodulator that demodulates the first color signal using a first subcarrier having first phase information corresponding to first color field information;
A second demodulator that demodulates the first color difference signal using a second subcarrier having second phase information corresponding to second color field information,
The first subtraction unit includes:
A second subtraction unit for obtaining a first difference value between the first color difference signal and the second color difference signal;
A third subtraction unit for obtaining a second difference value between the first color difference signal and the third color difference signal;
The first comparison unit includes:
A second comparison unit that compares the first difference value with the second difference value and outputs phase information of a subcarrier according to a smaller absolute value of the difference value as the color field information; The field synchronization device according to claim 3. A modulator that modulates the first color difference signal with a subcarrier corresponding to the color field information and outputs a second signal;
The field synchronization device according to claim 4, further comprising: an addition unit that adds a horizontal synchronization signal of the first signal, the second signal, and the composite video signal. The plurality of subcarriers each have different phase information;
4. The field synchronization device according to claim 3, wherein each phase information in each different phase information includes phase information that is an integral multiple of 360 [degrees] divided by the number of the plurality of subcarriers. A modulator that modulates the first color difference signal with a subcarrier corresponding to the color field information and outputs a second signal;
A phase shift unit configured to make phase information of the first horizontal synchronization signal of the composite video signal equal to phase information corresponding to the color field information and to output a second horizontal synchronization signal;
The field synchronization apparatus according to claim 4, further comprising: an addition unit that adds the first signal, the second signal, and the second horizontal synchronization signal. A first step of extracting a first signal having a frequency band of a color subcarrier of the composite video signal from a signal of a signal band of a luminance signal in a component signal separated from the composite video signal;
And a second step of detecting color field information relating to phase information in the component signal from first phase information of subcarriers included in the first signal.   The field synchronization method according to claim 8, wherein the first step includes a third step of extracting the first signal from the luminance signal by a band pass filter. The second step includes
A fourth step of demodulating a plurality of color difference signals from the first signal using a plurality of subcarriers;
A fifth step of obtaining a plurality of difference values between each color difference signal in the plurality of color difference signals and a first color difference signal that is a color difference signal of the component;
A sixth step of comparing each difference value in the plurality of difference values and outputting phase information of subcarriers having a smaller absolute value of the difference values as the color field information. Field synchronization method. The fourth step includes
A seventh step of demodulating a second color difference signal from the first signal using a first subcarrier having first phase information corresponding to first color field information;
An eighth step of demodulating the third color difference signal from the first signal using a second subcarrier having second phase information corresponding to second color field information;
The fifth step includes
A ninth step of obtaining a first difference value between the first color difference signal and the second color difference signal;
A tenth step of obtaining a second difference value between the first color difference signal and the third color difference signal;
The sixth step includes
An eleventh step of comparing the first difference value with the second difference value and outputting phase information of a subcarrier according to a smaller absolute value of the difference value as the color field information. Item 11. The field synchronization method according to Item 10. A twelfth step of modulating the color difference signal with a subcarrier corresponding to the color field information and outputting a third signal;
The field synchronization method according to claim 11, further comprising a thirteenth step of adding a horizontal synchronization signal of the first signal, the third signal, and the composite video signal.   Each of the plurality of subcarriers has different phase information, and each phase information in each different phase information includes phase information that is an integral multiple of 360 [degrees] divided by the number of the plurality of subcarriers. The field synchronization method according to claim 10. A fourteenth step of modulating the color difference signal with a subcarrier corresponding to the color field information and outputting a third signal;
A fifteenth step of making the phase information of the first horizontal synchronization signal of the composite video signal equal to the third phase information of the subcarrier and outputting a second horizontal synchronization signal;
The field synchronization method according to claim 13, further comprising: a sixteenth step of adding the first signal, the third signal, and the second horizontal synchronization signal. A field synchronization method used for processing to separate a composite video signal into a luminance signal and a color signal, re-modulate and synthesize a component signal obtained by color demodulation, and return the composite signal to the composite video signal,
A field synchronization method, wherein color field information is detected from information included in an effective video signal of a component signal without referring to color field information of an original composite video signal. Extracting the component of the color signal remaining in the luminance signal of the component signal;
The phase of the subcarrier so that the phase of the subcarrier included in the color signal matches the phase of the subcarrier when the BY color difference signal and the RY color difference signal of the component signal are modulated into the composite color signal. The field synchronization method according to claim 15, wherein the field synchronization method is selected. The high frequency component of the luminance signal is demodulated with the same subcarrier phase as that for modulating the BY color difference signal,
Extracting a luminance signal component remaining in the first color difference signal;
The field synchronization method according to claim 16, wherein the subcarrier phase is selected so that the phases of the subcarriers coincide with each other by comparing the two.   The field synchronization method according to claim 17, wherein a high frequency component and a residual color signal component of the luminance signal are separated and extracted from the luminance signal using a vertical filter between three lines.   The field synchronization method according to claim 17, wherein the BY color difference signal and the remaining luminance signal component are separated and extracted from the BY color difference signal using a vertical filter between three lines. The sign of the signal obtained by demodulating the high frequency component of the luminance signal with the modulation axis of the BY color difference signal is compared with the sign of the component of the luminance signal extracted from the BY color difference signal,
If they match, it is determined that the subcarrier phases match,
The field synchronization method according to claim 16, wherein if it does not match, it is determined that the phase of the subcarrier is inverted. Comparing the sign of the signal obtained by demodulating the residual color signal extracted from the luminance signal with the modulation axis of the BY color difference signal and the sign of the BY color difference signal;
If they match, it is determined that the subcarrier phases match,
The field synchronization method according to claim 16, wherein if it does not match, it is determined that the phase of the subcarrier is inverted.   The subcarrier phase information obtained from the luminance signal comparison and the subcarrier phase information obtained from the BY color difference signal are used together to select information detected by majority voting. 16. The field synchronization method according to 16. Four types of subcarrier phases, 0 [degree], 45 [degree], 90 [degree], and 135 [degree], are prepared,
The field synchronization method according to any one of claims 16 to 22, wherein an optimum subcarrier phase is selected. Shift the phase of the horizontal sync signal according to the difference from the determined horizontal sync phase of the subcarrier,
The field synchronization method according to claim 23, wherein an SCH phase is set to 0 and the luminance signal and the color signal are added.

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