JP3677872B2 - Television broadcast signal processing apparatus and method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a television broadcast signal processing apparatus and method, and in particular, a carrier color signal corresponding to a predetermined scanning line constituting a predetermined field, and a plurality of delayed carrier color signals corresponding to adjacent scanning lines. The present invention relates to a television broadcast signal processing apparatus and method for performing time axis correction by delaying a television broadcast signal so as to maximize the correlation defined in (1).
[0002]
[Prior art]
A TV broadcast signal broadcast from a television (TV) broadcast station or a TV broadcast signal reproduced by an analog VCR (Video Cassette Recorder) includes time axis fluctuation (jitter) and includes jitter. If the TV broadcast signal is displayed on the monitor as it is, the line slightly moves left and right, and high quality image quality cannot be obtained.
[0003]
FIG. 6 shows three lines of carrier color signals in a predetermined field in a TV broadcast signal including jitter. In FIG. 6, the carrier color signal of the 198th line in the predetermined (even) field is a solid line, the carrier color signal of the 200th line is a fine dotted line, and the carrier color signal of the 202nd line is a coarse dotted line. is there.
[0004]
Since the phase of the carrier color signal of each line is modulated corresponding to the color signal of each line, the phase of the carrier color signal of different lines basically does not match. However, since there is a correlation between adjacent lines, the correlation value is a relatively large value. However, if there is jitter, this correlation value becomes small.
[0005]
Accordingly, the correlation value between the carrier color signal of the 198th line and the carrier color signal of the 202th line, the correlation value of the carrier color signal of the 198th line and the carrier color signal of the 200th line, and the 200th line of the 200th line shown in FIG. When the correlation value between the carrier color signal and the carrier color signal of the 202nd line was obtained, it was 0.913390, -0.103358, or -0.104299, respectively.
[0006]
The correlation value between the carrier color signal of the 198th line and the carrier color signal of the 202nd line is a positive value, whereas the correlation value between the carrier color signal of the 198th line and the carrier color signal of the 200th line, or the 200th line. The correlation value between the carrier color signal of the line and the carrier color signal of the 202nd line is a negative value. This is because the reference phase of the carrier color signal is the same in the former, and the latter two are the opposite phases of the reference phase of the carrier color signal.
[0007]
The larger the absolute value of the correlation value, the less the influence of jitter and the more the phases are aligned. In this example, the absolute value of the correlation value between the 198th line and the 200th line and the correlation value between the 200th line and the 202nd line are both as small as 0.103358 or 0.104299. The absolute value of the correlation value between the 198th line and the 202nd line is relatively large at 0.913390, but it is not sufficient.
[0008]
Therefore, jitters are removed by using TBC (Time Base Corrector) in commercial equipment and consumer high-end equipment.
[0009]
FIG. 7 is a block diagram showing an example of the configuration of a conventional TBC 1.
[0010]
A TV broadcast signal broadcast and received from a TV broadcast station or a TV broadcast signal obtained by reproduction of a predetermined VCR is input to the H / V sync separation circuit 11 and the A / D conversion circuit 12 of the TBC 1. . The H / V synchronization separation circuit 11 separates a horizontal synchronization (H) signal and a vertical synchronization (V) signal from the TV broadcast signal and outputs them to the write clock generation circuit 13.
[0011]
A write clock generation circuit (PLL) 13 generates a write clock using a vertical synchronization signal and a horizontal synchronization signal, and supplies it to the A / D conversion circuit 12 and the write address counter 15. The A / D conversion circuit 12 converts an analog TV broadcast signal into a digital signal corresponding to the write clock supplied from the write clock generation circuit 13 and supplies the digital signal to the memory 14.
[0012]
The write address counter 15 increases a predetermined counter value corresponding to the write clock supplied from the write clock generation circuit 13 and supplies the counter value to the memory 14. The memory 14 stores the digital TV broadcast signal supplied from the A / D conversion circuit 12 at an address corresponding to the counter value supplied from the write address counter 15.
[0013]
The read clock generation circuit 19 is composed of a fixed crystal oscillation circuit or the like, and generates a read clock with a constant frequency and supplies it to the D / A conversion circuit 16 and the read address counter 17.
[0014]
The jump detection circuit 18 detects a difference between a write address and a read address (a counter value of the write address counter 15 and a counter value of the read address counter 17), and the difference is within a predetermined value (ideally a constant value). The read address counter 17 is controlled so that the difference becomes a predetermined value when it greatly changes from.
[0015]
The read address counter 17 increases a predetermined counter value corresponding to the clock supplied from the read clock generation circuit 19 and outputs it to the memory 14. The memory 14 reads a digital TV broadcast signal stored at an address corresponding to the counter value supplied from the read address counter 17 and supplies the digital TV broadcast signal to the D / A conversion circuit 16. The digital TV broadcast signal output from the memory 14 is converted into an analog signal by the D / A conversion circuit 16 and then input to a predetermined signal processing circuit.
[0016]
In this way, a write clock locked with the phase of the color signal carrier signal is generated using the synchronization signal included in the TV broadcast signal, writing is performed with this write clock, and a read clock with a constant phase is used. Jitter is removed by reading.
[0017]
[Problems to be solved by the invention]
However, as a method for reducing jitter included in a TV broadcast signal, there is only a method using TBC having the above-described structure, and there is a problem that selection options are narrow.
[0018]
The present invention has been made in view of such a situation, and can reduce jitter included in a TV broadcast signal without using the conventional TBC having the above-described structure. .
[0019]
[Means for Solving the Problems]
The television broadcast signal processing device according to claim 1 is a first delay means for delaying a television broadcast signal by a predetermined time, and a predetermined scanning of a predetermined field multiplexed with the television broadcast signal. A plurality of extraction means for extracting a carrier color signal of a line and a plurality of second carrier color signals of a second scanning line adjacent to the first scanning line with respect to the first carrier color signal of the first scanning line; The second delay means for delaying by the delay time, and the correlation between the first carrier color signal and the second carrier color signal delayed by a plurality of delay times are calculated, and the second carrier color that maximizes the correlation Control means for controlling the delay time of the television broadcast signal corresponding to the delay time of the signal.
[0020]
According to a third aspect of the present invention, there is provided a television broadcast signal processing method that delays a television broadcast signal by a predetermined time and outputs a carrier color signal of a predetermined scanning line in a predetermined field multiplexed on the television broadcast signal. Extracting and delaying the second carrier color signal of the second scanning line adjacent to the first scanning line by a plurality of delay times with respect to the first carrier color signal of the first scanning line, The correlation between the second carrier color signal delayed by a plurality of delay times and the second carrier color signal delayed by a plurality of delay times is calculated, and the delay of the television broadcast signal corresponds to the delay time of the second carrier color signal that maximizes the correlation. It is characterized by controlling time.
[0021]
The television broadcast signal processing device according to claim 1, wherein the first delay means delays the television broadcast signal by a predetermined time, and the extraction means is multiplexed with the television broadcast signal. The carrier color signal of a predetermined scanning line in the field of the second field is extracted, and the second delay means outputs the second carrier color signal of the second scanning line adjacent to the first scanning line to the first scanning line. The first carrier color signal is delayed by a plurality of delay times, and the control means calculates a correlation between the first carrier color signal and the second carrier color signal delayed by a plurality of delay times, and the correlation is calculated. Corresponding to the maximum delay time of the second carrier color signal, the delay time of the television broadcast signal is controlled.
[0022]
4. The television broadcast signal processing method according to claim 3, wherein the television broadcast signal is delayed by a predetermined time and multiplexed on the television broadcast signal, and the carrier color signal of a predetermined scanning line in a predetermined field. And the second carrier color signal of the second scan line adjacent to the first scan line is delayed by a plurality of delay times with respect to the first carrier color signal of the first scan line, Correlation between one carrier color signal and a second carrier color signal delayed by a plurality of delay times is calculated, and in accordance with the delay time of the second carrier color signal that maximizes the correlation, The delay time is controlled.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below. In order to clarify the correspondence between each means described in the claims and the following embodiments, the corresponding embodiment is shown in parentheses after each means. The characteristics of the present invention will be described with the addition of (one example). However, of course, this description does not mean that each means is limited to the description.
[0024]
The television broadcast signal processing apparatus according to claim 1 is multiplexed with the first delay means (for example, the FIFO circuit 44 of FIG. 2) for delaying the television broadcast signal by a predetermined time and the television broadcast signal. Extraction means (for example, a moving average correction circuit 43 in FIG. 2) for extracting a carrier color signal of a predetermined scanning line in a predetermined field, and a second scanning line adjacent to the first scanning line. Second delay means (for example, FIFOs 45-1 to 45-3 in FIG. 2) for delaying the carrier color signal of the first scanning color signal by a plurality of delay times with respect to the first carrier color signal of the first scanning line; Correlation between one carrier color signal and a second carrier color signal delayed by a plurality of delay times is calculated, and first delay means corresponding to the delay time of the second carrier color signal that maximizes the correlation Controls the delay time of television broadcast signals by Control means (e.g., the correlation value / phase decision circuit 46 in FIG. 2), characterized in that it comprises a.
[0025]
FIG. 1 is a block diagram showing the configuration of an embodiment of a television (TV) receiver 21 to which the television broadcast signal processing apparatus of the present invention is applied.
[0026]
The NTSC television broadcast signal is received by the antenna 22 and a predetermined TV broadcast channel is selected by the tuner 31 of the TV receiver 21. The video signal output from the tuner 31 is supplied to the time axis correction circuit 32. The audio signal output from the tuner 31 is supplied to the audio processing circuit 33. The audio processing circuit 33 performs processing such as demodulation and amplification on the audio signal and outputs the result to the speaker 35.
[0027]
The time axis correction circuit 32 extracts a carrier color signal multiplexed on the video signal, calculates a correlation between a predetermined scanning line and a plurality of delayed carrier color signals corresponding to the adjacent scanning lines, and calculates a correlation value. A delay time that maximizes the absolute value of (reducing jitter) is obtained, and a video signal delayed by a time corresponding to this delay time (video signal corrected for jitter) is output to the video processing circuit 34. ing. The video processing circuit 34 performs processing such as demodulation and amplification on the video signal supplied from the time axis correction circuit 32 and supplies it to the CRT 36.
[0028]
FIG. 2 is a block diagram showing a configuration of an embodiment of the time axis correction circuit 32. As shown in FIG.
[0029]
The video signal of the TV broadcast signal supplied from the tuner 31 is supplied to the A / D conversion circuit 42 of the time axis correction circuit 32. The A / D conversion circuit 42 converts an analog video signal into, for example, a digital signal represented by a dynamic range of 255 gradations in response to the clock signal supplied from the oscillation circuit 41, and a moving average correction circuit 43 and the FIFO circuit 44.
[0030]
The FIFO circuit 44 uses the clock signal supplied from the oscillation circuit 41 and the delay time supplied from the correlation value / phase determination circuit 46 to delay the video signal supplied from the A / D conversion circuit 42 by a predetermined time. After that, the video data is output to the video processing circuit 34.
[0031]
For example, the moving average correction circuit 43 extracts a carrier color signal multiplexed on the video signal based on the digitized video signal corresponding to three consecutive pixels, and adds 128 to the signal level. , And converted into a video signal having a signal level of 0 to 255, and then supplied to the FIFO circuits 45-1 to 45-3 and the correlation value / phase determination circuit 46.
[0032]
The FIFO circuits 45-1 to 45-3 delay the carrier color signals of the predetermined scanning lines constituting the predetermined field supplied from the moving average correction circuit 43 by a predetermined time, respectively, and then calculate the correlation value / The signal is output to the phase determination circuit 46. That is, for example, the FIFO circuits 45-1 to 45-3 transfer the carrier color signals of the predetermined scanning lines supplied from the moving average correction circuit 43 to the 1 + α line, 1 line, or 1-α line, respectively. After being delayed by a corresponding time, it is output to the correlation value / phase determination circuit 46.
[0033]
The correlation value / phase determination circuit 46 calculates the correlation between the carrier color signal supplied from the moving average correction circuit 43 and these delayed carrier color signals, and calculates a delay time that maximizes the absolute value of the correlation value. The selection result is supplied to the FIFO circuit 44.
[0034]
The FIFO circuit 44 outputs a video signal delayed by a time corresponding to the selection result (delay time) supplied from the correlation value / phase determination circuit 46 to the video processing circuit 34.
[0035]
FIG. 3 is a block diagram showing the configuration of one embodiment of the moving average correction circuit 43. As shown in FIG. The video signal output from the A / D conversion circuit 42 is supplied to the moving average calculation circuit 51 and the delay circuit 52 of the moving average correction circuit 43. The moving average calculation circuit 51 generates an average signal of video signals corresponding to a predetermined number of consecutive pixels, for example, three pixels, and outputs the average signal to the subtraction circuit 53.
[0036]
The subtracting circuit 53 subtracts a video signal corresponding to a predetermined pixel supplied from the delay circuit 52 from the average signal supplied from the moving average calculating circuit 51 by subtracting a signal delayed by one pixel from the average signal. A signal is extracted and supplied to the adder circuit 54. The adder circuit 54 adds a 128 level signal to the input carrier color signal to convert it into a carrier color signal having a level of 0 to 255, and the correlation value / phase determination with the FIFO circuits 45-1 to 45-3. The output is made to the circuit 46.
[0037]
Next, the processing operation of the TV receiver 21 will be described with reference to the flowchart of FIG.
[0038]
In step S 1 of FIG. 4, a TV broadcast signal broadcast from a predetermined TV broadcast station is received by the antenna 22. A tuner 31 selects a predetermined TV broadcast channel.
[0039]
In subsequent step S <b> 2, the tuner 31 supplies the audio signal to the audio processing circuit 33 and supplies the video signal to the time axis correction circuit 32. The A / D conversion circuit 42 of the time axis correction circuit 32 converts this video signal into a digital signal with a clock signal having a constant frequency input from the oscillation circuit 41 and outputs the digital signal to the FIFO circuit 44 and the moving average correction circuit 43.
[0040]
The FIFO circuit 44 delays the video signal using the clock signal supplied from the oscillation circuit 41.
[0041]
In the subsequent step 3, the moving average calculation circuit 51 of the moving average correction circuit 43 calculates the average value of the video signals corresponding to three consecutive pixels. When the average value of three consecutive pixels is input to the subtraction circuit 53, the delay circuit 52 outputs the data of the center pixel among the three consecutive pixels. The subtracting circuit 53 extracts the carrier color signal by calculating the difference between the two, and outputs it to the FIFO circuits 45-1 to 45-3 and the correlation value / phase determination circuit 46.
[0042]
That is, continuous pixel data constituting the same line of a predetermined field is represented by YI, YQ, where luminance data is Y, I signal data is I, and Q signal data is Q. , Y + I, Y + Q. Therefore, for example, when the data of three consecutive pixels is Y-I, Y-Q, and Y + I, the average value is Y + Q / 3. By subtracting YQ, which is data of an intermediate pixel among the three pixels, from this average value, -2Q / 3 is obtained. Therefore, Q signal data can be obtained based on the obtained value. Further, the I signal data can be obtained by performing the same calculation on the continuous pixels having YQ, Y + I, and Y + Q data, respectively. In this way, a carrier color signal can be extracted by calculating a moving average and subtracting data of a predetermined pixel.
[0043]
Next, in step S 4, the FIFO circuits 45-1 to 45-3 delay the carrier color signal supplied from the moving average correction circuit 43 by a predetermined time, and then send it to the correlation value / phase determination circuit 46. Output. The correlation value / phase determination circuit 46 calculates the correlation between the carrier color signal of the target line supplied from the moving average correction circuit 43 and the carrier color signal of the previous line supplied from the FIFO circuit 45-1. At the same time, the correlation between the carrier color signal of the target line and the carrier color signal of the previous line output from the FIFO circuit 45-2 or the FIFO circuit 45-3 is calculated.
[0044]
In subsequent step S5, the correlation value / phase determination circuit 46 selects the correlation value having the maximum absolute value from among the plurality of correlation values, and causes the FIFO circuit 44 to output a video signal having a corresponding delay time. .
[0045]
As described above, the delay times of the FIFO circuits 45-1 to 45-3 are set to slightly different values. In other words, the FIFO circuit 45-1 gives jitter that delays the signal one line before by α, and the FIFO circuit 45-3 gives jitter that advances by α. . The FIFO circuit 45-2 gives no jitter. Therefore, if the FIFO circuit 44 provides a delay time corresponding to the delay time (+ α, 0, or −α) at which the maximum absolute value can be obtained, the output has the maximum correlation with the output of the previous line. (Minimum jitter).
[0046]
Subsequently, in step S6, the video signal output from the FIFO circuit 44 is subjected to predetermined processing such as demodulation and amplification by the video processing circuit 34, and then output to the CRT 36. The audio signal input from the tuner 31 to the audio processing circuit 33 is subjected to predetermined processing such as demodulation and amplification by the audio processing circuit 33 and then output to the speaker 35.
[0047]
FIG. 5 shows a signal obtained by correcting the same carrier color signal as the carrier color signal shown in FIG. In FIG. 5, the carrier color signal corresponding to the 198th line in a predetermined field is a solid line, the carrier color signal corresponding to the 200th line is a fine dotted line, and the carrier color signal corresponding to the 202nd line is a coarse dotted line. It is shown.
[0048]
Further, the correlation value between the carrier color signal of the 198th line and the carrier color signal of the 202nd line, the correlation value of the carrier color signal of the 198th line and the carrier color signal of the 200th line, and the 200th line of the 200th line shown in FIG. The correlation values of the carrier color signal and the carrier color signal of the 202nd line were 0.968523, -0.968028, or -0.972247, respectively. These values are larger in absolute value than the values in FIG. Therefore, the carrier color signal output from the time axis correction circuit 32 is a signal that realizes high quality image quality with reduced jitter.
[0049]
In this way, jitter contained in a TV broadcast signal can be reduced without using the conventional TBC 1 having the structure shown in FIG.
[0050]
2 can be configured without using the write clock (PLL) 13 as shown in FIG.
[0051]
In the above-described embodiment, the carrier color signals delayed by three different times are generated by the FIFO circuits 45-1 to 45-3 of the time axis correction circuit 32. However, the number of stages is further increased to increase the number of stages. A carrier color signal delayed by a different time may be generated, the corresponding correlation value may be calculated, and the video signal may be output with a delay time that maximizes the absolute value of the correlation value. Further, the present invention can be applied to a VCR as well as a TV receiver.
[0052]
【The invention's effect】
As described above, according to the television broadcast signal processing device according to claim 1 and the television broadcast signal processing method according to claim 3, the first carrier color signal of the first scanning line, the first Calculating the correlation of the second carrier color signal delayed by a plurality of delay times of the second scanning line adjacent to the scanning line, and corresponding to the delay time of the second carrier color signal maximizing the correlation; Since the delay time of the television broadcast signal is controlled, it is possible to reduce time-axis fluctuations included in the television broadcast signal.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of an embodiment of a TV receiver 21 to which a television broadcast signal processing apparatus of the present invention is applied.
2 is a block diagram showing a configuration of an embodiment of a time axis correction circuit 32. FIG.
FIG. 3 is a block diagram showing a configuration of an example of the moving average correction circuit 43;
4 is a flowchart for explaining the processing operation of the TV receiver 21 of FIG. 1. FIG.
FIG. 5 is a graph in which TV broadcast signals corresponding to predetermined scanning lines corrected by the time axis correction circuit 32 are plotted.
FIG. 6 is a graph plotting a TV broadcast signal corresponding to a predetermined scanning line including jitter.
FIG. 7 is a block diagram showing a configuration of an example of a conventional TBC.
[Explanation of symbols]
1 TBC, 11 H / V sync separation circuit, 12 A / D conversion circuit, 13 write clock, 14 memory, 15 write address counter, 16 D / A conversion circuit, 17 read address counter, 18 jump detection circuit, 19 read clock , 21 TV receiver, 22 antenna, 31 tuner, 32 time axis correction circuit, 33 audio processing circuit, 34 video processing circuit, 35 speaker, 36 CRT, 41 oscillation circuit, 42 A / D conversion circuit, 43 moving average correction circuit, 44, 45-1 to 45-3 FIFO circuit, 46 correlation value / phase determination circuit, 51 moving average calculation circuit, 52 delay circuit, 53 subtraction circuit, 54 addition circuit

Claims (3)

First delay means for delaying the television broadcast signal by a predetermined time;
Extracting means for extracting a carrier color signal of a predetermined scanning line of a predetermined field, multiplexed on the television broadcast signal;
Second delay means for delaying the second carrier color signal of the second scan line adjacent to the first scan line by a plurality of delay times with respect to the first carrier color signal of the first scan line. When,
Calculating a correlation between the first carrier color signal and the second carrier color signal delayed by a plurality of delay times, and corresponding to the delay time of the second carrier color signal at which the correlation is maximized; A television broadcast signal processing apparatus comprising: control means for controlling a delay time of the television broadcast signal by the first delay means. The extraction means extracts the carrier color signal by subtracting the value of the television broadcast signal corresponding to a predetermined pixel from the average value of the television broadcast signal corresponding to a predetermined number of consecutive pixels. The television broadcast signal receiver according to claim 1. Delay the television broadcast signal by a predetermined time,
Extracting a carrier color signal of a predetermined scanning line of a predetermined field multiplexed with the television broadcast signal;
Delaying the second carrier color signal of the second scan line adjacent to the first scan line by a plurality of delay times with respect to the first carrier color signal of the first scan line;
Calculating a correlation between the first carrier color signal and the second carrier color signal delayed by a plurality of delay times, and corresponding to the delay time of the second carrier color signal at which the correlation is maximized; A television broadcast signal processing method, comprising: controlling a delay time of the television broadcast signal.

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