JP2642464B2 - Television signal converter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention has a larger number of scanning lines and a wider aspect ratio than a standard television signal, and two color difference signals are line-sequential by a dot interlace method. The present invention relates to a television converter for converting a high-definition television signal encoded by the TCI method into a standard television signal.

(Prior Art) A high-definition television signal having a larger number of scanning lines and a wider aspect ratio than a standard television signal and encoded by a TCI method in which two color difference signals are line-sequential by a dot interlace method is converted to a standard television signal. A system conversion device for converting data into an image has been developed.

In FIG. 6, a high-definition television signal is input to an analog / digital (A / D) converter 1 and digitized. For example, it is assumed that a luminance signal among high-definition television signals is transmitted in a sampling pattern as shown in FIG. The solid black circles represent, for example, sampling data of odd fields, and the black squares of broken lines represent sampling data of even fields.

The high-definition television signal digitized by the A / D converter 1 is input to the first converter 2. This first
The conversion device 2 converts 1125 scanning lines into 1050 scanning lines and simultaneously converts the time axis. That is, the first converter 2 converts a high-definition television signal from one horizontal scanning time of 1125 scanning lines to one horizontal scanning time of 1050 lines, and for example, changes the aspect ratio of 5: 3 to 4: 3. Converted to aspect ratio. The signal processing in this case is
Field memory etc. are used, delete the upper and lower 75 scanning lines out of 1125 scanning lines to 1050 lines, delete the left and right samples to convert the aspect ratio from 5: 3 to 4: 3, Processing is performed such that writing to the field memory is performed using the resample clock of the high-definition television signal and reading is performed using the resample clock of the standard television signal.

Among the output signals of the first converter 2, the luminance signal is input to the second converter 3. The second conversion device 3 performs a field interpolation process using data in the same field, and a vertical low-pass filter for removing aliasing components generated by converting the number of scanning lines from 1125 to 1050. (Hereinafter referred to as “vertical LPF”), filtering is performed, and interlaced conversion is performed to convert the number of scanning lines from 1050 lines to 525 lines. The output of the second converter 3 is
The signal is input to a digital-to-analog (hereinafter referred to as D / A) converter 21 and is converted into an analog signal.

On the other hand, two color difference signals (RY) and (BY) of the output signals of the first converter 2 are input to the third converter 4 and the fourth converter 5, respectively. The third conversion device 4 first converts the two chrominance signal signals, each of which has been compressed to 1/4, into four signals in order to perform TCI decoding of the (BY) signal.
Perform TCI elongation, which is twice as long. It also performs interlace conversion for converting the number of scanning lines from 1050 lines to 525 lines. The same applies to the fourth conversion device 5, which performs a conversion process on the (RY) signal. If a memory is used for the third and fourth converters 4 and 5, for example, the memory input clock 4
If data is read out using a clock having a double cycle, the time axis can be extended. The output signals of the third and fourth converters 4 and 5 are supplied to D and D via a first field interpolation circuit 6 and a second field interpolation circuit 7 for performing field interpolation and vertical interpolation, respectively. The signals are input to the / A converters 22 and 23 and converted into analog signals.

Output signals from the D / A converters 21, 22, and 23 are converted into R, G, and B signals by an inverse matrix circuit.

(Problem to be Solved by the Invention) As shown in FIG. 8 (a), a conversion method of performing processing in the time axis direction first, and then performing filtering in the vertical direction, as shown in FIG. 525 lines / 60H, 60Hz, 2: 1 interlace, 5: 3 aspect ratio signal
As in the example of converting into a standard television signal with z, 1: 1 interlace and aspect ratio of 4: 3, the upper and lower parts of 1125 scanning lines are cut down to 1050, and one out of two This is an effective method for a simple conversion in which 525 scanning lines are created by thinning out the scanning lines in proportion. However, according to this method, both ends of the transmitted image are lost, and the information contained in this portion cannot be viewed by the viewer. In order to prevent such a loss of information, the program provider needs to produce a screen in consideration of conversion from a high definition television signal to a standard television signal. However, when producing a screen in consideration of the conversion from a high-definition television signal to a standard television signal, on the contrary, for a viewer receiving a high-definition television signal, the screen is very difficult to view. There is a problem.

Here, in order to display a high-definition television signal without loss of information, as shown in FIG.
When converting a signal with an aspect ratio of 5: 3 and reducing it to 525 lines with an aspect ratio of 5: 3 and displaying it on a screen with an aspect ratio of 5: 4, the number of scanning lines can be reduced to 5: 2 or 3: 1. A conversion process is required. Such a conversion process is difficult to realize by the conversion method shown in FIG. Further, it is difficult to realize the conversion shown in FIGS. 8A and 8B with the same hardware.

Therefore, an object of the present invention is to provide a television signal conversion device capable of selectively realizing a plurality of types of conversion from a high-definition television signal to a standard television signal with the same hardware.

[Means for Solving the Problems] The present invention relates to a method for converting a high-definition television signal having a larger number of scanning lines and a different aspect ratio to a standard television signal and encoded by the TCI system into a standard television signal. An analog-to-digital converter for digitizing the high-definition television signal; and delaying an output signal from the analog-to-digital converter by one horizontal scanning time to output sampling data of a plurality of scanning lines. And a set of coefficient values to be multiplied to each sampling data in a state where sampling data of the plurality of scanning lines are input and the sampling data are equivalently arranged two-dimensionally around data to be interpolated. Adjustment can be arbitrarily switched, and scanning is performed by synthesizing the output multiplied by the coefficient value. A two-dimensional signal processing means for obtaining a number of interpolated output data, and a predetermined coefficient value stored for switching a combination of the coefficient values in the two-dimensional signal processing means; And a screen display mode control means for outputting to the two-dimensional signal processing means, and one horizontal scanning of a standard television signal from one horizontal scanning time of a high definition television signal for data outputted from the two-dimensional signal processing means. It comprises time axis conversion means for converting the time axis into time, and means for performing vertical interpolation of the color signal output from the time axis conversion means.

(Operation) By the above-mentioned means, the 1125 signals having an aspect ratio of 5: 3 shown in FIG. 8 (b) for displaying a high-definition television signal without loss of information are reduced with an aspect ratio of 5: 3. 52
Conversion such as displaying 5 screens with an aspect ratio of 5: 4,
That is, it is possible to realize a method of converting the number of scanning lines to, for example, 5: 2 or 3: 1 by interpolation processing, and selectively use both the conversion methods shown in FIGS. 8 (a) and 8 (b). Can be easily implemented with the same hardware, and 525 lines / 60
It is possible to provide a television signal converter that can easily convert to various formats such as 2: 1, 525 lines / 60 Hz at 1: 1 and 1050 lines / 60 Hz at 2: 1.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows an embodiment of the present invention. An analog / digital (A / D) converter 31 is supplied with a high-definition television signal from an input terminal 30. High-definition television signals
This is a signal that has a larger number of scanning lines and a wider aspect ratio than a standard television signal, and is encoded by the TCI method in which two color difference signals are line-sequentially scanned by the dot interlace method. The A / D converter 31 performs analog-to-digital conversion with a clock Φ1 of, for example, 16.2 MHz.

Here, 1125 scanning lines, 60 Hz field frequency, 2:
As shown in FIG. 8 (a), a high-definition television having one interlace and an aspect ratio of 5: 3 was obtained by removing the slope portion of the figure, and having 525 scanning lines, a field frequency of 60 Hz, and a 1: 1 interlace. It shall be converted to a standard television signal having an aspect ratio of 4: 3.

The output signal of the A / D converter 31 includes a line memory 32 for delaying a high definition television signal by one horizontal scanning period, and an adder 36.
Is supplied to a synchronization generation circuit 70 for generating a synchronization signal of the high definition television signal. The output signal of the line memory 32 is input to a similar line memory 33 and a coefficient adder 52. The output signal of the adder 36 is input to the coefficient adder 51.

In the figure, reference numeral 50 denotes a two-dimensional digital filter that simultaneously performs scanning line conversion and field interpolation. Coefficient adders 51 and 52
Shows the inside of one coefficient adder 51 specifically because of the same configuration. The output signal from the adder 36 is supplied to a horizontal one-sample delay unit 101 and an adder 106. The coefficient adder 51 is a horizontal one that forms a two-dimensional digital filter.
The sample delay units 101 and 102 are connected in series, and the output of the horizontal one-sample delay unit 102 is supplied to an adder 106. The output signal of the adder 106 is supplied to a coefficient unit 111. Also,
The output of the horizontal one-sample delay unit 101 is supplied to a coefficient unit 112, and the outputs of the coefficient units 111 and 112 are added by an adder 107. Then, the output signal of the adder 107 is supplied to the adder 109.

The output signal from the coefficient adder 52 is also supplied to the adder 109.

Next, the operation of the two-dimensional digital filter 50 will be described.

First, a case will be described in which a high-definition television signal is converted into a 525 line / 60 Hz, 1: 1 interlace signal by cutting the upper and lower scanning lines and performing field interpolation as described in FIG. .

FIG. 2 is an example of a coefficient value pattern of each sampling data of a luminance signal processed inside the two-dimensional digital filter 50. Here, for high-definition television signals, to perform field interpolation and scan line conversion simultaneously, and to convert to 525/60, 1: 1 interlace,
The combination of coefficient values in the odd field and the even field is changed as shown in FIG. FIG. 3 shows a sample pattern of the input signal of the two-dimensional digital filter 50. The solid line is an odd field line, and the broken line is an even field line.

In the odd-numbered field, for example, at the timing of interpolating the data at point A, a coefficient value set A ｛A in FIG. At the timing of interpolating the data at point B using｝, the coefficient value set B indicated by B in FIG. 2 (a) is a coefficient value not surrounded by a dashed line around point B. (However, including the center coefficient value 3/2) Use｝.

That is, when the data of the point A in FIG. 3 is created, the coefficient for the data a2, b1, b2, and c2 is set A (FIG. 2 (a)).
The coefficient units 111, 112, 121, and 122 are controlled so as to be 1/4 as shown in FIG. When the data at point B in FIG. 3 is interpolated (reproduced), the coefficients for data a1, a2, b1, c1, and c2 are set as shown in set B (FIG. 2 (a)). Then, the coefficient units 111, 112, 121 and 122 are controlled.

In other words, the data at point A is created by a2 (1/4) + b1 (1/4) + b2 (1/4) + c2 (1/4), and the data at point B is a1 (-1/8) + a2 ( -1/8) + b1 (3/2) + c1 (-1/8) +
Created by c2 (-1/8).

A coefficient control signal for this coefficient switching is provided from the mode control circuit 210 in the control unit 71 to each coefficient unit.

Next, in the even field (data of a dotted line arrives), for example, at the timing of interpolating the data of point A, a set A of coefficient values indicated by A in FIG. At the timing of interpolating the data at the point B using the coefficient value (coefficient value), a set B (coefficient value not surrounded by a dashed line) of the coefficient value indicated by B in FIG. 2B is used.

In the even field, the scanning line (broken line) is shifted from the solid line (scanning line in the odd field). But,
To generate interpolation data at the position (timing) indicated by a solid line, 1: 1 interlace conversion is performed. Therefore, when the data of the point A in FIG. 3 is created, the coefficient values for the data e2, d1, and d2 are 1/2, 1/4, and 1/4 as in the set A (FIG. 2B). Coefficient factor 1
11, 112, 121 and 122 are controlled. When the data at the point B in FIG. 3 is created, the coefficient values for the data e1, e2, and d1 are 1/4, 1/4, 1/2 as shown in the set B (FIG. 2 (b)). The coefficient units 111, 112, 121, and 122 are controlled such that

The field interpolation processing is similarly performed for the color signal processing.

The output signal from the adder 109 that has been subjected to the interpolation processing as described above has been subjected to the scanning line number conversion and the interlace conversion as shown in FIG. 8A. If the clock rate of the output signal of the two-dimensional digital filter 50 is, for example, 16.2 MHz, the clock rate of the output signal is twice as high as 32.4 MHz. Therefore, if this output signal is a luminance signal, it is necessary to further perform an aspect ratio conversion and a time axis conversion that match the standard method. In the case of a color signal, further expansion of the color signal is required.
This processing will be further described later.

Next, as shown in FIG. 8 (b), a case will be described in which the aspect ratio is reduced to 5: 3 so that the information of the high definition television signal is not lost (particularly, left and right information).

For example, assuming that the number of scanning lines of 1125 (60 Hz, 2: 1 interlace) is thinned out to 1/3, the luminance signal will be described.

FIG. 5 shows a sampling data pattern of an input signal of an odd field.

At the timing of interpolating (re-creating) the data at the point A1 in FIG. 5, the set K of the coefficient values in FIG.
At the timing of interpolating the data of point A2, FIG.
4A is used at the timing of interpolating the data at point A3, and at the timing of interpolating the data at point A4, the fourth set of coefficients is used. The set P of coefficient values shown in FIG. Further, at the timing of interpolating the data at point B1, the set L of coefficient values in FIG. 4A is used, and at the timing of interpolating the data at point B2, the coefficient value of FIG. The set P is used, and at the timing of interpolating the data at point B3, the set K of the coefficient values in FIG. 4A is used. At the timing of interpolating the data at point B4, FIG. Is used. Fifth
The six scanning lines in the odd field shown in the figure are converted into four scanning lines, and 525 lines (60 Hz, 1: 1 interlace)
A signal can be obtained from the 375 lines in the center as viewed from above and below. Similarly, when interpolating the data of the even field, the same 525 lines (60 Hz, 1: 1 interlace) as the odd field are obtained by obtaining the signal at the same scanning position as the odd field.
It is reduced to 3, and 375 signals in the center seen from above and below 375 lines (60 Hz, 1: 1 interlace) are obtained. As a result, the number of high-definition television signal scanning lines is 1125 (60 Hz, 2: 1
Interlaced) signal is obtained. That is, the number of scanning lines becomes 3: 1 before conversion (1125 lines) and after conversion (375 lines). Also, if thinning is performed at a ratio of 2.5, the ratio becomes 5: 3 before and after conversion. Of the signals whose scanning lines have been converted in this way, the luminance signal is time-axis converted by the time axis conversion circuit 61, and the color signal is expanded by the color signal time axis conversion circuit 62 for expanding the color signal.

In the case of the signal conversion of the system shown in FIG. 8A, the time axis conversion is performed as follows. That is, in the case of a luminance signal, the luminance signal
The output signal of the two-dimensional digital filter 50 is stored in the memory of it
At the clock rate of 32.4 MHZ, processing is performed in which a portion outside the area having an aspect ratio of 4: 3 is deleted and written.
Then, the aspect conversion and the time axis conversion are realized by reading from the memory at a clock rate of 20.8 MHz, for example. On the other hand, in the color signal time axis conversion circuit 62, in addition to the same processing as the luminance signal time axis conversion circuit 61, since the color signal is, for example, TCI-encoded and compressed to 1/4,
Here, the extension processing is performed simultaneously. Therefore, the readout is performed at a clock rate 1/4 of the readout rate of 20.8 MHz for the luminance signal.

On the other hand, when the conversion is performed by the method as shown in FIG. 8 (b), since the aspect conversion is not performed, the read clock is, for example, 27.728 MHz.

As described above, the clocks and control signals supplied to the time axis conversion circuits 61 and 62 are obtained from the control unit 71.

The synchronization signal of the high-definition television signal generated by the synchronization generation circuit 70 is used as a timing signal of the high-definition television signal system, and is also supplied to the synchronization generation circuit 212 of the standard television signal system of the control unit 71. ing. The synchronization generating circuit 212 for the standard television signal system generates the read clock and the timing signal for the standard television signal system. In addition, the switch 211 can be controlled by a switching signal from the mode control circuit 210 in the control unit 71 to perform various switching of the read clock.
For example, 525 lines / 60Hz, 2: 1 interlace, 525 lines / 60Hz,
It can output as signals of various formats of 1: 1 interlace, 1050 lines / Hz, and 2: 1 interlace. In response to this system conversion, the horizontal deflection frequency of the display (picture tube device) is selectively switched between 15.7 KHz and 31.5 KHz.

The digital luminance signal output from the time axis conversion circuit 61 is converted into an analog signal by the digital / analog converter 21 and input to the inverse matrix circuit 24. The digital color signal output from the time axis conversion circuit 62 is
Entered in 63. The vertical interpolation circuit 63 has line memories 631 and 632 having a delay amount of one horizontal period, an adder 633, and a selector 634, and interpolates and separates (RY) and (BY) signals. Then, the (RY) signal is supplied to the digital-to-analog converter 22, and the (BY) signal is supplied to the digital-to-analog converter 23. The signals output from the digital-to-analog converters 22 and 23 are converted by an inverse matrix circuit 24.
Supplied to In the inverse matrix circuit 24, R, G, B signals are generated and supplied to the display 25.

Means for synchronizing a plurality of scanning line signals by using a plurality of line memories and a method of multiplying sampling data by a coefficient value as shown in FIGS. 2 and 4 can be realized by various methods. It suffices if calculation patterns as shown in FIGS. 2 and 4 can be obtained. The example shown in FIG. 1 is a circuit devised so as to reduce the number of parts as much as possible.

As described above, according to the conversion method of the present invention, the two-dimensional digital filter 50 and the mode control circuit 210
Is characterized in that a set (pattern) of coefficient values can be switched in the two-dimensional signal processing unit according to the first embodiment.
As a result, various types of output signals can be obtained with the same hardware as described with reference to FIGS.

For example, as shown in FIG. 8 (a), upper and lower lines can be deleted to create a signal for a standard television signal, and as shown in FIG. 8 (b), A signal compressed by interpolation processing can be created without deleting lines (loss of information).

When the number of scanning lines in the vertical direction is converted and displayed on the display 25 in this manner, for example, an image that is a perfect circle in a high-definition television signal is displayed as a perfect circle image even in a standard television signal. It is desirable.

To cope with this, the read clock frequency of the memory in the time axis conversion circuits 61 and 62 is switched.

Hereinafter, the read clock rate when performing the time axis conversion will be described.

(In case of realizing the conversion method shown in Fig. 8 (b)) According to the HDTV studio standard, the horizontal effective scanning rate is 1920/2200 samples = 87.3% and the vertical effective scanning rate is 1035/1125 lines = 92.0%.

 According to the NTSC standard, the effective horizontal scanning rate is 52.656 / 63,556 μs = 82.8%. The effective vertical scanning rate is 1035/1125 lines = 92.0%.

Looking at the ratio of the true circle to the converted circle in HD (1 = no distortion, + is horizontal): (4/3) / (16/9) x (525/375) x (1 / 82.8 ) / (1 / 87.3) = 1.107 (10.7% landscape).

Since the encoder performs 12:11 compression, the number of samples in one horizontal period after decompression on the receiving side is 960 × (11/12) = 880 samples (after interpolation). Therefore, 880 × 1.107 = 974.16 samples are required to make a perfect circle after conversion. Therefore, if you want to keep the distortion of the circle within about 5% of horizontal length,
Is preferably 974.16 × (1.05 / 1.107) = 924 or more.

In order for the horizontal blanking after conversion to not appear on the screen, the HDTV horizontal effective scanning rate is 374/480 = 0.779960 x (77.9) / (82.8) = 903 samples or less.

In consideration of the above, for example, if the clock rate after conversion is 525 and non-interlace is 912fH = 28.728 MHz, a natural image can be obtained even if the conversion is performed as shown in FIG. 8 (b). .

Next, a case where the conversion as shown in FIG. 8A is performed will be described.

Now, it is assumed that a Hi-Vision signal has, for example, an aspect ratio of 16: 9 and 1125 scanning lines, and converts this into a signal with an aspect ratio of 4: 3 and 525 scanning lines.

In the HDTV signal, 1H is 960 samples (32,4 MHz rate). If the number of 1H samples after conversion of this signal is N, then N = 960 × (4/5) × (1050) / (1125) = 720 samples.

Here, it is necessary to expand the data compressed by the encoder to 11:12 on the decoder side. Therefore, the number of samples is 720 × (11) / (12) = 660 samples, and when the clock rate is calculated, 660fH = 20.79 MHz.

As described above, according to this embodiment, various conversion methods can be realized by switching the combination pattern of coefficient values with the same hardware. Also, 2
The output of the dimensional signal processing circuit can be subjected to an arbitrary time axis conversion in a time axis conversion circuit according to the aspect ratio of the display.

[Effects of the Invention] As described above, according to the present invention, when a high-definition television signal is subjected to system conversion, it can be converted into various systems by the same hardware, and the flexibility is abundant. Even if the standard on the display side is changed, a signal conforming to the standard can be converted. Further, conversion without loss of information is possible.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is an explanatory diagram showing a pattern of coefficient values shown for explaining the operation of the circuit of FIG. 1, and FIG. 3 is a high definition television. FIG. 4 is an explanatory view showing a signal sampling pattern, and FIG.
FIG. 5 is an explanatory diagram showing a pattern of coefficient values shown for explaining the operation of the circuit shown in FIG. 5, FIG. 5 is also an explanatory diagram showing a sampling pattern of a high-definition television signal, and FIG. FIG. 7 is an explanatory diagram showing a sampling pattern of a high-definition television signal, and FIG. 8 is an explanatory diagram showing an example of system conversion of a television signal. 31 A / D converter, 32, 33 Line memory, 36 Adder, 50 Two-dimensional digital filter, 51, 52 Coefficient adder, 61, 62 Time axis conversion circuit 63 vertical interpolation circuit, 70 synchronization generation circuit, 71 control unit.

Claims (5)

(57) [Claims] An apparatus for converting a high-definition television signal having a larger number of scanning lines and a different aspect ratio than a standard television signal into a standard television signal encoded by a TCI method, comprising: Analog-to-digital conversion means for digitizing; delay means for delaying an output signal from the analog-to-digital conversion means by one horizontal scanning time to output sampling data of a plurality of scanning lines; and sampling data of the plurality of scanning lines. Is input, and in a state where the sampling data is equivalently and two-dimensionally arranged around the data to be interpolated, the combination of coefficient values applied to each sampling data can be arbitrarily switched, and the coefficient value is multiplied. Two-dimensional signal that obtains interpolated output data with the number of scanning lines converted by combining the output Processing means; and a screen display for storing preset coefficient values for switching the combination of the coefficient values in the two-dimensional signal processing means, outputting the predetermined coefficient values at a predetermined timing, and supplying the output to the two-dimensional signal processing means. A mode control means, and a time axis conversion means for converting a time axis of the data output from the two-dimensional signal processing means from one horizontal scanning time of a high definition television signal to one horizontal scanning time of a standard television signal. Means for vertically interpolating the color signal output from the time axis converting means. 2. The time axis conversion means, for the luminance signal of the data output from the two-dimensional signal processing means, from one horizontal scanning time of a high-definition television signal to one horizontal scanning time of a standard television signal. First time axis conversion means for converting; and data output from the two-dimensional signal processing means.
The color signal is converted from one horizontal scanning time of a high-definition television signal to one horizontal scanning time of a standard television signal, and time-expanded to one horizontal scanning time of the standard television signal in accordance with time axis compression by the TCI method. 2. The television signal conversion device according to claim 1, further comprising: a second time axis conversion unit; and a unit for performing vertical interpolation of the color signal output from the second time conversion unit. 3. The screen display mode control means,
The coefficient value multiplying process in the two-dimensional signal processing means performs sampling data of three vertically adjacent scanning lines in the first field and sampling data of two vertically adjacent scanning lines in the second field. 2. The television signal conversion device according to claim 1, wherein the coefficient value is output so as to be performed. 4. The screen display mode control means includes:
2. The two-dimensional signal processing means according to claim 1, wherein said coefficient value is supplied to said two-dimensional signal processing means such that a combination of coefficient values applied to each sampling data is switched for each scanning line of data to be interpolated. Television signal converter. 5. The screen display mode control means includes:
2. The two-dimensional signal processing circuit according to claim 1, wherein said coefficient value is supplied to said two-dimensional signal processing circuit such that a combination of coefficient values applied to each sampled data is switched every horizontal sample of data to be interpolated. The television signal conversion device according to the above.