JP3087584B2 - Digital color encoder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital color encoder applied to digital signal processing of a digital component video signal to obtain a digital carrier color signal.

[0002]

2. Description of the Related Art To realize a digital color encoder, a color subcarrier must be generated. The operating frequency of the means for generating a color subcarrier as a simple configuration to be N times the frequency of the color subcarrier frequency f _s is considered.
However, when the relationship between the sampling frequency and the color subcarrier frequency f _s of the digital component video signal is not an integer ratio, there is a need to be operated at a frequency N times the sampling frequency to generate a color subcarrier.

[0003] NTSC system of color sub-carrier frequency f _s is 3.579549
Relationship between the horizontal scanning frequency f _h in (MHz) is expressed by equation (1).

[0004]

(Equation 1)

Further, the color subcarrier frequency f _s of the PAL is 4.43361
The relationship between the horizontal scanning frequency f _h and the vertical scanning frequency f _v at 875 (MHz) is expressed by (Equation 2).

[0006]

(Equation 2)

[0007] The color subcarrier of the NTSC method from the equation (1) it can be seen that can be generated by controlling the counter of the horizontal scanning frequency f _h min. However, color subcarrier of the PAL require additional vertical scanning frequency f _v content of the counter because it contains terms of the vertical scanning frequency f _v of equation (2).

FIG. 3 is a block diagram showing a configuration of a digital color encoder of a first conventional example. In FIG. 3, reference numeral 306 denotes a clock 301 which is reset by a color frame pulse 305 inputted in synchronization with the input digital component video signals 303 and 304, and is switched by an NTSC / PAL switching signal 302.
Is counted for one color frame of NTSC or PAL, a reset signal is output for each color frame to reset the color subcarrier phase output from the color subcarrier generation means 309, and output from the color subcarrier generation means 309. A color frame counter 307 that outputs a phase correction pulse to correct a color subcarrier phase shift is provided by an NTSC / PAL switching signal 3.
Switch with 02, control with color frame counter 306,
Color burst adding means for adding and outputting color burst data to the first digital component video signal _Cb 303 and the second digital component video signal _Cr 304, and a color frame counter 308 is switched by an NTSC / PAL switching signal 302. 306, and the second digital component video signal _Cr 304 by the color burst adding means 307.
Code information adding means for adding and outputting code information to a signal obtained by adding color burst data to, 309 resets the output color subcarrier phase with a reset signal output for each color frame from the color frame counter 306, The added value is switched by the phase correction pulse from the color frame counter 306, the added value is switched by the NTSC / PAL switching signal 302, and the color that generates the phase of the color subcarrier by adding to the output color subcarrier phase every clock 301 Subcarrier generation means, 31
0 is the carrier suppression amplitude modulation by the output signal of the color subcarrier generation means 309, the signal obtained by adding color burst data to the first digital component video signal _Cb 303 by the color burst addition means 307, and the output signal of the code information addition means 308. And 311 is an output signal of the balanced modulation means 310.

In the first prior art shown in FIG. 3, the color subcarrier generation means 309 is controlled by a color frame counter 306 which operates by being reset by a color frame pulse 305 inputted in synchronization with the input digital component video signals 303 and 304. Input digital component video signals 303 and 3
When the period of the color frame pulse 305 varies due to 04 including jitter and the like, the output signal of the color subcarrier generation unit 309 also varies.

FIG. 4 shows a second conventional example in which the output signal of the chrominance subcarrier generation means does not fluctuate following the input digital component video signal even if it contains jitter and the like.

FIG. 4 is a block diagram showing the configuration of a second conventional digital color encoder. In FIG. 4, reference numeral 406 denotes a reset by a color frame pulse 405 input in synchronization with the input component video signals 403 and 404, and NTSC / PAL
Switch the clock 401 with NTSC or
A color frame counter for counting one PAL color frame, 407 is switched by an NTSC / PAL switching signal 402, and the clock 401 is counted for one frame of NTSC or PAL,
A frame counter that outputs a phase correction pulse to correct the phase shift of the color subcarrier output from the color subcarrier generator 410, a 408 is switched by an NTSC / PAL switching signal 402, controlled by a color frame counter 406, digital component video signal C _b 403 and the second digital component video signal C _r color burst adding means 404 adds the color burst data output, 409 N
The signal is switched by a TSC / PAL switching signal 402, controlled by a color frame counter 406, and output by adding code information to a signal obtained by adding color burst data to the second digital component video signal C _r 404 by a color burst adding means 408. The code information adding means 410 switches the addition value with the phase correction pulse from the frame counter 407, switches the addition value with the NTSC / PAL switching signal 402, and adds the color subcarrier phase of the output signal for each clock 401 to add the color subcarrier. Color sub-carrier generation means for outputting the phase of the carrier, 411 is a color sub-carrier generation means 410
, A signal obtained by adding color burst data to the first digital component video signal _Cb 403 by the color burst adding means 408, and an output signal of the code information adding means 409, and carrier-suppressed amplitude modulated and output. A modulating means 412 is an output signal of the balanced modulating means 411.

In this second conventional example, since the color subcarrier generation means 410 is controlled by the frame counter 407 which operates without synchronizing with the digital component video signal, even if the input digital component video signals 403 and 404 contain jitter and the like. The frequency of the chrominance subcarrier does not change.

[0013]

However, in the configuration of the prior art described above, the input digital component video signal contains jitters and the like, and is reset by a color frame pulse input in synchronization with the digital component video signal to count the color frames. If the color frame counter cannot correct the phase of the chrominance subcarrier, a frame counter that counts the number of clocks for one frame is needed to generate the PAL chrominance subcarrier. There was a problem of inviting.

An object of the present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to generate both types (NTSC, PAL) of color subcarriers with a small number of circuits.

[0015]

In order to achieve this object, a digital color encoder according to the present invention operates with a clock having a frequency N times the sampling frequency of a digital component video signal, and comprises a first and a second color difference signal. , NT
SC / PAL switching signal, standard input switching signal, color frame pulse input in synchronization with first and second color difference signals are input, reset with color frame pulse, NT
Switching by SC / PAL switching signal, counts the clock for the color frame, outputs the first phase correction pulse, and color frame counter that switches by NTSC / PAL switching signal. Controlled by a clock counter that outputs a phase correction pulse and a color frame counter, additional data is switched by an NTSC / PAL switching signal, and color burst data is added to the first and second color difference signals to generate first and second signals. A color burst addition unit for outputting an output signal, and a code information addition unit controlled by a color frame counter to add code information to a second output signal of the color burst addition unit and output the same, and switched by a standard input switching signal. Controlled by the first phase correction pulse or the second phase correction pulse, and switched by the NTSC / PAL switching signal to generate the color subcarrier A color sub-carrier generating means, and a balanced modulation means for receiving the output signal of the color sub-carrier generating means, the first output signal of the color burst adding means, and the output signal of the code information adding means and outputting a carrier chrominance signal. It has the structure of.

[0016]

According to the present invention, the input digital component video signal includes jitter and the like, and is reset by a color frame pulse input in synchronization with the digital component video signal to count the number of clocks for the color frame. If the color frame counter cannot correct the phase of the color subcarrier, a frame counter that counts the number of clocks for one frame was required in addition to the color frame counter. Since the color subcarrier can be phase corrected by the clock counter to generate the PAL color subcarrier, the circuit scale can be reduced, and the cost and power consumption can be reduced.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a digital color encoder showing an embodiment of the present invention.

In FIG. 1, reference numeral 107 denotes an input component video signal 1
Color frame pulse 105 input in synchronization with 03, 104
The clock 101 is counted for one NTSC or PAL color frame by switching with the NTSC / PAL switching signal 102, and reset for each color frame to reset the color subcarrier phase output from the color subcarrier generator 111. A color frame counter that outputs a signal and outputs a first phase correction pulse to correct the phase shift of the color subcarrier output from the color subcarrier generator 111;
Switch with the PAL switching signal 102 and set the clock 101 to NTSC
Alternatively, a clock counter that counts half of one line of the PAL and outputs a second phase correction pulse to correct the color subcarrier phase shift output from the color subcarrier generation unit 111, and 109 is an NTSC / PAL switching signal 102 And a color burst counter 107 controlled by the color frame counter 107 to add and output color burst data to the first digital component video signal _Cb 103 and the second digital component video signal _Cr 104. / PAL switching signal 102, color frame counter 107
Code information adding means for adding code information to a signal obtained by adding color burst data to the second digital component video signal C _r 104 by a color burst adding means 109 and outputting the signal. 111 denotes a standard input switching signal 106. When indicating that the period of the color frame pulse 105 is a standard signal that does not fluctuate, the output color subcarrier phase is reset by a reset signal output for each color frame from the color frame counter 107, and the second signal from the color frame counter 107 is reset. When the addition value is switched by one phase correction pulse and the standard input switching signal 106 indicates that the period of the color frame pulse 105 fluctuates, the clock counter
The added value is switched by the second phase correction pulse from 108, and N
The added value is switched by the TSC / PAL switching signal 102, and the clock
A color subcarrier generation means for adding the color subcarrier phase to the output color subcarrier phase for each 101 and outputting the color subcarrier phase; 112, an output signal of the color subcarrier generation means 111 and a first digital component Signal obtained by adding color burst data to video signal _Cb 103 and code information adding means 11
Balanced modulation means 113 for performing carrier wave suppression amplitude modulation with an output signal of 0 and outputting the result is indicated by reference numeral 113.

[0020] PAL color subcarrier frequency f _s is 4.4336187
Relationship between the horizontal scanning frequency f _h in 5 (MHz) is expressed by equation (3).

[0021]

(Equation 3)

As an example, let the frequency of the input clock 101 be f
relationship between the horizontal scanning frequency f _h When _clk (= 27 MHz) is expressed by equation (4).

[0023]

(Equation 4)

Further, the relationship of f _v and f _h is expressed by equation (5).

[0025]

(Equation 5)

[0026] f _s than (number 3) and (number 4) (5) is (number 6).

[0027]

(Equation 6)

Therefore, f _s / f _clk becomes ( _Equation 7).

[0029]

(Equation 7)

Equation (7) is represented by 17 bits in consideration of the phase error, the upper 10 bits represent 360 °, and are obtained by dividing the first and second items into Equation (8) and Equation (9). Becomes

[0031]

(Equation 8)

[0032]

(Equation 9)

In order to faithfully realize the formula (9), a counter for one frame is required, so 173/5 ⁴ = 18/6
Approximate to 4 to obtain (Equation 10).

[0034]

(Equation 10)

Eventually, (Equation 11) is obtained.

[0036]

[Equation 11]

[0037] Similarly, the relationship of f _s and f _clk when the NTSC is expressed by equation (12).

[0038]

(Equation 12)

FIG. 2 shows a block diagram of the chrominance subcarrier generation means 111 for realizing (Equation 11) and (Equation 12) and its peripheral part.

In FIG. 2, when the cycle of the input digital component video signals 103 and 104 fluctuates, the addition is controlled by the clock counter 118, and the added value 204 is selected by the selector 207 once every 33 clocks. The selector 208 selects the addition value 206 once, the selector 210 selects the addition value 209 once every 1/2 line, and the NTSC / PAL switching signal 102 determines the output of the selector 207 and the output of the selector 210 by the selector 211. And adds to the output of the flip-flop 213, NTSC and P
AL color subcarriers can be generated.

If there is no change in the cycle of the input digital component video signals 103 and 104, the flip-flop 213 is reset by a reset signal output for each color frame from the color frame counter 117, and controlled by the color frame counter 117. Once every 33 clocks, the selector 207 selects the additional value 204, once every 27 clocks, the selector 208 selects the additional value 206, once every 1/2 line, the selector 210 selects the additional value 209, NTSC / PAL switching signal 102
The output of the selector 207 and the output of the selector 210 are selected by the selector 21.
Switching can be performed by 1, and the color subcarrier to which the color frame information is added by adding to the output of the flip-flop 213 can be generated.

Although the present invention has been described with reference to the embodiment, the structure of the present invention can be realized by various methods other than the above.

[0043]

As described above, according to the present invention, the input digital component video signal includes jitter and the like,
If the color sub-carrier phase cannot be corrected by the color frame counter that counts the number of clocks for the color frame by resetting with the color frame pulse input in synchronization with the digital component video signal, the conventional color frame counter In addition, a frame counter that counts the number of clocks for one frame was required.However, a clock counter that counts half the clock for one line generates the color subcarrier of NTSC and PAL by correcting the phase of the color subcarrier. Therefore, the circuit scale can be reduced, and cost and power consumption can be reduced.

When the input digital component video signal does not include jitter or the like, the color subcarrier can be phase corrected by a color frame counter to generate a carrier color signal including color frame information.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a digital color encoder according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a chrominance subcarrier generation means and its peripheral portion in the embodiment of the present invention.

FIG. 3 is a block diagram showing a configuration of a digital color encoder of a first conventional example.

FIG. 4 is a block diagram showing a configuration of a digital color encoder of a second conventional example.

[Explanation of symbols]

 107 Color Frame Counter 108 Clock Counter 109 Color Burst Addition Unit 110 Code Information Addition Unit 111 Color Subcarrier Generation Unit 112 Balance Modulation Unit

Continuation of the front page (56) References JP-A-63-256084 (JP, A) JP-A-63-185189 (JP, A) JP-A-1-177794 (JP, A) JP-A-5-30523 (JP) JP-A-6-62422 (JP, A) JP-A-55-86271 (JP, A) JP-A-55-86281 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB Name) H04N 9/44-9/78

Claims (1)

(57) [Claims] 1. The method according to claim 1, wherein the digital component video signal operates with a clock having a frequency N times higher than the sampling frequency.
First and second color difference signals, NTSC / PAL switching signal, standard input switching signal, color frame pulse input in synchronization with the first and second color difference signals are input, and reset with the color frame pulse. , The NTSC / PAL
A color frame counter that switches by a switching signal and counts the clock for a color frame, and outputs a first phase correction pulse, and switches by the NTSC / PAL switching signal, and switches the clock.
A clock counter that counts half of one line and outputs a second phase correction pulse, and is controlled by the color frame counter, and switches the additional data by the NTSC / PAL switching signal to the first and second color difference signals. A color burst addition unit that adds color burst data to output first and second output signals, and controls the color frame counter to add code information to a second output signal of the color burst addition unit. Code information adding means to be output, controlled by the first phase correction pulse or the second phase correction pulse by switching with the standard input switching signal,
A color subcarrier generating means for generating a color subcarrier by switching with an NTSC / PAL switching signal; an output signal of the color subcarrier generating means, a first output signal of a color burst adding means, and an output signal of the code information adding means A digital color encoder comprising balanced modulation means for inputting a signal and outputting a carrier color signal.