KR100213214B1 - Apparatus and method for shaving wave in dvcr - Google Patents

Abstract

Disclosed are a digital video system having a waveform shaping function and a waveform shaping method thereof. A digital decoder that inputs and decodes an analog signal or a compressed digital signal, outputs the decoded value as a digital video data signal, and a system that forms a waveform of a synchronization signal and outputs it to a TV has a level corresponding to the level of the synchronization signal. A first selecting means for selectively outputting a reference level signal and a video data signal having a second signal; and a digital low pass filter for removing and outputting high frequency components of a signal output from the first selecting means. A second selection means for inputting an output and an output of the first selection means, and selectively outputting the output of the second selection means in response to the delayed synchronization signal, and outputting the input signal to a TV broadcasting system. Digital encoder that encodes and outputs as video signal and analog by inputting output of digital encoder A DAC for converting to a call and outputting the converted analog signal to a television as a baseband composite video signal; a delayed synchronization signal is generated when the synchronization signal is enabled, and a delayed synchronization signal is not generated when the synchronization signal is disabled. It is characterized in that it does not, there is an effect of preventing the deterioration of the image quality.

Description

Digital video system having waveform shaping function and waveform shaping method thereof

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital video system, and more particularly, to a digital video system having a waveform shaping function for shaping a high frequency component of a synchronous signal carrying a digital video data signal into a low frequency component and a waveform shaping method performed in the system. It is about.

FIG. 1 is a block diagram of a general video system for explaining a digital video system having a waveform shaping function, which is composed of a digital decoder 10, a digital video system 20, and a monitor or television 30. As shown in FIG.

The digital decoder 10 shown in FIG. 1 inputs and decodes an analog signal or a digital signal compressed in MPEG through an input terminal IN, and decodes the decoded value into the digital video system 20 as a digital video data signal and a synchronization signal. Output The digital video system 20 inputs a digital video data signal and a synchronization signal output from the digital decoder 10 to shape a waveform of the synchronization signal, and outputs the shaped synchronization signal and the digital video signal to the RF of the monitor or television 30. Output to the receiving end (not shown).

2 is a block diagram of a digital video system having a conventional waveform shaping function, including a multiplexer (MUX) 40, an encoder 42, a digital to analog converter (DAC) 44, and ( Analog) filter 46.

3 is a waveform diagram of each unit in the apparatus shown in FIG. 2, (a) is a waveform diagram of a baseband composite video signal, and (b) is a waveform diagram of a synchronization signal.

The MUX 40 shown in FIG. 2 inputs a reference level signal having a level corresponding to the level of the digital video data signal and the synchronization signal output from the digital decoder 10 shown in FIG. 1 through input terminals IN1 and IN2. Then, one of the input signals is selectively output in response to the synchronization signal S1 shown in FIG. That is, when the synchronization signal is enabled, the digital video data signal is output to the encoder 42, and when the synchronization signal becomes the disable signal, the reference level signal is output to the encoder 42.

The encoder 42 inputs a signal output from the MUX 40, encodes it into a digital composite video signal, and outputs the encoded digital composite video signal to the DAC 44. The encoder 42 includes a modulation block (not shown) and a timing generator (not shown) for generating a digital video signal according to the television method, that is, NTSC, PAL or SECAM method, and 10-bit. Alternatively, data having a width of 8 bits or the like is output to the DAC 44. The DAC 44 converts the digital signal shown in FIG. 3 (a) output from the encoder 42 into an analog signal, and filters the analog baseband composite video signal (CVBS: composite video baseband signal). Will output At this time, noise is generated in the CVBS whose output voltage changes abruptly, and the point where the sudden change of the signal occurs in the video signal is likely to occur in the rising and falling sections of the horizontal and vertical synchronization signals. Big. The filter 46 inputs and filters the signal output from the DAC 44 to compensate for this.

However, since the video data 50 and the synchronization signal 52 shown in Fig. 3A are filtered together, there is a problem that causes deterioration of the image.

SUMMARY OF THE INVENTION The present invention has been made in an effort to provide a digital video system having a waveform shaping function to remove high frequency components generated in a rising and falling section of a synchronization signal and not affecting a video signal.

Another object of the present invention is to provide a waveform shaping method performed in a digital video system having a waveform shaping function according to the present invention.

1 is a block diagram of a general video system for explaining a digital video system having a waveform shaping function.

2 is a block diagram of a digital video system having a conventional waveform shaping function.

3 is a waveform diagram of each part in the apparatus shown in FIG.

4 is a block diagram of a waveform shaping device according to the present invention.

FIG. 5 is a diagram illustrating an embodiment of the digital low pass filter illustrated in FIG. 4.

FIG. 6 is a flowchart for describing a waveform shaping method performed in FIG. 4.

7 is a waveform diagram of a synchronization signal output from the apparatus shown in FIG. 4.

In order to achieve the above object, a digital decoder for inputting and decoding an analog signal or a compressed digital signal, outputting the decoded value as a digital video data signal, and the waveform shaping according to the present invention for shaping a waveform of a synchronization signal and outputting it to a television A digital video system having a function includes first selection means for selectively outputting a reference level signal having a level corresponding to the level of the synchronization signal and the video data signal in response to the synchronization signal, and from the first selection means. A digital low pass filter for removing and outputting a high frequency component of an output signal, a second selecting means for inputting an output of the digital low pass filter and an output of the first selecting means and selectively outputting the delayed synchronizing signal; Inputting the output of the second selection means and sending the input signal to the tele; A digital encoder that encodes and outputs a digital video signal corresponding to a broadcast method (PAL, SECAM, or NTSC) of a video source, and converts the output of the digital encoder into an analog signal, and converts the converted analog signal into a baseband composite video signal. And digital / analog conversion means for outputting to the television, wherein the delayed synchronization signal is generated when the synchronization signal is enabled, and the delayed synchronization signal is not generated when the synchronization signal is disabled.

In order to achieve the above object, a digital decoder which inputs and decodes an analog signal or a compressed digital signal, outputs the decoded value as a digital video data signal, and has a waveform shaping function of shaping a waveform of a synchronization signal and outputting it to a television. In the waveform shaping method according to the present invention performed in a digital video system, a determination step of determining whether the synchronization signal is input in an enabled state, and encoding the digital video data signal when the synchronization signal is input in an enabled state A first encoding step, a filtering step of removing a high frequency component of the sync signal when the sync signal is input in a disabled state, a second encoding step of encoding the sync signal from which the high frequency component has been removed, and the first or second The encoded digital signal is analyzed after two encoding steps. The signal conversion step is preferably performed by converting into a log signal and outputting to the television as a baseband composite video signal.

Hereinafter, a configuration and operation of a digital video system having a waveform shaping function according to the present invention and a waveform shaping method performed in the system will be described with reference to the accompanying drawings.

4 is a block diagram of a waveform shaping device according to the present invention, which selectively outputs a reference level signal IN2 and a video data signal IN1 having a level corresponding to the level of the synchronization signal in response to the synchronization signal S1. The first selector 60, the digital low pass filter 62 which removes and outputs the high frequency components of the signal output from the first selector 60, the output of the digital low pass filter 62, and the first selector. A second selector 64 for inputting the output of the 60 and selectively outputting in response to the delayed synchronization signal S2, and an output of the second selector 64; The digital encoder 66 and the digital encoder 66, which encodes and outputs a digital video signal corresponding to a broadcasting method (PAL, SECAM, or NTSC), are input and converted into analog signals, and the converted analog signals are converted into baseband signals. As a composite video signal (OUT) It consists of: (digital to analogue converter DAC) (68) the output digital / analog converter for.

FIG. 6 is a flowchart for explaining a waveform shaping method performed in FIG. 4, which includes selectively removing high frequency components (steps 70 and 72) according to a synchronization signal, and encoding signals (steps 74 and 76). Step), and the step of converting into an analog signal (step 78).

The first selection unit 60 of the waveform shaping apparatus shown in FIG. 4 inputs the digital video data signal from the digital decoder 10 shown in FIG. 1 through the input terminal IN1 and inputs the level of the synchronization signal through IN2. A reference level signal having a corresponding level is input, and one of the input signals is selectively output in response to the synchronization signal S1 shown in FIG. The first selector 60 determines whether the synchronization signal S1 is in an enabled state (step 70), and outputs a digital video data signal in the enabled state, and outputs a reference level signal in the disabled state. The digital low pass filter 62 shown in FIG. 4 may be implemented as a finite impulse response (FIR) filter. The low pass filter 62 inputs a signal output from the first selector 60 to perform a filtering function of removing high frequency components (step 72). At this time, the digital low pass filter 62 has a linear group delay, and in the fifth order, has a two clock delay.

For example, assuming that the transfer function of the digital low pass filter 62 has a fifth order coefficient, the transfer function according to the present invention is given by Equation 1 below.

Here, h (t) is a transfer function, n is an integer in z-n, and it means n clock delays. The output signal has a group delay compared to the input signal and has (n-1) / 2 clock delays.

FIG. 5 is a diagram illustrating an embodiment of the FIR filter when the digital low pass filter 62 shown in FIG. 4 is a finite impulse response (FIR) filter having a fifth order coefficient. 92, 94, 96, 98, six coefficient multipliers 100, 102, 104, 106, 108, and 110, and one adder 112, which may be implemented in many other ways.

X (nT) illustrated in FIG. 5 is an input signal of the finite impulse response filter illustrated in FIG. 4, and y (nT) represents a signal output to the second selector 64.

In the case of a finite impulse response filter having a fifth order coefficient as shown in Equation 1, two edge-triggerred registers may be connected in series to implement the same.

On the other hand, the second selector 64 inputs the signal output from the digital low pass filter 62 and the signal output from the first selector 60, and responds to the delayed synchronization signal S2. Optionally output to digital encoder 66. That is, the delayed sync signal S2 controls the digital video data signal output from the first selector 60 to be output to the second selector 64 when the sync signal is in the enabled state, and the sync signal is displayed. In the enabled state, the digital low pass filter 62 controls the selective data output of the second selector 64 so that the synchronization signal from which the high frequency is removed is output to the digital encoder 66.

The digital encoder 66 inputs the output of the second selector 64 in accordance with the clock CLK, encodes the synchronous signal and the digital video data signal (steps 74 and 76), and digital / analog the encoded signal. Output to converter 68. The DAC 68 inputs an encoded digital signal, converts it into an analog signal, and outputs the converted analog signal as a baseband composite video signal through an output terminal OUT.

FIG. 7 is a waveform diagram of a synchronization signal output from the apparatus shown in FIG. 4, reference numeral 120 denotes a waveform diagram of a non-waveform shaped sync signal, and 122 is a waveform diagram of a waveform shaped sync signal.

As shown in FIG. 7, it can be seen that the standing and falling portions of the synchronization signal are alleviated when comparing the waveform-formed synchronization signal with the synchronization signal that is not. That is, the high frequency component is removed. This prevents overshoot and ringing that may occur in the standing and falling portions of the synchronization signal.

As described above, the waveform shaping apparatus and method of the digital video system according to the present invention reduce overshooting or ringing of a signal input to a monitor or television, and filtering on a video signal is performed. Since it is not performed, there is an effect of preventing deterioration of image quality.

Claims (4)

A digital video system having a digital decoder for inputting and decoding an analog signal or a compressed digital signal, outputting the decoded value as a digital video data signal, and a waveform shaping function for shaping a waveform of a synchronous signal and outputting it to a television. First selecting means for selectively outputting a reference level signal having a level corresponding to the level of the synchronization signal and the video data signal in response to the synchronization signal; A digital low pass filter for removing and outputting high frequency components of the signal output from the first selecting means; Second selection means for inputting the output of the digital low pass filter and the output of the first selection means and selectively outputting in response to a delayed synchronization signal; A digital encoder which inputs the output of the second selection means, encodes the input signal into a digital video signal corresponding to the broadcast method (PAL, SECAM or NTSC) of the television; And Digital / analog conversion means for inputting the output of the digital encoder and converting it into an analog signal and outputting the converted analog signal to the television as a baseband composite video signal; The delayed synchronization signal is generated when the synchronization signal is enabled, and the delayed synchronization signal is not generated when the synchronization signal is disabled. The digital video system having a waveform shaping function according to claim 1, wherein the transfer function of the digital low pass filter is 1 + 4z-1 + 4z-2 + 6z-3 + 4z-4 + 1z-5. The digital video system having a waveform shaping function as claimed in claim 1, wherein the digital low pass filter is a finite impulse response filter. A waveform performed in a digital video system having a digital decoder which inputs and decodes an analog signal or a compressed digital signal, outputs the decoded value as a digital video data signal, and a waveform shaping function for shaping a waveform of a synchronous signal and outputting it to a television. In the shaping method, A determination step of determining whether the synchronization signal is input in an enabled state; A first encoding step of encoding the digital video data signal when the synchronization signal is input in an enabled state; Filtering the high frequency component of the synchronization signal when the synchronization signal is input in a disabled state; A second encoding step of encoding the synchronization signal from which a high frequency component is removed; And And a signal conversion step of converting the encoded digital signal into an analog signal and outputting the encoded digital signal to the television as a baseband composite video signal after the first or second encoding step. Waveform shaping methods performed on.