KR19990039345A - Multifunction video decoder - Google Patents

Abstract

A multifunctional video decoder is disclosed. A multifunction video decoder according to the present invention is a multifunction video decoder interfaced in series / parallel with an external microprocessor, comprising: a system clock signal generating means, a signal converting means for converting an analog video signal into a second digital video signal, A first selection means for selectively outputting one digital video signal or a second digital video signal, and outputting a first chroma signal, a second chroma signal, a luminance signal and a decoded vertical retrace signal from the first or second digital video signal; Signal separation means, residual component removal means, a down scaler for adjusting the number of pixels to be displayed, and data format means for outputting data in which luminance and first and second chromaticity signals are formatted corresponding to the first predetermined data format; In addition to the basic functions of the video decoder, residual components are removed and down. Scaling, and perform a variety of functions, such as the vertical blanking signal decoding and gamma correction, can be in addition to an analog video signal input is a digital video signal, there is an effect that it is possible to output various types of digital data.

Description

Multifunction video decoder

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to video decoders used in imaging systems such as televisions and video tape recorders, and more particularly to multifunctional video decoders that perform various functions such as residual component removal, downscaling, vertical retrace signal decoding, and gamma correction. .

In general, the function of the video decoder converts the externally input analog image data into a digital signal through an analog-to-digital converter, and separates the converted digital signal into a luminance signal and a color signal. It converts and outputs -bit digital image data. In addition to these basic functions, there is a need for a multi-function video decoder that includes a comb filter, a down scaler, a vertical retrace signal decoder, and a gamma compensator, which can be implemented as a single video decoder.

An object of the present invention is to provide a multifunctional video decoder that performs various functions such as residual component removal, down scaling, vertical retrace signal decoding, and gamma correction.

1 is a block diagram illustrating a multifunction video decoder according to the present invention.

In order to achieve the above object, the multifunction video decoder according to the present invention is a multifunction video decoder interfaced in series / parallel with an external microprocessor, the first system clock signal by inputting the first frequency signal and the second frequency signal from the outside Or a system clock signal generating means for generating a second system clock signal by inputting a first system clock signal, an external first digital video signal, a vertical synchronization signal of the first digital video signal, and a horizontal synchronization signal; Signal converting means for converting a signal into a second digital video signal and outputting the second digital video signal in response to a first system clock signal; under the control of a microprocessor, converting the first digital video signal or the second digital video signal First selecting means for selectively outputting, first or second input from the first selecting means; Signal separation means for separating the second digital video signal and outputting the first chroma signal, the second chroma signal, the luminance signal, and the decoded vertical retrace signal, the luminance component remaining in the first and second chroma signal and the luminance signal remaining in the luminance signal Residual component removal means for respectively removing chromatic components, and downscaler for adjusting the number of pixels to be displayed corresponding to a predetermined reduction ratio provided by a microprocessor by inputting luminance signals and first and second chromaticity signals from which residual components are removed. And data format means for outputting the luminance signal and the first and second chromaticity signals output from the downscaler corresponding to the first predetermined data format.

Hereinafter, a multifunction video decoder according to the present invention will be described with reference to the accompanying drawings.

1 is a block diagram illustrating a multifunction video decoder according to an embodiment of the present invention, wherein the system clock signal generator 100, the signal converter 200, the first selector 300, the signal separator 400, and the residual signal are shown. The component remover 500, the down scaler 600, and the data formatter 700 are included.

Referring to FIG. 1, the system clock signal generator 100 includes a first clock signal generator 110, a second clock signal generator 120, a second selector 130, and a line lock unit 140. do. The first clock signal generator 110 inputs a first frequency signal of 24.576 MHz and a second frequency signal of 26.8 MHz to generate a first clock signal, and the second clock signal generator 120 generates a first system clock. A signal, a first digital image signal D1, a vertical sync signal, and a horizontal sync signal are input to generate a second clock signal, and the second selector 130 is connected to the second select signal S2 generated by the microprocessor. In response, selectively outputs a first clock signal or a second clock signal. The line lock unit 140 performs a line lock by inputting a first clock signal or a second clock signal from the second selector 130, and then applies the line locked first or second clock signal to the first or second system clock. Output as signals CK1 and CK2. In this case, the first digital image data D1 is digitized image data through an external analog / digital converter (not shown) or 8-bit digital data in CCIR656 format.

The signal converter 200 converts an analog video signal input to the input terminals Y0 to CN into a second digital video signal D2 digitized through an internal analog / digital converter (not shown), and the first system clock signal. The second digital video signal D2 is output in correspondence with the CK1. In this case, the analog video signal is a video signal, a composite video signal, or a super-video signal separated into a luminance signal and first and second chromaticity signals, and 2N input terminals Y0 to CN when the input analog video signal is composite video data. 2N composite image data can be input, and in the case of super-video data composed of a luminance signal and a color signal, a luminance signal can be input to the input terminals Y0 to YN and a color signal to the input terminals C0 to CN, respectively. In the case of an image signal composed of the luminance signal and the first and second chroma signal, the luminance signal may be input to the input terminals Y0 to YN, and the first and second chroma signal Cb and Cr may be input to the input terminals C0 to CN, respectively.

The first selector 300 receives the first digital image signal D1 or the second digital image signal D2 in response to the first selection signal S1 generated by an external microprocessor (not shown). The first digital video signal D1 or the second digital video signal D2 is selectively output.

The signal separator 400 includes a luminance signal separator 410, a chroma signal separator 420, a low pass filter 430, and a vertical retrace signal decoder 440. The luminance signal separator 410 separates only luminance components from the first or second digital image signals D1 and D2 output from the first selector 300, and outputs the luminance components as luminance signals, and the chroma signal separator 420. Is separated from the first and second digital video signals and outputs only the first and second chromaticity components as the first and second chromaticity signals. The low pass filter 430 filters the low frequency components of the luminance signal and the first and second chroma signal to filter the luminance signal from which the noise of the high frequency component is removed, and the first and second chroma signal to the first adaptive comb filter and the second chroma signal. Output to the adaptive comb filter respectively. The vertical retrace signal decoder 440 separates the vertical retrace signal input during the vertical retrace period from the first and second digital video signals, decodes the separated vertical retrace signal, and outputs the same through the output terminal OUT1. As a signal, a caption signal, a teletext signal or an SMPTE code can be input.

The residual component remover 500 includes a first adaptive comb filter 510, a second adaptive comb filter 530, and a line memory 520. The residual component remover 500 has a similar signal between adjacent horizontal scanning lines, and an image signal having a phase difference of 180 ° between adjacent horizontal scanning lines (NTSC of interlaced scanning method) effectively uses a luminance signal and chromaticity by using an adaptive comb filter. The signal can be separated. The N-th and N + 1-th image signals E _N and E _{N + 1} having the characteristics described above may be expressed as Equation 1 and Equation 2, respectively.

E _N = E _YN + E _CbN ⋅sinω _c t + E _CrN ⋅cosω _c t

here, E _YN Wow E _CbN And E _CrN Denotes the luminance signal of the Nth image signal and the first and second chroma signal, respectively, ω _c Represents the frequency of the chroma signal.

E _{(N + 1)} = E _{Y (N + 1)} -E _{Cb (N + 1)} ⋅sinω _c tE _{Cr (N + 1)} ⋅cosω _c t

here, E _{Y (N + 1)} Wow E _{Cb (N + 1)} And E _{Cr (N + 1)} Denotes a luminance signal of the N + 1th video signal and a first and second chromaticity signal, respectively.

From the image signals E _N and E _{N + 1 as} described above, the N th image signal E _N and the N + 1 th image signal E _{N + 1} may be added to obtain an equation (3). .

In this case, two adjacent image signals E _N and E _{N + 1} may obtain relations such as Equation 4, Equation 5, and Equation 6 by using properties similar to each other. A luminance signal from which components have been removed can be obtained.

E _YN = E _{Y (N + 1)}

E _CbN = E _{Cb (N + 1)}

E _CrN = E _{Cr (N + 1)}

E _N + E _{(N + 1)} = 2E _YN

Further, in the N th video signal (E _N) by subtracting the (N + 1) th video signal (E _{N + 1)} to obtain an expression such as equation (8).

At this time, the first and second chromaticity signals Cb and Cr having the luminance component removed as shown in Equation 9 can be obtained by the relational expressions as shown in Equations 4, 5 and 6, respectively.

Through the above-described operation, the first adaptive comb filter 510 may obtain the luminance signal from which the chromatic component is removed, and the second adaptive comb filter 530 may be the first and second to remove the luminance component. A chroma signal can be obtained. The line memory 520 stores an image signal corresponding to a predetermined scan line so that the first and second adaptive comb filters can perform the above-described operation through a mutual relationship between adjacent scan lines.

The down scaler 600 inputs the luminance signal from which the residual component is removed and the first and second chroma signal to adjust the number of pixels to be displayed according to a predetermined reduction ratio provided by the microprocessor. The interpolation filter of the horizontal and vertical reducer (not shown) in the down scaler 600 is implemented as a digital tap impulse response filter of a predetermined tap capable of group delay of a predetermined point. For example, the horizontal reducer can be implemented as a 5-tap digital finite impulse response filter with 32 points of group delay adjustment, and the vertical reducer as a 3-tap digital finite impulse response filter with 16 points of group delay adjustment. , The phase of the pixel data is changed according to the combination of filter coefficients, and the group delay means the rate of change of phase with respect to frequency. That is, the filter coefficients are set to adjust the phase between each pixel on the horizontal axis and the vertical axis to 32 points and 16 points, and the position of the correct phase (1/32 resolution and 1/16 resolution) corresponding to the reduction ratio for each effective pixel. Adjusting the group delay with) produces the desired pixel data. This has the same effect as obtaining 32 and 16 samples between each pixel in the horizontal and vertical axes through linear interpolation, and then extracting the pixel data at the correct position based on the reduction ratio.

The data output unit 700 includes a color space converter 710, a gamma corrector 720, and a data format unit 730. The color space converter 710 receives the luminance signal and the first and second chromaticity signals output from the down scaler 600 and converts the image signals into R (Red), G (Green), and B (blue) shapes. The gamma correction unit 720 corrects a gamma characteristic of an image signal converted into an RGB form. In this case, the gamma characteristic is a phenomenon caused by nonlinearity of the phosphors used in display devices using all cathode ray tubes (CRT) such as televisions and computer monitors. It is a numerical expression of nonlinearity, and this unwanted gamma characteristic must be compensated for gamma before input to the display device. This is called gamma correction. In addition, the data format unit 730 outputs 16-bit or 24-bit digital data corresponding to the CCIR601 data format using the luminance signal and the first and second color signals output from the gamma-corrected RGB signal or the downscaler 600. Output via terminal OUT2.

As described above, the multi-function video decoder according to the present invention performs various functions such as residual component removal, downscaling, vertical retrace signal decoding, and gamma correction, in addition to the basic functions of the video decoder, and inputs digital video signals in addition to analog video signals. It is possible to output various types of digital data.

Claims (8)

In the multi-function video decoder interfaced in series / parallel with an external microprocessor, A first system clock signal is generated by inputting a first frequency signal and a second frequency signal from an external source, or the first system clock signal, an external first digital video signal, a vertical synchronization signal of the first digital video signal, and horizontal System clock signal generation means for inputting a synchronization signal to generate a second system clock signal; Signal conversion means for converting an analog video signal into a second digital video signal and outputting the second digital video signal corresponding to the first system clock signal; First selecting means for selectively outputting the first digital video signal or the second digital video signal under the control of the microprocessor; Signal separation means for separating the first or second digital video signal inputted from the first selection means and outputting a first chroma signal, a second chroma signal, a luminance signal and a decoded vertical retrace signal; Residual component removing means for removing the luminance component remaining in the first and second chroma signal and the chroma component remaining in the luminance signal, respectively; A down scaler for inputting the luminance signal from which the residual component is removed and the first and second chroma signal to adjust the number of pixels to be displayed according to a predetermined reduction ratio provided by the microprocessor; And And data format means for outputting digital data formatted according to the first predetermined data format by the luminance signal and the first and second chromaticity signals output from the downscaler. The method of claim 1, wherein the analog video signal is a video signal, a composite video signal, or a super-video signal separated into a luminance signal and a first and second chroma signal, and the first digital video signal is in a second predetermined data format. Multi-function video decoder characterized in that it is correspondingly formatted 8-bit digital data or digitized data. The method of claim 1, wherein the system clock signal generating means First clock signal generation means for inputting the first frequency signal and the second frequency signal to generate a first clock signal; Second clock signal generation means for inputting the first system clock signal, the first digital video signal, the vertical synchronization signal, and the horizontal synchronization signal to generate a second clock signal; Second selection means for selectively outputting the first clock signal or the second clock signal under control of the microprocessor; And A line for inputting the first clock signal or the second clock signal from the second selection means to perform a line lock, and outputting the line locked first or second clock signal as the first or second system clock signal A multifunction video decoder comprising lock means. The method of claim 1, wherein the signal separation means Luminance signal separation means for separating a luminance component from the first and second digital video signals and outputting the luminance component as the luminance signal; Chromaticity signal separation means for separating first and second chromaticity components from the first and second digital video signals and outputting the first and second chromaticity components as the first and second chromaticity signals; A low pass filter configured to filter out low frequency components of the luminance signal and the first and second chroma signal to remove noise of a high frequency component; And And a vertical retrace signal decoder which separates the vertical retrace signal input during the vertical retrace period from the first and second digital image signals, decodes the separated vertical retrace signal, and outputs the decoded vertical retrace signal as the decoded vertical retrace signal. Multifunction video decoder. 5. The multifunction video decoder of claim 1, wherein the vertical retrace signal is a caption signal, a teletext signal or an SMPTE code. The method of claim 1, wherein the residual component removal means A first adaptive comb filter for removing the chromaticity component remaining in the luminance signal by deriving a mutual relationship between adjacent predetermined scan lines; A second adaptive comb filter for deriving a mutual relationship between the adjacent predetermined scan lines to remove luminance components remaining in the first and second chroma signal; And And a line memory for storing video signals corresponding to the adjacent predetermined scan lines. The method of claim 1, wherein the data output means Color space converting means for converting the luminance signal and the first and second chromaticity signals inputted from the down scaler into an image signal in an RGB format; Gamma correction means for correcting a gamma characteristic by inputting an image signal converted into an R. G. ratio (RGB) form; And The gamma corrected RGB signal or the luminance signal outputted from the down scaler and the first and second chromaticity signals are converted into predetermined bits of digital data formatted according to a first predetermined data format. And a data format means for outputting. The multifunction video decoder of claim 1, wherein the predetermined bit of digital data is 8 bits, 16 bits, or 24 bits of digital data.