KR19980047720A - Video Format Inverter - Google Patents

Abstract

A video decoder which decodes a received MPEG bit stream after depacketizing and converts a sample rate of the decoded video data, performs filtering in a vertical direction, and performs interpolation in a horizontal direction. A filter unit for outputting video data having the same format as the luminance signal and the color difference signal, and outputting the image data having the same format as the luminance signal and the color difference signal, and OSD image data for the video data output from the filter unit. It consists of an OSD generation unit for outputting, and a mux unit for outputting the image data having the same format as the luminance signal and the color difference signal by mixing the image data output from the filter unit and the OSD generation unit respectively, the final output image data is luminance Since the components of the color difference signal are the same as those of the signal, the characteristics of the color difference signal are good. The.

Description

Video Format Inverter

The present invention relates to a video decoder, and more particularly, to a video format conversion apparatus for displaying an image.

In the era of satellite broadcasting, various channels and programs will increase, so it is necessary to display more characters or graphics on the screen (On Screen Display).

In this case, if a character or graphic is provided in the current image format, the boundary between the character and the screen is not clear, and thus the necessity of improving the characteristics of the color difference signal increases.

In general, the decoding process of the Moving Picture Experts Group (MPEG) of the video decoder established in the international standard is as follows.

FIG. 1 is a block diagram for explaining a configuration of a general video decoder, and FIG. 2 is a block diagram for explaining a configuration of the image format converter of FIG. 1. Depacketizing a received MPEG bitstream A transport demux unit 10 for outputting the video decompression unit 10, a video decoder unit 11 for receiving the video compressed data output from the transport demux unit 10 and restoring the original video data, and a character on a screen. B) a video format converting unit 12 for displaying a graphic and a video data output from the video decoder 11 at a predetermined ratio, converting the video data into 4: 2: 2 format, and outputting the converted video data; NTSC / PAL (National Television System Committee / Phase Alteration by Line) signal for receiving 4: 2: 2 image data output from the image format conversion unit 12 and displaying it on a TV screen Coding consists of the NTSC / PAL encoder section 13 for outputting.

Here, the image format converter 12 performs the SRC (Sample Rate Conversion) and the vertical direction filtering on the image data output from the video decoder 11 as shown in FIG. The SRC and vertical filter unit 121 outputs the signal Y: Cb: Cr in 4: 2: 2 format, and inputs OSD information to display characters or graphics on the screen, and Y: Cb: Cr is 4: 2. An OSD generator 122 for outputting a super impose signal indicating a ratio of reflecting OSD image data to video image data output from the: 2 format and the video image data output from the SRC and vertical filter unit 121; Y: Cb: Cr, which is output from the SRC and vertical filter unit 121 and OSD generation unit 122, is mixed with 4: 2: 2 format using superimposition signals, and Y: Cb: Cr is mixed. The mux unit 123 outputs image data in 4: 2: 2 format.

The operation of the video decoder according to the related art configured as described above will be briefly described. First, the transport demux unit 10 receives a compressed MPEG bitstream and depackets the video decoder bit stream to obtain a pure video compression bit stream. Output to section 11.

Then, the video decoder 11 restores the input video bit stream by variable length decoding, inverse quantization, motion compensation, and the like, and converts the image data having Y: Cb: Cr into 4: 2: 2 format into an image format converter 12. )

The image reconstructed by the image format converting unit 12 is displayed on the TV screen and output to the NTSC / PAL encoder unit 13, and the NTSC / PAL encoder unit 13 encodes the NTSC / PAL signal to analog video. Output the signal.

FIG. 3 is a diagram illustrating an output waveform of the mux unit of FIG. 2. In detail, the operation of the image format converter 12 in the above-described video decoder of the prior art includes the video decoder unit and the SRC and vertical filter unit 121. ITU-R Rec after filtering the SRC and vertical direction according to the 16: 9 or 4: 3 format image by receiving the image data whose Y: Cb: Cr output from (11) is 4: 2: 2 format (International Telecommunication Union-Radiocommunication Recommendation) 656 Converts to video format and outputs it to the mux unit 123. That is, Y: Cb: Cr is converted into video data having a 4: 2: 2 format, and output to the mux unit 123.

In addition, the OSD generator 122 receives the OSD information according to the OSD specifications ITU-R Rec. 656 A video format, that is, Y: Cb: Cr, is converted into video data having a 4: 2: 2 format, and output to the mux unit 123.

The MUX unit 123 receives video data in which the Y: Cb: Cr of the SRC and the vertical filter unit 121 and the OSD generator 122 are 4: 2: 2 format, respectively, and is mixed according to the super impose signal. After synchronizing with the pixel (PIX) clock as shown in 3, ITU-R Rec. 656 Y: Cb: Cr for video format outputs image data in 4: 2: 2 format.

That is, the image data of the Y: Cb: Cr format 4: 2: 2 output from the image format converter has half the color difference signal components compared to the luminance signal, because the human visual characteristics are less sensitive to the color difference signals. Use a lot.

The video format converter of the video decoder according to the prior art mixes the video data and the OSD video data at an appropriate ratio, and converts the final video data into a 4: 2: 2 format in which Y: Cb: Cr is output. Since the specification is not as good as that of the luminance signal, the boundary is blurred when displaying graphics or characters due to color blurring with adjacent pixels.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an apparatus for converting OSD image data into a 4: 2: 2 format in which Y: Cb: Cr is used to sharpen a color difference signal.

1 is a block diagram illustrating a configuration of a general video decoder.

FIG. 2 is a block diagram illustrating a configuration of an image format converter of FIG. 1. FIG.

3 is a view showing an output waveform of the mux part of FIG.

4 is a block diagram illustrating a configuration of an image format conversion apparatus according to the present invention.

5 is a view showing a detailed configuration of the mux portion of FIG.

6 is a view showing an output waveform of the mux part of FIG.

Explanation of symbols on the main parts of the drawings

411: SRC and vertical filter unit 412: OSD generation unit

413: musbu 511, 514: selection

512, 513: calculation unit

A feature of the image format conversion apparatus according to the present invention is to convert the video data decoded by the filter unit to the sample rate, perform filtering in the vertical direction and interpolation in the horizontal direction, and then output the video data having the same luminance signal and color difference signal. The OSD generating unit receives the OSD information, outputs image data having the same format as the luminance signal and the color difference signal, and outputs a mixed ratio of the OSD image data to the video data output from the filter unit. The video data output from the OSD generator is mixed to output video data having the same format as the luminance signal and the color difference signal.

Hereinafter, a video format conversion apparatus according to the present invention will be described with reference to the accompanying drawings.

4 is a block diagram illustrating a configuration of an image format conversion apparatus according to the present invention, and FIG. 5 is a detailed configuration diagram of the mux part of FIG. 4, and with reference to FIG. 1, an image format conversion apparatus according to the present invention. In the following description, SRC (Sample Rate Conversion) of the video data output from the video decoder unit 11 is performed, the filtering is performed in the vertical direction, and the interpolation is performed in the horizontal direction. SRC and vertical filter unit 411 for outputting Cb, Cr, and OSD information for displaying characters or graphics on the screen, and receiving 4: 1: 4 format image data OSD Y, OSD Cb, OSD Cr, and OSD generation unit 412 for outputting a reflection ratio (superimpose) signal of the OSD image data to the video image data output from the SRC and vertical filter unit 411, and the SRC and vertical filter unit 411 and OSD generation Y respectively output from the section 412: And a mux unit 413 for outputting image data Y OUT, Cb OUT, and Cr OUT of 4: 4: 4 format by appropriately mixing image data of 4: 2: 2 format with Cb: Cr.

Here, the mux unit 413 selects Y, Cb, and Cr output in the 4: 4: 4 format from the SRC and vertical filter unit 411 according to the video enable signal, respectively, as shown in FIG. 5 to Y 'and Cb'. And the first selector 511 for outputting Cr ', the Y', Cb ', Cr' output from the first selector 511, and the OSD Y, OSD Cb, OSD outputted from the OSD generator 412. The first operation unit 512 for outputting each difference of Cr OSD Y ', OSD Cb', and OSD Cr ', and the OSD Y', OSD Cb ', OSD Cr' and OSD generators output from the first operation unit 512. The Y ', Cb', and Cr 'signals output from the first selector 511 are respectively added to the signals multiplied by the superimposed signals output at 412 to output the OSD Y, OSD Cb, and OSD Cr signals. OSD enable of the second calculator 513 and the OSD Y, OSD Cb, OSD Cr signal output from the second calculator 513 or Y ', Cb', Cr 'signals output from the first selector 511. And a second selector 514 which selects according to the signal and outputs image data of Y OUT, Cb OUT, and Cr OUT.

Referring to the operation of the video format conversion apparatus according to the present invention configured as described above in detail, first, the SRC and the vertical filter unit 411 is a 16: 9, 4: 3 format of the video data input from the video decoder unit 11 After SRC and filtering in the vertical direction and interpolation in the horizontal direction, the video data Y, Cb, and Cr in 4: 4: 4 format are output to the mux unit 413.

In addition, the OSD generator 412 receives OSD information to display characters or graphics on the screen. The OSD information basically constitutes 4: 4: 4 format having the same luminance and color information. to be.

The input OSD information is used to output OSD Y, OSD Cb, and OSD Cr data in the same 4: 4: 4 format output from the SRC and vertical filter unit 411 by the OSD specification and color look up table (LUT). 413, and outputs a super impose signal indicating a reflection ratio between the video image data output from the SRC and the vertical filter unit 412 and the OSD image data to the mux unit 413.

The first selector 511 of the mux unit 413 is composed of three muxes, and each mux receives video image data Y, Cb, Cr and ground signals output from the SRC and vertical filter units 411, respectively. When the enable signal is applied, the input Y, Cb and Cr data are selected and output as Y ', Cb' and Cr 'data.

That is, the video enable signal is a mux control signal indicating whether or not to send the reconstructed image to the output.

The first operator 512 subtracts the OSD Y, OSD Cb, and OSD Cr data output from the OSD generator 412 from the output Y ', Cb', and Cr 'data, respectively, to display OSD Y', OSD Cb ', OSD Cr 'data is output, and the second calculator 513 multiplies the OSD Y', OSD Cb ', and OSD Cr' data with the superimpose signal output from the OSD generator 412, respectively.

The OSD Y ', OSD Cb', and OSD Cr 'data are multiplied by the superimpose signal, and the mixed values of the video data and the OSD image data are Y', Cb 'and Cr' output from the first selector 511. Data is added to each other and outputs OSD Y, OSD Cb, and OSD Cr data to the second selector 514.

The second selector 514 also includes three muxes, each of which mutes OSD Y, OSD Cb, OSD Cr data, or Y ', Cb', Cr 'data output from the first selector 511. The Y OUT, Cb OUT, and Cr OUT image data of 4: 4: 4 format are selected according to the application of the enable signal and output as shown in FIG. 6 in synchronization with the pixel clock.

At this time, the OSD enable signal is a signal indicating whether or not to display the OSD information in the video signal appearing at the final output.

Here, instead of the image data Y, Cb, Cr, and OSD Y, OSD Cb, and OSD Cr, signals in the form of R (Red), G (Green), and B (Blue) components may be used.

As described above, the image format conversion apparatus according to the present invention outputs the luminance signal and the chrominance signal component of the image data identically, so that the OSD screen becomes clear when the analog signal of NTSC / PAL format is output.

The image format conversion apparatus according to the present invention outputs Y, Cb, Cr data in 4: 4: 4 format by mixing moving image video data and OSD video data. That is, since the components of the color difference signal are the same as those of the luminance signal, the characteristics of the color difference signal are improved. In particular, since the OSD image data is basically 4: 4: 4 format, it can exhibit excellent performance with respect to the color difference signal of the OSD, so that color bleeding with adjacent pixels does not appear when configuring the OSD screen.

Claims (3)

In the video decoder to depacketize and decode the received MPEG bitstream, A filter unit for converting the decoded video data into a sample rate, performing filtering in a vertical direction and interpolating in a horizontal direction, and then outputting video data having the same format as the luminance signal and the color difference signal; An OSD generator which receives the OSD information and outputs image data having the same format as the luminance signal and the color difference signal, and outputs OSD image data about the video data output from the filter unit; And a mux unit for mixing the image data output from the filter unit and the OSD generating unit to output image data having the same format as the luminance signal and the color difference signal. The method of claim 1, The mux part A first selector configured to select and output image data having the same format as the luminance signal and the color difference signal output from the filter according to a video enable signal; A first calculator for outputting a difference between the image data output from the first selector and the image data output from the OSD generator; A second operation unit which multiplies the reflection ratio of the OSD image data with respect to the video data output from the first operation unit and the video data output from the filter unit, and adds and outputs the image data output from the first selection unit, respectively; , And a second selector configured to select and output the image data output from the second calculator or the image data output from the first selector according to an OSD enable signal. The method of claim 1, And a red, green, and blue component type signal may be used instead of the image data of the luminance signal and the color difference signal.