KR20000046164A - Digital satellite broadcasting receiver and method for processing digital caption data - Google Patents

Abstract

PURPOSE: A digital satellite broadcasting receiver and a method for processing digital caption data are provided to separate caption data from digital broadcasting video stream. CONSTITUTION: A digital satellite broadcasting receiver includes a user selector(300), a caption data detector(301), a caption data processor(302) and a caption data display(303). The user selector(300) selects user caption and display fonts for the user caption using the caption information of current broadcasting program. The caption data detector(301) detects the corresponding caption data and re-arranges the data according to the user selection. The caption data processor(302) analyzes the caption data and re-configures into bitmap data. The caption data display(303) includes text display which overlaps the bitmap data on a position corresponding to the video signal.

Description

Digital satellite broadcasting receiver and digital caption data processing method

The present invention relates to a digital satellite broadcasting receiver, and more particularly, to a digital satellite broadcasting receiver and a digital caption data processing method for displaying digital caption data on a screen using an on-screen display (OSD) function. will be.

1 is a block diagram showing a conventional digital satellite broadcast receiver.

Referring to FIG. 1, the channel unit 101 of the conventional digital satellite broadcasting receiver receives and tunes a broadcast signal from the satellite antenna 100 and demodulates it into a quadrature phase shit keying (QPSK) signal through an internal A / D converter. The error of the QPSK signal is corrected and output as a time multiplexed transport stream.

The microcomputer 102 includes a central processing unit (CPU), a demultiplexer, a communication port (Port), and the like as an I / O device. The demultiplexer receives the time-multiplexed transport stream output through the channel unit 101 as an input and performs demultiplexing. The demultiplexing here refers to a PID (packet identification) number, which is divided into a video signal sequence, an audio signal sequence, and an additional information signal sequence. At this time, the separated video signal sequence and audio signal sequence are applied to the MPEG A / V decoder 103, and the additional information signal sequence is databased as information to be displayed by a GUI through a filtering step.

The MPEG A / V decoder 103 expands and decompresses the compressed video signal stream and the audio signal stream. In addition, the NTSC encoder 104 encodes the digital video signal, which has been extended and reconstructed by the MPEG A / V decoder 103, into an NTSC signal so that the luminance signal Y and the color signal can be displayed on a general television or a monitor. (C) and a color video blank signal (CVBS), respectively. The D / A converter 105 converts the extended digital voice signal into an analog voice signal and outputs the analog voice signal.

Meanwhile, the signal transmitted from the satellite is a signal multiplexed with video information, audio information and additional information. In this case, the additional information refers to information on a channel currently being broadcast and a detailed description of a broadcast program being serviced in each channel. For example, the channel name, program name, broadcast time, rating, classification, language, screen type, and plot To refer. The additional information is extracted from the microcomputer 102 of the satellite broadcasting receiver and stored in the memory 106 for each channel. Based on this information, the microcomputer 102 determines the function desired by the user and displays the corresponding function on the screen.

Recently, caption broadcasting, which is an additional service for the elderly and hearing-impaired, has attracted attention and the enactment of standards is actively discussed. In conventional analog broadcasting, caption information is inserted and transmitted in the vertical blanking period of lines 21 and 284 of an NTSC video signal. In order to view the caption information on a television receiver, a caption-only decode chip for extracting caption information carried in the vertical blanking erasure period, analyzing the corresponding data, and displaying the caption information is necessary. Therefore, only the television receiver with the caption decode chip embedded therein can display the caption information on the screen.

Transmission of caption information in digital broadcasting is that the video encoder inserts video parameters and user data into the "picture header" of the video bit stream during encoding of the video signal in NPEG-2. User data is defined here in ISO / IEC 13818-2 (MPEG-2 video standard). The caption data is carried in user data of the MPEG-2 video stream as described above. The receiver then extracts this data and outputs the caption data carried in the vertical blanking period of line 21 or 284 when reconstructing the digital signal into an NTSC signal form via NTSC encoder 104. This standard complies with the US terrestrial caption standard EIA-608. In order to view this caption on the screen in a television receiver, caption data contained in the vertical blanking period of line 21 or 284 is extracted from the NTSC video signal, and the control code and character code of the caption data are interpreted and displayed according to the screen specifications by the OSD. Done. As a result, the viewer can view the caption information on the screen.

2 is a block diagram illustrating a caption data display apparatus in a conventional digital satellite broadcasting receiver.

Referring to FIG. 2, the caption data display device is equally applied to a settop box or a receiver built-in type capable of receiving digital broadcasting.

First of all, a digital broadcast receiver must be able to extract caption data transmitted in a video signal according to the MPEG-2 standard. The MPEG-2 A / V decoder 200 extracts caption information carried in the user data portion of the video stream and outputs caption information to the NTSC encoder 201 together with the decompressed video signal.

The NTSC encoder 201 is a kind of D / A converter, which carries this caption data during the vertical retrace period of line 21 or 284 to D / A convert the video signal. The output of the NTSC encoder 201 may be a composite signal including caption data, a luminance signal Y, and a color signal C.

Thus, the television receiver or monitor receives the signals to perform video-related signal processing, e.g., Y, C separation, in the NTSC video processing unit 202, and captions from the video signal in the caption decoder 203 as another signal processing step. Extracting, interpreting, and controlling data constitutes graphical data to be displayed on the screen. The caption multiplexer 204 then mixes the video signal with the graphic data of this caption. Through this process, since the caption information is mixed in the video signal output through the caption multiplexer 204, the viewer can view on the screen.

However, even if the NTSC encoder of the digital receiver carries the caption information on the video signal, the viewer cannot receive the caption service without the caption-decode chip (corresponding to 204 of FIG. 2) in the analog processor, that is, the television receiver or the monitor.

Therefore, by adding the caption-only chip, the unit cost of the product is increased, and the design of such a chip is difficult for each product.

The present invention has been made to solve the above-mentioned conventional problems, the present invention is to extract the caption information transmitted by mixing in the video stream in the digital broadcast and to provide a caption service to viewers digital receiver and digital The present invention provides a caption data processing method.

Another object of the present invention is to provide a digital satellite broadcasting receiver and a digital caption data processing method for displaying a variety of Hangul fonts using a limited memory.

In addition, another object of the present invention is to extract the caption information from the video stream using a 32-bit RISC CPU and a conventional OSD function used in the digital receiver, to interpret and control the caption information as a graphic data, and then extended / restored video By superimposing a signal, a digital satellite broadcasting receiver and a digital caption data processing method for allowing digital caption information to be viewed even without a caption dedicated decode chip in a television receiver or a monitor are provided.

1 is a block diagram showing a conventional digital satellite broadcast receiver

2 is a block diagram illustrating a caption data display apparatus in a conventional digital satellite broadcasting receiver.

3 is a block diagram showing a digital caption data display apparatus in a digital satellite broadcasting receiver according to the present invention;

4A is a screen configuration diagram for selecting caption information in the digital caption data display device of the present invention;

4B is a screen configuration diagram for selecting a font type in the digital caption data display device of the present invention.

5 is a diagram illustrating a video signal processing process in a caption data extractor according to the present invention.

Fig. 6 is a diagram showing a protocol (syntax) of pixel layer user data of the present invention.

7 is an operation flowchart of the caption data extraction unit of the present invention

8 is a flowchart illustrating operations of a caption data processor of the present invention.

Explanation of symbols for main parts of the drawings

101: antenna 102: micom

103: MPEG A / V decoder 104, 201: NTSC encoder

105: D / A converter 106: memory

200: MPEG-2 A / V decoder 202: NTSC video processing unit

203: Caption Decoder 204: Video / Caption Multiplexer

300: user selection unit 301: caption data extraction unit

302: caption data processing unit 303: display unit

304: Video signal with caption information superimposed

A feature of a digital satellite broadcasting receiver having a caption data display apparatus according to the present invention for achieving the above objects is a user selection unit for selecting a subtitle of a user and a display font for the subtitle by using subtitle information of a current broadcast program. A caption data extractor for extracting and rearranging the caption data according to a selection of the user selection unit; a caption data processor for interpreting the rearranged caption data and reconstructing position information and character information into bitmap data for screen display; A caption data display device comprising a character display unit configured to superimpose graphic bitmap data of caption characters on a corresponding position of a video signal using the bitmap data and output them to a screen.

A feature of the digital caption data processing method according to the present invention is to decode a picture header to search for picture headers for I pictures and P pictures, and if the search result picture headers correspond to I pictures and P pictures, the information is selected by the user. Extracting and storing caption data and transmitting previously stored caption data to a caption data processing unit. If the search result picture header corresponds to a B picture, caption data is extracted using user selection information and transmitted to the caption data processing unit. Caption data extraction process consisting of steps; And determining whether the caption data transmitted through the process is a control code or a character code, and analyzing and controlling the caption data if the caption data is a control code, and performing a desired caption mode if the caption data is a character code. Reconstructing the code into bitmap data, Caption data processing comprising the step of passing the reconstructed bitmap data to the character display and determining whether to perform the caption.

Hereinafter, a preferred embodiment of a digital caption data display method in a digital satellite broadcast receiver according to the present invention will be described in detail with reference to the accompanying drawings.

3 is a block diagram showing a digital caption data display apparatus in a digital satellite broadcasting receiver according to the present invention.

Referring to FIG. 3, the digital caption implementation algorithm of the present invention is processed as S / W in the CPU. First, the user selector 300 provides an environment for selecting a subtitle service and a font for displaying subtitles on the screen based on the subtitle service information of the current broadcast program extracted from the additional information. The caption data extractor 301 operates according to the selection of the user selector 300. When the user selects a specific language to view the caption, the caption data extractor 301 is loaded on the user data of the MPEG-2 video stream "picture header". Extract caption data. At this time, because the order of transmission and the order of display are different, a reordering process is performed. The data thus processed is input to the caption data processing unit 302.

The caption data processing unit 302 interprets the input data, reconstructs the bitmap data to be displayed on the screen, and outputs the bitmap data to the display unit 303 according to the caption mode. The bitmap data is reconstructed into bitmap data by converting the character code transmitted to the KSC-5601 completion type into a combination type in order to reduce the size of memory required for font storage. This method reduces the memory capacity required to store the same font and can support approximately four or more different fonts with the same memory capacity.

The character display unit 303 superimposes the graphic bitmap data of the caption character on the corresponding position of the video signal using the position information on the caption character and the bitmap data corresponding to the character. The video signal 304, which is the final output signal, is a signal in which graphic data of a caption character is superimposed on the video signal itself. This signal allows the television receiver or monitor to immediately view the caption information on the screen without using a dedicated caption decoder.

More specifically, the advantage of digital broadcasting is to broadcast by multiplexing additional information along with high-definition and high-quality video and audio signals. This additional information is information about a broadcast program, that is, a title, a plot, a broadcast time, a rating, and a broadcast classification of the broadcast program. This additional information consists of tables, each of which consists of a descriptor. An event information table (EIT), which is one of a plurality of tables, is extracted from a broadcast signal. And the closed caption descriptor which has caption information about each program is analyzed, and the caption information provided by the program currently broadcasting is made into a database.

When the user selects the caption key on the remote control using this information, the user selector 300 displays a screen as shown in FIG. 4A and allows the user to select the caption service by viewing the type of caption currently being serviced. Also, the user selection function allows you to select the font type of the characters to be displayed on the screen. This requires bitmap data for each character in order to display the characters on the screen, since the Hangul code of satellite broadcasting is transmitted to the complete type of KSC-5601. A large amount of memory is required to store bitmap data in complete code. Therefore, in the present invention, the memory usage is reduced by using bitmap data of a combinational code that requires less memory, and various types of fonts are used by using extra memory, so that a user can directly select a font. Provide the same selection screen. At this time, the process of converting the characters from the completed type to the combined type is performed by the caption data processing unit 302.

When the user selects a caption service, the caption data extractor 301 extracts caption data. Conventional analog captions are carried in the vertical blanking period of 21 (284) lines of odd / even fields, respectively, while digital captions are carried in the user data portion of the MPEG-2 video signal "picture header". User data is defined in ISO / IEC 13818-2 (MPEG-2 Video Standard).

5 is a diagram illustrating a video signal processing process in a caption data extractor according to the present invention.

The MPEG-2 image compression algorithm adopts interframe prediction as a compression method using spatial correlation with DCT (Discrete Cosine Transform) as a compression method using spatial correlation. These predictions are bidirectional predictions using both forward prediction from past playback images and backward prediction from future playback images. Then, information compression is obtained by using quantization and variable length codes.

Referring to FIG. 5, three types of video signals such as an I picture, a P picture, and a B picture are defined to realize bidirectional prediction. The I picture is an intra coded image and is encoded using only the screen information, and is generated without using inter-frame prediction. The P picture is a predictive coded picture and is generated by inter-frame forward predictive coding from an I picture or a P picture. The B picture is a bidirectionally predicted encoded image and is generated by bidirectional prediction.

In the bidirectional prediction process, the B picture is skipped at the time of encoding, and the next I or P picture is first encoded, and the B picture in between is decoded and played immediately, but the I and P pictures are interleaved even after decoding. Displayed after the processing of the B picture is completed. Therefore, the I and P pictures are delayed until the next I and P pictures appear. As a result, the caption data extracted when decoding the video signal is not transferred directly to the caption data processor, but must be rearranged in the display order. The operation procedure of this caption data extracting unit 301 is disclosed in FIG. 7 described later.

7 is an operation flowchart of the caption data extraction unit 301 of the present invention.

First, the operation of the extractor 301 is started by the user's selection. An internal video picture header detector decodes an image and finds a head portion of the picture (701).

When the next picture head is found, it is determined whether the picture is an I or P picture (702).

If it is determined that the I and P pictures are determined, caption data is extracted according to the user selection information 709, and the extracted I and P pictures are temporarily stored in a buffer for delay until the next I and P pictures are displayed (703). At this time, the syntax of the caption data carried in the user data portion of the picture head is as shown in FIG. Here, cc_data (601) and cc_data (602) represent caption data of 2 bytes corresponding to each caption type. When extracting data, the user may extract caption data (English and Korean) desired by referring to the user selection information 709 (703).

After passing caption data extracted from the next previously stored I and P pictures to the caption data processing unit 302 (704), it is checked whether the caption is to be continued (707) and the picture header decoding step (701) again to proceed with the caption. Feedback or end this process.

If the picture head is not an I or P picture but a B picture, caption data is extracted using the user selection information 709 (step 705), and the information is directly reproduced, so that the caption data processing unit immediately transfers the caption data to the caption data processing unit. (706). Then, it is checked whether to continue captioning (707).

8 is an operation flowchart of the caption data processing unit 302 according to the present invention.

The caption data processing unit 302 analyzes and controls the data extracted by the caption data extraction unit 301, configures bitmap data of the corresponding character, and transmits the bitmap data to the character display unit 303.

First, caption data extracted from the caption data extraction unit is input (801).

Then, it is determined whether the caption data is a control code or an English character code (802) (804). If it is a control code, the control code is interpreted and control thereof is performed (803).

The control code may be a caption mode (instantaneous caption, continuous caption, raising caption), and may be various in color, background color, display position, and the like. Such information is transmitted to the character display unit 303 and displayed in the caption mode designated at the designated position of the screen.

It is checked whether to continue to perform the next caption process (810). If the caption processing is to be continued, it is fed back to the caption data input step 801 to receive the caption data again, and repeats the caption data processing, otherwise the caption data processing is terminated (811).

If the caption data is not a control code but a character code, it is determined whether the character code is an English character or a Korean character (804). At this time, the caption data transmitted in the broadcast signal is sent in the complete character code according to KSC-5601. Therefore, storing and using bitmap data for more than 2000 characters in memory is quite inefficient in memory management.

Therefore, in the present invention, after storing the combined bitmap data requiring a smaller amount of memory in the memory, converts the transmitted complete code into a combined code, and configures the bitmap data for one character using the converted combined code. do. The extra memory left by this effect is used for storing the combined bitmap data of other fonts, so that the font (shape) of the characters displayed on the screen can be selected (see Figs. 4A and 4B) according to the user's preference. By doing so, the user's taste can be reflected to the maximum.

Next, if the determination result of the character code is (804) an English character, it is configured as bitmap data of the corresponding English character by referring to the English bitmap data stored in the memory according to the type of font selected on the user selection screen (805) (806). ).

If the Hangul code, the Hangul complete code is converted into a combined code (807). By using the converted code, the bitmap data of the initial, neutral, and final of the combined code is composed of the bitmap data of the corresponding Hangul characters by referring to the Hangul character bitmap data stored in the memory according to the type of font selected by the user ( 808).

The bitmap data of the corresponding character configured as described above is transmitted to the character display unit 303.

It is then checked whether to continue captioning (810), and fed back to the caption data input step (801) or ends.

The character display unit 303 superimposes and outputs the caption data on the stretched / restored video signal at a corresponding position in accordance with the caption mode by using bitmap data of the character transmitted from the caption data processor 302.

Accordingly, since the caption information is superimposed on the video signal in the form of OSD, the caption information is superimposed on the video signal 304, and thus the caption information can be simply enjoyed without additional equipment for caption data processing.

According to the digital satellite broadcasting receiver and the digital caption data processing method proposed by the present invention, various fonts can be provided even within a limited memory, and the user can also view captions in a television receiver without a conventional caption decoding function provided that only the digital broadcasting receiver is provided.

As described in detail above, according to the digital satellite broadcasting receiver and the digital caption data processing method of the present invention, since the digital caption is processed in software using the OSD function of the CPU of the digital receiver, the caption can be provided to the viewer without a dedicated caption decode chip. In addition, a variety of fonts can be provided even within a limited memory, thereby expanding the user's choice.

In addition, the present invention can reduce the unit cost of the product from the provider side because the caption can be viewed in the television receiver without the existing caption decode function if only the digital broadcast receiver is provided from the user side.

Since the digital satellite broadcasting receiver and the digital caption data processing method of the present invention can be modified or changed in various ways by those skilled in the art, the present invention is not limited only to the above-described configuration and operation, and the technical features of the present invention. It includes all modifications and equivalents that fall within the scope of the idea.

Claims (9)

A user selection unit for selecting a subtitle of the user and a display font for the subtitle by using the subtitle information of the current broadcast program; A caption data extraction unit for extracting and rearranging subtitle data according to selection of the user selection unit; A caption data processor configured to interpret the rearranged caption data and reconstruct position information and character information into bitmap data for screen display; And a caption data display device comprising: a character display unit configured to superimpose graphic bitmap data of caption characters on a corresponding position of a video signal using the bitmap data and output the caption data to a screen. The digital satellite broadcasting receiver of claim 1, wherein the caption data extractor extracts caption data by intra-coded image processing, predictive coded image processing, and bidirectional predictive coded image processing. The digital satellite broadcasting receiver as claimed in claim 1, wherein the caption data processing unit reconstructs the bitmap data according to selection information of the user selection unit. 4. The digital satellite broadcasting receiver as claimed in claim 3, wherein the bitmap data comprises a combination code. The digital satellite broadcasting receiver of claim 1, wherein the user selector enables the user to select a caption service based on a type of caption currently being serviced. Decoding picture headers from the video stream to retrieve picture headers for I and P pictures; if the search result picture headers correspond to I and P pictures, extract and store caption data according to information selected by the user Transmitting caption data stored in the caption data processing unit; extracting caption data using user selection information and transmitting the caption data to the caption data processing unit when the search result picture header corresponds to the B picture; And Determining whether the caption data transmitted through the process is a control code or a character code; and analyzing and controlling the caption data if the caption data is a control code; and performing a desired caption mode if the caption data is a character code; Reconstructing the data into bitmap data, transferring the reconstructed bitmap data to a text display, and determining whether to perform caption. 7. The method of claim 6, wherein the bitmap data is reconstructed into bitmap data of English or Korean characters according to user selection information. The method of claim 6, wherein the Hangul characters are converted from the complete code to the combined code, and the bitmap data of the initial, neutral, and final bitmap data of the combined code is referenced in accordance with the type of font selected by the user. Digital caption data processing method characterized in that the reconstruction with bitmap data of the Hangul characters. The digital caption data processing method of claim 6, wherein the English character is reconstructed into bitmap data of the corresponding English character by referring to the English bitmap data stored in the memory according to the type of font selected by the user.