KR20080036329A - Caption display apparatus and method - Google Patents

Abstract

An apparatus and a method for caption display are provided to determine whether DTVCC data is included into user data and display caption, thereby displaying received caption data on a screen if the actual DTVCC data is received even when a caption service descriptor can not be searched. A TP(Transport Packet) stream decoder(310) divides a received TP stream into audio data, video data, and other information data including a PSIP(Program and System Information Protocol). A PSIP parser(350) parses the divided PSIP data. A control unit(380) determines whether DTVCC(Digital TV Closed Caption) data is included into the divided video data when a descriptor about a DTVCC is not included into the parsed PSIP data. A video parser(320) divides the DTVCC data according to the determination of the control unit. A DTVCC decoder(340) decodes the divided DTVCC data.

Description

Caption display apparatus and method

1 is a diagram illustrating DTVCC caption data included in a general digital TV bit stream.

2 is a flowchart illustrating a process of extracting caption data included in a digital TV bit stream and displaying captions;

3 is a block diagram illustrating a configuration of a caption display apparatus for displaying captions by determining whether user data includes DTVCC data according to an embodiment of the present invention.

4 is a flowchart illustrating a process of determining whether DTVCC data is included in user data according to an embodiment of the present invention.

5 is a flowchart illustrating a process of displaying a caption by determining whether user data includes DTVCC data as an embodiment according to the present invention.

* Explanation of symbols for the main parts of the drawings

310: TP stream decoder 320: video parser

330: video decoder 340: DTVCC decoder

350: PSIP Parser 360: Channel Manager

370: video synthesizer 380: control unit

The present invention relates to a caption display apparatus and method, and more particularly to a digital caption display apparatus and method.

The terrestrial broadcasting standard for analog TV in the United States uses closed captions in English and Spanish using the 21st line of the VBI (Vertical Blanking Interval) section of the NTSC (NTSC) broadcasting signal. (closed caption: CC), and the related standard is EIA (Electronic Industries Association: EIA) 608.

According to the EIA 608 standard, there are eight types of services that can be transmitted for analog closed caption (analog CC) in the United States.

The service types include CC1 (main synchronous subtitle service), CC2 (special asynchronous subtitle), CC3 (sub synchronous subtitle service), CC4 (special asynchronous subtitle), Text1 (first character information service), Text2 (second character information service), 8 types of Text3 (third character information service) and Text4 (fourth character information service).

In the case of analog captions in the United States, the user must determine the above eight settings, but since the actual broadcast program does not have information about which of the above eight services is being performed, the user can see the caption service desired. In order to continue to change the settings to find out what services are provided inconvenient.

In the case of analog TV broadcasting in Korea, due to the difference between the supported languages as Korean and English, there are some differences in the table and detailed rules regarding the values of actual letters and command sets. The transmission of caption information using the 21st line of the VBI is identical.

Meanwhile, as the broadcasting environment is switched from analog to digital broadcasting, ATSC (Advanced Television System Committee (ATSC)) standard has been established as a terrestrial broadcasting standard in the United States. Caption: A standard (EIA 708) relating to DTVCC is established and used.

The DTVCC will be described with reference to the accompanying drawings.

1 is a diagram of DTVCC caption data described in the EIA 708 standard in a bit stream of a general digital TV.

As shown in FIG. 1, a bit stream of a digital TV is composed of an audio data area, a video data area, and a control data area.

In the case of the DTVCC, caption data itself is transmitted using a user data area included in a header of a picture constituting the video data area, and conforms to the MPEG-2 video standard and the ATSC standard (A53). At this time, the transfer amount can be transferred up to 128 bytes in each user data area, and the total transfer amount cannot exceed 9600bps (bit per second).

In comparison, the analog-closed caption based on EIA 608 is 10 times the bandwidth increase compared to 960bps.

In the case of the DTVCC based on the EIA 708, a total of 63 caption services can be provided in consideration of the extended bandwidth.

As with the analog closed captions discussed earlier on the 63 possible caption services, it's unreasonable to keep users changing their settings to find the caption service they want.

Therefore, in the ATSC standard, when a DTVCC is provided, a broadcasting station must include information called a caption service descriptor in an event information table (EIT) or a program map table (PMT) in a PSIP (Program and System Information Protocol (PSIP)). It must be included.

However, the actual broadcast signal may be received by being included in a table which does not have the caption service descriptor or does not refer to it. In this case, even if the actual DTVCC data is received, there is a problem that the caption is not displayed.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to display the received caption data on the screen when the actual closed digital caption data is received even when a descriptor including caption information cannot be found. It is to provide a caption display apparatus and method for enabling the same.

A feature of the caption display apparatus according to the present invention for solving the above problems is a TP stream decoder for separating the received TP stream into other information data including audio, video, PSIP, parsing the separated PSIP data A controller for determining whether the parsed PSIP data includes digital closed caption data in the parsed PSIP data, according to a judgment of the controller And a video parser for separating the digital closed caption data, and a digital closed caption decoder for decoding the separated digital closed caption data.

A feature of the caption display method according to the invention comprises the steps of: separating the received TP stream into other information data, including audio, video, and PSIP; parsing the separated PSIP data; and digitalizing the parsed PSIP data. If the descriptor regarding the closed caption information is not included, determining whether the separated video data includes the digital closed caption data, and separating the digital closed caption data according to the determination to display the digital closed caption. Displaying on the screen.

Other objects, features and advantages of the present invention will become apparent from the following detailed description of embodiments taken in conjunction with the accompanying drawings.

In addition, the terms used in the present invention was selected as a general term widely used as possible now, but in certain cases, the term is arbitrarily selected by the applicant, in which case the meaning is described in detail in the corresponding description of the invention, It is to be clear that the present invention is to be understood as the meaning of terms rather than names.

The operation of the caption display apparatus and method according to the present invention configured as described above will be described in detail with reference to the accompanying drawings.

FIG. 2 is a flowchart illustrating a process of extracting caption data included in a digital TV bit stream and displaying captions.

The PSIP of the ATSC standard includes information on a broadcast stream to be transmitted, and the information on the DTVCC is included in a caption service descriptor in an EIT or PMT.

Accordingly, the receiver parses the PSIP data in the received broadcast stream (S210) and determines whether the caption service descriptor exists (S220). The caption service descriptor includes information such as caption language, caption service number, and the like.

If the caption service descriptor is included in the received broadcast stream as a result of parsing the PSIP data, it is determined whether the DTVCC supports the language selected by the user (S230).

When the user supports the language selected by the user, the service number of the language selected by the user is selected (S240), and the DTVCC data corresponding to the service number is extracted and displayed on the screen (S250).

If the language selected by the user is not supported as a result of the determination in S230, a service number of a language set as a default is selected (S260). English and the like are set in advance in the default language.

If there is a service number of the language set as the default in the DTVCC data (S270), the DTVCC data of the language set as the default is extracted and displayed on the screen (S250).

If there is no service number of the language set as the default (S270), the caption is not displayed on the screen and only the received image is displayed on the screen (S275).

If it is determined in S220 that the caption service descriptor is not included in the PSIP data, it is determined that the DTVCC data is not included in the received broadcast stream.

When the caption service descriptor is not included in the PSIP data, for example, the caption service descriptor is not included in the promised table and is included in another table, or the caption service descriptor itself is not included in the PSIP data. If not, etc. can be mentioned.

In this case, the receiver determines whether analog CC data is included in the received broadcast stream (S280). If analog CC data exists, the receiver extracts the analog CC data and displays a caption on the screen (S250). However, since the analog CC and the DTVCC have different data formats, the analog CC is displayed on the screen through a separate decoding process from the DTVCC.

If analog CC data is not included in the received broadcast stream (S280), the caption is not displayed on the screen and only the received image is displayed on the screen (S285).

Therefore, if it is determined in the determination of S220 that the caption service descriptor is not included, the analog CC data is immediately processed and displayed.

3 is a block diagram illustrating a configuration of a caption display apparatus displaying a caption by determining whether user data includes DTVCC data as an embodiment according to the present invention.

The caption display apparatus includes a TP (Transport Packet) stream decoder 310, a video parser 320, a video decoder 330, a DTVCC decoder 340, a PSIP parser 350, and a channel manager 360. ), A video synthesizer 370, and a controller 380.

The receiver receives a TP stream carrying a broadcast program through a tuner (not shown). The TP stream decoder 310 separates the received TP stream into audio, video, and other information (PSIP data, etc.) data.

The separated audio data is decoded in an audio decoder (not shown) and delivered to a user through a speaker (not shown).

The video data separated by the TP stream decoder 310 is transmitted to the video parser 320. The video parser 320 separates data related to a video image included in the video data and DTVCC data included in user data.

Data related to the video image separated by the video parser 320 is decoded by the video decoder 330, and DTVCC data is decoded by the DTVCC decoder 340, respectively.

The PSIP parser 350 receives and parses the PSIP data separated by the TP stream decoder 310. As a result of the parsing, it is determined whether a caption service descriptor exists in the EIT or PMT. If the caption service descriptor exists, information such as a caption language and a service number is obtained from the descriptor.

The channel manager 360 transmits to the DTVCC decoder 340 whether a caption service descriptor exists in the current channel, information extracted from the caption service descriptor, and service number information selected by the user.

The DTVCC decoder 340 decodes the DTVCC data of the service number selected by the user using the information transmitted from the channel manager 360.

The video decoded by the video decoder 330 and the caption decoded by the DTVCC decoder 340 are transmitted to the video synthesizer 370. The video synthesizer 370 synthesizes the image processed by the video decoder 330 and the caption processed by the DTVCC decoder 340 into one screen and transmits the combined caption to the display unit.

If the caption service descriptor does not exist as a result of parsing the PSIP data by the PSIP parser 350, the controller 380 determines whether the DTVCC data is included in the user data.

4 is a flowchart illustrating a process of determining whether DTVCC data is included in user data according to an embodiment of the present invention.

User data is extracted from the received broadcast stream (S410), and it is determined whether the user data includes DTVCC data (S420).

The user data is a series of 128 byte bit streams. The DTVCC data in the bit stream starts with a series of bits of 47 (0100 0111) 41 (0100 0001) 39 (0011 1001) 34 (0011 0100). The 47 41 39 34 value is defined as the Identifier in the EIA 708 standard.

Therefore, if the extracted user data includes a bit stream starting with 47 41 39 34, it is determined that the DTVCC data is included (S430). If the bit stream starting with the value is not included, the DTVCC data is not included. It is determined that it is not (S440).

In order to reliably determine whether the DTVCC data is included, if more than a certain number of bit streams starting with 47 41 39 34 are detected, the DTVCC data is included. If not, the DTVCC data is included. It may be set as not to determine whether DTVCC data is included.

For example, if the bit stream starting with 47 41 39 34 is counted more than 10 times in the user data, it is determined that the DTVCC data is included, and the bit stream starting with 47 41 39 34 is not included in the user data. If the count is 10 or more times, it may be determined that DTVCC data is not included.

As a result of the determination, if the DTVCC data is included in the user data, the video parser 320 extracts data corresponding to the caption service number selected by the user and transmits the data to the DTVCC decoder 340.

The DTVCC decoder 340 decodes the transmitted DTVCC data and displays a caption on the screen through the video synthesizer 370.

If it is determined that the caption service descriptor is not included in the parsed PSIP data or that the DTVCC data is not included in the user data, the controller 380 determines whether analog CC data is included in the video data.

If analog CC data is included, the video parser 320 extracts the analog CC data and transmits the analog CC data to an analog CC decoder (not shown). The video synthesizer 370 synthesizes the analog caption decoded by the analog CC decoder and the image decoded by the video decoder 330 into one screen and displays the same on the screen.

If the analog CC data is not included, the caption data does not exist in the received broadcast stream. Therefore, the caption is not displayed on the screen, and only the received image is displayed on the screen.

The controller 380 also controls the above process.

5 is a flowchart illustrating a process of displaying a caption by determining whether user data includes DTVCC data as an embodiment according to the present invention.

The receiver parses the PSIP data in the received broadcast stream (S510) and determines whether a caption service descriptor is included (S520). The caption service descriptor includes information such as caption language, caption service number, and the like.

If the caption service descriptor is included in the received broadcast stream as a result of parsing the PSIP data, it is determined whether the DTVCC supports the language selected by the user (S530).

When the user supports the language selected by the user, the service number of the language selected by the user is selected (S540), and the DTVCC data corresponding to the service number is extracted and displayed on the screen (S550).

If the language selected by the user is not supported as a result of the determination in S530, a service number of a language set as a default is selected (S560). English and the like are set in advance in the default language.

If the service number of the language set as the default exists in the DTVCC data (S570), the DTVCC data of the language set as the default is extracted and displayed on the screen (S550).

If there is no service number of the language set as the default (S570), the caption is not displayed on the screen, and only the received image is displayed on the screen (S575).

If the caption service descriptor is not included in the PSIP data as a result of the determination in S520, it is determined whether the DTVCC data is included in the user data by the determination method as shown in FIG. 4 (S580).

As a result of the determination of S580, if the DTVCC data is included in the user data (S585), the caption is displayed on the screen through the DTVCC data processing (S530 to S575).

However, if the determination result of the S580 determines that the user data does not include the DTVCC data (S585), it is assumed that the received broadcast stream does not include the DTVCC data.

Therefore, it is determined whether analog CC data is included in the received broadcast stream (S590). If analog CC data is included, the analog CC data is extracted and a caption is displayed on the screen (S550). However, since the analog CC and the DTVCC have different data formats, the analog CC is displayed on the screen through a separate decoding process from the DTVCC.

If the S590 determination result does not include analog CC data (S590), since the received broadcast stream does not include caption data, the caption is not displayed on the screen, and only the received image is displayed on the screen (S595).

The apparatus and method for displaying captions by determining whether CC data is included as described above may be applied to a video display device such as a digital TV (DTV) or a multimedia broadcasting receiver supporting captions.

The present invention is not limited to the above-described embodiments, and as can be seen in the appended claims, modifications can be made by those skilled in the art to which the invention pertains, and such modifications are within the scope of the present invention.

As described above, according to the caption display apparatus and method of the present invention, even when the caption service descriptor cannot be found, the received caption data can be displayed on the screen when the actual closed digital caption data is received. .

Claims (10)

A TP stream decoder for separating the received TP stream into other information data including audio, video, and PSIP; A PSIP parser for parsing the separated PSIP data; A controller that determines whether the digital video closed caption data is included in the separated video data when the parsed PSIP data does not include a descriptor about the digital closed caption information; A video parser that separates the digital closed caption data according to a determination of the controller; And And a digital closed caption decoder for decoding the separated digital closed caption data. The method of claim 1, And a descriptor regarding the information of the digital closed caption is a 'caption service descriptor'. The method of claim 1, The determination of whether the digital closed caption data is included, And determining whether the digital closed caption data is included according to whether a bit stream having a DTVCC identifier is included in user data of the video data. The method of claim 1, The determination of whether the digital closed caption data is included, If the user data of the video data is counted more than a certain number of bit streams having a DTVCC identifier, it is determined that the digital closed caption data is included. If the bit stream having the DTVCC identifier is not counted more than a certain number, the digital closed caption data is included. Caption display apparatus characterized in that it does not determine. The method according to claim 3 or 4, And the DTVCC identifier is a value having a bit of 47 41 39 34 (hexadecimal). Separating the received TP stream into other information data including audio, video, PSIP; Parsing the separated PSIP data; If the parsed PSIP data does not include a descriptor about the information of the digital closed caption, determining whether the separated video data includes the digital closed caption data; And dividing the digital closed caption data according to the determination to display the digital closed caption on a screen. The method of claim 6, The caption display method according to claim 1, wherein the descriptor regarding the information of the digital closed caption is 'caption service descriptor'. The method of claim 6, The determination of whether the digital closed caption data is included, And determining whether digital closed caption data is included according to whether a bit stream having a DTVCC identifier is included in the user data of the video data. The method of claim 6, The determination of whether the digital closed caption data is included, If the user data of the video data counts more than a certain number of bit streams with the DTVCC identifier, it is determined that the digital closed caption data is included. If the bit streams with the DTVCC identifier is not counted, the digital closed caption data is included. Caption display method characterized in that it is determined that not. The method according to claim 8 or 9, The DTVCC recognizer is a value having a bit of 47 41 39 34 (hexadecimal).

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