KR100980048B1 - Apparatus for receiving a digital broadcast signal and method of receiving a digital broadcast signal - Google Patents

Abstract

The present invention relates to a digital broadcast receiver and a digital broadcast signal processing method. The present invention relates to whether a digital television closed caption service exists in the video stream or a line 21 closed caption service exists in the video stream according to an electronic industry association (EIA) 708. Provided is a digital broadcast signal processing method capable of processing caption information indicating whether the information is present.

Description

Apparatus for receiving a digital broadcast signal and method of receiving a digital broadcast signal}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to caption data of a digital TV, and more particularly, to a method of transmitting and receiving closed caption data that conforms to an open cable and a cable ready standard of digital cable broadcasting.

The terrestrial broadcasting standard for analog TV in the US transmits closed captions such as English and Spanish using the 21st line of the VBI (Vertical Blanking Interval) section of the National Television System Committee (NTSC) broadcasting signal. The relevant standard is EIA 608.

Based on the EIA 608 standard, in the United States, 8 types of services that can be transmitted for analog closed caption (analog CC) are shown in Table 1 below.

NTSC Field 1 Line 21 Caption NTSC Field 2 Line 21 Caption CC1 (Main Synchronous Subtitle Service) CC3 (synchronous subtitle service) CC2 (Special Asynchronous Subtitles) CC4 (Special Asynchronous Subtitles) Text1 (First Character Information Service) Text3 (third character information service) Text2 (Second Character Information Service) Text4 (fourth character information service)

In the case of analog captions in the United States, the user must determine the eight settings as shown in Table 1 above, but since the actual broadcast program does not have any information about which of the above eight services, the caption service desired by the user In order to see the continued change of settings to find out what services are inconvenient to find.

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) standard has been established as the terrestrial broadcasting standard in the United States, and for this purpose, digital closed caption (DTVCC), which is reinforced than the conventional analog closed caption, is established. ) (EIA 708) has been 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 9600 bps (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 caption_service_descriptor in an event information table (EIT) or a program map table (PMT) in a PSIP (Program and System Information Protocol).

This allows the DTV receiver to know what kind of DTVCC is included in the program, which is shown in FIG. 2.

FIG. 2 is a diagram illustrating syntax of a caption_service_descriptor defined in an ATSC standard (A65, Program and System Information Protocol for Terrestrial Broadcast and Cable).

For example, suppose that a broadcaster provides analog closed captions and six digital closed caption services for a program:

NTSC Field1 line 21 caption: 4 types

NTSC Field2 line 21 caption: 4 types

Caption Service 1: English

Caption Service 2: Spanish

Caption Service 3: English (with easy_reader flag)

Caption Service 4: Spanish (with easy_reader flag)

Caption Service 5: French

Caption Service 6: French (with easy_reader flag)

In this case, the information is transmitted to the caption_service_descriptor in the PSIP in the table form as shown in FIG.

Therefore, the digital TV notifies the user of the above information, selects the caption desired by the user, or allows the user to automatically select a caption service suitable for a preset language.

In this case, it can be seen that the digital TV does not merely provide a pure DTVCC (DTVCC) based on the EIA 708.

That is, the user data area including the DTVCC also includes analog closed captions in units of 2 bytes according to EIA 608.

In the case of digital TVs, it is common to output S-VHS or Composite output to a conventional analog TV. In this case, analog closed caption data loaded in the user data area is encoded into VBI line 21 of the S-VHS or Composite output. When encoding and outputting, the caption display is performed through an analog closed caption decoder installed in an analog TV to which S-VHS or composite is input.

In addition, in satellite broadcasting standards such as Direc TV, analog closed caption data carried in a user data region, rather than a DTVCC, is used for decoding purposes.

On the other hand, unlike terrestrial broadcasting, cable broadcasting has taken its own way due to the nature of the market. The characteristics of the cable broadcasting is that the broadcasting method is generally similar to each other depending on the region, service company, or supplier of broadcasting equipment, but there are some differences.

In particular, the closed caption is operated based on the same character value and command set as defined in EIA 608, but is similar to terrestrial analog broadcasting, but uses a VBI section other than the 21st line of the VBI. The difference is that it is also transmitted.

That is, in some broadcasts, captions are transmitted using the 6th line of the VBI, and in some broadcasts, captions are transmitted using the 10th line.

This characteristic of analog cable broadcasting has made the closed caption specification for digital broadcasting standalone as the cable has been converted to digital broadcasting.

Called SCTE 20 or DVS 157, the basic intent of this standard is to convert analog closed captions used in analog cable broadcasting to the user data area within the video data area of a digital TV.

There is no new standard closed caption (DTVCC) as in EIA 708. Only the existing analog closed caption is defined, and the form of the table is shown in FIG.

FIG. 3 is a diagram illustrating syntax of picture user data defined in SCTE 20 (DVS 157). FIG.

As mentioned earlier, in cable broadcasting, analog closed captions are transmitted on various lines including the 21st line of the VBI.

Accordingly, the caption data of SCTE 20 or DVS 157 as shown in the table of FIG. 3 is information about whether a caption is transmitted through a certain field (even or odd) for each two-byte caption data (field_number represented by 2 bits of FIG. 3). In addition, information (line_offset represented by 5 bits of FIG. 3) indicating whether the caption data is transmitted through the VBI line is also transmitted.

In the case of SCTE 20 or DVS 157, as described above, there is no definition of a new type of DTVCC.

In addition, the ATSC standard related to the DTVCC of FIG. 2 described above does not consider closed captions according to SCTE 20 or DVS 157, which are caption transmission standards used in cable broadcasting.

In case of cable broadcasting in the conventional closed market, a cable broadcasting service company has provided a service by distributing a cable broadcasting receiver (cable set top box) suitable for its broadcasting to each user, and appropriate caption_service_descriptor This is because the cable broadcasting receiver developer grasped the broadcasting equipment setting of the cable broadcasting service company and developed the receiver according to the broadcasting equipment setting without transmitting the data, so there was no problem in the digital cable broadcasting until the open cable.

However, the new digital broadcast environment, represented by open cables and cable ready, requires a different view of the problem.

In other words, in open cable and cable ready environments, the purpose is to provide a cable connection to a device that is generally available on the market, rather than to a specific cable broadcast receiver provider for a specific cable broadcaster. The receiving method is a very complicated problem.

If you look at this more closely, first of all, digital TV that can receive open cable broadcasting under the Federal Communications Commission (FCC) regulations must be included in DTVCC and analog CC (original line 21) as defined by EIA 708. Closed captions).

It must also decode user data in other formats as defined in SCTE 20 or DVS 157, and encode the corresponding captions on the VBI lines of the S-Video, Composite, 480i, and Component outputs.

This requires the following work on a digital TV receiving open cable broadcasts.

Identify what kind of caption data is included in the digital cable broadcast being received (the pure DTVCC of the EIA 708, the analog CC included in the DTVCC, or the analog CC according to SCTE 20 or DVS 157).

-Choose the appropriate caption among the identified caption data.

-Decode the selected caption.

-Encode the caption transmitted in the appropriate VBI transmission section of the analog output (S-Video, Composite, ...).

It is difficult to understand what kind of caption data is included in the digital cable broadcast being received. Therefore, if it is not possible to automatically determine what kind of caption data is included, the user is forced to make a selection, for example, to select the following options from a key or menu on the remote control. .

DTVCC, analog CC (EIA 708), analog CC (SCTE 20 or DVS 157)

It is a method of repeatedly selecting whether to decode caption data of any of the above standards to find out what is available for viewing. In fact, it is not unreasonable to ask the user for the above, and the type of service described above Since the caption can be viewed only by selecting CC1, CC2, CC3, ...), the inconvenience is greatly increased.

Accordingly, an object of the present invention is to solve the problems of the prior art, to provide a closed caption in accordance with the open cable and cable ready standard, to provide a method for simplifying the operation of the receiver and the operation of the receiver. To present.

It is another object of the present invention to ensure that the above method does not cause a malfunction of the cable broadcasting receiver according to the conventional ATSC standard.

The present invention includes a demultiplexer for demultiplexing a program map table (PMT), an event information table (EIT) and a video stream from a received broadcast stream; Whether the caption data included in the video stream from at least one of the PMT and the EIT is caption data according to a digital television closed caption service or the caption data is a line according to an electronic industry association (EIA) 708 A control unit for decoding caption information indicating whether line 21 closed caption service data is present; A video parser for parsing the video stream; A video decoder for decoding the video data output by the video parser; A caption decoder for decoding the caption data output by the video parser; And a video synthesizer for combining the decoded video data and the decoded caption data.

Demultiplexing a program map table (PMT), an event information table (EIT) and a video stream from the received broadcast stream; Whether the caption data included in the video stream from at least one of the PMT and the EIT is caption data according to a digital television closed caption service or the caption data is a line according to an electronic industry association (EIA) 708 Decoding caption information indicating whether the line is 21 closed caption service data; Parsing the video stream; Decoding video data of the parsed video stream; Decoding the caption data of the parsed video stream; And combining the decoded video data and the decoded caption data.

The caption transmission and reception method in the digital broadcasting system according to the present invention has the following effects.

First, there is an effect of efficiently transmitting and receiving captions in the transmission environment based on open cable and cable ready standards.

Second, there is an effect that can be used in the open cable and cable ready standard without a large modification of the conventional digital broadcast receiver that conforms to the ATSC standard.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention.

Therefore, the technical scope of the present invention should not be limited to the contents described in the examples, but should be defined by the claims.

1 is a diagram illustrating DTVCC caption data in a general digital TV bit stream.
2 is a diagram illustrating caption_service_descriptor syntax defined in the ATSC standard according to the prior art;
3 is a diagram illustrating syntax of user data defined in SCTE 20 or DVS 157 according to the prior art.
4 illustrates a syntax of caption_service_descriptor according to the present invention.
5A to 5C are block diagrams illustrating the structure of a digital broadcast receiver according to the present invention.

Hereinafter, a configuration and an operation according to a preferred embodiment of the present invention will be described with reference to the accompanying drawings.

Open cable and cable ready specifications are compliant with the ATSC standard. Therefore, the object of the present invention is achieved by modifying the caption_service_descriptor defined in the ATSC standard (A65, Program and System Information Protocol for Terrestrial Broadcast and Cable), and included in the PMT on EIT or MPEG System Information on PSIP as shown in FIG. Done.

4 is a view showing the content of the caption_service_descriptor modified to meet the open cable and cable ready standard according to the present invention. Modifications are shown in bold.

First, the caption_service_descriptor contents of FIG. 4 will be described as follows.

descriptor_tag: Represented by 8 bits and checks the type of descriptor.

descriptor_length: It is expressed by 8 bits and indicates the length of the entire structure.

number_of_services: Represented by 5 bits and represents the total number of caption services.

language: Indicates language information of the corresponding caption, such as English of Service 1 or Spanish of Service 2. A three-byte language code according to ISO 639.2 / B, where each letter is coded eight bits and inserted into a 24-bit field.

cc_type: Represented by 1 bit, cc_type = 1 is an advanced caption, and cc_type = 0 is an analog caption (analog caption included in the EIA 708 standard or SCTE 20 (DVS157)).

analog_cc_type: Analog caption (analog caption included in EIA 708 standard or SCTE 20 (DVS157)), that is, when cc_type == 0, and analog_cc_type == 1 is transmitted to VBI line 21 according to EIA 608 It means caption data. When analog_cc_type == 0, caption data may be included in a line other than VBI line 21 according to SCTE 20 or DVS 157.

line_offset: Represented by 5 bits, this indicates whether the caption is included in the caption data according to SCTE 20 or DVS 157, that is, the caption included in the VBI when analog_cc_type == 0.

line_field: Indicates whether the caption is included in the even field or the caption included in the odd field. That is, if line_field == 0, the caption is included in the odd field. If line_field == 1, the caption is included in the even field.

caption_service_number: It is expressed by 6 bits and represents 1 to 63 caption service numbers in case of digital caption, that is, when cc_type == 1.

easy_reader: Flag that indicates whether the caption is easy for the user to read.

wide_aspect_ratio: Flag that indicates whether the caption is for a 16: 9 screen.

This configuration is a method utilizing the space reserved in the configuration of the conventional caption_service_descriptor.

That is, reserved 1 bit after cc_type shown in FIG. 2 is used to identify analog_cc_type, and reserved 5 bits in the if statement are used as an information space representing whether the caption data is included in the VBI line.

* This will be described below with reference to FIG. 4 showing the present invention.

First, when cc_type == 0, it means an analog caption. Such analog captions include analog captions according to the EIA 608 standard, analog captions included in the EIA 708 standard, and analog captions according to the SCTE 20 or DVS 157 standard as described above, but analog captions according to the EIA 608 standard are pure. The analog caption does not correspond to the closed caption of the digital TV mentioned in the present invention, so it is excluded.

Accordingly, the analog caption corresponding to the case where cc_type == 0 means either an analog caption included in the EIA 708 standard or an analog caption according to the SCTE 20 (DVS 157) standard.

Therefore, the process of selecting one of the two types of captions is 1 bit allocated to analog_cc_type of FIG. 4.

When the analog_cc_type is 0, it means that the caption is included in the video data area in the user data format according to the SCTE 20 or DVS 157 which is a standard for digital cable broadcasting.

In this case, since the caption is not known to which line of the VBI the caption is allocated due to the characteristics of the cable broadcast, it is expressed as the number of lines of the VBI by 5 bits allocated to the line_offset.

When analog_cc_type is 1, it means that the analog caption included in the EIA 708 standard is included in the video data area in the user data format.

In this case, since the caption is assigned to the 21st line of the VBI, the line_offset value is not necessary. Accordingly, 5 bits allocated to line_offset are reserved bits, and 1 bit is allocated to line_field indicating whether a caption is included in an even field or a caption is included in an odd field. If line_field == 0, the caption is included in the odd field. If line_field == 1, the caption is included in the even field.

As described above, whether the caption data included in the digital cable broadcast is an analog caption or a digital caption through information included in the caption_service_descriptor, and if the analog caption is an analog caption included in the EIA 708 standard or the SCTE 20 or DVS 157 standard. If the caption is a cable broadcasting caption or a caption according to the SCTE 20 or DVS 157 standard, it is determined whether the caption data is included in the VBI line. If the caption data is a digital caption, which of 63 service types is included Make sure you have information about.

When the caption_service_descriptor information is transmitted through digital cable broadcasting, the operation of the receiver will be described as follows.

FIG. 5A is a block diagram showing a configuration of a digital broadcast receiver centered on closed caption data processing according to the present invention, and FIG. 5B is a block diagram showing a configuration of a digital broadcast receiver centering on digital caption processing in the configuration of FIG. 5A. FIG. 5C is a block diagram showing the configuration of a digital broadcast receiver centering on analog caption processing.

As shown in FIG. 5A, in the digital broadcast receiver according to the present invention, an MPEG-2 transport stream transmitted through digital cable broadcasting is decoded and demultiplexed into video, audio, and control information. MPEG demultiplexer 501, PMT buffer 502, EIT buffer 503, PMT buffer 502, or EIT buffer 503 in which PMT and EIT in PSIP belonging to the control information are stored separately. A user processor 504 for processing caption_service_descriptor information and caption information input by a user, and parsing video data decoded by the MPEG demultiplexer 501 to user data region (user_data ()). And a DTVCC decoder to generate digital captions through signals processed by the video parser 505 and the user processor 504 and the video parser 505 for converting to MPEG-2 video data. An analog CC decoder 506 for generating a 507 and an analog caption, an MPEG-2 video decoder 508 for decoding a MPEG-2 video data generated by the video parser 505 to generate a video program, and the user The user graphic unit 510 for generating a GUI screen such as an OSD menu through the information generated by the processor 504, and synthesizes the generated analog or digital caption data with a video program and an OSD menu. A video combiner 509 to generate and a video reconstructor 309 to encode the caption generated by the analog CC decoder 506 to the 21st line of the VBI.

Referring to the operational relationship of the digital broadcast receiver according to the present invention configured as described above are as follows.

First, MPEG-2 transport streams transmitted through digital cable broadcasting are demultiplexed into video, audio, and control information through the MPEG demultiplexer.

Thereafter, the PMT and the EIT in the PSIP belonging to the control information are separately stored and stored in the PMT buffer 502 and the EIT buffer 503. The PSIP defines EPG (Electronic Program Guide) and SI (System Information) as one, terrestrial wave defined to provide various information about a program by parsing the messages encoded by the method of MPEG-2. ATSC standard for cable digital broadcasting (1997 DEC. Document A65).

That is, the PSIP consists of several tables for transmitting and receiving A / V data in MPEG-2 video and AC-3 audio formats, and transmitting information about channels of each broadcasting station and information about each program of the channel. Among them, the information on the PMT (Program Map Table) is stored in the PMT buffer 502, and the information on the EIT (Event Information Table) is stored in the EIT buffer 503.

According to the ATSC standard, the caption_service_descriptor described above must be included in the PMT or the EIT. Accordingly, caption_service descriptor information is stored in the PMT buffer 502 or the EIT buffer 503.

Based on the caption_service_descriptor information stored in the PMT buffer 502 or the EIT buffer 503, the user processor 504 finds caption data included in the digital cable broadcasting based on the type of caption service set by the user. .

The service type of the found caption service may be a case of DTVCC which is digital caption information according to EIA 708 standard, that is, when cc_type == 1 in FIG. 4, and an analog caption, that is, cc_type == 0. May be the case.

The analog caption is classified into an analog caption according to the EIA 708 standard, that is, analog_cc_type == 1, and an analog caption according to the SCTE 20 or DVS 157 standard, that is, analog_cc_type == 0.

For convenience of description, the following description will be given with reference to the accompanying drawings for each type of caption divided as described above.

5B is a block diagram of blocks corresponding to cases in which a caption received by a digital broadcast receiver according to the present invention is digital.

When the user processor 504 of FIG. 5B determines that digital information according to EIA 708 is included through caption_service_descriptor information (if cc_type == 1), the language information selected by the user (off (not selecting to view caption)) , Caption information for the language based on the language, English, Spanish, etc.).

The caption information of the corresponding language uses information (service ID) represented by 6 bits in caption_service_number.

The service ID of the found caption information is transmitted to the DTVCC decoder 507.

The DTVCC decoder 507 extracts caption data corresponding to the service ID from the user data area of the picture header separated by the video parser 505.

The extracted caption data is synthesized with a GUI screen using video and OSD such as a video program decoded by the MPEG-2 video decoder 508 through the video synthesizer 509 and a TV menu screen generated by the user graphic unit 510. It is generated as an image and output.

In this case, according to FIG. 5A, the output of the video synthesizer 509 passes through the video reconstructor 511. The video reconstructor 511 is for analog caption. The output is bypassed in video reconstructor 511.

On the other hand, when cc_type == 0 in the user processor 504, the caption exists through line_field information corresponding to the caption service based on the caption service type selected by the user (off, cc1, cc2, cc3, ...). Determine the field. As described above, the caption exists in the odd field when line_field == 0 and in the even field when line_field == 1.

Caption information corresponding to the determined line_field is found in the caption_service_descriptor. That is, analog_cc_type information in the capton_service_descriptor is used.

Whether the information found is analog caption according to EIA 708 standard (analog_cc_type == 1) or analog caption according to SCTE 20 or DVS 157 (analog_cc_type == 0).

In the case of the analog caption according to the SCTE 20 or the DVS 157, a process of selecting caption data included in the digital cable broadcasting is shown in FIG. 5C.

The configuration of FIG. 5C shows blocks required in the case of analog caption according to SCTE 20 or DVS 157 in the configuration of FIG. 5A.

After confirming that the user processor 504 of FIG. 5C is an analog caption corresponding to SCTE 20 or DVS 157 through analog_cc_type, the VBI line information indicating the position of the caption represented by 5 bits in line_offset is checked.

The checked VBI line information and line_field information are input to the analog CC decoder 506. The analog CC decoder 506 finds analog caption data in SCTE 20 or DVS 157 format using the VBI line information and line_field information in the user data area in the video input from the video parser 505.

According to FIG. 5A, user data input to the analog CC decoder 506 passes through the DTVCC decoder 507. In this case, the user data is bypassed.

The found analog caption data is synthesized with a GUI screen using video and OSD such as a video program decoded by the MPEG-2 video decoder 508 through the video synthesizer 509 and a TV menu screen generated by the user graphic unit 510. The image is generated as an image and then output through the video reconstructor 511.

The video reconstructor serves to reconstruct the caption by encoding the analog caption data generated by the analog CC decoder 506 to the VBI 21 line. This is to prevent an open caption when the generated image is stored in a storage medium such as a VCR.

In addition, when the result determined in the user data area is cc_type == 0 and analo_cc_type == 1, that is, it is an analog caption according to the EIA 708 standard.

This is a case where 2 bytes of analog caption data is included for the analog receiver in the user data area including the DTVCC.

This case will be described with reference to FIG. 5A.

First, when the user processor 504 determines that cc_type == 0 through caption_service_descriptor information, the corresponding line_field is determined based on the caption service type selected by the user (off, cc1, cc2, cc3, ...). .

Based on the determined line_field information, if it is determined to be an analog caption according to the EIA 708 standard through analog_cc_type, the line_field information is transmitted to the analog CC decoder 506. In this case, since the analog caption information is located on the VBI 21 line, the line_offset value is not necessary.

In this case, two bytes of analog data are extracted from the DTVCC decoder 507 video parser 505 and the user data area including the input DTVCC is input to the analog CC decoder 506.

The analog CC decoder 506 finds analog caption data existing on the VBI 21 line from the two bytes of analog data based on the line_field information.

The found analog caption data is synthesized with a GUI screen using video and OSD such as a video program decoded by the MPEG-2 video decoder 508 through the video synthesizer 509 and a TV menu screen generated by the user graphic unit 510. The image is generated as an image and then output through the video reconstructor 511.

Even in this case, the video reconstructor serves to reconstruct the caption by encoding the analog caption data generated by the analog CC decoder 506 to the VBI 21 line.

If both an analog caption according to EIA 708 and an analog caption according to SCTE 20 or DVS 157 are present, the analog caption according to EIA 708 takes precedence.

In addition, when both a digital caption and an analog caption according to EIA 708 exist, the digital caption takes precedence.

501 MPEG demultiplexer 502 PMT buffer
503: EIT buffer 504: user processor
505: Video Parser 506: Analog CC Decoder
507: DTVCC decoder 508: MPEG-2 video decoder
509: video synthesizer 510: user graphics unit
511: Video Reconstructor

Claims (5)

A demultiplexer for demultiplexing a program map table (PMT), an event information table (EIT), and a video stream from the received broadcast stream;
Whether the caption data included in the video stream is caption data according to a digital television closed caption service or the caption data is a line 21 closed caption service according to an electronic industry association (EIA) 708. service) a control unit which decodes caption information indicating whether data is from at least one of the PMT and the EIT;
A video parser for parsing the video stream;
A video decoder for decoding the video data output by the video parser;
A caption decoder for decoding the caption data output by the video parser; And
And a video synthesizer for combining the decoded video data and the decoded caption data. The method of claim 1,
One of the PMT and the EIT includes a caption descriptor including the caption information. The method of claim 2,
And the caption descriptor describes the caption data according to the number of caption services of the caption data included in the video stream. The method of claim 2,
The caption descriptor includes a service identifier of a caption service transmitted in the received broadcast stream. Demultiplexing a program map table (PMT), an event information table (EIT) and a video stream from the received broadcast stream;
Whether the caption data included in the video stream is caption data according to a digital television closed caption service or the caption data is a line 21 closed caption service according to an electronic industry association (EIA) 708. service) decoding caption information indicating whether data is from at least one of the PMT and the EIT;
Parsing the video stream;
Decoding video data of the parsed video stream;
Decoding the caption data of the parsed video stream; And
And combining the decoded video data and the decoded caption data.

Images