KR20160118076A - Method and apparatus for processing caption in digital broadcasting - Google Patents

Abstract

The present invention relates to a method and an apparatus for processing captions in order to support various caption specifications in digital broadcasting. A method for processing captions in digital broadcasting according to an embodiment of the present invention comprises the steps of: receiving digital broadcast data; separating caption data and video data from the digital broadcast data; receiving a caption service number; determining whether the caption data uses an extended caption specification; performing adaptive decoding based on the extended caption specification when it is determined that the caption data uses the extended caption specification; overlaying video with captions by using the decoded caption data and the video data; and outputting video in which the former video has been overlaid with the captions.

Description

[0001] METHOD AND APPARATUS FOR PROCESSING CAPTION IN DIGITAL BROADCASTING [0002]

The present invention relates to a subtitle processing method and apparatus in digital broadcasting.

Closed Caption in digital broadcasting in Korea and North America is being transmitted based on CEA-708 series standard, and recently supports a method for transmitting stereoscopic caption for 3D broadcasting.

The CEA-708 caption specification is based on the MPEG-2 system standard. The caption is inserted into the Picture User Data area, and the subtitle service descriptor is inserted into the Program Mapping Table (PMT) or the EIT (Event Information Table) (Caption Service Descriptor). The CEA-708 specifies a fixed bandwidth of 9,600 bps for subtitles and provides a total of 63 services with six standard services and up to 57 extended services within this range. An example of such prior art subtitles is shown in FIG.

FIG. 1 is a diagram illustrating a digital broadcast subtitle according to the related art.

Referring to FIG. 1, in the prior art, a caption is provided in a caption data window in a safe-image area of a digital broadcasting screen by specifying a background color, a font color, a font, a font size, and an effect of the caption.

An object of the present invention is to provide a subtitle processing method and apparatus for supporting various subtitle standards in digital broadcasting.

A method of processing a subtitle in a digital broadcasting according to an exemplary embodiment of the present invention includes receiving digital broadcasting data, separating subtitle data and video data from the digital broadcasting data, inputting a subtitle service number, Determining whether an extended caption standard is used, performing adaptive decoding according to an extended standard when determining that the caption data uses the extended caption standard, performing a step of performing adaptive decoding according to the extended standard, The method comprising the steps of: overlaying a caption and a video using data; and outputting an image in which the caption and the video are overlaid.

According to the present invention, it is possible to provide improved subtitle service by transmitting new subtitle while maintaining compatibility with the prior art.

FIG. 1 is a diagram illustrating a digital broadcast subtitle according to the related art.
2 is a diagram illustrating a digital broadcast subtitle according to an embodiment of the present invention.
3 is a flowchart illustrating a method of transmitting a subtitle in a digital broadcast according to an exemplary embodiment of the present invention.
4 is a flowchart illustrating a method of receiving a subtitle in a digital broadcasting according to an exemplary embodiment of the present invention.
5 is a diagram illustrating a bitstream structure in digital broadcasting.
6 is a diagram illustrating a caption data receiving unit in a digital broadcasting receiving terminal.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Note that, in the drawings, the same components are denoted by the same reference symbols as possible. Further, the detailed description of well-known functions and constructions that may obscure the gist of the present invention will be omitted.

Throughout the specification, when a part is referred to as being "connected" to another part, it includes not only "directly connected" but also "indirectly connected" between the devices in the middle. Throughout the specification, when an element is referred to as "comprising ", it means that it can include other elements as well, without excluding other elements unless specifically stated otherwise.

2 is a diagram illustrating a digital broadcast subtitle according to an embodiment of the present invention.

There are a number of subtitle standards newly emerging according to the development of the web and multimedia technology of the digital age at present. Referring to FIG. 2, the newly introduced subtitle standards include dynamic and colorful effects such as free position, expression, and three-dimensional representation beyond the conventional two-dimensional text service, and a new type of subtitle specification will continuously appear Is predicted.

In the domestic TTAK.KO-07.0093 (Audio Visual Intervention Assisted Broadcasting Service) standard, the signaling of the caption information through the caption service descriptor in the broadcasting environment based on the MPEG-2 system must be performed through the PMT, , Cable) service information (Service Information) standards. The minimum requirements of the subtitle decoder and the receiver are such that the decoder does not exceed an average of 25% of the total subtitle bandwidth per second, that is, the decoder has a capability and buffer for processing the subtitle data up to 2,400 bps per service. In order to use the subtitle standard newly introduced in the current digital broadcasting environment, it is necessary to revise many related standards. However, according to the present invention, it is possible to transmit a new type of subtitle while maintaining compatibility with the prior arts, Can be provided.

3 is a flowchart illustrating a method of transmitting a subtitle in a digital broadcast according to an exemplary embodiment of the present invention.

Referring to FIG. 3, in step 310, a caption transmission terminal inputs a CEA 708 standard caption and an extended standard caption. At this time, it is possible to input different numbers of subtitles to be served for each broadcasting company for each medium. Accordingly, the subtitles can be expressed in various ways.

Thereafter, in step 320, a service number is assigned to each subtitle. Here, the service number is a logical service number, and six standard services or extended service numbers can be allocated according to the number of subtitles to be served. The subtitle descriptor of an extended standard subtitle may include a language field. According to an embodiment of the present invention, a language field may be displayed as 'kor' or 'KOR' in order to process Korean subtitles. In addition, according to one embodiment, the service number may include at least one of digital TV closed-caption (DTVCC) Korean, digital TV closed caption English 2, Can be assigned.

Next, in step 330, subtitles are encoded. At this time, the subtitles can be encoded according to the coding layer specification of the CEA 708 standard. Finally, in step 340, digital broadcast data including caption data is transmitted.

Through this process, a new type of subtitle can be transmitted while maintaining compatibility with the conventional techniques by transmitting the subtitle of the extended standard at the subtitle transmission end.

4 is a flowchart illustrating a method of receiving a subtitle in a digital broadcasting according to an exemplary embodiment of the present invention.

First, the digital broadcasting data is received in step 410, and the subtitle data and the video data are separated from the digital broadcasting data received in step 420. According to an embodiment of the present invention, an MPEG-2 transport stream can be received and a video ES (Elementary Stream) can be delivered to a video parser and separated from signaling data. Further, it is possible to analyze information related to the subtitles by analyzing signaling data such as PMT (Program Mapping Table), EIT (Event Information Table), PSIP (Program Specific Information Protocol), SI (Service Information)

Next, in step 430, a subtitle service number is input from the user. According to an embodiment of the present invention, when a user selects a subtitle service number, the user can notify the subtitle player of the selected service to output the selected subtitle to the screen.

Then, it is determined whether the extended caption standard is used in step 440. This is to determine how to decrypt the caption data. If it is determined in step 440 that the extended caption standard is used, the method proceeds to step 450 and adaptive decoding is performed according to the extended caption standard. If it is determined that the extended caption standard is not used in step 440, And performs decoding according to the CEA 708 standard. Compatibility with the conventional techniques can be maintained by selecting the decoding method differently according to the standard of the received caption data.

In step 470, the subtitle and video data are used to overlay the subtitles and the video. That is, the subtitles and video are synthesized so that they can be displayed on one screen. Finally, in step 480, the overlaid image is output.

The embodiments of the invention thus far described may be embodied in instructions carried out by a processor and stored in a computer-readable storage medium. When these instructions are executed by a processor, they may generate means for implementing the functions / operations specified in the flowcharts and / or block diagrams described above. Each block in the flowcharts / block diagrams may represent hardware and / or software modules or logic that implement embodiments of the present invention. Further, the functions referred to in the block diagrams may occur outside the order mentioned in the drawings, or may occur simultaneously.

The computer-readable medium can include, for example, but is not limited to, a nonvolatile memory such as a floppy disk, ROM, flash memory, disk drive memory, CD-ROM, and other persistent storage, Available.

5 is a diagram illustrating a bitstream structure in digital broadcasting.

Referring to FIG. 5, in an embodiment of the present invention, a caption service (Caption Service) 521 in a caption channel 510 of an MPEG-2 bitstream used for transmitting a caption of a new standard, 522) as a container. Thus, by using the caption service already existing in the prior art as a container, a new type of caption can be processed while maintaining compatibility.

6 is a diagram illustrating a caption data receiving unit in a digital broadcasting receiving terminal.

6, the caption data receiving unit includes an MPEG demultiplexer 610, a PMT buffer 621, an EIT buffer 622, a user-defined processor 630, a DTV caption reproducer 640, a video parser 650, A video player 660, a video synthesizer 670, an MPEG-2 video decoder 680, and a user-defined graphic 690. In this way, the caption data receiving unit shown in FIG. 6 uses the digital broadcast caption data standard model as it is. As described above, in one embodiment of the present invention, caption processing is performed according to the conventional standard, so that a new type of caption can be processed while maintaining compatibility.

The embodiments of the present invention disclosed in the present specification and drawings are merely illustrative examples of the present invention and are not intended to limit the scope of the present invention in order to facilitate understanding of the present invention. It will be apparent to those skilled in the art that other modifications based on the technical idea of the present invention are possible in addition to the embodiments disclosed herein.

610: MPEG demultiplexer
621: PMT buffer
622: EIT buffer,
630: Custom Processor
640: DTV subtitle player
650: Video parser
660: Video Player
670: Video synthesizer
680: MPEG-2 video decoder
690: Custom Graphics

Claims (1)

Receiving digital broadcast data;
Separating subtitle data and video data from the digital broadcasting data;
Receiving a caption service number;
Determining whether the caption data uses an extended caption standard;
Performing adaptive decoding according to an extended standard when determining that the caption data uses the extended caption standard;
Overlaying the caption and the video using the decrypted caption data and the video data; And
And outputting an image overlaid on the subtitle and the video.

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