JP7328039B2 - transmitter and receiver - Google Patents

Description

The present invention relates to a transmitting device and a receiving device used in a broadcasting system.

Non-Patent Document 1 defines ARIB-TTML (Timed Text Markup Language), which is a caption encoding method for new 4K8K satellite broadcasting. ARIB-TTML is an XML (Extensible Markup Language)-based description language that is an extension of TTML recommended by W3C, and can specify the display timing and layout of text.

When subtitle data is encoded using ARIB-TTML, the amount of data per subtitle page is 8 to 12 times greater than when it is encoded using 8-unit code, which is the subtitle encoding method for digital terrestrial broadcasting. increase to

Therefore, in the new 4K8K satellite broadcasting transmission system, a system for compressing and transmitting XML data, which is ARIB-TTML-encoded caption data, has been defined (see Non-Patent Document 2). As a compression method at this time, EXI (Efficient XML Interchange) defined by W3C is used (see Non-Patent Document 3).

When compressing XML data using EXI, the XML data can be compressed at a high compression rate by using the schemaId option for specifying an XML schema that defines the data structure of the XML data for compression. However, when the transmitting side compresses XML data using an XML schema, the compressed data cannot be expanded correctly unless the receiver also has the same XML schema.

Association of Radio Industries and Businesses Standards: Multimedia Coding Method for Digital Broadcasting (Second Generation) Volume 1 Part 3”, ARIB STD-B62 Version 2.1 (2019) Association of Radio Industries and Businesses Standards: “Media Transport Method by MMT in Digital Broadcasting”, ARIB STD-B60 Version 1.13 (2018) W3C Efficient XML Interchange (EXI) Format 1.0 (Second Edition), W3C Recommendation

The new 4K8K satellite broadcasting standard defines the XML schema of ARIB-TTML, and the XML schema that can be used by the transmitting side and the receiver when compressing and decompressing XML data is fixed.

For this reason, when specifying an XML schema to compress XML data at a high compression rate, it is not possible to use an XML schema that is not defined by the standard, and it is not possible to flexibly change the definition of the data structure of the XML data. There is a problem.

SUMMARY OF THE INVENTION Accordingly, the present invention provides a transmitting device and a receiving device that enable compression of XML data at a high compression ratio using an XML schema in a broadcasting system, and that enable flexible changes in the definition of the data structure of the XML data. With the goal.

A transmission device according to a first aspect is a transmission device used in a broadcasting system, and includes a data compression unit that compresses the XML data using an XML schema that defines the data structure of the XML data described in XML; a multiplexing unit for outputting broadcast content by multiplexing the XML schema used when the data compression unit compresses the XML data and the XML data compressed by the data compression unit; and a transmission path. and a transmitting unit configured to transmit the broadcast content output from the multiplexing unit to a receiving device via the multiplexing unit.

A receiving device according to a second aspect is a receiving device used in a broadcasting system, and includes an XML schema that defines the data structure of XML data described in XML via a transmission path, and compression using the XML schema. a receiving unit for receiving, from a transmitting device, broadcast content in which the XML data and the XML data are multiplexed; a demultiplexing unit for separating the XML schema and the XML data from the broadcast content received by the receiving unit; A compressed data decompression unit that decompresses the XML data demultiplexed by the demultiplexing unit using the XML schema demultiplexed by the demultiplexer.

According to the present invention, in a broadcasting system, it is possible to provide a transmitting device and a receiving device that can flexibly change the definition of the data structure of XML data while compressing XML data at a high compression rate using an XML schema.

1 is a diagram showing the configuration of a broadcasting system according to an embodiment; FIG. 1 is a diagram showing the configuration of a transmission device according to an embodiment; FIG. FIG. 4 is a diagram showing an example of transmission of subtitles/superimposed text according to the embodiment; FIG. 4 is a diagram showing an example of a data structure when storing an XML schema in a control message according to the embodiment; It is a figure which shows an example of the MP table which concerns on embodiment. It is a figure which shows an example of compression_type which concerns on embodiment. It is a figure which shows the structure of the receiver which concerns on embodiment. FIG. 10 is a diagram showing the configuration of a transmission device according to a modification; It is a figure which shows an example of the general-purpose data which concerns on the example of a change. FIG. 11 is a diagram showing the configuration of a receiving device according to a modification;

Embodiments will be described with reference to the drawings. In the description of the drawings, the same or similar parts are denoted by the same or similar reference numerals.

(broadcast system)
First, the broadcasting system according to this embodiment will be described. FIG. 1 is a diagram showing the configuration of a broadcasting system 10 according to this embodiment. The broadcasting system 10 is, for example, a system based on new 4K8K satellite broadcasting. The broadcasting system 10 can complementarily use not only broadcast waves but also communication as a transmission path.

As shown in FIG. 1, the broadcasting system 10 has a transmitting device 100 and a receiving device 300 . The transmitting device 100 transmits broadcast content to the receiving device 300 via the transmission path 200 .

Transmission line 200 may be a broadcast transmission line. In this case, the transmission device 100 performs broadcast transmission using broadcast waves.

Alternatively, transmission line 200 may be a communication transmission line. In this case, the transmitting device 100 performs broadcast transmission, multicast transmission, or unicast transmission via a communication network such as the Internet.

Broadcast content transmitted from the transmitting device 100 to the receiving device 300 via the transmission path 200 includes video data, audio data, and caption data.

In this embodiment, caption data is XML data encoded using ARIB-TTML defined in Non-Patent Document 1. However, any XML data defined by an XML schema may be used, and the type of XML data is not limited to caption data.

In addition, in the present embodiment, video data, audio data, and subtitle data (XML data) are received from the transmitting device 100 in a multiplexed state using MMT (MPEG Media Transport) defined in Non-Patent Document 2. shall be transmitted to the device 300 .

(Transmitter)
Next, the transmission device 100 according to this embodiment will be described. FIG. 2 is a diagram showing the configuration of the transmission device 100 according to this embodiment.

As shown in FIG. 2 , transmitting device 100 has video transmitting section 101 , audio transmitting section 102 , data compressing section 103 , control message generating section 105 , multiplexing section 106 and transmitting section 107 .

Video transmission unit 101 compresses and encodes video data constituting broadcast content according to a video encoding method, and outputs the data to multiplexing unit 106 .

Audio transmission section 102 compresses and encodes audio data constituting broadcast content according to an audio encoding method, and outputs the data to multiplexing section 106 .

The data compression unit 103 encodes the XML data, which is subtitle data constituting the broadcast content, in accordance with ARIB-TTML, compresses the XML data in accordance with EXI defined in Non-Patent Document 3, and then transmits the data to the multiplexing unit 106. Output. The XML data compressed by the data compression unit 103 is hereinafter referred to as "compressed XML data". Compressed XML data may include not only subtitles but also superimposed characters. Subtitles refer to text related to the video content of broadcast content, and superimposed text refers to text unrelated to the video content of broadcast content (for example, emergency news, etc.).

FIG. 3 is a diagram showing an example of transmission of subtitles/superimposed text. A series of programs delivered according to a schedule is called a "service". As shown in FIG. 3, in MMT, the unit of broadcast content is defined as a "package", and this package is used in one-to-one correspondence with a service.

In MMT, components such as video data and audio data are defined as assets. An asset has a structure in which MPUs (Media Processing Units) are continuous. A program is defined as a package consisting of one or more assets and control messages.

In the closed caption/superimposed text transmission method, one asset transmits closed captions or superimposed text in one language. Therefore, multiple assets are used to transmit multilingual captions and superimposed text. FIG. 3 shows an example in which subtitles and superimposed characters are transmitted in two languages.

The data compression unit 103 can compress XML data using a schemaId option that designates an XML schema that defines the data structure of XML data for compression.

In the present embodiment, the data compression unit 103 converts XML data using an XML schema defined by the ARIB-TTML standard (hereinafter referred to as "an XML schema defined by the standard") or an arbitrary XML schema. Compress. The data compression unit 103 may individually set for each asset whether to perform compression using an XML schema defined by the standard or using an arbitrary XML schema.

When compression is performed using an XML schema stipulated by the standard, the XML schema is stored in the receiving device 300 in advance, so there is no need to transmit the XML schema to the receiving device 300 .

On the other hand, when performing compression using an arbitrary XML schema, this XML schema is transmitted to the receiving device 300 . In this embodiment, the data compression unit 103 outputs this XML schema to the control message generation unit 105 when performing compression using an arbitrary XML schema.

Control message generation section 105 generates a message containing control information (SI: Signal Information) defined by ARIB STD-B60 (Non-Patent Document 2) and outputs the generated control message to multiplexing section 106 . A control message is a message containing control information regarding multiplexing and transmission of video data, audio data, and caption data (compressed XML data).

In this embodiment, the control message generation unit 105 stores the XML schema output from the data compression unit 103 in the control message, and outputs the control message containing the XML schema to the multiplexing unit 106 . That is, the control message output by control message generator 105 includes an XML schema used when data compressor 103 compresses XML data.

For example, the control message generator 105 stores an XML schema as a table forming control messages. FIG. 4 shows an example of the data structure when storing the XML schema in the control message. The data structure (MML_Compression_Message) shown in FIG. 4 includes an XML schema name (xml_schema_name) and XML schema data (xml_schema_data_byte).

In this embodiment, the control message generator 105 stores the MP table in the control message. FIG. 5 is a diagram showing an example of an MP table.

As shown in FIG. 5, the control message generation unit 105 arranges an MH-data coding scheme descriptor describing additional information about subtitles and superimposed text in the MP table, and assigns data_component_id. In the receiving device 300, by referring to the MP table, the location information of the asset is identified, the packet ID of the asset that transmits subtitles and superimposed characters is identified, and the MPU transmitted within the asset of the identified packet ID is identified. You can expand the data and get the files sent as subtitles and superimposed characters.

The control message generator 105 stores the additional identification information in the additional_data_component_info field defined for each encoding scheme of the MH-data encoding scheme descriptor. This additional identification information includes compression_type regarding compression of caption data. FIG. 6 is a diagram showing an example of compression_type.

As shown in FIG. 6, the control message generator 105 sets compression_type to "0000" when compressing caption data, and sets compression_type to "0001" when compressing caption data without specifying an XML schema. set.

Also, the control message generation unit 105 sets compression_type to “0010” when compressing the XML data using the XML schema defined by the standard, that is, the XML schema stored in advance in the receiving device 300 .

Furthermore, when compressing XML data using an arbitrary XML schema, that is, an XML schema transmitted via transmission path 200, compression_type is set to "0011".

Thus, receiving device 300 can determine which schema to use when decompressing compressed caption data by looking at compression_type.

In this embodiment, when compressing XML data using an arbitrary XML schema, the control message generation unit 105 periodically generates control messages including this XML schema during the period during which XML data compression using this XML schema is continued. output to multiplexing section 106 .

In other words, the control message generation unit 105 does not include the XML schema in all control messages, but includes the XML schema in control messages at certain time intervals. As a result, the XML schema used for XML data compression is periodically multiplexed with broadcast content and transmitted. As a result, while saving the band of the transmission line 200, the receiving device 300 that receives the broadcast content from the middle can expand the caption data (compressed XML data).

Multiplexing section 106 combines video data output from video transmission section 101, audio data output from audio transmission section 102, compressed XML data output from data compression section 103, and output from control message generation section 105. By multiplexing the received control message, the broadcast content is output to the transmission unit 107 .

In the present embodiment, multiplexing section 106 performs multiplexing using the MMT method defined in Non-Patent Document 2. FIG. Specifically, the multiplexing unit 106 sets each of the video data, the audio data, and the caption data (compressed XML data) as an MPU, puts them on an MMTP (MMT Protocol) payload, forms them into MMTP packets, and converts the MMTP packets into IP packets. The IP packet is placed on the payload to be IP-packetized, and the IP packet is placed on the payload of the TLV packet to be TLV-packetized and transmitted.

Transmitting section 107 transmits the broadcast content output from multiplexing section 106 to receiving apparatus 300 via transmission line 200 . The transmission line 200 may be a broadcasting transmission line or a communication transmission line.

(receiving device)
Next, the receiving device 300 according to this embodiment will be described. FIG. 7 is a diagram showing the configuration of the receiving device 300 according to this embodiment.

As shown in FIG. 7, the receiving device 300 includes a receiving unit 301, a demultiplexing unit 302, a control message processing unit 303, a compressed data expansion unit 304, a data processing unit 305, a video processing unit 306, an audio and a processing unit 307 .

Receiving section 301 receives broadcast content transmitted from transmitting apparatus 100 via transmission path 200 and outputs the received broadcast content to demultiplexing section 302 . Broadcast content includes control messages and data for video, audio, and subtitle assets. In this embodiment, the receiving unit 301 receives broadcast content in which a control message containing an XML schema and closed caption data, which is XML data compressed using this XML schema, are multiplexed.

The demultiplexing unit 302 demultiplexes the broadcast content output from the receiving unit 301 into a control message, caption data (compressed XML data in this embodiment), video data, and audio data, and sends the control message to the control message processing unit 303. , and outputs the caption data to the compressed data expansion unit 304 . The demultiplexing unit 302 also outputs the video data to the video processing unit 306 and the audio data to the audio processing unit 307 .

The control message processing unit 303 reads the value of compression_type of the additional identification information included in the control message output from the demultiplexing unit 302, and if this value is "0010" or "0011", the ARIB-TTML caption It determines that the data is compressed using the XML schema, and outputs information to that effect to the compressed data expansion unit 304 . When there are a plurality of assets for transmitting subtitles/superimposed characters, the control message processing unit 303 may perform processing to determine the value of compression_type for each of these assets.

Also, when the value of compression_type is “0011”, control message processing section 303 acquires the XML schema stored in the control message output from demultiplexing section 302 , and converts the acquired XML schema to compressed data expansion section 304 . output to

When the subtitle data output from the demultiplexing unit 302 is compressed using an XML schema, the compressed data expansion unit 304 expands the subtitle data (compressed XML data) using the XML schema, and extracts the expanded subtitle data. is output to the data processing unit 305 .

For example, when the value of compression_type is "0010", the compressed data expansion unit 304 expands caption data using the default XML schema. On the other hand, when the value of compression_type is "0011", the compressed data expansion unit 304 expands caption data using the XML schema output from the control message processing unit 303 (that is, the transmitted XML schema).

The data processing unit 305 decodes and outputs the subtitle data (that is, the expanded XML data) output from the compressed data expansion unit 304 .

The video processing unit 306 decodes and outputs the video data output from the demultiplexing unit 302 .

Audio processing section 307 decodes and outputs the audio data output from demultiplexing section 302 .

(Summary of embodiment)
As described above, the transmission device 100 according to the present embodiment includes the data compression unit 103 that compresses XML data using an XML schema that defines the data structure of XML data written in XML, and the data compression unit 103 broadcast content by multiplexing the XML data compressed by the data compression unit 103 and the control message with the control message generation unit 105 that generates a control message containing the XML schema used when compressing the XML data. It has a multiplexing unit 106 for output and a transmission unit 107 for transmitting the broadcast content output by the multiplexing unit 106 to the receiving device 300 via the transmission line 200 .

The receiving device 300 according to the present embodiment transmits broadcast content in which a control message storing an XML schema and XML data compressed using this XML schema are multiplexed from the transmitting device 100 via the transmission path 200. Using the receiving unit 301 that receives, the demultiplexing unit 302 that separates the control message and XML data from the broadcast content received by the receiving unit 301, and the XML schema stored in the control message separated by the demultiplexing unit 302, and a compressed data expansion unit 304 that expands the XML data demultiplexed by the demultiplexing unit 302 .

As a result, according to the present embodiment, even if an XML schema is specified and XML data is to be compressed at a high compression ratio, any XML schema that is not defined by the standard can be used. The definition of the data structure of XML data can be changed flexibly.

Therefore, in the broadcasting system 10, it is possible to provide the transmission device 100 and the reception device 300 that can flexibly change the definition of the data structure of the XML data while compressing the XML data at a high compression rate using the XML schema.

(Change example)
In the embodiment described above, an example of storing the XML schema used when the data compression unit 103 compresses the XML data in the control message has been described.

In this modified example, instead of storing the XML schema in the control message, the XML schema is stored in the general-purpose data transmitted by the asynchronous general-purpose data transmission method defined in Non-Patent Document 2.

The general-purpose data transmission method is a method for transmitting various types of data in a synchronous or asynchronous manner, and is used for data used by players that present data other than video, audio, and subtitles, and for data used in multimedia services. This method is suitable for transmission.

The asynchronous general-purpose data transmission system encapsulates data in an asynchronous MPU and transmits it, and is used when timing synchronization with video/audio is unnecessary. The asynchronous general-purpose data transmission scheme is defined in Non-Patent Document 2.

FIG. 8 is a diagram showing the configuration of transmitting apparatus 100 according to this modification.

As shown in FIG. 8 , transmitting apparatus 100 according to this modification has general-purpose data transmitting section 104 . The general-purpose data sending unit 104 generates general-purpose data of the asynchronous general-purpose data transmission method and outputs this general-purpose data to the multiplexing unit 106 .

In this modified example, the general-purpose data sending unit 104 stores the XML schema used when the data compression unit 103 compresses the XML data in the general-purpose data.

The multiplexing unit 106 multiplexes the general-purpose data output from the general-purpose data transmitting unit 104 and the XML data compressed by the data compression unit 103, and outputs broadcast content.

FIG. 9 is a diagram showing an example of general-purpose data according to this modified example.

As shown in FIG. 9, the MPU is the unit of processing in general-purpose data transmission processing. The MPU contains data to be used at a certain timing, and is a unit capable of decoding video and audio by itself. MFU is a smaller unit than MPU. For example, the general-purpose data sending unit 104 stores one XML schema as a file in one MFU. The general-purpose data sending unit 104 may store one MFU in which one XML schema file is stored in one MPU.

FIG. 10 is a diagram showing the configuration of receiving apparatus 300 according to this modification.

As shown in FIG. 10 , receiving device 300 according to this modification has general-purpose data processing section 308 . Demultiplexing section 302 separates general-purpose data from broadcast content and outputs the separated general-purpose data to general-purpose data processing section 308 .

General-purpose data processing unit 308 acquires the XML schema stored in the general-purpose data output from demultiplexing unit 302 and outputs this XML schema to compressed data expansion unit 304 .

Compressed data decompressing section 304 decompresses caption data (compressed XML data) output from demultiplexing section 302 using the XML schema output from general-purpose data processing section 308 , and outputs the decompressed caption data to data processing section 305 .

As described above, transmitting apparatus 100 according to this modification includes data compression section 103 that compresses XML data using an XML schema that defines the data structure of XML data written in XML, and data compression section 103 that compresses XML data. General-purpose data transmission unit 104 for outputting general-purpose data storing XML schema used when compressing XML data, and XML data compressed by data compression unit 103 and general-purpose data are multiplexed to produce broadcast contents. It has a multiplexing unit 106 that outputs, and a transmission unit 107 that transmits the broadcast content output by the multiplexing unit 106 to the receiving device 300 via the transmission line 200 .

Receiving apparatus 300 according to this modification transmits broadcast content in which general-purpose data storing an XML schema and XML data compressed using this XML schema are multiplexed from transmitting apparatus 100 via transmission line 200. Using a receiving unit 301 for receiving, a demultiplexing unit 302 for separating general-purpose data and XML data from the broadcast content received by the receiving unit 301, and an XML schema stored in the general-purpose data separated by the demultiplexing unit 302, and a compressed data expansion unit 304 that expands the XML data demultiplexed by the demultiplexing unit 302 .

Therefore, according to this modification, in the broadcasting system 10, the transmission device 100 and the reception device 100 can flexibly change the definition of the data structure of the XML data while compressing the XML data at a high compression rate using the XML schema. A device 300 can be provided.

<Other embodiments>
A program that causes a computer to execute each process performed by the transmission device 100 and a program that causes a computer to execute each process that the reception device 300 performs may be provided. The program may be recorded on a computer readable medium. A computer readable medium allows the installation of the program on the computer. Here, the computer-readable medium on which the program is recorded may be a non-transitory recording medium. The non-transitory recording medium is not particularly limited, but may be, for example, a recording medium such as CD-ROM or DVD-ROM.

Further, functional units (circuits) that execute each process performed by the transmission device 100 may be integrated, and the transmission device 100 may be configured as a semiconductor integrated circuit (chipset, SoC). Similarly, functional units (circuits) that execute each process performed by the receiving device 300 may be integrated, and the receiving device 300 may be configured as a semiconductor integrated circuit (chipset, SoC).

An embodiment has been described in detail above with reference to the drawings, but the specific configuration is not limited to the one described above, and various design changes can be made without departing from the spirit of the invention. .

10: Broadcasting system 100: Transmission device 101: Video transmission unit 102: Audio transmission unit 103: Data compression unit 104: General-purpose data transmission unit 105: Control message generation unit 106: Multiplexing unit 107: Transmission unit 200: Transmission path 300: Receiving device 301 : Receiving unit 302 : Demultiplexing unit 303 : Control message processing unit 304 : Compressed data expansion unit 305 : Data processing unit 306 : Video processing unit 307 : Audio processing unit 308 : General purpose data processing unit

Claims (8)

A transmitting device used in a broadcasting system,
a data compression unit that compresses the XML data using an XML schema that defines the data structure of the XML data written in XML;
a multiplexing unit for outputting broadcast content by multiplexing the XML schema used when the data compression unit compresses the XML data and the XML data compressed by the data compression unit;
and a transmitting unit that transmits the broadcast content output from the multiplexing unit to a receiving device via a transmission line. further comprising a control message generator that generates a control message;
wherein the control message generation unit stores the XML schema used when the data compression unit compresses the XML data in the control message;
2. The transmitting apparatus according to claim 1, wherein the multiplexing unit multiplexes the control message output from the control message generating unit and the XML data compressed by the data compressing unit. further comprising a general-purpose data transmission unit for outputting general-purpose data of the asynchronous general-purpose data transmission method,
The general-purpose data sending unit stores the XML schema used when the data compression unit compresses the XML data in the general-purpose data,
2. The transmission device according to claim 1, wherein the multiplexing unit multiplexes the general-purpose data output from the general-purpose data sending unit and the XML data compressed by the data compression unit. The multiplexing unit multiplexes information indicating which of an XML schema stored in advance in the receiving device and an XML schema transmitted via the transmission path should be used for compressing and decompressing the XML data into the broadcast content. 4. The transmitting device according to claim 1, wherein the transmitting device converts the The multiplexing unit periodically adds the XML schema used when the data compression unit compresses the XML data to the broadcast content while the data compression unit continues to compress the XML data using the XML schema. 5. The transmitting apparatus according to claim 1, wherein the transmitting apparatus multiplexes the . A receiving device for use in a broadcasting system,
Receiving broadcast content in which an XML schema defining a data structure of XML data written in XML and the XML data compressed using the XML schema are multiplexed from a transmission device via a transmission path. Department and
a demultiplexer that separates the XML schema and the XML data from the broadcast content received by the receiver;
a compressed data decompressing unit that decompresses the XML data demultiplexed by the demultiplexing unit using the XML schema demultiplexed by the demultiplexing unit. The XML schema is stored in a control message defined by MMT,
the demultiplexer demultiplexes the control message and the compressed XML data from the broadcast content;
3. The compressed data expansion unit expands the XML data demultiplexed by the demultiplexer using the XML schema stored in the control message demultiplexed by the demultiplexer. 7. The receiving device according to 6. The XML schema is stored in general-purpose data of an asynchronous general-purpose data transmission method,
The demultiplexing unit demultiplexes the general-purpose data and the compressed XML data from the broadcast content,
3. The compressed data expansion unit expands the XML data demultiplexed by the demultiplexer using the XML schema stored in the general-purpose data demultiplexed by the demultiplexer. 7. The receiving device according to 6.

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