ITU-R BT 2074-0-2015 Service configuration media transport protocol and signalling information for MMT-based broadcasting systems《基于多媒体传输技术的广播系统的服务配置 媒体传输协议和信令信息》.pdf

1、 Recommendation ITU-R BT.2074-0 (05/2015) Service configuration, media transport protocol, and signalling information for MMT-based broadcasting systems BT Series Broadcasting service (television) ii Rec. ITU-R BT.2074-0 Foreword The role of the Radiocommunication Sector is to ensure the rational, e

2、quitable, efficient and economical use of the radio-frequency spectrum by all radiocommunication services, including satellite services, and carry out studies without limit of frequency range on the basis of which Recommendations are adopted. The regulatory and policy functions of the Radiocommunica

3、tion Sector are performed by World and Regional Radiocommunication Conferences and Radiocommunication Assemblies supported by Study Groups. Policy on Intellectual Property Right (IPR) ITU-R policy on IPR is described in the Common Patent Policy for ITU-T/ITU-R/ISO/IEC referenced in Annex 1 of Resolu

4、tion ITU-R 1. Forms to be used for the submission of patent statements and licensing declarations by patent holders are available from http:/www.itu.int/ITU-R/go/patents/en where the Guidelines for Implementation of the Common Patent Policy for ITU-T/ITU-R/ISO/IEC and the ITU-R patent information da

5、tabase can also be found. Series of ITU-R Recommendations (Also available online at http:/www.itu.int/publ/R-REC/en) Series Title BO Satellite delivery BR Recording for production, archival and play-out; film for television BS Broadcasting service (sound) BT Broadcasting service (television) F Fixed

6、 service M Mobile, radiodetermination, amateur and related satellite services P Radiowave propagation RA Radio astronomy RS Remote sensing systems S Fixed-satellite service SA Space applications and meteorology SF Frequency sharing and coordination between fixed-satellite and fixed service systems S

7、M Spectrum management SNG Satellite news gathering TF Time signals and frequency standards emissions V Vocabulary and related subjects Note: This ITU-R Recommendation was approved in English under the procedure detailed in Resolution ITU-R 1. Electronic Publication Geneva, 2015 ITU 2015 All rights r

8、eserved. No part of this publication may be reproduced, by any means whatsoever, without written permission of ITU. Rec. ITU-R BT.2074-0 1 RECOMMENDATION ITU-R BT.2074-0 Service configuration, media transport protocol, and signalling information for MMT-based broadcasting systems (2015) Scope This R

9、ecommendation defines the service configuration, media transport protocol, and signalling information required for broadcasting systems using ISO/IEC 23008-1 (MPEG Media Transport). It specifies the constraints to ISO/IEC 23008-1 for MMT-based broadcasting systems. Keywords: transport, MMT, multiple

10、xing, IP-based broadcasting, hybrid delivery, UHDTV The ITU Radiocommunication Assembly, considering a) that multimedia services consist of various media components such as audio, video, closed captions, and other data; b) that various media components for multimedia services may be delivered in bro

11、adcasting channels and broadband networks; c) that multimedia services have also been introduced in broadband networks where IP packets are used; d) that an IP-friendly media transport protocol is desirable for multimedia broadcasting systems to enable harmonization of broadcasting and broadband; e)

12、 that synchronized presentation of various media components over various delivery channels is required for multimedia broadcasting applications; f) that efficient and reliable transport of various media components is required over broadcasting channels; g) that ISO/IEC 23008-1 “MPEG Media Transport

13、(MMT)” specifies an encapsulation format of media components, delivery protocol, and signalling information for various applications including broadcasting applications; h) that a common MMT protocol packet syntax has been specified in ISO/IEC 23008-1; i) that practical implementation of broadcastin

14、g systems may require certain constraints on ISO/IEC 23008-1; j) that it is desirable for such constraints to be in common with MMT-based broadcasting systems for development and deployment of systems including receiver terminals, recommends 1 that broadcasting systems using MPEG Media Transport as

15、per ISO/IEC 23008-1 should be designed on the basis of the system structure and service configuration described in Annex 1; 2 that the broadcasting systems using MPEG Media Transport should comply with the media transport protocol and signalling information described in Annex 2. Note 1 Attachment 1

16、shows additional signalling information specified in ARIB systems. 2 Rec. ITU-R BT.2074-0 References Normative references ISO/IEC 23008-1:2014: Information technology High efficiency coding and media delivery in heterogeneous environments Part 1: MPEG media transport (MMT). Informative references Re

17、commendation ITU-T H.222.0 | ISO/IEC 13818-1:2013: Information technology Generic coding of moving pictures and associated audio information: Systems. IETF RFC 768: User Datagram Protocol, Aug. 1980. IETF RFC 791: Internet Protocol, Sep. 1981. IETF RFC 2460: Internet Protocol, Version 6 (IPv6) Speci

18、fication, Dec. 1998. IETF RFC 5905: Network Time Protocol Version 4: Protocol and Algorithms Specification, June 2010. Recommendation ITU-R BT.1869-0 (2010) Multiplexing scheme for variable-length packets in digital multimedia broadcasting systems. Recommendation ITU-T H.265 | ISO/IEC 23008-2 (2013)

19、 Information technology High efficiency coding and media delivery in heterogeneous environments Part 2: High efficiency video coding. Abbreviations AAC Advanced audio coding AIT Application information table AL-FEC Application layer forward error correction ALS Audio lossless coding AMT Address map

20、table BIT Broadcaster information table CA Conditional access CAS Conditional access system CDT Common data table CRI Clock relation information DCI Device capability information DCM Download control message DMM Download management message ECM Entitlement control message EIT Event information table

21、EMM Entitlement management message EPG Electronic programme guide GFD Generic file delivery GOP Group of pictures HEVC High efficiency video coding Rec. ITU-R BT.2074-0 3 HRBM Hypothetical receiver buffer model IP Internet Protocol IRAP Intra random access point LAOS Low overhead audio stream LATM L

22、ow overhead audio transport multiplex LCT Layout configuration table LDT Linked description table MFU Media fragment unit MMT MPEG media transport MMTP MMT protocol MPI MMT presentation information MPT MMT package table MPU Media processing unit NIT Network information table NPT Normal play time NTP

23、 Network time protocol PA Package access PLT Package list table SDT Service description table SDTT Software download trigger table TLV Type length value UDP User datagram protocol 4 Rec. ITU-R BT.2074-0 Annex 1 System structure and service configuration 1 System structure This section describes the

24、general structure of MMT-based broadcasting systems. Fig. 1 shows the protocol stack of MMT-based broadcasting systems. FIGURE 1 Protocol stack of MMT-based broadcasting systems B T . 2 0 7 4 - 01T i meSi g n al l i n gi n fo rmat i o n V i d eo A u d i o Cc A p p l i cat i o nMMTU D P/ IPIP mu l t

25、i p l ex i n g s ch eme (l ay er 2 )Bro ad cas t i n g ch an n el (ch an n el co d i n g an d mo d u l at i o n )In these systems, media components, such as video, audio, and closed captions (cc), constituting a TV programme are encapsulated into media fragment units (MFUs)/media processing units (M

26、PUs). They are carried as MMT protocol (MMTP) payloads of MMTP packets and delivered in IP packets. Data applications that are related to a TV programme are also encapsulated into MFUs/MPUs, carried in MMTP packets, and delivered in IP packets. IP packets generated like this are multiplexed over bro

27、adcasting channels with an IP multiplexing scheme, also referred to as a layer 2 (L2) protocol, e.g. the TLV multiplexing scheme described in Recommendation ITU-R BT.1869. The systems also have MMT signalling information (MMT-SI). MMT-SI is signalling information on the structure of a TV programme a

28、nd associated information on TV services like the electronic programme guide (EPG). MMT-SI is carried in MMTP packets and delivered in IP packets. In order to provide Coordinated Universal Time (UTC) in broadcasting systems for receiver terminals to synchronize with broadcast station, time informati

29、on is also delivered in IP packets. 2 Service configuration 2.1 Services in a broadcasting channel ISO/IEC 23008-1 specifies the MMT package as a logical structure of content. The MMT package includes presentation information and associated Assets that constitute content. A broadcasting service is g

30、enerally a series of TV programmes. In MMT-based broadcasting systems, one MMT package corresponds to one broadcasting service. The relationship between the broadcasting service and the MMT package is shown in Fig. 2. As shown in the figure, one TV programme is distinguished from the rest of the ser

31、vice by its start and end times and corresponds to one event. Rec. ITU-R BT.2074-0 5 FIGURE 2 Relationship between a broadcasting service and MMT package in a broadcasting channel B T . 2 0 7 4 - 0 2 IP d at a fl o wev en t(p ro g ra m m e)P h y s i ca l b ro ad ca s t i n g ch an n elL ay er 2 s t

32、re amL ay er 2 s t re ams er v i cep ac k ag es er v i cep ac k ag es er v i cep ac k ag es er v i ceM M T p ac k ag eVideocomponentAudiocomponentClosedcaptionClosedcaptionAudiocomponentVideocomponentVideocomponentVideocomponentAudiocomponentIn ISO/IEC 23008-1, an Asset is defined as a media compone

33、nt. An Asset is equivalent to a series of MPUs. In MMT-based broadcasting systems, one TV programme is an MMT package including one or more Assets and signalling information. A package access (PA) Message is an MMT-SI, and the MMT package table (MPT) carried in the PA message identifies Assets const

34、ituting the TV programme. Multiple MMT packages can be delivered in one IP data flow, as shown in Fig. 2. Here, an IP data flow is defined as a sequence of IP packets of which the source IP address, destination IP address, protocol, source port number, and destination port number are the same combin

35、ation. There may be other IP data flows carrying content for download services or extended services in addition to IP data flows carrying MMT packages. Multiple IP data flows might be multiplexed into one layer 2 stream. The layer 2 stream includes signalling information for demultiplexing IP packet

36、s from broadcasting signals. 2.2 Services in broadcasting channels and broadband networks ISO/IEC 23008-1 has been developed to support delivery of media data over heterogeneous networks including broadcasting channels and broadband networks. In the MMT specifications, broadcasting channels and broa

37、dband networks can be treated in the same way for delivery of content. Figure 3 shows a service configuration using both broadcasting channels and broadband networks. In the figure, video component 1, audio component 1, and closed caption 1 are delivered on broadcasting channels. In addition to thes

38、e components, video component 2, audio component 2, and closed caption 2 are delivered on broadband networks. 6 Rec. ITU-R BT.2074-0 In the broadcasting channels, the three components are multiplexed into one IP data flow and delivered in one layer 2 stream, since all transmitted information is deli

39、vered to all receiver terminals. On the other hand, in the broadband networks, components are delivered as a separate IP data flow, since each component is delivered to the receiver terminal requesting it. In MMT-based broadcasting systems, media components delivered in different channels can easily

40、 be included in one MMT package. MMT-based broadcasting systems support hybrid delivery of multimedia content. FIGURE 3 Service configuration over both broadcasting channels and broadband networks B T . 2 0 7 4 - 0 3IP d at a fl o wIP d at a fl o wi n b ro ad b an d n et w o rk sPh y s i cal b ro ad

41、 cas t i n g ch an n elL ay er 2 s t reamev en t(p ro g ram me )Videocomponent 2Audiocomponent2Closedcaption2Closedcaption1Audiocomponent 1Videocomponent1Ser v i ceMMT p ack ag eAnnex 2 Media transport protocol and signalling information 1 Media transport protocol 1.1 Introduction MMT-based broadcas

42、ting systems use the syntax and semantics of the MMTP payload and MMTP packet specified in ISO/IEC 23008-1. The extensions described below are intended for broadcast applications. Rec. ITU-R BT.2074-0 7 1.2 Header extension of MMTP packets ISO/IEC 23008-1 specifies a header extension in the MMTP pac

43、ket. The header extension has three fields: extension_type, extension_length, and header_extension_value. Although the header extension can be used for various purposes, it contains only one piece of information. The multi-type header extension described below enables it to contain multiple pieces o

44、f information. header_extension_value When the extension_type field is set to 0x0000, this field has the structure shown in Table 1. TABLE 1 Structure of multi-type header extension Syntax No. of bits Mnemonic Header_extension_value for (i=0; iN; i+) hdr_ext_end_flag 1 bslbf hdr_ext_type 15 uimsbf h

45、dr_ext_length 16 uimsbf for (j=0; jM; j+) hdr_ext_byte 8 bslbf hdr_ext_end_flag When this flag is set to “1”, this multi-type header extension is the end of the header extension. When this flag is set to “0”, this multi-type header extension is not the end of the header extension. hdr_ext_type This

46、field specifies the type of multi-type header extension. hdr_ext_length This field specifies the number of bytes of the following hdr_ext_byte field. hdr_ext_byte This field provides information on multi-type header extension. 2 Encapsulation of multimedia data 2.1 Introduction In order to improve t

47、he interoperability of MMT-based broadcasting systems, the following constraints apply to carriage of multimedia data in MMTP packets. 2.2 Encapsulation of video data 2.2.1 MFU format for HEVC stream When a high efficiency video coding (HEVC) stream is carried in the MMT protocol, input to the MMT p

48、rocess is a sequence of network abstraction layer (NAL) units. A NAL unit is encapsulated into an MFU when an HEVC stream is carried in the MMT protocol. 8 Rec. ITU-R BT.2074-0 If an HEVC encoder generates the byte stream format specified in Recommendation ITU-T H.265 | ISO/IEC 23008-2 Annex B, one

49、start code prefix (0x000001) followed by one NAL unit is replaced with 32-bit length information of the NAL unit (unsigned integer format). Namely, the NAL unit together with the length information are encapsulated into one MFU. Figure 4 shows an overview of generating MMTP packets and MFUs from a sequence of NAL units output from an HEVC encoder. FIGURE 4 Overview of packetization of NAL units of HEVC streams B T . 2 0 7 4 - 0 4 A U de l i m i t e r SPS PPS S E Is l i c e s e gm e nt N o. 1s l i c e s e gm e nt N o.