ITU-T H 761-2014 Nested context language (NCL) and Ginga-NCL (Study Group 16)《嵌套的上下文语言(NCL)和银河-NCL(研究组16)》.pdf

1、 I n t e r n a t i o n a l T e l e c o m m u n i c a t i o n U n i o n ITU-T H.761 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (11/2014) SERIES H: AUDIOVISUAL AND MULTIMEDIA SYSTEMS IPTV multimedia services and applications for IPTV IPTV multimedia application frameworks Nested context language

2、NCL) and Ginga-NCL Recommendation ITU-T H.761 ITU-T H-SERIES RECOMMENDATIONS AUDIOVISUAL AND MULTIMEDIA SYSTEMS CHARACTERISTICS OF VISUAL TELEPHONE SYSTEMS H.100H.199 INFRASTRUCTURE OF AUDIOVISUAL SERVICES General H.200H.219 Transmission multiplexing and synchronization H.220H.229 Systems aspects H

3、230H.239 Communication procedures H.240H.259 Coding of moving video H.260H.279 Related systems aspects H.280H.299 Systems and terminal equipment for audiovisual services H.300H.349 Directory services architecture for audiovisual and multimedia services H.350H.359 Quality of service architecture for

4、 audiovisual and multimedia services H.360H.369 Telepresence H.420H.429 Supplementary services for multimedia H.450H.499 MOBILITY AND COLLABORATION PROCEDURES Overview of Mobility and Collaboration, definitions, protocols and procedures H.500H.509 Mobility for H-Series multimedia systems and service

5、s H.510H.519 Mobile multimedia collaboration applications and services H.520H.529 Security for mobile multimedia systems and services H.530H.539 Security for mobile multimedia collaboration applications and services H.540H.549 Mobility interworking procedures H.550H.559 Mobile multimedia collaborati

6、on inter-working procedures H.560H.569 BROADBAND, TRIPLE-PLAY AND ADVANCED MULTIMEDIA SERVICES Broadband multimedia services over VDSL H.610H.619 Advanced multimedia services and applications H.620H.629 Ubiquitous sensor network applications and Internet of Things H.640H.649 IPTV MULTIMEDIA SERVICES

7、 AND APPLICATIONS FOR IPTV General aspects H.700H.719 IPTV terminal devices H.720H.729 IPTV middleware H.730H.739 IPTV application event handling H.740H.749 IPTV metadata H.750H.759 IPTV multimedia application frameworks H.760H.769 IPTV service discovery up to consumption H.770H.779 Digital Signage

8、H.780H.789 E-HEALTH MULTIMEDIA SERVICES AND APPLICATIONS Interoperability compliance testing of personal health systems (HRN, PAN, LAN and WAN) H.820H.859 Multimedia e-health data exchange services H.860H.869 For further details, please refer to the list of ITU-T Recommendations. Rec. ITU-T H.761 (1

9、1/2014) i Recommendation ITU-T H.761 Nested context language (NCL) and Ginga-NCL Summary Recommendation ITU-T H.761 gives the specification of the nested context language (NCL) and of an NCL presentation environment called Ginga-NCL to provide interoperability and harmonization among Internet protoc

10、ol television (IPTV) multimedia application frameworks. NCL is a declarative glue language that holds media object presentations synchronized in time and space, no matter the types of the media objects. Ginga-NCL is an NCL presentation engine built as a component of a digital television (DTV) middle

11、ware. This Recommendation includes an electronic attachment containing NCL 3.1 module schemas used in the enhanced DTV profile. History Edition Recommendation Approval Study Group Unique ID* 1.0 ITU-T H.761 2009-04-29 16 11.1002/1000/9715 2.0 ITU-T H.761 v2 2011-06-13 16 11.1002/1000/11307 3.0 ITU-T

12、 H.761 2014-11-29 16 11.1002/1000/12237 _ * To access the Recommendation, type the URL http:/handle.itu.int/ in the address field of your web browser, followed by the Recommendations unique ID. For example, http:/handle.itu.int/11.1002/1000/11830-en. ii Rec. ITU-T H.761 (11/2014) FOREWORD The Intern

13、ational Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, ope

14、rating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn,

15、produce Recommendations on these topics. The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. In some areas of information technology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. NOTE In

16、 this Recommendation, the expression “Administration“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g.

17、 interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words “shall“ or some other obligatory language such as “must“ and the negative equivalents are used to express requirements. The use of such words does not sug

18、gest that compliance with the Recommendation is required of any party. INTELLECTUAL PROPERTY RIGHTSITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evid

19、ence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which m

20、ay be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2015 All rights reserved. No part of this publication may b

21、e reproduced, by any means whatsoever, without the prior written permission of ITU. Rec. ITU-T H.761 (11/2014) iii Table of Contents Page 1 Scope . 1 2 References . 1 3 Definitions 2 3.1 Terms defined elsewhere 2 3.2 Terms defined in this Recommendation . 3 4 Abbreviations and acronyms 5 5 NCL and G

22、inga-NCL . 6 6 Ginga-NCL harmonization with other IPTV declarative environments . 7 7 NCL: XML application declarative language for multimedia presentations 8 7.1 Identifiers for NCL 3.1 module and language profiles . 9 7.2 NCL modules 11 7.3 NCL language profiles for IPTV 62 8 Media objects in NCL

23、presentations . 69 8.1 The media player API . 70 8.2 Expected behaviour of basic media players . 72 8.3 Expected behaviour of declarative hypermedia players in NCL applications . 76 8.4 Expected behaviour of imperative-object media players in NCL applications . 80 8.5 Expected behaviour of media pla

24、yers after actions applied to composite objects . 84 8.6 Relation between the presentation-event state machine of a node and the presentation-event state machine of its parent-composite node . 85 9 NCL editing commands 86 9.1 Private bases . 86 9.2 Command parameters XML schemas 97 9.3 NCL editing c

25、ommands in Ginga-NCL . 98 10 Lua imperative objects in NCL presentations 102 10.1 Lua language functions removed from the standard Lua library 102 10.2 Execution model . 102 10.3 Additional modules 102 11 Security API 124 11.1 Security control in Ginga-NCL 124 11.2 The NCLua security API 125 Annex A

26、 NCL 3.1 module schemas used in the enhanced DTV profile 129 Annex B XML schemas for the media player API . 130 B.1 Data types for the parameters used in the media player API . 130 B.2 Input control API 134 iv Rec. ITU-T H.761 (11/2014) Page Appendix I Ginga architecture 135 Appendix II An NCL examp

27、le 137 Bibliography. 138 Electronic attachment: NCL 3.1 module schemas used in the enhanced DTV profile. Rec. ITU-T H.761 (11/2014) v Introduction Nested context language (NCL) is a declarative XML-based language initially designed for hypermedia document specification for the web. The intrinsic abi

28、lity of NCL for easily defining spatio-temporal synchronization among media assets, including viewer interactions, in addition to the languages flexibility, reusability, multi device support and application content adaptability, make it an outstanding solution for IPTV systems. NCL is also the decla

29、rative language used in the Japanese Brazilian terrestrial DTV standard (ISDB-T). NCL is a glue language that holds media objects together in a multimedia presentation, no matter which object types they are. In this sense, media objects may be image objects (JPEG, PNG, etc.), video objects (MPEG, MO

30、V, etc.), audio objects (MP3, WMA, etc.), text objects (TXT, PDF, etc.), imperative objects (with Lua code, etc.), other declarative objects (HTML, LIME, SVG, MHEG, nested NCL applications, etc.), etc. Which media objects are supported depends on which media players are embedded in the NCL player (p

31、art of the Ginga-NCL environment). As an example, NCL treats an HTML document as one of its possible media objects. In this way, NCL does not substitute but instead embeds HTML-based documents. The same reasoning applies to other media content and multimedia content objects and also to objects with

32、content coded in any computer language. Ginga-NCL is an NCL presentation engine built as a component of a DTV middleware. An open source reference implementation of Ginga-NCL is available under the GPLv2 licence (http:/www.gingancl.org.br/index_en.html). This reference implementation was developed i

33、n such a way so that it can easily integrate a variety of media-object players for audio, video, image, text, etc., including imperative execution engines and other declarative language players. A special NCL object type defined in Ginga-NCL is NCLua, an imperative media-object with Lua code as its

34、content. Because of its simplicity, efficiency and powerful data description syntax, Lua is considered the default scripting language for Ginga-NCL. The Lua engine is small and written in ANSI/C, making it easily portable to several hardware platforms. The Lua engine is also distributed as free soft

35、ware under the Massachusetts Institute of Technology (MIT) licence (http:/www.lua.org/license.html). Rec. ITU-T H.761 (11/2014) 1 Recommendation ITU-T H.761 Nested context language (NCL) and Ginga-NCL 1 Scope This Recommendation1 specifies the nested context language (NCL) and an NCL presentation en

36、vironment, called Ginga-NCL, to provide interoperability and harmonization among IPTV multimedia application frameworks. To provide global standard IPTV services, it is foreseeable that a combination of different standard multimedia application frameworks will be used. Therefore, this Recommendation

37、 specifies the nested context language, as one of those standards that compose the multimedia application frameworks, to provide interoperable use of IPTV services. Ginga-NCL is an NCL presentation environment that integrates NCL and Lua players. NCL and Lua frameworks can be used in other declarati

38、ve environments, but if they are used together they shall follow the Ginga-NCL specification. 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the

39、editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently

40、valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. ITU-T H.222.0 Recommendation ITU-T H.222.0 (2014) | ISO/IEC 13818-1:2007, Information technology Generic coding of m

41、oving pictures and associated audio information: Systems. ITU-T H.750 Recommendation ITU-T H.750 (2008), High-level specification of metadata for IPTV services. ITU-T J.200 Recommendation ITU-T J.200 (2010), Worldwide common core Application environment for digital interactive television services. I

42、TU-T X.509 Recommendation ITU-T X.509 (2012), Information technology Open Systems Interconnection The Directory: Public-key and attribute certificate frameworks. ITU-T Y.1901 Recommendation ITU-T Y.1901 (2009), Requirements for the support of IPTV services. IETF RFC 1421 IETF RFC 1421 (1993), Privac

43、y Enhancement for Internet Electronic Mail. IETF RFC 6726 IETF RFC 6726 (2012), FLUTE File Delivery over Unidirectional Transport. ISO/IEC 8859-1 ISO/IEC 8859-1:1998, Information technology 8-bit single-byte coded graphic character sets Part 1: Latin alphabet No. 1. ISO/IEC 13818-6 ISO/IEC 13818-6:1

44、998, Information technology Generic coding of moving pictures and associated audio information Part 6: Extensions for DSM-CC. _ 1 This Recommendation includes an electronic attachment containing NCL 3.1 module schemas used in the enhanced DTV profile. 2 Rec. ITU-T H.761 (11/2014) ISO/IEC 18033-3 ISO

45、/IEC 18033-3:2010, Information technology Security techniques Encryption algorithms Part 3: Block cyphers. 3 Definitions 3.1 Terms defined elsewhere This Recommendation uses the following terms defined elsewhere: 3.1.1 application ITU-T J.200: Information that expresses a specific set of observable

46、behaviour. 3.1.2 application environment (environment) ITU-T J.200: The context or software environment in which an application is processed. 3.1.3 application programming interface (API) ITU-T J.200: Software libraries that provide uniform access to system services. 3.1.4 character ITU-T J.200: Spe

47、cific “letter“ or other identifiable symbol, e.g., “A“. 3.1.5 data carousel ITU-T J.200: A transmission scheme defined in ISO/IEC 13818-6, with which data is transmitted repetitively. It can be used for downloading various data in broadcasting. It is the scheme of the DSM-CC User-to-Network Download

48、 protocol that embodies the cyclic transmission of data. 3.1.6 declarative application ITU-T J.200: An application which primarily makes use of declarative information to express its behaviour; an XML document instance is an example of a declarative application. 3.1.7 declarative application environ

49、ment ITU-T J.200: An environment that supports the processing of declarative applications; an XML user agent (browser) is an example of a declarative application environment. 3.1.8 digital storage media command and control (DSM-CC) ITU-T J.200: A control method defined in ISO/IEC 13818-6, which provides access to files and streams for digital interactive services. 3.1.9 electronic program guide (EPG) b-ITU-T Y.1901: A