1、BRITISH STANDARD BS EN 62297-2:2005 Triggering messages for broadcast applications Part 2: Transport methods The European Standard EN 62297-2:2005 has the status of a British Standard ICS 33.170 BS EN 62297-2:2005 This British Standard was published under the authority of the Standards Policy and St
2、rategy Committee on 5 December 2005 BSI 5 December 2005 ISBN 0 580 46332 X National foreword This British Standard is the official English language version of EN 62297-2:2005. It is identical with IEC 62297-2:2005. The UK participation in its preparation was entrusted to Technical Committee EPL/100,
3、 Audio, video and multimedia systems and equipment, which has the responsibility to: A list of organizations represented on this committee can be obtained on request to its secretary. Cross-references The British Standards which implement international or European publications referred to in this do
4、cument may be found in the BSI Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic Catalogue or of British Standards Online. This publication does not purport to include all the necessary provisions of a contrac
5、t. Users are responsible for its correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for
6、change, and keep UK interests informed; monitor related international and European developments and promulgate them in the UK. Summary of pages This document comprises a front cover, an inside front cover, the EN title page, pages 2 to 13 and a back cover. The BSI copyright notice displayed in this
7、document indicates when the document was last issued. Amendments issued since publication Amd. No. Date CommentsEUROPEAN STANDARD EN 62297-2 NORME EUROPENNE EUROPISCHE NORM June 2005 CENELEC European Committee for Electrotechnical Standardization Comit Europen de Normalisation Electrotechnique Europ
8、isches Komitee fr Elektrotechnische Normung Central Secretariat: rue de Stassart 35, B - 1050 Brussels 2005 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members. Ref. No. EN 62297-2:2005 E ICS 33.170 English version Triggering messages for broadcas
9、t applications Part 2: Transport methods (IEC 62297-2:2005) Messages de dclenchement pour les applications de radiodiffusion Partie 2: Mthodes de transport (CEI 62297-2:2005) Triggernachrichten fr Rundfunkanwendungen Teil 2: bertragungsverfahren (IEC 62297-2:2005) This European Standard was approved
10、 by CENELEC on 2005-05-01. CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
11、 standards may be obtained on application to the Central Secretariat or to any CENELEC member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CENELEC member into its own language an
12、d notified to the Central Secretariat has the same status as the official versions. CENELEC members are the national electrotechnical committees of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxem
13、bourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EN 62297-2:2005 2 Foreword The text of document 100/911/FDIS, future edition 1 of IEC 62297-2, prepared by IEC TC 100, Audio, video and multimedia systems and equipment, was submit
14、ted to the IEC-CENELEC parallel vote and was approved by CENELEC as EN 62297-2 on 2005-05-01. The following dates were fixed: latest date by which the EN has to be implemented at national level by publication of an identical national standard or by endorsement (dop) 2006-02-01 latest date by which t
15、he national standards conflicting with the EN have to be withdrawn (dow) 2008-05-01 Annex ZA has been added by CENELEC. _ Endorsement notice The text of the International Standard IEC 62297-2:2005 was approved by CENELEC as a European Standard without any modification. _ 3 EN 62297-2:2005 CONTENTS I
16、NTRODUCTION.4 1 Scope 5 2 Normative references .5 3 Terms, definitions and abbreviations.5 3.1 Definitions.5 3.2 Abbreviations 6 4 Teletext-based methods .6 4.1 Page-format method 6 4.1.1 Maximum length of a trigger message 7 4.1.2 Data stream.7 4.1.3 Transmission aspects.8 4.2 Independent data line
17、 method8 4.2.1 Maximum length of a trigger message 8 4.2.2 Data stream.9 4.2.3 Packet structure.9 5 MPEG-2 transmission based method.10 Annex A (informative) Code of practice 12 A.1 Page-format teletext transmissions 12 A.1.1 General 12 A.1.2 Page number .12 A.1.3 Magazine Inventory Page.12 A.1.4 20
18、ms page delay12 A.2 Independent data line teletext transmissions 12 A.2.1 General 12 A.2.2 Alternative protocol stacks .12 A.2.3 Fast trigger applications.12 Annex ZA (normative) Normative references to international publications with their corresponding European publications13 Figure 1 Protocol sta
19、ck 8 Table 1 Coding of Packet 28/0, format 1.8 Table 2 Coding of the four message bits in the Format Type byte9 Table 3 Stream Event Descriptor11 EN 62297-2:2005 4 INTRODUCTION This part of IEC 62297 focuses on the transport methods of the trigger messages defined in IEC 62297-1. 5 EN 62297-2:2005 T
20、RIGGERING MESSAGES FOR BROADCAST APPLICATIONS Part 2: Transport methods 1 Scope This part of IEC 62297 specifies how the trigger messages defined in IEC 62297-1 are transmitted. A trigger is defined as information sent from a service provider as part of a data broadcasting transmission that initiate
21、s an application in a receiver. Additional information in the trigger message allows filtering or prioritization techniques to be applied at the receiver. Examples of possible use include the forcing of the display of information to warn of severe weather conditions and advising of extreme content i
22、n the TV programme. In an interactive system, a message or icon might be displayed inviting on-line access to vote, to register an interest in an advertised product, or to browse programme-related content. This standard specifies how trigger messages are broadcast using teletext technology. Both Pag
23、e Format-Clear and Independent Data Line methods are defined, using protocols defined in ETSI EN 300 708. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, th
24、e latest edition of the referenced document (including any amendments) applies. IEC 62297-1, Triggering messages for broadcast applications Part 1: Format ISO/IEC 13818-6, Information technology Generic coding of moving pictures and associated audio information Part 6: Extensions for DSM-CC ETSI EN
25、300 706, Enhanced Teletext specification ETSI EN 300 708, Data transmission within Teletext ETSI TS 101 231, Television systems; Register of Country and Network Identification (CNI), Video Programming System (VPS) codes and Application codes for Teletext based systems 3 Terms, definitions and abbrev
26、iations 3.1 Definitions For the purposes of this document, the following terms and definitions, in singular or plural form, apply. 3.1.1 Application Data Block one instance of the application data to be transmitted via the Page Format-Clear method and following the addition of any error protection/c
27、orrection data EN 62297-2:2005 6 3.1.2 Bundle group of 490 application bytes for transmission via IDL format B and to which the FEC algorithm is applied 3.1.3 Bundle Information Structure data within the stream carried by the Page Format-Clear method that indicates the applications present in the st
28、ream 3.1.4 Data Stream continuous or periodic sequence of data comprising application and transmission related components 3.1.5 Hamming 8/4 method of protecting data against transmission path errors. A protection bit is added for every data bit. Single bit errors per byte can be corrected, two bit e
29、rrors can be detected 3.1.6 Independent Data Line teletext packet with address 30 or 31 that does not form part of a teletext page and can be inserted at any point in the transmission cycle 3.1.7 Page Format-Clear page-based method of broadcasting serial data streams via teletext when the applicatio
30、n does not require encryption techniques to be applied to the data 3.1.8 Structure Header data that precedes an Application Data Block to indicate the application to which it belongs and the size of the block 3.1.9 Trigger message definition of a trigger event including a URL and optional attributes
31、 to specify, for example, a countdown time and an expire time 3.2 Abbreviations FEC Forward Error Correction IDL Independent Data Line MIP Magazine Inventory Page URL Uniform Resource Locator 4 Teletext-based methods 4.1 Page-format method The Page Format-Clear protocol, fully defined in ETSI EN 300
32、 708, is used to transmit one or more trigger messages. A serial data stream is formed and broadcast via successive versions of a Page Format-Clear encoded teletext page. 7 EN 62297-2:2005 4.1.1 Maximum length of a trigger message The encoding method and the maximum payload size of the Page Format-C
33、lear protocol limits the maximum length of a trigger message to 1 022 bytes. 4.1.2 Data stream A serial data stream according to 4.2 in ETSI EN 300 708 is created from Application Data Blocks, Structure Headers, Bundle Information Structures and Block Separators. 4.1.2.1 Application Data Blocks In p
34、reparation for transmission, each 8-bit byte of a trigger message defined according to IEC 62297-1 is divided into two four-bit nibbles. Each nibble is then Hamming 8/4 encoded according to 8.2 of ETSI EN 300 706. The low-order nibble is encoded, and ultimately transmitted, before the high-order nib
35、ble. The resulting bytes are assembled in sequence to form an Application Data Block. 4.1.2.2 Structure Header Each Application Data Block is preceded by a Structure Header, as defined in 4.2.2 of ETSI EN 300 708. This consists of application identity and block length information, all Hamming 8/4 en
36、coded. 4.1.2.3 Bundle Information Structure Bundle Information Structures, coded according to 4.2.3 in ETSI EN 300 708, shall be inserted in the data stream at frequent intervals to indicate the type of application(s) present. 4.1.2.4 Application Type value The Application Type value (0 0010) alloca
37、ted to trigger applications and carried in the Bundle Information Structure is recorded in ETSI TS 101 231. 4.1.2.5 Transport page The page consists of a packet X/0 (mandatory), some or all of packets X/1-X/25, and X/28/0 (mandatory). Packets X/1-X/25 are used to carry Application Data Blocks and Bu
38、ndle Information Structures. Packet X/28/0 provides a “signature” to help a receiver confirm that the page carries trigger information. 4.1.2.6 Page address The default page number is allocated in ETSI EN 300 706 and has the value 0x1E7. However, if this page number is not available to the service p
39、rovider, the page in use shall be indicated in a Magazine Inventory Page (MIP), as defined in ETSI EN 300 706. The MIP code for a page carrying trigger information is 0 FC. 4.1.2.7 Coding of packet X/0 Packet X/0 shall be coded according to 4.3.1 in ETSI EN 300 708. Triggers must be encoded as data
40、stream 1 (S3 = 0). 4.1.2.8 Coding of packet X/28 The page shall include a packet X/28/0 format 1 to define unambiguously the page type and its coding. The general coding of a packet X/28/0, format 1, is defined in 9.4.2 of ETSI EN 300 706. The coding of the packet defined here in Table 1 replaces th
41、e generic Page Format-Clear coding specified in ETSI EN 300 708. EN 62297-2:2005 8 Table 1 Coding of Packet 28/0, format 1 Triplet Bits Function 1 1-4 Page function These bits define the function of the data in packets 1 up to 25 of the page. They shall be set to the value 1 100 as allocated in ETSI
42、 EN 300 706 to indicate a page containing trigger messages defined according to IEC 62297-1 1 5-7 Page coding These bits define the coding of packets 1 up to 25 of the page. They shall be set to the value 011 as allocated in ETSI EN 300 706 to indicate that the packets are coded in the Hamming 8/4 f
43、ormat 1 8-18 Set to 11111111100 (bits 8 to 18). This value is chosen to ensure existing data broadcasting decoders, designed to Clause 5 of ETSI EN 300 708, ignore this page 2-13 1-18 Reserved for future use 4.1.2.9 Coding of packet X/1 to X/25 Packets X/1 to X/25 carry the data stream formed from A
44、pplication Data Blocks and Bundle Information Structures. One or more Block Separator bytes (value = 0 A1), as defined in 4.3.2.3 of ETSI EN 300 708, shall be inserted before each Structure Header. The first data byte of the packet contains the Block Pointer value, as defined in 4.3.2.4 of ETSI EN 3
45、00 708. This indicates the location in the packet of the first Block Separator byte, if present. 4.1.3 Transmission aspects A page encoded in the Page Format-Clear protocol can be transmitted in several fragments. The decision whether or not to allow the page to be transmitted without a 20 ms delay
46、between the packet X/0 and the remaining packets is left open and should be defined by the application. Transmitting a page comprising a packet X/0, a packet X/28/0 format 1 and a single Bundle Information Structure starting in packet X/1 shall signal the presence of an inactive trigger service. Suc
47、h a page should be broadcast at least once every teletext cycle ( 20 s). 4.2 Independent data line method IDL format B, fully defined in 6.8 of ETSI EN 300 708, allows serial data to be broadcast in an efficient way. A Forward Error Correcting (FEC) algorithm protects the user data. To broadcast tri
48、gger messages, a serial data stream is formed from one or more trigger messages. The protocol stack is shown in Figure 1. Trigger message Framing protocol FEC IDL format B Figure 1 Protocol stack 4.2.1 Maximum length of a trigger message The use of IDL format B does not place an upper limit on the s
49、ize of a trigger message. 9 EN 62297-2:2005 4.2.2 Data stream A data stream is formed from one or more trigger messages. The data stream is transmitted in the User Data bytes of the IDL. The 8-bit data bytes of a trigger message are not modified or encoded in any way in preparation for transmission. To allow a receiver to identify the start and finish of individual trigger
