1、 International Telecommunication Union ITU-T J.215TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (12/2007) SERIES J: CABLE NETWORKS AND TRANSMISSION OF TELEVISION, SOUND PROGRAMME AND OTHER MULTIMEDIA SIGNALS Interactive systems for digital television distribution Client digital program insertion A
2、PI Recommendation ITU-T J.215 Rec. ITU-T J.215 (12/2007) i Recommendation ITU-T J.215 Client digital program insertion API Summary The digital program insertion (DPI) Recommendations given in ITU-T J.181 and ITU-T J.280 have enabled cable operators to provide local ad insertion on digital content at
3、 a head-end level, using equipment available from multiple vendors. Recommendation ITU-T J.215 enables similar functionality for DPI including addressable commercials, or other content, to be inserted at a device level in the consumer premises equipment. Source Recommendation ITU-T J.215 was approve
4、d on 14 December 2007 by ITU-T Study Group 9 (2005-2008) under the ITU-T Recommendation A.8 procedures. ii Rec. ITU-T J.215 (12/2007) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication te
5、chnologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The World Tel
6、ecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. In some
7、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 this Recommendation, the expression “Administration“ is used for conciseness to indicate both a telecommunication administration and a recognized
8、operating agency. Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words “s
9、hall“ or some other obligatory language such as “must“ and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. INTELLECTUAL PROPERTY RIGHTS ITU draws attention to the possibility that the
10、practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation de
11、velopment process. As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are the
12、refore strongly urged to consult the TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2010 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. Rec. ITU-T J.215 (12/2007) iii CONTENTS Page 1 Scope 1 2 Refere
13、nces. 1 2.1 Normative References 1 2.2 Informative References 1 3 Definitions 1 4 Acronyms 2 5 Conventions 2 6 DPI overview 3 7 Requirements for digital program insertion (DPI) 4 7.1 DPI signalling. 4 7.2 Switch engine behaviour 7 7.3 Switch Engine API . 8 Annex A OCAP 1.1 Digital Program Insertion
14、API. 12 A.1 SwitchEngineException class. 12 A.2 SwitchEngineListener interface 13 A.3 SwitchEngineManager Class 16 A.4 SwitchInstruction Class 19 Rec. ITU-T J.215 (12/2007) 1 Recommendation ITU-T J.215 Client digital program insertion API 1 Scope This Recommendation defines requirements for digital
15、program insertion, henceforth referred to as DPI. This recommendation enables digital program insertion in host devices (“client devices“) within customers homes, enabling addressable commercials to be inserted and addressed at a household level (or even at an individual television set level). 2 Ref
16、erences 2.1 Normative 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 editions indicated were valid. All Recommendations and other references ar
17、e 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 valid ITU-T Recommendations is regularly published. The reference to a doc
18、ument within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. ITU-T J.202 Recommendation ITU-T J.202 (2005), Harmonization of procedural content formats for interactive TV applications. ITU-T J.280 Recommendation ITU-T J.280 (2005), Digital Program Ins
19、ertion: Splicing application program interface. DVB-SAD ETSI TS 102 823 v1.1.1 (2005), Digital Video Broadcasting (DVB); Specification for the carriage of synchronized auxiliary data in DVB transport streams, http:/pda.etsi.org/pda/queryform.asp. ANSI/SCTE 138 ANSI/SCTE 138 (2009), Stream Conditioni
20、ng for Switching of Addressable Content in Digital Television Receivers. 2.2 Informative references ITU-T J.181 Recommendation ITU-T J.181 (2004), Digital program insertion cueing message for cable television systems. ITU-T J.201 Recommendation ITU-T J.201 (2004), Harmonization of declarative conten
21、t format for interactive television applications. 3 Definitions This Recommendation defines the following terms: 3.1 application: An application is a functional implementation realized as software running in one or spread over several interplaying hardware entities. 3.2 application program interface
22、 (API): An application program interface is the software interface to system services or software libraries. An API can consist of classes, function calls, subroutine calls, descriptive tags, etc. 2 Rec. ITU-T J.215 (12/2007) 3.3 broadcast: A broadcast is a service that is delivered to all customers
23、. Each customer may select a particular broadcast channel out of many. 3.4 broadcast application: A broadcast application is an application running on the set-top converter that is loaded through in-band information, inserted either at the head-end or by a content provider farther upstream. 3.5 clie
24、nt device: The CPE that is connected to the cable network in the consumers home, receives the television signals at the clients premises, and presents it for display on a display device. 3.6 digital program insertion (DPI): Insertion of alternative content into digitally encoded content in response
25、to messaging in the stream. 3.7 packet identifier (PID): MPEG-2 assigns a PID to each data packet. Packets with the same PID belong to the same logical channel. 3.8 program map table (PMT): This is a MPEG-2 entity that contains all of the PIDs that make up a program. 3.9 switch engine: This term ref
26、ers to the functionality that executes switching in the host device. This switching can either be seamless, or non-seamless. Because this functionality needs to be implemented in a real-time way, with predictable timing behaviour, the switching engine is implemented as part of an OpenCable Applicati
27、ons Platform (OCAP) implementation (“below the line“). It exposes an API to OCAP applications (targeting engines) to select which commercials are switched to/from. A switching engine can be implemented in hardware, software, or a combination of both. 3.10 unicast advertising: Advertising content dir
28、ected at a single target or small group of targets. 4 Abbreviations and acronyms This Recommendation uses the following abbreviations: API Application Program Interface DPI Digital Program Insertion OCAP OpenCable Applications Platform PMT Program Map Table 5 Conventions The following words are used
29、 throughout this Recommedation to define the significance of particular requirements: SHALL This word, or the adjective REQUIRED, means that the item is an absolute requirement of this Recommedation. SHALL NOT This phrase means that the item is an absolute prohibition of this Recommendation. SHOULD
30、This word, or the adjective RECOMMENDED, means that valid reasons may exist in particular circumstances to ignore this item, but the full implications should be understood and the case carefully weighed before choosing a different course. SHOULD NOT This phrase means that there may exist valid reaso
31、ns in particular circumstances when the listed behaviour is acceptable or even useful, but the Rec. ITU-T J.215 (12/2007) 3 full implications should be understood and the case carefully weighed before implementing any behaviour described with this label. MAY This word, or the adjective OPTIONAL, mea
32、ns that this item is truly optional. One vendor may choose to include the item because a particular marketplace requires it or because it enhances the product, for example; another vendor may omit the same item. 6 DPI overview The digital program insertion (DPI) standards within ITU-T J.181 and ITU-
33、T J.280 have enabled cable operators to provide local ad insertion on digital content at a head-end level, using equipment available from multiple vendors. This Recommendation enables similar functionality for DPI including addressable commercials, or other content, to be inserted at a device level.
34、 To allow for programmability by a cable operator as well as meet time sensitive insertion requirements, the DPI functionality is separated into two logical components: a switch engine implemented as part of the J.201 platform that performs real-time functions of switching between programs and progr
35、am elements, and one or more targeting engine applications that control the behaviour of the switch engine. A switch engine performs switch operations to present inserted content. In the broadcast scenario, which is the only scenario defined herein, inserted content MAY be within the same MPEG-2 tra
36、nsport stream as the original program or broadcast within a different MPEG-2 transport stream. Other scenarios, such as those where the original or inserted content are available on a storage device, may be defined elsewhere. A switch engine implements two distinct types of switches; a Level 0 (L0)
37、switch, which appears to the viewer as a channel change, and a Level 1 (L1) switch, which is totally invisible to the viewer. During an L0 switch, a switch engine may be required to tune to a different channel to access an insertion stream. An L1 switch never requires tuning; in this case, all of th
38、e insertion streams are within the same transport stream as the original program content. Requirements on content to enable L0 and L1 switches are defined by ANSI/SCTE 138. The switch engine behaviour is defined in clause 7.2. Detailed requirements on OCAP to perform L0 and L1 switches are defined i
39、n Annex A. An illustration of the logical components of the OCAP DPI capability is provided in Annex A. Figure 1 OCAP DPI overview 4 Rec. ITU-T J.215 (12/2007) Indicated as (1) in Figure 1, a targeting engine API is defined Annex A to enable applications to provide the switch engine with instruction
40、s and to receive status information on previously submitted instructions. Indicated as (2) in Figure 1, DPI signalling are messages that are processed by the switch engine. Signalling may be in the form of DPI triggers or timelines. See clause 7.1 below for detailed requirements on processing DPI si
41、gnalling. Where instructed by a targeting engine, the switch engine performs a program insertion operation on receipt of a DPI trigger, or based on a timeline. The DPI API provides the mechanism by which a targeting engine application configures the switch engine to perform a switch operation. A swi
42、tch operation occurs when the switch engine is properly configured by a targeting application through the DPI API, and the proper signalling is subsequently detected. Indicated as (3) in Figure 1, content feeds are MPEG-2 transport streams that carry program feeds and may contain other insertion fee
43、ds, such as advertising feeds. The program feeds (as well as the separate insertion feeds) may contain DPI signalling that is used by the switch engine to insert content, such as addressable commercials during addressable breaks. The program feeds and insertion feeds may be subject to certain encodi
44、ng (and other) restrictions that make it easier for the switching engine to switch to and from insertion content, see ANSI/SCTE 138. The command and control element shown in Figure 1 represents a hypothetical private communication channel between a targeting engine and an associated network componen
45、t. Advanced advertising systems are expected to incorporate logical components within the cable network that manage both the insertion of DPI signalling and the actions of a targeting engine. No security model has been defined to protect signalling from detection by non-authorized users. Because of
46、the extremely tight synchronization between signalling and video content needed to perform seamless L1 switches, signalling must be in-band, in the same program stream as the original content feed. Strategies for obfuscating signals may be developed, but none are described herein. 7 Requirements for
47、 digital program insertion (DPI) 7.1 DPI signalling This clause describes signaling used to enable a switch engine to perform its operations. Two signalling protocols are used to support DPI: DPI triggers and DPI timelines. DPI trigger messages embedded within a content segment indicate opportunitie
48、s to perform a switch operation. DPI timelines are messages embedded within a content segment to enable the implementation to maintain a metadata timeline for a segment. Switch operations MAY be based on timelines. All DPI signalling is expected to be carried on a single data PID within the original
49、 content stream. This data stream SHALL be identified by DPI registration descriptor in a programs PMT. Figure 2 DPI signalling stream Rec. ITU-T J.215 (12/2007) 5 Figure 2 illustrates a hypothetical MPEG-2 program stream containing DPI signalling. The DVB-SAD PID contains a series of timeline descriptors, and examples of L0 and L1 triggers. The details of these descriptors and their placement are provided below. 7.1.1 DPI Signalling descriptor The dpi_signaling_descriptor is defined for use in the elementary stream information loop of the PMT. This des
