ETSI TR 101 211 V1.9.1 (2009-06)

Technical Report
Digital Video Broadcasting (DVB);
Guidelines on implementation and usage
of Service Information (SI)
European Broadcasting Union Union Européenne de Radio-Télévision
EBU·UER
2 ETSI TR 101 211 V1.9.1 (2009-06)

Reference
RTR/JTC-DVB-260
Keywords
broadcasting, digital, DVB, MPEG, TV, video
ETSI
650 Route des Lucioles
F-06921 Sophia Antipolis Cedex - FRANCE

Tel.: +33 4 92 94 42 00  Fax: +33 4 93 65 47 16

Siret N° 348 623 562 00017 - NAF 742 C
Association à but non lucratif enregistrée à la
Sous-Préfecture de Grasse (06) N° 7803/88

Important notice
Individual copies of the present document can be downloaded from:
http://www.etsi.org
The present document may be made available in more than one electronic version or in print. In any case of existing or
perceived difference in contents between such versions, the reference version is the Portable Document Format (PDF).
In case of dispute, the reference shall be the printing on ETSI printers of the PDF version kept on a specific network drive
within ETSI Secretariat.
Users of the present document should be aware that the document may be subject to revision or change of status.
Information on the current status of this and other ETSI documents is available at
http://portal.etsi.org/tb/status/status.asp
If you find errors in the present document, please send your comment to one of the following services:
http://portal.etsi.org/chaircor/ETSI_support.asp
Copyright Notification
No part may be reproduced except as authorized by written permission.
The copyright and the foregoing restriction extend to reproduction in all media.

© European Telecommunications Standards Institute 2009.
© European Broadcasting Union 2009.
All rights reserved.
TM TM TM TM
DECT , PLUGTESTS , UMTS , TIPHON , the TIPHON logo and the ETSI logo are Trade Marks of ETSI registered
for the benefit of its Members.
TM
3GPP is a Trade Mark of ETSI registered for the benefit of its Members and of the 3GPP Organizational Partners.
LTE™ is a Trade Mark of ETSI currently being registered
for the benefit of its Members and of the 3GPP Organizational Partners.
GSM® and the GSM logo are Trade Marks registered and owned by the GSM Association.
ETSI
3 ETSI TR 101 211 V1.9.1 (2009-06)
Contents
Intellectual Property Rights . 6
Foreword . 6
1 Scope . 7
2 References . 7
2.1 Normative references . 7
2.2 Informative references . 8
3 Definitions and abbreviations . 9
3.1 Definitions . 9
3.2 Abbreviations . 10
4 Rules of operation . 12
4.1 Service Information (SI) table information . 12
4.1.1 Network Information Table (NIT) information . 13
4.1.2 Bouquet Association Table (BAT) information . 14
4.1.3 Service Description Table (SDT) information . 14
4.1.4 Event Information Table (EIT) information . 14
4.1.4.1 EIT Present/Following information . 15
4.1.4.2 EIT Schedule information . 16
4.1.4.2.1 EIT Schedule structure . 16
4.1.4.2.2 EIT scrambling . 17
4.1.5 Time and Date Table (TDT) . 17
4.1.6 Time Offset Table (TOT) . 17
4.1.7 Running Status Table (RST) . 17
4.1.8 Stuffing Table (ST) . 18
4.1.9 Transport Stream Description Table (TSDT) . 18
4.1.9.1 Digital Satellite News Gathering (DSNG) . 18
4.1.10 Table update mechanism . 18
4.1.11 Table segmentation . 19
4.1.11.1 Generic segmentation rules . 19
4.1.11.1.1 General rules . 19
4.1.11.1.2 NIT and BAT . 19
4.1.11.1.3 SDT and EIT . 19
4.1.11.2 Segmentation rules for DVB-H and DVB-SH systems . 20
4.1.11.2.1 General rules . 20
4.1.11.2.2 NIT and BAT for DVB-SH and DVB-H . 20
4.1.11.2.3 SDT for DVB-SH and DVB-H . 21
4.2 SI descriptor allocation and usage . 21
4.2.1 Descriptors of the Network Information Table (NIT) . 21
4.2.1.1 First descriptor loop . 22
4.2.1.1.1 Linkage descriptor . 22
4.2.1.1.2 Multilingual network name descriptor . 22
4.2.1.1.3 Network name descriptor. 22
4.2.1.1.4 Cell list descriptor. 22
4.2.1.1.5 Network change notify descriptor . 22
4.2.1.2 Second descriptor loop . 23
4.2.1.2.1 Delivery system descriptors . 23
4.2.1.2.2 Service list descriptor . 23
4.2.1.2.3 Frequency list descriptor . 23
4.2.1.2.4 Cell frequency link descriptor . 23
4.2.2 Descriptors of the Bouquet Association Table (BAT) . 23
4.2.2.1 First descriptor loop . 24
4.2.2.1.1 Bouquet name descriptor . 24
4.2.2.1.2 CA identifier descriptor . 24
4.2.2.1.3 Country availability descriptor . 24
4.2.2.1.4 Linkage descriptor . 24
ETSI
4 ETSI TR 101 211 V1.9.1 (2009-06)
4.2.2.1.5 Multilingual bouquet name descriptor . 24
4.2.2.2 Second descriptor loop . 25
4.2.2.2.1 Service list descriptor . 25
4.2.3 Descriptors of the Service Description Table (SDT) . 25
4.2.3.1 Announcement support descriptor . 25
4.2.3.2 Bouquet name descriptor . 25
4.2.3.3 CA identifier descriptor . 25
4.2.3.4 Component descriptor . 26
4.2.3.5 Country availability descriptor . 26
4.2.3.6 Data_broadcast_descriptor . 26
4.2.3.7 Linkage descriptor . 26
4.2.3.8 Mosaic descriptor . 27
4.2.3.9 Multilingual service name descriptor . 27
4.2.3.10 NVOD reference descriptor . 27
4.2.3.11 Service descriptor . 27
4.2.3.12 Service availability descriptor . 27
4.2.3.12.1 Network Implementation Considerations . 28
4.2.3.12.2 IRD implementation considerations . 28
4.2.3.13 Telephone descriptor . 28
4.2.3.14 Time shifted service descriptor . 29
4.2.4 Descriptors of the Event Information Table (EIT) . 29
4.2.4.1 CA identifier descriptor . 29
4.2.4.2 Component descriptor . 30
4.2.4.3 Content descriptor . 30
4.2.4.4 Data_broadcast_descriptor . 30
4.2.4.5 Extended event descriptor . 30
4.2.4.6 Linkage descriptor . 30
4.2.4.7 Multilingual component descriptor . 31
4.2.4.8 Parental rating descriptor . 31
4.2.4.9 PDC descriptor . 31
4.2.4.10 Short event descriptor . 32
4.2.4.11 Telephone descriptor . 32
4.2.4.12 Time shifted event descriptor . 32
4.2.5 Descriptors of the Time Offset Table (TOT) . 32
4.2.5.1 Local time offset descriptor. 32
4.2.6 Descriptors of the Program Map Table (PMT) . 33
4.2.6.1 AC-3 descriptor . 33
4.2.6.2 Adaptation field data descriptor . 33
4.2.6.3 Ancillary data descriptor . 33
4.2.6.4 Data broadcast id descriptor . 33
4.2.6.5 Mosaic descriptor . 33
4.2.6.6 Service move descriptor . 33
4.2.6.7 Stream identifier descriptor . 34
4.2.6.8 Subtitling descriptor . 34
4.2.6.9 Teletext descriptor . 34
4.2.6.10 VBI data descriptor . 34
4.2.6.11 VBI teletext descriptor . 34
4.2.7 Other descriptors . 34
4.2.7.1 Private data specifier descriptor . 34
4.2.7.2 Stuffing descriptor . 35
4.2.7.3 Data_broadcast_descriptor . 35
4.2.7.4 Transport_stream_descriptor . 35
4.2.8 ISO/IEC 13818-1 descriptors . 35
4.2.9 Unknown descriptors . 35
4.3 Program Specific Information (PSI) and DVB SI operational interaction states . 36
4.4 Minimum repetition rates . 36
4.4.1 Satellite and cable delivery systems . 36
4.4.2 Terrestrial delivery systems . 37
4.5 Terrestrial systems . 37
4.5.1 Terms used within terrestrial systems . 37
4.5.2 The use of alternative frequencies for multiplexes . 39
4.5.3 Regional or local services . 40
ETSI
5 ETSI TR 101 211 V1.9.1 (2009-06)
4.5.4 Hand-over . 42
4.5.4.1 General description of the requirements . 42
4.5.4.2 Hand-over by means of the frequency_list_descriptor . 42
4.5.4.3 The occurrence of tuning failures . 43
4.5.4.4 Hand-over methods with a reduced risk of tuning failures . 44
4.5.4.4.1 Local SI insertion . 45
4.5.4.4.2 Cell identification . 45
4.5.4.4.3 Performance enhancement with GPS data . 45
4.5.4.4.4 Two front-end solution . 45
4.5.4.5 Performance considerations . 46
4.5.4.6 Receiver guidelines . 46
4.5.4.6.1 Hand-over by means of the frequency_list_descriptor . 46
4.5.4.6.2 Hand-over by means of cell identification . 47
4.5.4.6.3 Hand-over by means of cell description and GPS position . 47
4.5.4.6.4 Hand-over with two-front-end solutions . 48
4.5.4.7 Additional linkage modes . 48
4.5.4.8 Additional remarks . 49
4.6 Text string formatting . 49
4.6.1 Use of control codes in names . 49
4.6.2 Use of control codes in text . 50
4.6.3 Use of UTF-8 . 50
5 Applications . 50
5.1 NVOD services . 50
5.2 Mosaic services . 52
5.2.1 General considerations . 52
5.2.2 Relationship between mosaic service and SI/PSI Tables . 53
5.3 Transitions at broadcast delivery media boundaries . 54
5.3.1 Seamless transitions . 54
5.3.2 Non-seamless transitions without re-multiplexing. 55
5.3.3 Transitions with re-multiplexing . 55
5.4 Announcements . 56
6 Storage media . 56
6.1 Program Association Table (PAT) . 56
6.2 Program Map Table (PMT) . 56
6.3 SI tables (NIT, SDT, EIT, BAT, RST, TDT, TOT) . 56
6.4 Selection Information Table (SIT) . 57
6.5 Discontinuity Information Table (DIT) . 57
History . 58

ETSI
6 ETSI TR 101 211 V1.9.1 (2009-06)
Intellectual Property Rights
IPRs essential or potentially essential to the present document may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in
respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web
server (http://webapp.etsi.org/IPR/home.asp).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web
server) which are, or may be, or may become, essential to the present document.
Foreword
This Technical Report (TR) has been produced by Joint Technical Committee (JTC) Broadcast of the European
Broadcasting Union (EBU), Comité Européen de Normalisation ELECtrotechnique (CENELEC) and the European
Telecommunications Standards Institute (ETSI).
The present document is based on the DVB document TM1324, rev. 8/162 rev. 22, and it may be converted into a
standard after market feedback. For this purpose, the wording of a standard (normative elements) rather than of a
technical report (informative elements) has been used.
NOTE: The EBU/ETSI JTC Broadcast was established in 1990 to co-ordinate the drafting of standards in the
specific field of broadcasting and related fields. Since 1995 the JTC Broadcast became a tripartite body
by including in the Memorandum of Understanding also CENELEC, which is responsible for the
standardization of radio and television receivers. The EBU is a professional association of broadcasting
organizations whose work includes the co-ordination of its members' activities in the technical, legal,
programme-making and programme-exchange domains. The EBU has active members in about
60 countries in the European broadcasting area; its headquarters is in Geneva.
European Broadcasting Union
CH-1218 GRAND SACONNEX (Geneva)
Switzerland
Tel: +41 22 717 21 11
Fax: +41 22 717 24 81
Founded in September 1993, the DVB Project is a market-led consortium of public and private sector organizations in
the television industry. Its aim is to establish the framework for the introduction of MPEG-2 based digital television
services. Now comprising over 200 organizations from more than 25 countries around the world, DVB fosters
market-led systems, which meet the real needs, and economic circumstances, of the consumer electronics and the
broadcast industry.
ETSI
7 ETSI TR 101 211 V1.9.1 (2009-06)
1 Scope
The present document provides implementation guidelines for the use and implementation of the DVB Service
Information (SI) coding in a DVB digital TV environment including satellite - cable - and terrestrial networks.
The guidelines are intended to be highly recommended rules for the usage of the DVB SI syntax specified in
EN 300 468 [i.1]. As such, they facilitate the efficient and reliable implementation of basic user-interaction functions in
Integrated Receiver-Decoders (IRD).
The rules apply to broadcasters, network operators as well as manufacturers.
The rules are specified in the form of constraints on the DVB SI streams or in terms of intended interpretation by IRDs.
The specification of these functions in no way prohibits IRD manufacturers from including additional features, and
should not be interpreted as stipulating any form of upper limit to the performance.
The guidelines do not cover features related to user-interface details or advanced Electronic Program Guides (EPG).
Such issues are left to the marketplace.
NOTE: It is highly recommended that the IRD should be designed to allow for future compatible extensions to
the DVB SI syntax. All the fields "reserved" (for ISO), "reserved_future_use" (for ETSI), and "user
defined" in the EN 300 468 [i.1] should be ignored by IRDs designed not to make use of them. The
"reserved" and "reserved_future_use" fields may be specified in the future by the respective bodies,
whereas the "user defined" fields will not be standardized.
The present document uses the terminology defined in EN 300 468 [i.1] and should be read in conjunction with that EN.
It is envisaged that the present document become a Technical Specification (TS), and therefore the text used throughout
the present document is that of a TS.
2 References
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific.
• For a specific reference, subsequent revisions do not apply.
• Non-specific reference may be made only to a complete document or a part thereof and only in the following
cases:
- if it is accepted that it will be possible to use all future changes of the referenced document for the
purposes of the referring document;
- for informative references.
Referenced documents which are not found to be publicly available in the expected location might be found at
http://docbox.etsi.org/Reference.
NOTE: While any hyperlinks included in this clause were valid at the time of publication ETSI cannot guarantee
their long term validity.
2.1 Normative references
The following referenced documents are indispensable for the application of the present document. For dated
references, only the edition cited applies. For non-specific references, the latest edition of the referenced document
(including any amendments) applies.
Not applicable.
ETSI
8 ETSI TR 101 211 V1.9.1 (2009-06)
2.2 Informative references
The following referenced documents are not essential to the use of the present document but they assist the user with
regard to a particular subject area. For non-specific references, the latest version of the referenced document (including
any amendments) applies.
[i.1] ETSI EN 300 468: "Digital Video Broadcasting (DVB); Specification for Service Information (SI)
in DVB systems".
[i.2] ISO/IEC 13818-1: "Information technology - Generic coding of moving pictures and associated
audio information: Systems".
[i.3] ETSI EN 300 472: "Digital Video Broadcasting (DVB); Specification for conveying ITU-R
System B Teletext in DVB bitstreams".
[i.4] ETSI TS 101 162: "Digital Video Broadcasting (DVB); Allocation of Service Information (SI)
codes for DVB systems".
[i.5] ETSI EN 301 192: "Digital Video Broadcasting (DVB); DVB specification for data broadcasting".
[i.6] ETSI TR 101 202: "Digital Video Broadcasting (DVB); Implementation guidelines for Data
Broadcasting".
[i.7] ITU-R Recommendation BS.1196-1: "Audio coding for digital terrestrial television broadcasting".
NOTE 1: Available at http://www.itu.int/rec/recommendation.asp?type=items&lang=e&parent=R-REC-BS.1196-1-
200104-I.
NOTE 2: Annex 2 "Digital Audio Compression (AC-3) Standard (ATSC Standard)", contains additional
information on the AC-3 audio encoding algorithm and decoding requirements, relevant to the present
document. Appendix 1 to annex 2 of this Recommendation should be disregarded as it is not applicable to
the present document.
[i.8] ETSI EN 300 744: "Digital Video Broadcasting (DVB); Framing structure, channel coding and
modulation for digital terrestrial television".
[i.9] ETSI TR 101 154: "Digital Video Broadcasting (DVB); Implementation guidelines for the use of
MPEG-2 Systems, Video and Audio in satellite, cable and terrestrial broadcasting applications".
[i.10] ETSI EN 301 775: "Digital Video Broadcasting (DVB); Specification for the carriage of Vertical
Blanking Information (VBI) data in DVB bitstreams".
[i.11] ETSI EN 301 210: "Digital Video Broadcasting (DVB); Framing structure, channel coding and
modulation for Digital Satellite News Gathering (DSNG) and other contribution applications by
satellite".
[i.12] ETSI EN 300 231: "Television systems; Specification of the domestic video Programme Delivery
Control system (PDC)".
[i.13] ISO/IEC 13818-3: "Information technology - Generic coding of moving pictures and associated
audio information - Part 3: Audio".
[i.14] ISO/IEC 11172-3: "Information technology - Coding of moving pictures and associated audio for
digital storage media at up to about 1,5 Mbit/s - Part 3: Audio".
[i.15] ETSI EN 300 743: "Digital Video Broadcasting (DVB); Subtitling systems".
[i.16] ETSI EN 300 401: "Radio Broadcasting Systems; Digital Audio Broadcasting (DAB) to mobile,
portable and fixed receivers".
[i.17] ETSI TS 102 006: "Digital Video Broadcasting (DVB); Specification for System Software Update
in DVB Systems".
[i.18] ISO/IEC 13818-2: "Information technology - Generic coding of moving pictures and associated
audio information: Video".
ETSI
9 ETSI TR 101 211 V1.9.1 (2009-06)
[i.19] "Implementation guidelines for use of telecommunications interfaces in the Digital Broadcasting
systems" (DVB Project office).
[i.20] ATSC Document A/56: "System Information for Digital Television".
NOTE: Available at http://www.atsc.org.
3 Definitions and abbreviations
3.1 Definitions
For the purposes of the present document, the following terms and definitions apply:
AC-3: refers to the coding of audio using the Dolby AC-3 method (ITU-R Recommendation BS.1196-1 [i.7])
NOTE: The Service Information requirements for AC-3 streams carried in DVB systems is described in annex E
of EN 300 468 [i.1]. The carriage of AC-3 elementary streams as private data within MPEG systems is
described in annex C of TR 101 154 [i.9].
bouquet: collection of services marketed as a single entity
broadcaster (SERVICE Provider): organization which assembles a sequence of events or programmes to be delivered
to the viewer based upon a schedule
cell: geographical area that is covered with DVB-T signals delivering one or more particular transport streams
throughout the area by means of one or more transmitters
NOTE: The cell may in addition contain repeaters. Two neighbouring cells may be intersecting, or fully
overlapping. The cell_id that is used to uniquely identify a cell is unique within each original_network_id.
For hand-over purposes it is more convenient if the transport streams associated with the cell cover
exactly the same area, or only one transport stream per cell is used.
component (ELEMENTARY Stream): one or more entities which together make up an event
EXAMPLE: Video, audio, Teletext.
Conditional Access (CA) system: system to control subscriber access to services, programmes and events
EXAMPLE: Videoguard, Eurocrypt.
delivery system: physical medium by which one or more multiplexes are transmitted
EXAMPLE: Satellite system, wide-band coaxial cable, fibre optics, terrestrial channel of one emitting point.
event: grouping of elementary broadcast data streams with a defined start and end time belonging to a common service
EXAMPLE: First half of a football match, News Flash, first part of an entertainment show.
MPEG-2: refers to the standard ISO/IEC 13818:
NOTE: Systems coding is defined in part 1 [i.2].
Video coding is defined in part 2 [i.18].
Audio coding is defined in part 3 [i.13].
multiplex: stream of all the digital data carrying one or more services within a single physical channel
network: collection of MPEG-2 TS multiplexes transmitted on a single delivery system
EXAMPLE: All digital channels on a specific cable system.
ETSI
10 ETSI TR 101 211 V1.9.1 (2009-06)
programme: concatenation of one or more events under the control of a broadcaster
EXAMPLE: News show, entertainment show.
section: syntactic structure used for mapping all service information into ISO/IEC 13818-1 [i.2]
NOTE: Transport Stream (TS) packets.
service: sequence of programmes under the control of a broadcaster which can be broadcast as part of a schedule
Service Information (SI): digital data describing the delivery system, content and scheduling/timing of broadcast data
streams, etc.
NOTE: It includes MPEG-2 Program Specific Information (PSI) together with independently defined extensions.
subcell: geographical area that is part of the cell's coverage area and that is covered with DVB-T signals by means of a
transposer
NOTE: In conjunction with the cell_id the cell_id_extension is used to uniquely identify a subcell.
sub-table: comprising a number of sections with the same value of table_id, table_id_extension and version_number
NOTE: The table_id_extension field is equivalent to the fourth and fifth byte of a section when the
section_syntax_indicator is set to a value of "1".
table: comprising a number of sections with the same value of table_id
Transport Stream (TS): data structure defined in ISO/IEC 13818-1 [i.2]
NOTE: It is the basis of the DVB standards.
3.2 Abbreviations
For the purposes of the present document, the following abbreviations apply:
AC-3 dolby AC-3 audio coding
ASCII American Standard Code for Information Interchange
ATSC Advanced Television Systems Committee of the USA
BAT Bouquet Association Table
CA Conditional Access
CR Carriage Return character
DAB Digital Audio Broadcasting
DIT Discontinuity Information Table
DSNG Digital Satellite News Gathering
DVB Digital Video Broadcasting
DVD Digital Versatile Disc
EIT Event Information Table
EPG Electronic Program Guide
ES Elementary Stream
GPS Global Positioning System
IRD Integrated Receiver-Decoder
LF Line Feed Character
MFN Multi-Frequency Network
MJD Modified Julian Date
MPEG Moving Pictures Expert Group
NIT Network Information Table
NVOD Near Video On Demand
PAT Program Association Table
PDC Programme Delivery Control
PID Packet IDentifier
PIL Programme Identification Label
PMT Program Map Table
PSI Program Specific Information
QAM Quadrature Amplitude Modulation
ETSI
11 ETSI TR 101 211 V1.9.1 (2009-06)
QPSK Quadrature Phase Shift Keying
RST Running Status Table
SDT Service Description Table
SFN Single Frequency Network
SHY Soft HYphen
SI Service Information
SIT Selection Information Table
SMATV Satellite Master Antenna TeleVision
ST Stuffing Table
TDT Time and Date Table
TOT Time Offset Table
TPS Transmission Parameter Signalling
TS Technical Specification
TS Transport Stream
TSDT Transport Stream Description Table
UCS Universal Character Set
UTC Universal Time Coordinated
UTF UCS Transformation Format
VBI Vertical Blanking Interval
VPS Video Programme System
WSS Wide Screen Signalling
ETSI
12 ETSI TR 101 211 V1.9.1 (2009-06)
4 Rules of operation
This clause contains some recommendations on the usage of the Digital Video Broadcasting (DVB) Service
Information (SI) syntax.
4.1 Service Information (SI) table information

Figure 1: SI table information
ETSI
13 ETSI TR 101 211 V1.9.1 (2009-06)
4.1.1 Network Information Table (NIT) information
The Network Information Table (NIT) provides a grouping of Transport Streams (TSs) and the relevant tuning
information. The NIT could be used during set-up procedures of the IRD and the relevant tuning information may be
stored in non-volatile memory. The NIT also could be used to signal changes of tuning information. The following rules
apply to the NIT:
a) transmission of the NIT is mandatory for the actual delivery system;
b) the NIT describing the actual delivery system is valid if and only if it contains applicable delivery system
descriptors for the actual delivery system. This rule specifies the conditions under which the NIT contains
valid information. At some transitions of broadcast delivery system boundaries, the NIT carried in a TS is
allowed to describe an earlier network in the broadcast chain. A different mechanism has to be selected by the
IRD to obtain the relevant tuning information for the actual delivery system. If a satellite IRD receives a
satellite delivery system descriptor for the actual delivery system, then it is valid. If a cable IRD receives a
cable delivery system descriptor for the actual delivery system, then it is valid. If a cable IRD receives a
satellite delivery system descriptor for the actual delivery system, then it is assumed to be invalid for the cable
IRD;
c) if a valid NIT for the actual delivery system is present in the SI bit stream then it will list all TSs of the actual
delivery system;
d) the SI stream will have at least 8 TS packets per 10 s carrying NIT data or NULL packets. This rule simplifies
the replacement of the NIT at broadcast delivery system boundaries. With the simple replacement mechanism,
local frequency control is possible with relatively low cost equipment.
The SI uses two labels related to the concept of a delivery system, namely the network_id and the original_network_id.
The latter is intended to support the unique identification of a service, contained in a TS, even if that TS has been
transferred to another delivery system than the delivery system where it originated. A TS can be uniquely referenced
through the path original_network_id/transport_stream_id.
A service can be uniquely referenced through the path original_network_id/transport_stream_id/service_id. The
network_id, thus, is not part of this path.
In addition each service_id will be unique within each original_network_id. When a service (contained inside a TS) is
transferred to another delivery system, only the network_id changes, whereas the original_network_id remains
unaffected.
By way of example, consider the following, where two services (A and B), which originate in two different delivery
systems and happen to have the same service_ids and transport_stream_ids, are transferred to a new delivery system.
In the example, the two services are located on different TSs (X and Y) in the new network. If the two services were
being combined onto the same TS, then it would be necessary to modify the identification of
...