ISO/IEC 13818-9:1996
(Main)Information technology — Generic coding of moving pictures and associated audio information — Part 9: Extension for real time interface for systems decoders
Information technology — Generic coding of moving pictures and associated audio information — Part 9: Extension for real time interface for systems decoders
Does not change or supersede any of the requirements in ISO/IEC 13818-1. All transport streams, whether or not they are delivered in accordance with the RTI shall comply with ISO/IEC 13818-1.
Technologies de l'information — Codage générique des images animées et des informations sonores associées — Partie 9: Extension pour interface temps réel pour systèmes décodeurs
General Information
Standards Content (Sample)
ISO/IEC
INTERNATIONAL
STANDARD 13818-9
First edition
1996-I 2-l 5
Information technology - Generic coding
of moving pictures and associated audio
information -
Part 9:
Extension for real time interface for systems
decoders
Technologies de I ‘information - Codage g&&-ique des images aim&es
et des informations sonores associ6es -
Partie 9: Extension pour interface temps r&e/ pour systemes dbcodeurs
Reference number
lSO/IEC 13818-9:1996(E)
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(El
Foreword
IS0 (the International Organization for Standardization) and IEC
(the International Electrotechnical Commission) form the specialized
system for worldwide standardization. National bodies that are
members of IS0 or IEC participate in the development of Inter-
national Standards through technical committees established by the
respective organization to deal with particular fields of technical
activity. IS0 and IEC technical committees collaborate in fields of
mutual interest. Other international organizations, governmental and
non-governmental, in liaison with IS0 and IEC, also take part in the
work.
In the field of information technology, IS0 and IEC have established
a joint technical committee, ISO/IEC JTC 1. Draft International
Standards adopted by the joint technical committee are circulated to
national bodies for voting. Publication as an International Standard
national bodies casting a
requires approval by at least 75 % of the
vote.
International Standard ISO/IEC 13 8 18-9 was prepared by Joint
Technical Committee ISO/IEC JTC 1, Information technology,
Subcommittee SC 29, Coding of audio, picture, multimedia and
hypermedia information.
ISO/IEC 138 18 consists of the following parts, under the general
title Information technology - Generic coding of moving pictures
and associated audio information:
- Part 1: Systems
- Part 2: Video
- Part 3: Audio
- Part 4: Compliance testing
- Part 6: Extensions for DSiWCC
- Part 9: Extension for real time interface for systems decoders
0 ISO/IEC 1996
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or
utilized in any form or by any means, electronic or mechanical, including photocopying and micro-
film, without permission in writing from the publisher.
ISO/IEC Copyright Office l Case postale 56 l CH-1211 Geneve 20 l Switzerland
Printed in Switzerland
ii
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0 lSO/IEC ISO/IEC 13818=9:1996(E)
Introduction
Conformance for ISO/IEC 138 18- 1 Transport Streams is specified in
terms of the normative specifications defined therein. These
specifications include, among other requirements, a Transport
Stream System Target Decoder (T-STD) (ISO/IEC 13818-1, 2.4.2)
which specifies the behaviour of an idealized decoder when the
stream is input to such a decoder. The T-STD model, and the
associated verification, do not include information concerning the
stream in real time.
This part of ISO/IEC 138 18 specifies the timing of the real-time
delivery of the bytes of Transport Stream packets at a Real Time
Interface (RTI). Equipment which includes some type of interface
for Transport Stream data, the timing characteristics of which are
said to comply with the RTI specification, must be able to operate
normally with any input which complies with the RTI specification.
In no case, however, is a piece of equipment required to implement
an RTI interface.
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INTERNATIONAL STANDARD @ lSO/IEC ISO/IEC 13818=9:1996(E)
Information technology - Generic coding of moving pictures and
associated audio information -
Part 9:
Extension for real time interface for systems decoders
1 Scope
This part of ISO/IEC 13 8 18 does not change or supersede any of the requirements in ISO/IEC 138 1% 1.
All Transport Streams, whether or not they are delivered in accordance with the RTI shall comply with
ISO/IEC 13 8 18-l. In particular, the accuracy requirement in ISO/IEC 138 18-l for PCRs in Transport
Streams is not changed by the requirements of this part of ISO/IEC 138 18. Compliance with this part of
ISO/IEC 138 18 is not required for compliance with ISO/IEC 138 18- 1.
This part of ISO/IEC 138 18 does not address decoder requirements related to clock acquisition and slew
rate constraints. For example, suppose a system utilizes the 27 MHz system clock to derive an ITU-R PAL
chroma clock of 4.434 MHz, with a 0.1 Hz/set slew rate limitation. With a source clock of 0.1 ppm
accuracy, a decoder clock of 30 ppm accuracy, and straightforward phase-locked loop clock recovery
circuitry, a decoder could require about 305,000 bits to prevent buffer under/overflow during frequency
acquisition, even with low-jitter delivery. The actual number of bits a decoder requires for this purpose
could be higher or lower, depending on the implementation.
Figure 1 provides a simplified view of the scope of this part of ISO/IEC 138 18. This figure shows a Data
Link Interface Adaptor, a Real-Time Interface Decoder (RTD), and the location of the Transport Stream
which complies with the RTI Specification. It should be noted that the Data Link Interface Adaptor is
responsible for removing any data link protocol or data structures, as well as any timing variations (i.e.
jitter) in order to produce a compliant RTI Transport Stream.
Figure II - Scope ofRT1
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0 ISO/lEC
ISO/IEC 13818=9:1996(E)
2 Real-Time Interface Requirements
2.1 The Real-Time Interface Decoder Model
The Real-Time Interface Decoder Model, called the RTD, is a conceptual model used to define the RTI
normative requirements. The RTD is used only for this purpose. Neither its architecture nor the timing
described precludes uninterrupted, synchronized playback by a variety of decoders with different
architectures or timing schedules.
The RTD is exactly the same as the T-STD model defined in ISO/IEC 138 18-1, except that:
l the byte delivery schedule defined in the T-STD is replaced by the actual byte arrival time in the RTD;
l real-time constraints are imposed on the values of PCR in relation to their arrival time in the RTD;
l the buffer sizes defined in the T-STD are different in the RTD; and
there is an extra requirement on the Transport Buffer occupancy (see the end of 2.4).
2.2 Clock Frequency Requirements
The requirements on the system clock with respect to frequency and frequency slew given in
ISO/IEC 138 18.1,2.4.2.1 are also mandatory for the Real-Time Interface.
2.3 PCR Accuracy Requirements
This subclause defines a single constraint on the relationship between the arrival time of all the bytes
containing the last bit of a program clock reference base field for a single program of a Transport Stream,
- - -
and the value carried in the corresponding program clock references.
Specifically,
l let system clock counter(t) be a counter that counts cycles of a system clock that satisfies the
frequencyrequirGments specified in 2.2 above, where t represents time;
l let i” be the index of a byte containing the last bit of a program clock reference base field;
l let t(i”) be the time at which byte i” arrives in the RTD; and - - -
l let PCR(i”) be the value of the program clock reference associated with byte i”;
then there shall exist such a system clock counter(t), a sequence of times e(F), and a constant tjitter (see
ISO/IEC 138 18-l Annex J) that satisfy -
PCR(i”) = system clock counter((t(i”) + e(i”))%(300 x 233)), and
- -
- tjitter/2 5 e(i”> 5 tjitter/:!.
2.4 Buffer Requirements
The buffers in the RTD have the same names as those in the T-STD, but are denoted with a “ r” suffix.
-
Their sizes are:
TBS_r, = TBS, + (tjitter x Rx,) + 188 bytes
= TBS,,, + ( tjitter x Rxn) + 188 bytes
TBS rsys
sb sL r = sb size + ( tjitter x sb leak
rate) + 188 bytes
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It should be noted that the use of the smoothing buffer (see ISO/IEC 138 18-1, 2.630) is opthA for this
part of ISO/IEC 13818, as it is in ISO/IEC 13818-l.
2
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0 lSO/IEC
ISO/IEC 13818-9: 1996(E)
The multiplex buffer (for video) and the decoder buffer (for audio and systems data) in the
RTD have the sizes:
= MBS, + (2x tjitter x Rx,),
MBS-r,
= BS, + (2 x tjitter x Rx& and
BS_rn
= BS,,, + (2 x tjitter x Rx,),
BS - rsys
...
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