IEC International ISO Standard ISO/IEC 14496-34 Information technology - Coding of First edition 2025-05 audio-visual objects Part 34: Syntactic description language Technologies de I'information - Codage des objets audiovisuels Partie 34: Langage de description syntaxique Reference number IS0/IEC 14496-34:2025(en) @ ISO/IEC 2025 IS0/IEC 14496-34:2025(en) COPYRIGHT PROTECTED DOCUMENT @IS0/IEC 2025 All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may below or IsO's member body in the country of the requester. ISO copyright office CP 40i : Ch. de Blandonnet 8 CH-1214 Vernier, Geneva Phone: +41 22 749 01 11 Email: [email protected] Website: www.iso.org Published in Switzerland @ IS0/IEC 2025 - All rights reserved ii IS0/IEC 14496-34:2025(en) Contents Page Foreword. Introduction. .vi Scope. 1 1 2 Normative references. 1 3 Terms and definitions. 1 4 Notation. .3 4.1 General. .3 4.2 Rule formatting. .3 4.3 Rule tokens. .3 4.4 Bitstream examples .3 5 Language concepts and lexical elements. 5.1 Character set. 5.2 Whitespace. 5.3 Case sensitivity .5 .5 5.4 Comments. 5.5 Identifiers. .5 5.6 .6 Punctuators. 5.7 Keywords. 5.8 Operators. .7 5.8.1 List of operators. 5.8.2 Operator precedence and associativity .8 5.8.3 Specific operator behaviour. ..8 5.9 Expressions and evaluation.. .9 5.10 Statements. .9 Built-in operators. 5.11 10 5.12 Numbers. 12 5.12.1 Endianness. 12 Representation of numbers 12 5.12.2 5.12.3 Number limits. 12 5.12.4 Value coercion. 12 5.13 13 Logic values.. 5.14 Binary literal values.. 13 5.15 Hexadecimal literal values. .14 5.16 Multiple character literal values .14 5.17 Integer, decimal and floating-point literal values. 15 String literal values. 5.18 .16 5.19 Scope. .17 5.19.1 General ..17 5.19.2 Parsed variable scope .18 5.19.3 Computed variable scope 18 5.20 SDL specification limits. .19 Elementary data types. .19 6 6.1 General. ..19 6.2 Constant-length direct representation bit fields 20 6.2.1 Alignment. 20 6.2.2 Type. 20 6.2.3 .21 Length. Value.. 6.2.4 .21 6.2.5 Constants .21 6.2.6 22 Look-ahead 6.2.7 Legacy. 22 6.2.8 23 Reserved. 6.3 Variable length direct representation bit fields 23 @ IS0/IEC 2025 - All rights reserved ii IS0/IEC 14496-34:2025(en) 6.4 Constant-length indirect representation bit fields .24 6.5 Variable length indirect representation bit fields. 26 6.6 Variable length strings. .27 6.7 String value.. 28 Composite data types. 28 7.1 Classes. 28 7.2 Base and derived classes. 29 7.3 Abstract classes. 30 7.4 Polymorphism in class declaration. .31 7.4.1 .31 General Polymorphism for abstract classes. 7.4.2 33 33 7.5 Expandable classes 7.6 Parameter types 35 7.7 39 Arrays... 7.7.1 39 General. Alignment. 7.7.2 40 7.8 Multi-dimensional arrays. 40 7.9 Partial arrays. .41 7.10 Implicit arrays. 43 Computed variables. .44 8 8.1 General .44 8.2 Elementary data types. .44 8.2.1Value. .45 8.3 .45 Arrays.. 8.4 Multi-dimensional arrays 45 9 Syntactic flow control .46 9.1 General. 9.2 Conditionals. .46 9.3 Loops 49 Annex A (informative) SDL user guide .53 Bibliography .57 @ IS0/IEC 2025 - All rights reserved iv IS0/IEC 14496-34:2025(en) Foreword ISO (the International Organization for Standardization) and IEC (the International Electrotechnical Commission) form the specialized system for worldwide standardization. National bodies that are members of IsO or IEC participate in the development of International Standards through technical committees established by the respective organization to deal with particular fields of technical activity. IsO and IEC technical committees collaborate in fields of mutual interest. Other international organizations, governmental and non-governmental, in liaison with ISO and IEC, also take part in the work. The procedures used to develop this document and those intended for its further maintenance are described in the IsO/EC Directives, Part 1. In particular, the different approval criteria needed