ISO/IEC 14496-34:2025

Information technology — Coding of audio-visual objects — Part 34: Syntactic description language

This document specifies a syntactic description language for describing the structure of binary data. It covers the representation of an SDL specification in plain text, the syntax of the SDL and the semantic rules of the SDL. In scenarios where the usage or interpretation of the SDL are ambiguous or undefined, this document attempts to specify whether such a scenario is considered an invalid SDL specification or will result in undefined behaviour. NOTE While the SDL borrows from and contains some aspects of a general-purpose programming language, it is not intended, nor is it suitable, to be used for such a purpose. This is reflected in the fact that many concepts related to general-purpose programming languages are not addressed in this document. Examples of concepts considered irrelevant to the SDL and therefore not addressed in this document include storage of an SDL specification in a file, compilation, execution, input/output, execution environment and machine architecture.

Technologies de l'information — Codage des objets audiovisuels — Partie 34: Langage de description syntaxique

General Information

• Status: Published
• Publication Date: 12-May-2025
• ICS: 35.040.40 - Coding of audio, video, multimedia and hypermedia information
• Technical Committee: ISO/IEC JTC 1/SC 29 - Coding of audio, picture, multimedia and hypermedia information
• Drafting Committee: ISO/IEC JTC 1/SC 29 - Coding of audio, picture, multimedia and hypermedia information
• Current Stage: 6060 - International Standard published
• Start Date: 13-May-2025
• Due Date: 02-Sep-2025
• Completion Date: 13-May-2025

Standards Content (Sample)

International
Standard
ISO/IEC 14496-34
First edition
Information technology — Coding of
2025-05
audio-visual objects —
Part 34:
Syntactic description language
Technologies de l'information — Codage des objets
audiovisuels —
Partie 34: Langage de description syntaxique
Reference number
© ISO/IEC 2025
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© ISO/IEC 2025 – All rights reserved
ii
Contents Page
Foreword .v
Introduction .vi
1 Scope . 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 . 4
5.1 Character set .4
5.2 Whitespace .5
5.3 Case sensitivity .5
5.4 Comments .5
5.5 Identifiers .5
5.6 Punctuators .6
5.7 Keywords.6
5.8 Operators .7
5.8.1 List of operators .7
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
5.11 Built-in operators .10
5.12 Numbers . 12
5.12.1 Endianness . . 12
5.12.2 Representation of numbers . 12
5.12.3 Number limits . 12
5.12.4 Value coercion . 12
5.13 Logic values . 13
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
5.18 String literal values .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
6 Elementary data types . 19
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 Length .21
6.2.4 Value .21
6.2.5 Constants .21
6.2.6 Look-ahead . 22
6.2.7 Legacy . 22
6.2.8 Reserved . 23
6.3 Variable length direct representation bit fields . 23

© ISO/IEC 2025 – All rights reserved
iii
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
7 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 General .31
7.4.2 Polymorphism for abstract classes . 33
7.5 Expandable classes . 33
7.6 Parameter types .
...