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© ISO/IEC ISO/IEC 13818-2: 1995 (E) MPEG2 Video IS Contents Page1 Purpose 4 2 Application 4 3 Profiles and levels 4 4 The scalable and the non-scalable syntax 4 1 Scope 8 2 Normative references 8 3 Definitions 9 4 Abbreviations and symbols 14 4.1 Arithmetic operators 14 4.2 Logical operators 14 4.3 Relational operators 14 4.4 Bitwise operators 14 4.5 Assignment 15 4.6 Mnemonics 15 4.7 Constants 15 5 Conventions 16 5.1 Method of describing bitstream syntax 16 5.2 Definition of functions 16 5.3 Reserved, forbidden and marker_bit 17 5.4 Arithmetic precision 17
6.1 Structure of coded video data 18 6.2 Video bitstream syntax 28 6.3 Video bitstream semantics 39 7 The video decoding process 58 7.1 Higher syntactic structures 58 7.2 Variable length decoding 58 7.3 Inverse scan 61 7.4 Inverse quantisation 62 7.5 Inverse DCT 66 7.6 Motion compensation 66 7.7 Spatial scalability 79 7.8 SNR scalability 89 7.9 Temporal scalability 94 7.10 Data partitioning 97 7.11 Hybrid scalability 99 8 Profiles and levels 103 8.1 ISO/IEC 11172-2 compatibility 104 8.2 Relationship between defined profiles 104 8.3 Relationship between defined levels 105 8.4 Scalable layers 106 8.5 Parameter values for defined profiles, levels and layers 107 Annex A 111 Annex B 112 B.1 Macroblock addressing 112 B.2 Macroblock type 112 B.3 Macroblock pattern 115 B.4 Motion vectors 116 B.5 DCT coefficients 117 Annex C 127 Annex D 132 D.1 Overview 132 D.2 Video formats 132 D.3 Picture quality 133 D.4 Data rate control 133 D.5 Low delay mode 133 D.6 Random access/channel hopping 133 D.7 Scalability 134 D.8 Compatibility 139 D.9 Differences between this specification and ISO/IEC 11172-2 140 D.10 Complexity 142 D.11 Editing encoded bitstreams 142 D.12 Trick modes 142 D.13 Error resilience 143 D.14 Concatenated sequences 149
E.1 Syntax element restrictions in profiles 150 E.2 Permissible layer combinations 158
Foreword(Foreword to be provided by ISO) Introduction 1 PurposeThis Part of this specification was developed in response to the growing need for a generic coding method of moving pictures and of associated sound for various applications such as digital storage media, television broadcasting and communication. The use of this specification means that motion video can be manipulated as a form of computer data and can be stored on various storage media, transmitted and received over existing and future networks and distributed on existing and future broadcasting channels. 2 ApplicationThe applications of this specification cover, but are not limited to, such areas as listed below: BSS Broadcasting Satellite Service (to the home) CATV Cable TV Distribution on optical networks, copper, etc. CDAD Cable Digital Audio Distribution DSB Digital Sound Broadcasting (terrestrial and satellite broadcasting) DTTB Digital Terrestrial Television Broadcasting EC Electronic Cinema ENG Electronic News Gathering (including SNG, Satellite News Gathering) FSS Fixed Satellite Service (e.g. to head ends) IPC Interpersonal Communications (videoconferencing, videophone, etc.) ISM Interactive Storage Media (optical disks, etc.) NCA News and Current Affairs NDB Networked Database Services (via ATM, etc.) SSM Serial Storage Media (digital VTR, etc.)
3 Profiles and levelsThis specification is intended to be generic in the sense that it serves a wide range of applications, bitrates, resolutions, qualities and services. Applications should cover, among other things, digital storage media, television broadcasting and communications. In the course of creating this specification, various requirements from typical applications have been considered, necessary algorithmic elements have been developed, and they have been integrated into a single syntax. Hence this specification will facilitate the bitstream interchange among different applications. Considering the practicality of implementing the full syntax of this specification, however, a limited number of subsets of the syntax are also stipulated by means of “profile” and “level”. These and other related terms are formally defined in clause 3 of this specification. A “profile” is a defined subset of the entire bitstream syntax that is defined by this specification. Within the bounds imposed by the syntax of a given profile it is still possible to require a very large variation in the performance of encoders and decoders depending upon the values taken by parameters in the bitstream. For instance it is possible to specify frame sizes as large as (approximately) 214 samples wide by 214 lines high. It is currently neither practical nor economic to implement a decoder capable of dealing with all possible frame sizes. In order to deal with this problem “levels” are defined within each profile. A level is a defined set of constraints imposed on parameters in the bitstream. These constraints may be simple limits on numbers. Alternatively they may take the form of constraints on arithmetic combinations of the parameters (e.g. frame width multiplied by frame height multiplied by frame rate). Bitstreams complying with this specification use a common syntax. In order to achieve a subset of the complete syntax flags and parameters are included in the bitstream that signal the presence or otherwise of syntactic elements that occur later in the bitstream. In order to specify constraints on the syntax (and hence define a profile) it is thus only necessary to constrain the values of these flags and parameters that specify the presence of later syntactic elements.
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