ETSI TS 103 190-2 V1.2.1 (2018-02) TECHNICAL SPECIFICATION Digital Audio Compression (AC-4) Standard; Part 2: Immersive and personalized audio 2 ETSI TS 103 190-2 V1.2.1 (2018-02) Reference RTS/JTC-043-2 Keywords audio, broadcasting, codec, content, digital, distribution, object audio, personalization 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 The present document can be downloaded from: http://www.etsi.org/standards-search The present document may be made available in electronic versions and/or in print. The content of any electronic and/or print versions of the present document shall not be modified without the prior written authorization of ETSI. 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ETSI 3 ETSI TS 103 190-2 V1.2.1 (2018-02) Contents Intellectual Property Rights .............................................................................................................................. 17 Foreword ........................................................................................................................................................... 17 Modal verbs terminology .................................................................................................................................. 17 Introduction ...................................................................................................................................................... 18 Motivation ......................................................................................................................................................................... 18 Structure of the present document ..................................................................................................................................... 18 1 Scope ...................................................................................................................................................... 19 2 References .............................................................................................................................................. 19 2.1 Normative references ....................................................................................................................................... 19 2.2 Informative references ...................................................................................................................................... 19 3 Definitions, symbols, abbreviations and conventions ............................................................................ 20 3.1 Definitions ........................................................................................................................................................ 20 3.2 Symbols ............................................................................................................................................................ 25 3.3 Abbreviations ................................................................................................................................................... 25 3.4 Conventions ...................................................................................................................................................... 26 4 Decoding the AC-4 bitstream ................................................................................................................. 28 4.1 Introduction ...................................................................................................................................................... 28 4.2 Channels and objects ........................................................................................................................................ 28 4.3 Immersive audio ............................................................................................................................................... 29 4.4 Personalized Audio........................................................................................................................................... 29 4.5 AC-4 bitstream ................................................................................................................................................. 30 4.5.1 Bitstream structure ...................................................................................................................................... 30 4.5.2 Data dependencies ...................................................................................................................................... 32 4.5.3 Frame rates.................................................................................................................................................. 33 4.6 Decoder compatibilities .................................................................................................................................... 33 4.7 Decoding modes ............................................................................................................................................... 34 4.7.1 Introduction................................................................................................................................................. 34 4.7.2 Full decoding mode .................................................................................................................................... 34 4.7.3 Core decoding mode ................................................................................................................................... 34 4.8 Decoding process ............................................................................................................................................. 35 4.8.1 Overview .................................................................................................................................................... 35 4.8.2 Selecting an audio presentation .................................................................................................................. 36 4.8.3 Decoding of substreams .............................................................................................................................. 36 4.8.3.1 Introduction ........................................................................................................................................... 36 4.8.3.2 Identification of substream type ............................................................................................................ 37 4.8.3.3 Substream decoding overview .............................................................................................................. 39 4.8.3.4 Decoding of object properties ............................................................................................................... 40 4.8.3.4.1 Introduction ..................................................................................................................................... 40 4.8.3.4.2 Object audio metadata location ....................................................................................................... 40 4.8.3.5 Spectral frontends ................................................................................................................................. 41 4.8.3.6 Stereo and multichannel processing (SMP) .......................................................................................... 42 4.8.3.7 Inverse modified discrete cosine transformation (IMDCT) .................................................................. 42 4.8.3.8 Simple coupling (S-CPL) ...................................................................................................................... 42 4.8.3.9 QMF analysis ........................................................................................................................................ 42 4.8.3.10 Companding .........................................................................................................................................