1、 ETSI TS 102 366 V1.3.1 (2014-08) Digital Audio Compression (AC-3, Enhanced AC-3) Standard TECHNICAL SPECIFICATION ETSI ETSI TS 102 366 V1.3.1 (2014-08)2Reference RTS/JTC-026 Keywords audio, broadcasting, coding, digital ETSI 650 Route des Lucioles F-06921 Sophia Antipolis Cedex - FRANCE Tel.: +33 4
2、 92 94 42 00 Fax: +33 4 93 65 47 16 Siret N 348 623 562 00017 - NAF 742 C Association but non lucratif enregistre la Sous-Prfecture de Grasse (06) N 7803/88 Important notice The present document can be downloaded from: http:/www.etsi.org The present document may be made available in electronic versi
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7、munications Standards Institute 2014. European Broadcasting Union 2014. All rights reserved. DECTTM, PLUGTESTSTM, UMTSTMand the ETSI logo are Trade Marks of ETSI registered for the benefit of its Members. 3GPPTM and LTE are Trade Marks of ETSI registered for the benefit of its Members and of the 3GP
8、P Organizational Partners. GSM and the GSM logo are Trade Marks registered and owned by the GSM Association. ETSI ETSI TS 102 366 V1.3.1 (2014-08)3Contents Intellectual Property Rights 15g3Foreword . 15g3Modal verbs terminology 15g3Introduction 15g31 Scope 19g32 References 19g32.1 Normative referenc
9、es . 19g32.2 Informative references 19g33 Definitions and abbreviations . 20g33.1 Definitions 20g33.2 Abbreviations . 21g34 Bit stream syntax 24g34.1 Synchronization frame . 24g34.2 Semantics of syntax specification. 25g34.3 Syntax specification . 25g34.3.1 syncinfo - Synchronization information . 2
10、5g34.3.2 bsi - Bit stream information 26g34.3.3 audblk - Audio block 27g34.3.4 auxdata - Auxiliary data 30g34.3.5 errorcheck - Error detection code . 30g34.4 Description of bit stream elements . 30g34.4.1 syncinfo - Synchronization information . 30g34.4.1.1 syncword - Synchronization word - 16 bits
11、. 30g34.4.1.2 crc1 - Cyclic redundancy check 1 bit to 16 bits 30g34.4.1.3 fscod - Sample rate code - 2 bits . 30g34.4.1.4 frmsizecod - Frame size code - 6 bits 31g34.4.2 bsi - Bit stream information 31g34.4.2.1 bsid - Bit stream identification - 5 bits 31g34.4.2.2 bsmod - Bit stream mode - 3 bits 31
12、g34.4.2.3 acmod - Audio coding mode - 3 bits . 31g34.4.2.4 cmixlev - Centre mix level - 2 bits 32g34.4.2.5 surmixlev - Surround mix level - 2 bits . 32g34.4.2.6 dsurmod - DolbySurround mode - 2 bits . 32g34.4.2.7 lfeon - Low frequency effects channel on - 1 bit . 33g34.4.2.8 dialnorm - Dialogue norm
13、alization - 5 bits . 33g34.4.2.9 compre - Compression gain word exists - 1 bit . 33g34.4.2.10 compr - Compression gain word - 8 bits . 33g34.4.2.11 langcode - Language code exists - 1 bit 33g34.4.2.12 langcod - Language code - 8 bits 33g34.4.2.13 audprodie - Audio production information exists - 1 b
14、it . 33g34.4.2.14 mixlevel - Mixing level - 5 bits . 33g34.4.2.15 roomtyp - Room type - 2 bits 34g34.4.2.16 dialnorm2 - Dialogue normalization, Ch2 - 5 bits . 34g34.4.2.17 compr2e - Compression gain word exists, Ch2 - 1 bit 34g34.4.2.18 compr2 - Compression gain word, Ch2 - 8 bits. 34g34.4.2.19 lang
15、cod2e - Language code exists, Ch2 - 1 bit 34g34.4.2.20 langcod2 - Language code, Ch2 - 8 bits 34g34.4.2.21 audprodi2e - Audio production information exists, Ch2 - 1 bit 34g34.4.2.22 mixlevel2 - Mixing level, Ch2 - 5 bits 34g34.4.2.23 roomtyp2 - Room type, Ch2 - 2 bits 34g34.4.2.24 copyrightb - Copyr
16、ight bit - 1 bit 34g34.4.2.25 origbs - Original bit stream - 1 bit . 35g3ETSI ETSI TS 102 366 V1.3.1 (2014-08)44.4.2.26 timecod1e, timecod2e - Time code (first and second) halves exists - 2 bits . 35g34.4.2.27 timecod1 - Time code first half - 14 bits . 35g34.4.2.28 timecod2 - Time code second half
17、- 14 bits 35g34.4.2.29 addbsie - Additional bit stream information exists - 1 bit . 35g34.4.2.30 addbsil - Additional bit stream information length - 6 bits . 35g34.4.2.31 addbsi - Additional bit stream information - (addbsil + 1) x 8) bits 35g34.4.3 audblk - Audio block 35g34.4.3.1 blkswch - Block
18、switch flag - 1 bit . 35g34.4.3.2 dithflagch - Dither flag - 1 bit . 36g34.4.3.3 dynrnge - Dynamic range gain word exists - 1 bit 36g34.4.3.4 dynrng - Dynamic range gain word - 8 bits . 36g34.4.3.5 dynrng2e - Dynamic range gain word exists, Ch2 - 1 bit 36g34.4.3.6 dynrng2 - dynamic range gain word,
19、Ch2 - 8 bits . 36g34.4.3.7 cplstre - Coupling strategy exists - 1 bit 36g34.4.3.8 cplinu - Coupling in use - 1 bit 36g34.4.3.9 chincplch - Channel in coupling - 1 bit 36g34.4.3.10 phsflginu - Phase flags in use - 1 bit . 36g34.4.3.11 cplbegf - Coupling begin frequency code - 4 bits . 36g34.4.3.12 cp
20、lendf - Coupling end frequency code - 4 bits 37g34.4.3.13 cplbndstrcsbnd - Coupling band structure - 1 bit 37g34.4.3.14 cplcoech - Coupling coordinates exist - 1 bit . 37g34.4.3.15 mstrcplcoch - Master coupling coordinate - 2 bits . 37g34.4.3.16 cplcoexpchbnd - Coupling coordinate exponent - 4 bits
21、38g34.4.3.17 cplcomantchbnd - Coupling coordinate mantissa - 4 bits 38g34.4.3.18 phsflgbnd - Phase flag - 1 bit 38g34.4.3.19 rematstr - Rematrixing strategy - 1 bit 38g34.4.3.20 rematflgrbnd - Rematrix flag - 1 bit . 38g34.4.3.21 cplexpstr - Coupling exponent strategy - 2 bits . 38g34.4.3.22 chexpst
22、rch - Channel exponent strategy - 2 bits . 38g34.4.3.23 lfeexpstr - Low frequency effects channel exponent strategy - 1 bit . 38g34.4.3.24 chbwcodch - Channel bandwidth code - 6 bits . 39g34.4.3.25 cplabsexp - Coupling absolute exponent - 4 bits . 39g34.4.3.26 cplexpsgrp - Coupling exponents - 7 bit
23、s . 39g34.4.3.27 expschgrp - Channel exponents - 4 bits or 7 bits . 39g34.4.3.28 gainrngch - Channel gain range code - 2 bits . 39g34.4.3.29 lfeexpsgrp - Low frequency effects channel exponents - 4 bits or 7 bits 39g34.4.3.30 baie - Bit allocation information exists - 1 bit . 39g34.4.3.31 sdcycod -
24、Slow decay code - 2 bits . 39g34.4.3.32 fdcycod - Fast decay code - 2 bits . 39g34.4.3.33 sgaincod - Slow gain code - 2 bits . 39g34.4.3.34 dbpbcod - dB per bit code - 2 bits . 40g34.4.3.35 floorcod - Masking floor code - 3 bits . 40g34.4.3.36 snroffste - SNR offset exists - 1 bit . 40g34.4.3.37 csn
25、roffst - Coarse SNR offset - 6 bits . 40g34.4.3.38 cplfsnroffst - Coupling fine SNR offset - 4 bits 40g34.4.3.39 cplfgaincod - Coupling fast gain code - 3 bits . 40g34.4.3.40 fsnroffstch - Channel fine SNR offset - 4 bits 40g34.4.3.41 fgaincodch - Channel fast gain code - 3 bits . 40g34.4.3.42 lfefs
26、nroffst - Low frequency effects channel fine SNR offset - 4 bits . 40g34.4.3.43 lfefgaincod - Low frequency effects channel fast gain code - 3 bits . 40g34.4.3.44 cplleake - Coupling leak initialization exists - 1 bit 40g34.4.3.45 cplfleak - Coupling fast leak initialization - 3 bits 40g34.4.3.46 cp
27、lsleak - Coupling slow leak initialization - 3 bits 40g34.4.3.47 deltbaie - Delta bit allocation information exists - 1 bit 41g34.4.3.48 cpldeltbae - Coupling delta bit allocation exists - 2 bits 41g34.4.3.49 deltbaech - Delta bit allocation exists - 2 bits . 41g34.4.3.50 cpldeltnseg - Coupling delt
28、a bit allocation number of segments - 3 bits . 41g34.4.3.51 cpldeltoffstseg - Coupling delta bit allocation offset - 5 bits 41g34.4.3.52 cpldeltlenseg - Coupling delta bit allocation length - 4 bits . 41g34.4.3.53 cpldeltbaseg - Coupling delta bit allocation - 3 bits . 41g34.4.3.54 deltnsegch - Chan
29、nel delta bit allocation number of segments - 3 bits . 42g34.4.3.55 deltoffstchseg - Channel delta bit allocation offset - 5 bits 42g3ETSI ETSI TS 102 366 V1.3.1 (2014-08)54.4.3.56 deltlenchseg - Channel delta bit allocation length - 4 bits . 42g34.4.3.57 deltbachseg - Channel delta bit allocation -
30、 3 bits . 42g34.4.3.58 skiple - Skip length exists - 1 bit . 42g34.4.3.59 skipl - Skip length - 9 bits . 42g34.4.3.60 skipfld - Skip field - (skipl x 8) bits 42g34.4.3.61 chmantchbin - Channel mantissas - 0 bits to 16 bits 42g34.4.3.62 cplmantbin - Coupling mantissas - 0 bits to 16 bits 43g34.4.3.63
31、 lfemantbin - Low frequency effects channel mantissas - 0 bits to 16 bits 43g34.4.4 auxdata - Auxiliary data field . 43g34.4.4.1 auxbits - Auxiliary data bits - nauxbits bits . 43g34.4.4.2 auxdatal - Auxiliary data length - 14 bits 44g34.4.4.3 auxdatae - Auxiliary data exists - 1 bit 44g34.4.5 error
32、check - Frame error detection field . 45g34.4.5.1 crcrsv - CRC reserved bit - 1 bit . 45g34.4.5.2 crc2 - Cyclic redundancy check 2 - 16 bits . 45g34.5 Bit stream constraints . 45g35 Decoding the AC-3 bit stream 45g35.1 Introduction 45g35.2 Summary of the decoding process 45g35.2.1 Input bit stream .
33、 45g35.2.1.1 Continuous or burst input 46g35.2.1.2 Byte or word alignment . 46g35.2.2 Synchronization and error detection . 46g35.2.3 Unpack BSI, side information. 47g35.2.4 Decode exponents . 48g35.2.5 Bit allocation . 48g35.2.6 Process mantissas 48g35.2.7 Decoupling 48g35.2.8 Rematrixing 48g35.2.9
34、 Dynamic range compression . 48g35.2.10 Inverse transform 48g35.2.11 Window, overlap/add 49g35.2.12 Downmixing . 49g35.2.13 PCM output buffer 49g35.2.14 Output PCM 49g36 Algorithmic details . 49g36.1 Exponent coding . 49g36.1.1 Overview 49g36.1.2 Exponent strategy . 50g36.1.3 Exponent decoding . 51g
35、36.2 Bit allocation 54g36.2.1 Overview 54g36.2.2 Parametric bit allocation . 54g36.2.2.1 Initialization 55g36.2.2.2 Exponent mapping into psd . 56g36.2.2.3 psd integration . 56g36.2.2.4 Compute excitation function . 56g36.2.2.5 Compute masking curve 58g36.2.2.6 Apply delta bit allocation 58g36.2.2.7
36、 Compute bit allocation 59g36.2.3 Bit allocation tables 60g36.3 Quantization and decoding of mantissas 66g36.3.1 Overview 66g36.3.2 Expansion of mantissas for asymmetric quantization (6 bap 15) . 66g36.3.3 Expansion of mantissas for symmetrical quantization (1 bap 5) 67g36.3.4 Dither for zero bit ma
37、ntissas (bap = 0) . 67g36.3.5 Ungrouping of mantissas 68g36.4 Channel coupling 69g36.4.1 Overview 69g36.4.2 Sub-band structure for coupling 69g3ETSI ETSI TS 102 366 V1.3.1 (2014-08)66.4.3 Coupling coordinate format 70g36.5 Rematrixing 71g36.5.1 Overview 71g36.5.2 Frequency band definitions . 72g36.5
38、.2.1 Coupling not in use . 72g36.5.2.2 Coupling in use, cplbegf 2 . 72g36.5.2.3 Coupling in use, 2 cplbegf 0 . 72g36.5.2.4 Coupling in use, cplbegf = 0 . 73g36.5.3 Encoding technique. 73g36.5.4 Decoding technique 73g36.6 Dialogue normalization 73g36.7 Dynamic range compression 74g36.7.1 Overview 74g
39、36.7.2 Dynamic range control; dynrng, dynrng2 . 75g36.7.2.1 Overview . 75g36.7.2.2 Detailed implementation . 76g36.7.3 Heavy compression; compr, compr2 77g36.7.3.1 Overview . 77g36.7.3.2 Detailed implementation . 77g36.8 Downmixing . 78g36.8.1 General downmix procedure . 78g36.8.2 Downmixing into tw
40、o channels 81g36.9 Transform equations and block switching 82g36.9.1 Overview 82g36.9.2 Technique . 82g36.9.3 Decoder implementation . 83g36.9.4 Transformation equations . 83g36.9.4.1 512-sample IMDCT transform 83g36.9.4.2 256-sample IMDCT transforms 85g36.9.5 Channel gain range code . 87g36.10 Erro
41、r detection 88g36.10.1 CRC checking . 88g36.10.2 Checking bit stream consistency . 89g37 Encoding the AC-3 bit stream 91g37.1 Introduction 91g37.2 Summary of the encoding process 91g37.2.1 Input PCM 91g37.2.1.1 Input word length 91g37.2.1.2 Input sample rate . 91g37.2.1.3 Input filtering 91g37.2.2 T
42、ransient detection 92g37.2.3 Forward transform 93g37.2.3.1 Windowing 93g37.2.3.2 Time to frequency transformation . 94g37.2.4 Coupling strategy 94g37.2.4.1 Basic encoder 94g37.2.4.2 Advanced encoder . 94g37.2.5 Form coupling channel . 94g37.2.5.1 Coupling channel 94g37.2.5.2 Coupling coordinates 94g
43、37.2.6 Rematrixing 95g37.2.7 Extract exponents 95g37.2.8 Exponent strategy . 95g37.2.9 Dither strategy 95g37.2.10 Encode exponents . 95g37.2.11 Normalize mantissas . 95g37.2.12 Core bit allocation . 96g37.2.13 Quantize mantissas . 96g37.2.14 Pack AC-3 syncframe . 96g3Annex A (normative): AC-3 bit st
44、reams in the MPEG-2 multiplex 97g3ETSI ETSI TS 102 366 V1.3.1 (2014-08)7A.1 Introduction 97g3A.2 Detailed specification for System A (ATSC) . 97g3A.2.1 Stream_type 97g3A.2.2 Stream_id . 97g3A.2.3 Registration_descriptor 98g3A.2.4 AC-3 audio_descriptor . 98g3A.2.5 ISO_639_language_code 101g3A.2.6 STD
45、 audio buffer size . 101g3A.3 Specification for System B (DVB) . 102g3A.4 PES constraints . 102g3A.4.1 Encoding. 102g3A.4.2 Decoding 102g3A.4.3 Byte-alignment . 103g3Annex B (informative): Void . 104g3Annex C (informative): AC-3 karaoke mode . 105g3C.1 Introduction 105g3C.2 Detailed specification .
46、105g3C.2.1 Karaoke mode indication 105g3C.2.2 Karaoke mode channel assignment 105g3C.2.3 Reproduction of karaoke mode bit streams 106g3C.2.3.1 Karaoke-aware decoder 106g3C.2.3.2 Karaoke-capable decoders 106g3Annex D (normative): Alternate bit stream syntax . 108g3D.1 Specification . 108g3D.1.1 Indic
47、ation of alternate bit stream syntax . 108g3D.1.2 Alternate bit stream syntax specification 108g3D.1.3 Description of alternate syntax bit stream elements . 109g3D.1.3.1 xbsi1e: Extra bit stream information #1 exists, 1 bit 109g3D.1.3.2 dmixmod: Preferred stereo downmix mode, 2 bits . 109g3D.1.3.3 l
48、trtcmixlev: Lt/Rt centre mix level, 3 bits . 110g3D.1.3.4 ltrtsurmixlev: Lt/Rt surround mix level, 3 bits 110g3D.1.3.5 lorocmixlev: Lo/Ro centre mix level, 3 bits . 110g3D.1.3.6 lorosurmixlev: Lo/Ro surround mix level, 3 bits 111g3D.1.3.7 xbsi2e: Extra bit stream information #2 exists, 1 bit 111g3D.
49、1.3.8 dsurexmod: Dolby Surround EXmode, 2 bits . 111g3D.1.3.9 dheadphonmod: DolbyHeadphone mode, 2 bits . 111g3D.1.3.10 adconvtyp: A/D converter type, 1 bit 112g3D.1.3.11 xbsi2: Extra bit stream information, 8 bits 112g3D.1.3.12 encinfo: Encoder information, 1 bit 112g3D.2 Decoder processing 112g3D.2.1 Compliant decoder processing . 112g3D.2.1.1 Two-channel downmix selection 112g3D.2.1.2 Two-channel downmix processing . 112g3D.2.1.3 Informational parameter processing 113g3D.2.2 Legacy decode
