1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationDigital audio Interface for non-linear PCM encodedaudio bitstreams lying IEC 60958Part 11: MPEG-4 AAC and its extensions in LATM/LOASBS EN 61937-11:2010appNational forewordThis B
2、ritish Standard is the UK implementation of EN 61937-11:2010. It isidentical to IEC 61937-11:2010.The UK participation in its preparation was entrusted to Technical CommitteeEPL/100, Audio, video and multimedia systems and equipment.A list of organizations represented on this committee can be obtain
3、ed onrequest to its secretary.This publication does not purport to include all the necessary provisions of acontract. Users are responsible for its correct application. BSI 2010ISBN 978 0 580 65708 5ICS 33.160.30; 33.170Compliance with a British Standard cannot confer immunity fromlegal obligations.
4、This British Standard was published under the authority of the StandardsPolicy and Strategy Committee on 31 July 2010.Amendments issued since publicationAmd. No. Date Text affectedBRITISH STANDARDBS EN 61937-11:2010EUROPEAN STANDARD EN 61937-11 NORME EUROPENNE EUROPISCHE NORM June 2010 CENELEC Europ
5、ean Committee for Electrotechnical Standardization Comit Europen de Normalisation Electrotechnique Europisches Komitee fr Elektrotechnische Normung Management Centre: Avenue Marnix 17, B - 1000 Brussels 2010 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CEN
6、ELEC members. Ref. No. EN 61937-11:2010 E ICS 33.160.30; 33.170 English version Digital audio - Interface for non-linear PCM encoded audio bitstreams applying IEC 60958 - Part 11: MPEG-4 AAC and its extensions in LATM/LOAS (IEC 61937-11:2010) Audionumrique - Interface pour les flux de bits audio cod
7、age MIC non linaire conformment la CEI 60958 - Partie 11 : MPEG-4 AAC et ses extensions en LATM/LOAS (CEI 61937-11:2010) Digitalton Schnittstelle fr nichtlinear-PCM-codierte Audio-Bitstrme unter Verwendung von IEC 60958 Teil 11: MPEG-4-AAC und dessen Erweiterungen in LATM/LOAS (IEC 61937-11:2010) Th
8、is European Standard was approved by CENELEC on 2010-06-01. CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical re
9、ferences concerning such national standards may be obtained on application to the Central Secretariat or to any CENELEC member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CENELE
10、C member into its own language and notified to the Central Secretariat has the same status as the official versions. CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hu
11、ngary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. BS EN 61937-11:2010EN 61937-11:2010 - 2 - Foreword The text of document 100/1491/CDV, future edition 1 of I
12、EC 661937-11, prepared by IEC TC 100, Audio, video and multimedia systems and equipment, was submitted to the IEC-CENELEC parallel vote and was approved by CENELEC as EN 61937-11 on 2010-06-01. Attention is drawn to the possibility that some of the elements of this document may be the subject of pat
13、ent rights. CEN and CENELEC shall not be held responsible for identifying any or all such patent rights. The following dates were fixed: latest date by which the EN has to be implemented at national level by publication of an identical national standard or by endorsement (dop) 2011-03-01 latest date
14、 by which the national standards conflicting with the EN have to be withdrawn (dow) 2013-06-01 Annex ZA has been added by CENELEC. _ Endorsement notice The text of the International Standard IEC 61937-11:2010 was approved by CENELEC as a European Standard without any modification. In the official ve
15、rsion, for Bibliography, the following notes have to be added for the standards indicated: IEC 61937 series NOTE Harmonized in EN 61937 series (not modified). IEC 61937-6 NOTE Harmonized as EN 61937-6. _ BS EN 61937-11:2010- 3 - EN 61937-11:2010 Annex ZA (normative) Normative references to internati
16、onal publications with their corresponding European publications The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amend
17、ments) applies. NOTE When an international publication has been modified by common modifications, indicated by (mod), the relevant EN/HD applies. Publication Year Title EN/HD Year IEC 60958 Series Digital audio interface EN 60958 Series IEC 61937-1 - Digital audio - Interface for non-linear PCM enco
18、ded audio bitstreams applying IEC 60958 - Part 1: General EN 61937-1 - IEC 61937-2 - Digital audio - Interface for non-linear PCM encoded audio bitstreams applying IEC 60958 - Part 2: Burst-info EN 61937-2 - ISO/IEC 14496-3 2009 Information technology - Coding of audio-visual objects - Part 3: Audio
19、 - - BS EN 61937-11:2010 2 61937-11 IEC:2010(E) CONTENTS INTRODUCTION.5 1 Scope.6 2 Normative references .6 3 Terms, definitions and abbreviations 6 3.1 Terms and definitions 6 3.2 Abbreviations 8 4 Mapping of the audio bit stream on to IEC 61937-1 8 4.1 General .8 4.2 Burst-info for MPEG-4 AAC and
20、its extensions in LATM/LOAS 8 5 Format of data-burst for MPEG-4 AAC and its extensions in LATM/LOAS.9 5.1 General .9 5.2 Pause data-bursts for MPEG-4 AAC and its extensions in LATM/LOAS .9 5.3 Audio data-bursts 10 5.3.1 MPEG-4 AAC and its extensions in LATM/LOAS10 5.3.2 LATM/LOAS framing12 5.3.3 Lat
21、ency .12 Annex A (informative) Calculation of delay and data-burst repetition rates, guidelines .14 Bibliography16 Figure 1 Data-burst structure .10 Figure 2 Latency diagram for burst reception and decoding .13 Table 1 Values for data-type and sub-data-type .9 Table 2 Repetition period of pause data
22、-bursts 9 Table 3 Data-type-dependent information 11 Table A.1 Examples Calculation of delay and data-burst repetition rates.14 BS EN 61937-11:201061937-11 IEC:2010(E) 5 INTRODUCTION Modern digital video broadcasting standards such as DVB include support for the MPEG-4 HE AAC and/or HE AAC v2 audio
23、codecs as specified in ISO/IEC 14496-3. An increasing number of countries are adopting these new codecs for their standard definition and high definition digital video broadcasting services and have started with implementations. For MPEG-2 AAC audio (ISO/IEC 13818-7) the specified framing format for
24、 the audio bit stream is ADTS and its transport over an IEC 60958 interface is specified in IEC 61937-6. However, the MPEG-4 (ISO/IEC 14496-3) audio codecs introduce new features and capabilities that require a framing format that supports more flexible signaling and delivery mechanisms. Therefore,
25、MPEG-2 Systems (ISO/IEC 13818-1) specifies the MPEG-4 LATM/LOAS framing format for MPEG-4 audio codecs to overcome the limitations of ADTS. In order to be able to pass the MPEG-4 audio bit stream from a Set Top Box to an A/V receiver connected via the IEC 60958 interface without needing to reframe t
26、he audio bit stream within ADTS, the MPEG-4 LATM/LOAS framing format needs to be supported by IEC 61937. BS EN 61937-11:2010 6 61937-11 IEC:2010(E) DIGITAL AUDIO INTERFACE FOR NON-LINEAR PCM ENCODED AUDIO BITSTREAMS APPLYING IEC 60958 Part 11: MPEG-4 AAC and its extensions in LATM/LOAS 1 Scope This
27、part of IEC 61937 describes the method to convey non-linear PCM bitstreams encoded according to the MPEG-4 AAC format and its extensions spectral band replication, parametric stereo and MPEG surround, framed in MPEG-4 LATM/LOAS. 2 Normative references The following referenced documents are indispens
28、able for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. IEC 60958 (all parts), Digital audio interface IEC 61937-1, Digital audio Interface for non-linea
29、r PCM encoded audio bitstreams applying IEC 60958 Part 1: General IEC 61937-2, Digital audio Interface for non-linear PCM encoded audio bitstreams applying IEC 60958 Part 2: Burst-info ISO/IEC 14496-3:2009, Information technology Coding of audio-visual objects Part 3: Audio 3 Terms, definitions and
30、abbreviations For the purposes of this document the terms, definitions and abbreviations of IEC 61937-1, IEC 61937-2 and the following apply. 3.1 Terms and definitions 3.1.1 access unit smallest entity to which timing information can be attributed; an access unit is the smallest individually decodab
31、le unit; a decoder consumes access units 3.1.2 AudioMuxElement(1) LATM element that carries payload data for at least one audio elementary stream, related payload length information and multiplex configuration information NOTE This element carries payload data in form of PayloadMux elements. The num
32、ber in brackets indicates multiplexing configuration (StreamMuxConfig) is multiplexed into AudioMuxElements, that is in-band transmission. 3.1.3 AudioSpecificConfig configuration structure used to convey parameters to initialize the MPEG-4 audio decoder BS EN 61937-11:201061937-11 IEC:2010(E) 7 3.1.
33、4 low overhead MPEG-4 audio transport multiplex LATM multiplexing layer defined by ISO/IEC 14496-3; used for multiplexing of audio elementary streams 3.1.5 low overhead audio stream LOAS synchronisation layer defined by ISO/IEC 14496-3; three different formats of LOAS are defined, each of which is d
34、esigned to address the specific characteristics of the underlying transmission layer 3.1.6 MPEG-4 AAC profile contains only the MPEG-4 AAC low complexity audio object type; MPEG-4 AAC low complexity object type is the counterpart to the MPEG-2 AAC low complexity profile; in addition to the MPEG-2 AA
35、C LC profile the MPEG-4 AAC low complexity object type enables the usage of the PNS tool NOTE The MPEG-4 AAC Low Complexity object type is used when there are restrictions on the usage of RAM and processing complexity. 3.1.7 MPEG-4 high efficiency AAC profile contains the spectral band replication o
36、bject type in conjunction with the MPEG-4 AAC low complexity object type NOTE For further information please refer to ISO/IEC 14496-3. The MPEG-4 high efficiency AAC profile is a superset of the MPEG-4 AAC profile. 3.1.8 MPEG-4 high efficiency AAC profile version 2 contains the parametric stereo obj
37、ect type and the spectral band replication object type in conjunction with the AAC low complexity object type NOTE The MPEG-4 high efficiency AAC profile version 2 is a superset of the MPEG-4 high efficiency AAC profile. 3.1.9 MPEG surround technology used for coding of multichannel signals based on
38、 a downmixed signal of the original multichannel signal, and associated spatial parameters NOTE MPEG surround is defined in ISO/IEC 23003-1. 3.1.10 PayloadMux payload data chunk in an AudioMuxElement that contains potentially multiplexed payload data for multiple audio elementary streams; in general
39、 PayloadMux elements can be concatenated inside AudioMuxElements 3.1.11 SpatialSpecificConfig configuration structure used to initialize the MPEG surround decoder 3.1.12 StreamMuxConfig configuration structure that describes the structure of the LATM payload multiplex BS EN 61937-11:2010 8 61937-11
40、IEC:2010(E) 3.1.13 Sub-data-type reference to the type of payload of the data-bursts defined for the use with the specified data-type 3.1.14 modified discrete cosine transformation MDCT transformation schema used by AAC 3.1.15 transformation length (of the AAC codec or core codec) AAC can operate in
41、 two modes using either a 960 lines or 1 024 lines MDCT transformation for long blocks; an MDCT line is a spectral component described by frequency, amplitude and phase 3.2 Abbreviations AAC Advanced Audio Coding AAC LC MPEG-4 AAC Low Complexity HE AAC MPEG-4 High Efficiency AAC and MPEG-4 High Effi
42、ciency AAC Version 2 ADTS Audio Data Transport Stream DVB Digital Video Broadcasting MDCT Modified Discrete Cosine Transformation MPEG Moving Picture Experts Group MPS MPEG Surround PNS Perceptual Noise Substitution PS Parametric Stereo SBR Spectral Band Replication TL AAC Transformation Length 4 Ma
43、pping of the audio bit stream on to IEC 61937-1 4.1 General The coding of the bit stream and data-burst is in accordance with IEC 61937-1 and IEC 61937-2. 4.2 Burst-info for MPEG-4 AAC and its extensions in LATM/LOAS The 16-bit burst-info contains information about the data which will be found in th
44、e data-burst (see Table 1). BS EN 61937-11:201061937-11 IEC:2010(E) 9 Table 1 Values for data-type and sub-data-type Data-type according to IEC 61937-2 Value of Pc bits 04 Sub-data-type Value of Pc bits 56 Contents Reference point R Repetition period of data-bursts in IEC 60958 frames 022 03 Accordi
45、ng to IEC 61937 0 According to IEC 61937-10 Definition specific to IEC 61937-10 1 AAC LC Bit 0 of Pa 960 / 1 024 2 HE AAC Bit 0 of Pa 1 920 / 2 048 23 3 Reserved for future definition of other applications reserved Reserved for future definition of other applications 2431 03 According to IEC 61937 B
46、its 04 of the burst-info (Pc) signal the data-type used for transmission. For MPEG-4 AAC-based audio in LATM/LOAS, the signaled data-type is 23. The Pc bits 56 indicate if the transmitted data stream contains audio encoded in AAC LC or HE AAC (including high efficiency AAC version 2). Only values 1
47、and 2 refer to the transmission of AAC LC or HE AAC based audio. The values 0 and 3 are used for indication of codec types which are described by other or future parts of IEC 61937. 5 Format of data-burst for MPEG-4 AAC and its extensions in LATM/LOAS 5.1 General This clause specifies the data-burst
48、 for MPEG-4 AAC audio and its extensions in LATM/LOAS. Specific properties such as reference points, repetition period, the method of filling stream gaps and decoding latency are specified. The decoding latency (or delay), indicated for the sub-data-types, should be taken into account by the transmi
49、tter to schedule data-bursts as necessary to establish synchronisation between picture and decoded audio. 5.2 Pause data-bursts for MPEG-4 AAC and its extensions in LATM/LOAS Pause data-bursts for MPEG-4 AAC and its extensions in LATM/LOAS are defined in Table 2. Table 2 Repetition period of pause data-bursts Repetition period of pause data-burst Data-type of audio data-burst Mandatory Recommended Sub-data-type for MPEG-4 audio in LATM/LOAS based on
