1、B CReference numberISO/IEC 13818-3:1998(E)INTERNATIONALSTANDARDISO/IEC13818-3Second edition1998-04-15Information technology Generic codingof moving pictures and associated audioinformation Part 3:AudioTechnologies de linformation Codage gnrique des images animeset des informations sonores associes P
2、artie 3: SonAdopted by INCITS (InterNational Committee for Information Technology Standards) as an American National Standard. Date of ANSI Approval: 4/5/02 Published by American National Standards Institute, 25 West 43rd Street, New York, New York 10036 Copyright 2002 by Information Technology Indu
3、stry Council (ITI). All rights reserved. These materials are subject to copyright claims of International Standardization Organization (ISO), International Electrotechnical Commission (IEC), American National Standards Institute (ANSI), and Information Technology Industry Council (ITI). Not for resa
4、le. No part of this publication may be reproduced in any form, including an electronic retrieval system, without the prior written permission of ITI. All requests pertaining to this standard should be submitted to ITI, 1250 Eye Street NW, Washington, DC 20005. Printed in the United States of America
5、 ISO/IEC 13818-3:1998(E)iiContentsPageSection 1: General. 11.1 Scope. 11.2 Normative references. 1Section 2: Technical elements 22.1 Definitions. 22.2 Symbols and abbreviations 132.3 Method of describing bit stream syntax. 162.4 Requirements for Extension of ISO/IEC 11172-3 to Lower Sampling Frequen
6、cies 182.5 Requirements for Extension of ISO/IEC 11172-3 to Multichannel Audio 242.6 Registration of Copyright Identifiers. 65AnnexesA. Diagrams. 66B. Tables . 69C. The encoding process . 73D. Psychoacoustic models . 84E. Ancillary Data Use 108F. List of patent holders. 110G. Registration Procedure
7、. 112H. Registration Application Form . 114I. Registration Authority 115 ISO/IEC 1998All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or byany means, electronic or mechanical, including photocopying and microfilm, without permissi
8、on in writing from thepublisher.ISO/IEC Copyright Office Case Postale 56 CH1211 Genve 20 SwitzerlandPrinted in Switzerland. ISO/IEC ISO/IEC 13818-3:1998(E)iiiForewordISO (the International Organization for Standardization) and IEC (the International ElectrotechnicalCommission) form the specialized s
9、ystem for worldwide standardization. National bodies that are members ofISO or IEC participate in the development of International Standards through technical committees establishedby the respective organization to deal with particular fields of technical activity. ISO and IEC technicalcommittees co
10、llaborate in fields of mutual interest. Other international organizations, governmental and non-governmental, in liaison with ISO and IEC, also take part in the work.In the field of information technology, ISO and IEC have established a joint technical committee, ISO/IECJTC 1. Draft International St
11、andards adopted by the joint technical committee are circulated to national bodiesfor voting. Publication as an International Standard requires approval by at least 75 % of the national bodiescasting a vote.International Standard ISO/IEC 13818-3 was prepared by Joint Technical Committee ISO/IEC JTC
12、1,Information technology, Subcommittee SC 29, Coding of audio, picture, multimedia and hypermediainformation.This second edition cancels and replaces the first edition (ISO/IEC 13818-3:1995), which has been technicallyrevised.ISO/IEC 13818 consists of the following parts, under the general title Inf
13、ormation technology Generic codingof moving pictures and associated audio information: Part 1: Systems Part 2: Video Part 3: Audio Part 4: Compliance testing Part 5: Software simulation Part 6: Extensions for DSM-CC Part 7: Advanced Audio Coding (AAC) Part 9: Extension for real time interface for sy
14、stems decoders Part 10: Conformance extensions for DSM-CCAnnexes A and B form an integral part of this part of ISO/IEC 13818. Annexes C to I are for information only.ISO/IEC 13818-3:1998(E) ISO/IECivIntroductionISO/IEC 13818 was prepared by SC29/WG11, also known as MPEG (Moving Pictures Expert Group
15、). MPEGwas formed in 1988 to establish a standard for the coded representation of moving pictures and associated audiostored on digital storage media.ISO/IEC 13818 is published in three parts. Part 1 - systems - specifies the system coding layer of the standard. Itdefines a multiplexed structure for
16、 combining audio and video data and means of representing the timinginformation needed to replay synchronised sequences in real-time. Part 2 - video - specifies the codedrepresentation of video data and the decoding process required to reconstruct pictures. Part 3 - audio - specifiesthe coded repres
17、entation of audio data and the decoding process required to decode audio signals.The technical changes in this 2nd edition compared to the first publication of ISO/IEC 13818-3 (1995) are:1. In the first publication, certain combinations of dynamic crosstalk and prediction were not prohibited but not
18、practically implementable. In this 2nd revision, these combinations are explicitly prohibited.2. In the first publication, a low-pass filter was to be applied to the monophonic surround signal in matrixmode 2 (analogue surround mode). This filter is omitted in this edition, greatly simplifying the d
19、ecoder.3. The description of the syntax of the LFE channel was ambiguous. This description has been clarified.Next to these technical changes, many editorial changes have been made, improving readability and clarity.0.1 Extension of ISO/IEC 11172-3 Audio Coding to Lower Sampling FrequenciesIn order
20、to achieve better audio quality at very low bit rates ( 0| x | = 0 when x = 0| x | = x when x 0Sign(x) = 0 when x = 0Sign(x) = 1 when x Greater than.= Greater than or equal to. Shift right with sign extension. Shift left with zero fill.2.2.5 Assignment= Assignment operator.2.2.6 MnemonicsThe followi
21、ng mnemonics are defined to describe the different data types used in the coded bit stream.bslbf Bit string, left bit first, where “left“ is the order in which bit strings are written inISO/IEC 13818. Bit strings are written as a string of 1s and 0s within single quotemarks, e.g. 1000 0001. Blanks w
22、ithin a bit string are for ease of reading and have nosignificance.centre_chan Index of centre channel.centre_limited Variable which indicates whether a subband of the centre is not transmitted. It is usedin the case of Phantom coding of centre channel.ch Channel. If ch has the value 0, the left cha
23、nnel of a stereo signal or the first of twoindependent signals is indicated.dyn_cross dyn_cross means that dynamic crosstalk is used for a certain transmission channel anda certain subband.gr Granule of 3 * 32 subband samples in audio Layer II, 18 * 32 subband samples inaudio Layer III.Lo, Ro Compat
24、ible stereo audio signals.L, C, R, LS, RS Left, centre, right, left surround and right surround audio signals.Lw, Cw, Rw,LSw, RSwWeighted left, centre, right, left surround and right surround audio signals. Theweighting is necessary for two reasons:1) All signals have to be attenuated prior to encod
25、ing to avoid overload whencalculating the compatible stereo signal.2) The matrix equations contain attenuation factors and other processing like phaseshifting.The weighted and processed signals are actually coded, transmitted and denormalisedin the decoder.left_surr_chan Index of left surround chann
26、el.main_data The main_data portion of the bit stream contains the scalefactors, Huffman encodeddata and ancillary information.mlsblimit Maximum used subband in multilingual part of bitstream.mono_surr_chan Index of the mono surround channel. This index is identical to the index of the leftsurround c
27、hannel.msblimit Maximum used subband in multichannel extension part of bitstream.nch Number of channels; equal to 1 for single_channel mode, 2 in other modes.nmch Number of channels in the multichannel extension part.nmlch Number of multilingual channels.ISO/IEC 13818-3:1998(E) ISO/IEC16npred Number
28、 of allowed predictors according to the tables in 2.5.2.15.npredcoeff Number of prediction coefficients used.part2_length The number of main_data bits used for scalefactors.pci index of predictor0, 1, 2.px index of predictor0, 1, , npred-1.right_surr_chan Index of right surround channel.rpchof Remai
29、nder polynomial coefficients, highest order first.sb Subband.sbgr Groups of individual subbands according to subbandgroup table in 2.5.2.15.sblimit The number of the lowest subband for which no bits are allocated.scfsi Scalefactor selection information.switch_point_l Number of scalefactor band (long
30、 block scalefactor band) from which point onwindow switching is used.switch_point_s Number of scalefactor band (short block scalefactor band) from which point onwindow switching is used.T0, T1, T2, T3, T4 Audio transmission channels. The assignment of audio signals to transmissionchannels is determi
31、ned by the dematrixing procedure and the transmission channelallocation information.tc Transmitted channel.uimsbf Unsigned integer, most significant bit first.vlclbf Variable length code, left bit first, where “left“ refers to the order in which the VLCcodes are written.window Number of the actual t
32、ime slot in case of block_type=2, 0 = window = 2(Layer III).The byte order of multi-byte words is most significant byte first.2.2.7 Constantspi 3,14159265358.e 2,71828182845.2.3 Method of describing bit stream syntaxThe bit stream retrieved by the decoder is described in 2.4.1 and 2.5.1. Each data i
33、tem in the bit stream is in boldtype. It is described by its name, its length in bits, and a mnemonic for its type and order of transmission.The action caused by a decoded data element in a bit stream depends on the value of that data element and ondata elements previously decoded. The decoding of t
34、he data elements and the definition of the state variablesused in their decoding are described in 2.4.2, 2.4.3, 2.5.2 and 2.5.3. The following constructs are used to expressthe conditions when data elements are present, and are in normal type:Note this syntax uses the C-code convention that a variab
35、le or expression evaluating to a non-zero value isequivalent to a condition that is true.while ( condition ) data_element. . .If the condition is true, then the group of data elements occurs next in the datastream. This repeats until the condition is not true.ISO/IEC ISO/IEC 13818-3:1998(E)17do data
36、_element. . . while ( condition )The data element always occurs at least once. The data element is repeateduntil the condition is not true.if ( condition) data_element. . .If the condition is true, then the first group of data elements occurs next in thedata stream.else data_element. . .If the condi
37、tion is not true, then the second group of data elements occurs nextin the data stream.for (expr1; expr2; expr3) data_element. . .Expr1 is an expression specifying the initialisation of the loop. Normally itspecifies the initial state of the counter. Expr2 is a condition specifying a test,made befor
38、e each iteration of the loop. The loop terminates when thecondition is not true. Expr3 is an expression that is performed at the end ofeach iteration of the loop, normally it increments a counter.Note that the most common usage of this construct is as follows:for ( i = 0; i n; i+) data_element. . .T
39、he group of data elements occurs n times. Conditional constructs within thegroup of data elements may depend on the value of the loop control variable i,which is set to zero for the first occurrence, incremented to one for the secondoccurrence, and so forth.As noted, the group of data elements may c
40、ontain nested conditional constructs. For compactness, the may beomitted when only one data element follows.data_element data_element is an array of data. The number of data elements is indicatedby the context.data_element n data_element n is the n+1th element of an array of data.data_element mn dat
41、a_element mn is the m+1,n+1 th element of a two-dimensional array ofdata.data_element lmn data_element lmn is the l+1,m+1,n+1 th element of a three-dimensionalarray of data.data_element mn data_element mnis the inclusive range of bits between bit m and bit n in thedata_element.While the syntax is ex
42、pressed in procedural terms, it should not be assumed that 2.4.3 and 2.5.3 implement asatisfactory decoding procedure. In particular, it assumes a correct and error-free input bit stream. Actualdecoders must include a means to look for start codes in order to begin decoding correctly.Definition of b
43、ytealigned functionThe function bytealigned ( ) returns 1 if the current position is on a byte boundary; that is the next bit in the bitstream is the first bit in a byte. Otherwise it returns 0.Definition of nextbits functionThe function nextbits ( ) permits comparison of a bit string with the next
44、bits to be decoded in the bit stream.Definition of next_start_code functionThe next_start_code function removes any zero bit and zero byte stuffing and locates the next start code.ISO/IEC 13818-3:1998(E) ISO/IEC18Syntax No. of bits Mnemonicnext_start_code() while ( !bytealigned() )zero_bit 1 0while
45、( nextbits() != 0000 0000 0000 0000 0000 0001 )zero_byte 8 00000000This function checks whether the current position is bytealigned. If it is not, zero stuffing bits are present. Afterthat any number of zero bytes may be present before the start-code. Therefore start-codes are always bytealignedand
46、may be preceded by any number of zero stuffing bits.2.4 Requirements for Extension of ISO/IEC 11172-3 to Lower Sampling Frequencies2.4.1 Specification of the Coded Audio Bit Stream Syntax2.4.1.1 Audio SequenceSee ISO/IEC 11172-3, 2.4.1.1.2.4.1.2 Audio FrameSee ISO/IEC 11172-3, 2.4.1.2.2.4.1.3 Header
47、See ISO/IEC 11172-3, 2.4.1.3.2.4.1.4 Error CheckSee ISO/IEC 11172-3, 2.4.1.4.2.4.1.5 Audio Data Layer ISee ISO/IEC 11172-3, 2.4.1.5.2.4.1.6 Audio Data Layer IISee ISO/IEC 11172-3, 2.4.1.6.2.4.1.7 Audio Data Layer IIISyntax No. of bits Mnemonicaudio_data()main_data_begin 8 uimsbfif (mode=single_chann
48、el)private_bits 1 bslbfelseprivate_bits 2 bslbffor (ch=0; chnch; ch+) part2_3_lengthch 12 uimsbfISO/IEC ISO/IEC 13818-3:1998(E)19big_valuesch 9 uimsbfglobal_gainch 8 uimsbfscalefac_compressch 9 bslbfwindow_switching_flagch 1 bslbfif (window_switching_flagch=1) block_typech 2 bslbfmixed_block_flagch
49、1 uimsbffor (region=0; region2; region+)table_selectchregion 5 bslbffor (window=0; window3; window+)subblock_gainchwindow 3 uimsbfelse for (region=0; region3; region+)table_selectchregion 5 bslbfregion0_countch 4 bslbfregion1_countch 3 bslbfscalefac_scalech 1 bslbfcount1table_selectch 1 bslbfmain_data ()The main data bit stream is defined below. The main_data field in the audio_data() syntax contains bytes fromthe main data bit strea
