1、B CReference numberISO/IEC 13818-4:1998/Amd.1:1999(E)INTERNATIONALSTANDARDISO/IEC13818-4First edition1998-12-01AMENDMENT 11999-06-15Information technology Generic codingof moving pictures and associated audioinformation Part 4:Conformance testingAMENDMENT 1: Advanced Audio Coding(AAC) conformance te
2、stingTechnologies de linformation Codage gnrique des images animes etdes informations sonores associes Partie 4: Essais de conformitAMENDEMENT 1: Essai de conformit de codage audio avancAdopted by INCITS (InterNational Committee for Information Technology Standards) as an American National Standard.
3、Date of ANSI Approval: 11/1/00Published by American National Standards Institute,25 West 43rd Street, New York, New York 10036Copyright 2002 by Information Technology Industry Council (ITI).All rights reserved.These materials are subject to copyright claims of International Standardization Organizat
4、ion (ISO), InternationalElectrotechnical Commission (IEC), American National Standards Institute (ANSI), and Information Technology Industry Council(ITI). Not for resale. No part of this publication may be reproduced in any form, including an electronic retrieval system, withoutthe prior written per
5、mission 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 AmericaISO/IEC 13818-4:1998/Amd.1:1999(E) ISO/IEC 1999All rights reserved. Unless otherwise specified, no part of this publication may be repro
6、duced orutilized in any form or by any means, electronic or mechanical, including photocopying and micro-film, without permission in writing from the publisher.ISO/IEC Copyright Office Case postale 56 CH-1211 Genve 20 SwitzerlandPrinted in SwitzerlandiiForewordISO (the International Organization for
7、 Standardization) and IEC (the InternationalElectrotechnical Commission) form the specialized system for worldwide standardiz-ation. National bodies that are members of ISO or IEC participate in the developmentof International Standards through technical committees established by the respectiveorgan
8、ization to deal with particular fields of technical activity. ISO and IEC technicalcommittees collaborate in fields of mutual interest. Other international organizations,governmental and non-governmental, in liaison with ISO and IEC, also take part in thework.In the field of information technology,
9、ISO and IEC have established a joint technicalcommittee, ISO/IEC JTC 1. Draft International Standards adopted by the jointtechnical committee are circulated to national bodies for voting. Publication as anInternational Standard requires approval by at least 75 % of the national bodies castinga vote.
10、Amendment 1 to ISO/IEC 13818-4:1998 was prepared by Joint TechnicalCommittee ISO/IEC JTC 1, Information technology, Subcommittee SC 29, Coding ofaudio, picture, multimedia and hypermedia information. ISO/IEC ISO/IEC 13818-4:1998/Amd.1:1999(E)1Information technology Generic coding of moving pictures
11、andassociated audio information Part 4: Conformance testingAMENDMENT 1Advanced Audio Coding (AAC) conformance testing1) Add the following reference to subclause 1.2 Normative References:ITU-R Document TG10-2/3- E only, “ Basic Audio Quality Requirements for Digital Audio Bit-Rate Reduction Systems f
12、orBroadcast Emission and Primary Distribution“, 28 October 1991.2) Replace the following definitions in subclause 2.1 with the following:2.1.142 low frequency enhancement (LFE) channel: A limited bandwidth channel for low frequency audio effects in amultichannel system.2.1.151 modified discrete cosi
13、ne transform (MDCT): A transform which has the property of time domain aliasingcancellation. An analytical expression for the MDCT can be found in B 2.3.1.2.2.1.258 variable length code (VLC): A code word assigned by variable length encoder (see variable length coding).2.1.259 variable length decode
14、r (VLD): A procedure to obtain the symbols encoded with a variable length coding technique.3) Add the following definitions in subclause 2.1 as indicated:2.1.145.1 main audio channels: All single_channel_elements (see 3.2.1) or channel_pair_elements (see 3.2.1) in oneprogram.2.1.193.1 program AAC: A
15、 set of main audio channels, coupling_channel_elements (see 3.2.1), lfe_channel_elements (see3.2.1), and associated data streams intended to be decoded and played back simultaneously. A program may be defined bydefault (see 3.5.1) or specifically by a program_configuration_element (see 3.2.1). A giv
16、en single_channel_element (see 3.2.1),channel_pair_element (see 3.2.1), coupling_channel_element, lfe_channel_element or data channel may accompany one ormore programs in any given bitstream.2.1.214.1 Sampling Frequency (Fs): Defines the rate in Hertz which is used to digitize an audio signal during
17、 the samplingprocess.2.1.230.1 spectral coefficients: Discrete frequency domain data output from the analysis filterbank.2.1.259.1 variable length encoder: A procedure to assign variable length codewords to symbols.4) Add the following Arithmetic Operator in subclause 2.2.1 following the operatorSig
18、n(x) = -1 when x Profile ISO/IEC 13818-7 AAC Decoder, where A is replaced by the number of main audio channels, L by thenumber of LFE channels, I by the number of independent coupling channels, D by the number of dependently switchedcoupling channels, and Profile Name by the actual profile name (Mai
19、n, Low-Complexity, or Scaleable Sampling Rate). Anexample would be a 5.1.1.1 Channel Main Profile ISO/IEC 13818-7 AAC Decoder, indicating a decoder capable of decoding 5main audio channels, one LFE channel, one independent coupling channel, and one dependent coupling channel, with each ofthe channel
20、s using the profile specified. This can be abbreviated as M.5.1.1.1. Similarly, a Low Complexity decoder can bespecified by a leading “L“, and an SSR profile by an “S“.A conforming decoder must support a minimum capability in terms of the number of main audio channels, LFE channels,independent coupl
21、ing channels, and dependent coupling channels as specified below:Table 2-8 Minimum Decoder Capability for 1, 2, 3, 4, 5, and 7 Main Audio Channels vs. ProfileNumber of Main Audio Channels Main ProfileCapabilityLow ComplexityProfile CapabilitySSR ProfileCapability1 1.0.0.0 1.0.0.0 1.0.0.02 2.0.0.0 2.
22、0.0.0 2.0.0.03 3.0.1.0 3.0.0.1 3.0.0.04 4.0.1.0 4.0.0.1 4.0.0.05 5.1.1.1 5.1.0.1 5.1.0.07 7.1.1.2 7.1.0.2 7.1.0.0Note that a decoder may support more than the number of channel elements specified in the table above and still be aconformant decoder. Thus, M.5.1.1.1, M.5.1.1.2, L.5.1.1.1,and S.5.1.0.0
23、 are all conformant 5 channel configurations. However,M.5.1.0.0, L.5.1.0.0, and S.5.0.0.0 are not conformant 5 channel configurations.2.6.4.2 Decoder ModificationsA conforming decoder may also support any of the following modifications of some parameters in audio bitstreams:Bitstream Characteristic
24、Normative Clause Variationsampling rate 3 a decoder may support only a subset of possiblesampling rates, decoder manufacturers must specifythe rates which are supportedprofile 2.1 a decoder may support additional channel elementsbeyond the minimums listed for its profileprogram configuration 3.5 a d
25、ecoder is only required to decode one program of amulti-program bitstreamdata_stream_element 3.6 a decoder is not required to store or present datarecovered from data_stream_elementsmono-mixdown element 3.3.8 a decoder is not required to present audio from themono-mixdown elementISO/IEC 13818-4:1998
26、/Amd.1:1999(E) ISO/IEC4stereo-mixdown element 3.3.8 a decoder is not required to present audio from thestereo-mixdown elementmatrix-mixdown 3.3.8 a decoder is not required to calculate a matrix-mixdown signal2.6.4.3 Decoder Buffer RequirementsRefer to 3.2.2 of ISO/IEC 13818-7.2.6.5 Procedure to Test
27、 Bitstream ConformanceEach bitstream shall meet the syntactic and semantic requirements specified in ISO/IEC 13818-7. This subclause describes a setof semantic tests to be performed on bitstreams. The procedure to verify whether the syntax is correct is straight forward andtherefore not defined in t
28、his subclause. In the description of the semantic tests it is assumed that the tested bitstream contains noerrors due to transmission or other causes. For each test the condition or conditions that must be satisfied are given, as well asthe prerequisites or conditions in which the test can be applie
29、d. Note that the application of these tests requires parsing of thebitstream to the appropriate levels, which in some cases goes as far as the spectral_data recovery.2.6.5.1 Parsing an ADIF headeradif_id: shall be encoded with the value 0x41444946, the ASCII representation of the string ADIF“.2.6.5.
30、2 Parsing ADTS headers2.6.5.2.1 adts_fixed_headersyncword: shall be encoded with the binary value 1111 1111 1111.ID: shall not be encoded with the value 0.layer: shall be encoded with the binary value 00.profile: shall not be encoded with the binary value 11.sampling_frequency_index: shall be encode
31、d with a value no greater than 0xb.2.6.5.2.2 adts_variable_headerframe_length: shall be encoded with the length of the frame, including headers and error check (if present)2.6.5.3 Decoding of raw data blocksid_syn_ele: if a program configuration element (PCE) is present, it must be the first syntact
32、ic element in a raw_data_block,indicated by id_syn_ele encoded with a value of ID_PCEelement_instance_tag: ensure that element_instance_tag numbers within each element type are unique within each frame. Thisrestriction does not apply to data_stream_elements (DSE), which may have duplicated element_i
33、nstance_tags.2.6.5.4 Decoding an individual_channel_streamics_reserved_bit: must be set to zeromax_sfb: must be = num_swb_long or num_swb_short as appropriate for window_sequence and sampling frequency2.6.5.5 Noiseless Codingsect_cbgi: shall not be encoded with the binary values 1100 or 1101.Intensi
34、ty codebooks INTENSITY_HCB and INTENSITY_HCB2 shall not occur in a single_channel_element, the left channelof a channel pair element, a coupling channel element, or an LFE. Intensity codebooks can only occur in achannel_pair_element if the common_window field is set to 1. ISO/IEC ISO/IEC 13818-4:199
35、8/Amd.1:1999(E)5sect_len_incr: the sum of all sect_len_incr elements for a given window group shall equal max_sfb.hcod_sf : shall only be encoded with the values listed in the scalefactor Huffman table, Table A.1.hcodsect_cbgiwxyz: shall only be encoded with the values listed in Huffman codebooks 1,
36、 2, 3, or 4.hcodsect_cbgiyz: shall only be encoded with the values listed in Huffman codebooks 5 thru 11.hcod_esc_y: shall be encoded with a value no larger than 8191, i.e., it shall be encoded with an initial escape sequenceconsisting of no more than nine 1 bits followed by an escape separator of 0
37、.hcod_esc_z: shall be encoded with a value no larger than 8191, i.e., it shall be encoded with an initial escape sequenceconsisting of no more than nine 1 bits followed by an escape separator of 0.pulse_data_present: shall be encoded with a value of 0 when window_sequence is EIGHT_SHORT_SEQUENCE.pul
38、se_start_sfb: shall be smaller than num_swb_long_windowfs_index.pulse_offseti: swb_offset_long_windowpulse_start_sfb + pulse_offset0 + . + pulse_offsetnumber_pulse must be nogreater than 1023.pulse_ampi: shall be encoded with a value small enough such that the compensated quantized spectral coeffici
39、ent is nogreater than 8191.2.6.5.6 Scalefactorshcod_sf : shall only be encoded with the values listed in the scalefactor Huffman table, Table A.1.2.6.5.7 Joint Coding2.6.5.7.1 MS Stereoms_mask_present: shall not be encoded with the binary value 11.2.6.5.7.2 Intensity Stereohcod_sf : shall only be en
40、coded with the values listed in the scalefactor Huffman table, Table A.1.Intensity codebooks INTENSITY_HCB and INTENSITY_HCB2 shall not occur in a single_channel_element, the left channelof a channel pair element, a coupling channel element, or an LFE. Intensity codebooks can only occur in achannel_
41、pair_element if the common_window field is set to 1.2.6.5.8 Coupling ChannelThe number of dependently-switched and independently-switched coupling channel elements must not exceed the allowednumbers specified by the profile naming convention (see 0, Decoder Characteristics).ind_sw_cce_flag: shall no
42、t be encoded with the binary value of 1 if independently-switched coupling channel elements are notspecified by the profile naming convention (see 0, Decoder Characteristics).num_coupled_elements: shall not be encoded with a value greater than the total number of single_channel_elements andchannel_p
43、air_elements.cc_target_is_cpe: shall be encoded with the binary value 1 if the syntactic element with element_instance_tag ofcc_target_tag_select is a channel_pair_element; otherwise, it shall be encoded with the binary value of 0.cc_target_tag_select: shall only be encoded with a binary value equal
44、 to the element_instance_tag of asingle_channel_element or a channel_pair_element of the current frame.2.6.5.9 Predictionpredictor_data_present: shall not be encoded with the binary value of 1 for low-complexity or SSR profiles.predictor_reset: shall be encoded with the binary value of 1 for at leas
45、t one out of every eight consecutive frames for programsin which predictor_data_present is 1.predictor_reset_group_number: shall not be encoded with the binary values 00000 or 11111; every valid value shall occuronce within a consecutive series of 30 occurrences of pred_reset_group_number.ISO/IEC 13
46、818-4:1998/Amd.1:1999(E) ISO/IEC62.6.5.10 Temporal Noise Shapinglengthwfilt: must be small enough such that the lower bound of the filtered region, indicated by bottom, does not exceedthe start of the array containing the spectral coefficients (specw)orderwfilt: must not exceed the maximum permitted
47、 order depending on the specified profile (see 2.1.1 of ISO/IEC13818-7)2.6.5.11 Filterbank and Block Switchingwindow_sequence: The meaningful window_sequence transitions are as follows:from ONLY_LONG_SEQUENCE to LONG_START_SEQUENCEONLY_LONG_SEQUENCEfrom LONG_START_SEQUENCE to LONG_STOP_SEQUENCEEIGHT
48、_SHORT_SEQUENCEfrom LONG_STOP_SEQUENCE to LONG_START_SEQUENCEONLY_ LONG_SEQUENCEfrom EIGHT_SHORT_SEQUENCE to LONG_STOP_SEQUENCEEIGHT_SHORT_SEQUENCEOther, non-meaningful, window_sequence transitions are also possible:from ONLY_LONG_SEQUENCE to LONG_STOP_SEQUENCEEIGHT_SHORT_SEQUENCEfrom LONG_START_SEQ
49、UENCE to LONG_START_SEQUENCEONLY_ LONG_SEQUENCEfrom LONG_STOP_SEQUENCE to LONG_STOP_SEQUENCEEIGHT_SHORT_SEQUENCEfrom EIGHT_SHORT_SEQUENCE to LONG_START_SEQUENCEONLY_LONG_SEQUENCEA conformant bitstream must consist of only meaningful window_sequence transitions. However, decoders are required tohandle non-meaningful window_sequence transitions as well. Test bitstreams L3 and S17 are provided respectively for Main,Low-Complexity, and Scaleable Sampling Rate profiles to test deco
