ISO/IEC 14496-3:2001/Amd 3:2005

Information technology — Coding of audio-visual objects — Part 3: Audio — Amendment 3: MPEG-1/2 audio in MPEG-4

Technologies de l'information — Codage des objets audiovisuels — Partie 3: Codage audio — Amendement 3: Audio MPEG-1/2 dans MPEG-4

General Information

• Status: Withdrawn
• Publication Date: 06-Apr-2005
• Withdrawal Date: 06-Apr-2005
• ICS: 35.040 - Information coding
• ICS: 35.040.40 - Coding of audio, video, multimedia and hypermedia information
• Technical Committee: ISO/IEC JTC 1/SC 29 - Coding of audio, picture, multimedia and hypermedia information
• Drafting Committee: ISO/IEC JTC 1/SC 29 - Coding of audio, picture, multimedia and hypermedia information
• Current Stage: 9599 - Withdrawal of International Standard
• Completion Date: 14-Mar-2006

Relations

• Revised: ISO/IEC 14496-3:2005 - Information technology — Coding of audio-visual objects — Part 3: Audio
• Effective Date: 15-Apr-2008

Standards Content (Sample)

INTERNATIONAL ISO/IEC
STANDARD 14496-3
Second edition
2001-12-15
AMENDMENT 3
2005-04-01


Information technology — Coding of
audio-visual objects —
Part 3:
Audio
AMENDMENT 3: MPEG-1/2 Audio in
MPEG-4
Technologies de l'information — Codage des objets audiovisuels —
Partie 3: Codage audio
AMENDEMENT 3: Audio MPEG-1/2 dans MPEG-4




Reference number
ISO/IEC 14496-3:2001/Amd.3:2005(E)
©
ISO/IEC 2005

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ISO/IEC 14496-3:2001/Amd.3:2005(E)
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ii © ISO/IEC 2005 – All rights reserved

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ISO/IEC 14496-3:2001/Amd.3:2005(E)
Foreword
ISO (the International Organization for Standardization) and IEC (the International Electrotechnical
Commission) form the specialized system for worldwide standardization. National bodies that are members of
ISO or IEC participate in the development of International Standards through technical committees
established by the respective organization to deal with particular fields of technical activity. ISO and IEC
technical committees collaborate 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/IEC JTC 1.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of the joint technical committee is to prepare International Standards. Draft International
Standards adopted by the joint technical committee are circulated to national bodies for voting. Publication as
an International Standard requires approval by at least 75 % of the national bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO and IEC shall not be held responsible for identifying any or all such patent rights.
Amendment 3 to ISO/IEC 14496-3:2001 was prepared by Joint Technical Committee ISO/IEC JTC 1,
Information technology, Subcommittee SC 29, Coding of audio, picture, multimedia and hypermedia
information.
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ISO/IEC 14496-3:2001/Amd.3:2005(E)
Information technology — Coding of audio-visual objects —
Part 3:
Audio
AMENDMENT 3: MPEG-1/2 Audio in MPEG-4
In subclause 1.2 (Normative references), add:
ISO/IEC 14496-1, Information technology - Coding of audio-visual objects - Part 1: Systems
ISO/IEC 14496-11, Information technology - Coding of audio-visual objects - Part 11: Scene description and
application engine

In subclause 1.5.1.1 (Audio object type definition), replace the following line in Table 1.1:

(reserved)           30
(reserved)           31

with:

(reserved)           30
(escape)           31
Layer-1           32
Layer-2           33
Layer-3           34
(reserved)           35
-
95


In subclause 1.5.1.1(Audio object type definition), Table 1.1 (Audio Object Type definition), add three tools as
additional columns:
• Layer-1, enter X in row for AOT 32
• Layer-2, enter X in row for AOT 33
• Layer-3, enter X in row for AOT 34
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ISO/IEC 14496-3:2001/Amd.3:2005(E)
Add the following subclauses:

1.5.1.2.26 Layer-1 Audio object type
The Layer-1 object is the counterpart of the audio coding scheme Layer-1 specified in ISO/IEC 11172-3 and
13818-3.
1.5.1.2.27 Layer-2 Audio object type
The Layer-2 object is the counterpart of the audio coding scheme Layer-2 specified in ISO/IEC 11172-3 and
ISO/IEC 13818-3.
1.5.1.2.28 Layer-3 Audio object type
The Layer-3 object is very similar to the audio coding scheme Layer-3 specified in ISO/IEC 11172-3 and
ISO/IEC 13818-3. However, the use of Layer 3 encoded data as defined in ISO/IEC 13818-3 is limited to the
“Lower Sampling Frequencies” case, i.e. the Layer 3 multi-channel syntax defined in ISO/IEC 13818-3 is not
permitted in this scope. Furthermore, additional sampling rates have been specified.

In subclause 1.6.2.1 (AudioSpecificConfig), Table 1.8 (Syntax of AudioSpecificConfig), replace (as often as it
appears):

audioObjectType; 5 bslbf

with:

audioObjectType = GetAudioObjectType();


In subclause 1.6.2.1 (AudioSpecificConfig), Table 1.8 (Syntax of AudioSpecificConfig), replace (as often as it
appears):

extensionAudioObjectType; 5 bslbf

with:

extensionAudioObjectType = GetAudioObjectType();


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ISO/IEC 14496-3:2001/Amd.3:2005(E)
In subclause 1.6.2.1 (AudioSpecificConfig), add below Table 1.8 (Syntax of AudioSpecificConfig):

Table 1.8a – Syntax of GetAudioObjectType()
Syntax No. of bits Mnemonic
GetAudioObjectType()
{
audioObjectType; 5 uimsbf
if (audioObjectType == 31) {
 audioObjectType = 32 + audioObjectTypeExt; 6 uimsbf
}
return audioObjectType;
}


In subclause 1.6.2.1 (AudioSpecificConfig), Table 1.8 (Syntax of AudioSpecificConfig), add above of the data
element epConfig:

 if ( audioObjectType == 32 || audioObjectType == 33 ||
 audioObjectType == 34 )
 MPEG_1_2_SpecificConfig();

Add the following subclause:

1.6.2.1.10 MPEG_1_2_SpecificConfig
Defined in ISO/IEC 14496-3 subpart 9.

In subclause 1.6.2.2.1 (Overview), add the following lines to Table 1.9:

Layer-1 32 ISO/IEC 14496-3 subpart 9
Layer-2 33 ISO/IEC 14496-3 subpart 9
Layer-3 34 ISO/IEC 14496-3 subpart 9

Add after subclause 1.6.3.1 (AudioObjectType):

1.6.3.1a AudioObjectTypeExt
This data element extends the range of audio object types.
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ISO/IEC 14496-3:2001/Amd.3:2005(E)
Create a new subpart, with the following content:
Subpart 9: MPEG-1/2 Audio in MPEG-4

9.1 Scope
The MPEG-1/2 Audio in MPEG-4 subpart of MPEG-4 Audio specifies the usage of MPEG-1/2 Layer-1, 2 or 3
in an MPEG-4 oriented way, i.e. such that signalling and access unit handling on Systems level is identical to
the other MPEG-4 audio object types.
In order to be carried in MPEG-4, the MPEG-1/2 Layer 1, 2 or 3 bitstream frames are re-formatted such that
they become self-contained MPEG-4 access units. This facilitates transport over packet based networks,
random access, and editability. Those self-contained access units, as used in an MPEG-4 Systems compliant
transport or storage format, can be re-converted to MPEG-1/2 compliant bitstreames, and then decoded with
any MPEG-1/2 compliant decoder. Several methods of re-conversion are given in an informative annex.
The MPEG-4 Audio syntax is further extended to allow multi-channel configurations based on
ISO/IEC 11172-3 and ISO/IEC 13818-3 Layer 3. The multi-channel configurations are similar to the
configurations defined for the other multi-channel capable MPEG-4 audio object types. Note that for
MPEG-1/2 Layer 1 and 2 the format is not extended. The multi-channel format for these layers is described in
ISO/IEC 13818-3.
Furthermore, the permitted sampling frequencies for Layer-3 are extended.
Assistance is furthermore provided in the use of decSpecificInfo and accessUnit as to utilize MPEG-1/2 Layer
1, 2 or 3 in the MPEG-4 world by means of the legacy MPEG-4 Systems interface using ObjectTypeIndication
0x69 or 0x6b.
9.2 MPEG_1_2_SpecificConfig
Table 9.1 – MPEG_1_2_SpecificConfig()
Syntax No. of bits Mnemonic
MPEG_1_2_SpecificConfig()
{
extension; 1 bslbf
}

extension shall be zero.
9.3 Channel Mapping
The following rules apply:
• single_channel_element()’s and lfe_element()’s are represented by mono audio frames.
• channel_pair_element()’s are represented by stereo audio frames.
• For Layer-1 and Layer-2, not more than one mono audio frame representing a single_channel_element()
or one stereo audio frame representing a channel_pair_element() is permitted.
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ISO/IEC 14496-3:2001/Amd.3:2005(E)
9.4 Access Unit Format
9.4.1 Layer 1 and 2
One audio frame maps directly to one access unit.
9.4.2 Layer 3
One access unit consists of one or more mp3_channel_elements. An mp3_channel_element equals a Layer 3
audio frame with the following modifications compared to its definition in ISO/IEC 11172-3 or
ISO/IEC 13818-3:
syncword (12 bit) signals the total length in bytes of the mp3_channel_element (consisting of
header, error_check, side info and main data).
main_data_begin (9/8 bit) is either set to the correct value of the corresponding MPEG-1/2 Layer 3
bitstream or to zero.
main_data() is generally stored after the side information.
All other data elements shall be set according to their specification in ISO/IEC 11172-3 or ISO/IEC 13818-3.
All settings in the header shall correspond to the settings in the AudioSpecificConfig().
All mp3_channel_elements belonging to the same timestamp are stored sequentially into one access unit
according to the order given in subpart 1, subclause 1.6.3.4, Table 1.11 (Channel Configuration). An example
of a 5.1 channel configuration is given in Figure 9.1.
mp3_channel_element mp3_channel_element mp3_channel_element mp3_channel_element
center (mono) front (stereo) surround (stereo) LFE (mono)
H SI MD H SI MD H SI MD H SI MD
H: Header, SI: SideInfo, MD: MainData

Figure 9.1 – Access Unit containing mp3_channel_elements for a 5.1 channel configuration
9.5 Sampling rate extension for Layer 3
This subsection provides specifications to allow the usage of Layer 3 with sampling rates not specified in
ISO/IEC 11172-3 or ISO/IEC 13818-3.
The bitstream syntax and description for the extension towards sampling frequencies lower than those
specified in ISO/IEC 13818-3 are in accordance of ISO/IEC 13818-3 (one frame covers 576 samples).
The subsequent subclauses outline the necessary extensions.
9.5.1 Bitrates
Table 9.1 specifies the bitrate depending on the bitrate_index and sampling frequency.
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ISO/IEC 14496-3:2001/Amd.3:2005(E)
Table 9.1 – Bitrate depending on bitrate_index and sampling frequency
bitrate_index bitrate specified (kbit/s)
8, 11.025, 12 kHz 16, 22.05, 24 kHz 32, 44.1, 48 kHz
(see ISO/IEC 13818-3) (see ISO/IEC 1aa72-3)
'0000' free free free
'0001' 8 8 32
'0010' 16 16 40
'0011' 24 24 48
'0100' 32 32 56
'0101' 40 40 64
'0110' 48 48 80
'0111' 56 56 96
'1000' 64 64 112
'1001' forbidden 80 128
'1010' forbidden 96 160
'1011' forbidden 112 192
'1100' forbidden 128 224
'1101' forbidden 144 256
'1110' forbidden 160 320
'1111' forbidden forbidden forbidden

9.5.2 Samping frequency
Depending on the sampling frequency signaled in the AudioSpecificConfig, the data element
sampling_frequency in the header has to be set as specified in Table 9.2.
Table 9.1 – Setting of the data element sampling_frequency depending on the sampling frequency
specified in the AudioSpecificconfig()
sampling_frequency sampling frequency
00 11.025 kHz and multiples thereof
01 12 kHz and multiples thereof
10 8 kHz and multiples thereof
11 reserved

9.5.3 Padding
Padding is necessary with a sampling frequency of 11.025 kHz and multiples thereof.
9.5.4 Scalefactor bands
The subdivision of the spectrum into scalefactor bands is fixed for every block length and sampling frequency
and stored in tables in the coder and decoder. The tables for the sampling frequencies not specified in
ISO/IEC 11172-3:1993 or ISO/IEC 13818-3:1998 are specified in Annex 9.A. In accordance with
ISO/IEC 11172-3 or ISO/IEC 13818-3, the scale factor for frequency lines above the highest line in the tables
is zero, which means that the actual multiplication factor is 1.0.
9.5.5 Intensity stereo mode
Step 3 of the intensity stereo mode decoding (see ISO/IEC 11172-3, subclause 2.4.3.4.9.3) is clarified as
follows:
- if only the uppermost scalefactor band is in intensity stereo mode, then
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ISO/IEC 14496-3:2001/Amd.3:2005(E)
is_ratio(20) = 1 for long blocks
is_ratio(11) = 1 for sho
...