ISO/IEC 14496-3:2005/Amd 2:2006

Information technology — Coding of audio-visual objects — Part 3: Audio — Amendment 2: Audio Lossless Coding (ALS), new audio profiles and BSAC extensions

Technologies de l'information — Codage des objets audiovisuels — Partie 3: Codage audio — Amendement 2: Codage audio sans perte (ALS), nouveaux profils audio et extensions BSAC

General Information

• Status: Withdrawn
• Publication Date: 19-Mar-2006
• Withdrawal Date: 19-Mar-2006
• 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: 26-Aug-2009

Relations

• Amends: ISO/IEC 14496-3:2005 - Information technology — Coding of audio-visual objects — Part 3: Audio
• Effective Date: 06-Jun-2022
• Revised: ISO/IEC 14496-3:2009 - Information technology — Coding of audio-visual objects — Part 3: Audio
• Effective Date: 23-May-2009
• Child: 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
Third edition
2005-12-01
AMENDMENT 2
2006-03-15


Information technology — Coding of
audio-visual objects —
Part 3:
Audio
AMENDMENT 2: Audio Lossless Coding
(ALS), new audio profiles and BSAC
extensions
Technologies de l'information — Codage des objets audiovisuels —
Partie 3: Codage audio
AMENDEMENT 2: Codage audio sans perte (ALS), nouveaux profils
audio et extensions BSAC




Reference number
ISO/IEC 14496-3:2005/Amd.2:2006(E)
©
ISO/IEC 2006

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ISO/IEC 14496-3:2005/Amd.2:2006(E)
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ii © ISO/IEC 2006 – All rights reserved

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ISO/IEC 14496-3:2005/Amd.2:2006(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 2 to ISO/IEC 14496-3:2005 was prepared by Joint Technical Committee ISO/IEC JTC 1,
Information technology, Subcommittee SC 29, Coding of audio, picture, multimedia and hypermedia
information.
This amendment specifies the Audio Lossless Coding (ALS) scheme. The amendment further defines a new
profile, the High Efficiency AAC v2 Profile, that incorporates all the features of the High Efficiency AAC Profile
and in addition the Parametric Stereo tool. The amendment also specifies the way in which the audio object
type ER BSAC is extended to support multi-channel format, providing backward compatibility.

© ISO/IEC 2006 – All rights reserved iii

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ISO/IEC 14496-3:2005/Amd.2:2006(E)

Information technology — Coding of audio-visual objects —
Part 3:
Audio
AMENDMENT 2: Audio Lossless Coding (ALS), new audio profiles
and BSAC extensions
In the Introduction, at the end of subclause "Lossless Audio Coding Tools", add:
MPEG-4 ALS (Audio Lossless Coding) provides lossless coding of digital audio signals. Input signals can be
integer PCM data with 8 to 32-bit word length or 32-bit IEEE floating-point data. Up to 65536 channels are
supported.

In Part 3: Audio, Subpart 1, in subclause 1.3 Terms and Definitions, add:
ALS: Audio Lossless Coding

and increase the index-number of subsequent entries.

© ISO/IEC 2006 – All rights reserved 1

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ISO/IEC 14496-3:2005/Amd.2:2006(E)
In Part 3: Audio, Subpart 1, in subclause 1.5.1.1 Audio object type definition, replace table 1.1 with the table
below:
Table 1.1 — Audio Object Type definition based on Tools/Modules
Audio Object
Type
0 Null
1 AAC main X X X X X X X X X  X           2)
2 AAC LC X X X X X X X X  X
3 AAC SSR X X X  X X X X X X  X
4 AAC LTP X X X X X X X X X  X           2)
5 SBR                X
6 AAC Scalable X X X X X X X X X X X X           6)
7 TwinVQ  X X X X X  X   X
8 CELP            X
9 HVXC             X
10 (reserved)
11 (reserved)
12 TTSI                X
13 Main              X X X     3)
synthetic
14 Wavetable              X X     4)
synthesis
15 General MIDI               X
16 Algorithmic              X
Synthesis and
Audio FX
17 ER AAC LC X X X X X X X  X X X X
18 (reserved)
19 ER AAC LTP X X X X X X X X  X X X X         5)
20 ER AAC X X X X X X X X X X X X X X         6)
scalable
21 ER TwinVQ X X X X   X   X X X
22 ER BSAC X X X X X X X   X X X
23 ER AAC LD  X X X X X X X  X X X X
24 ER CELP           X X X X
25 ER HVXC           X X X X
26 ER HILN           X X    X
27 ER           X X X X  X
Parametric
28 SSC                  X X
29 PS                X   X
30 (reserved)
31 (escape)
32 Layer-1                 X
33 Layer-2                 X
34 Layer-3                  X
35 DST                   X
36 ALS                    X
37 - (reserved)
95

In Part 3: Audio, Subpart 1, in subclause 1.5.1.2 Description, add:
1.5.1.2.30 ALS object type
The ALS object type is the counterpart of the Audio Lossless Coding (ALS) scheme and contains the
corresponding ALS tools.
2 © ISO/IEC 2006 – All rights reserved

Object Type ID
gain control
block switching
window shapes - standard
window shapes – AAC LD
filterbank - standard
filterbank - SSR
TNS
LTP
intensity
coupling
frequency deomain prediction
PNS
MS
SIAQ
FSS
upsampling filter tool
quantisation&coding - AAC
quantisation&coding – TwinVQ
quantisation&coding - BSAC
AAC ER Tools
ER payload syntax
EP Tool 1)
CELP
Silence Compression
HVXC
HVXC 4kbit/s VR
SA tools
SASBF
MIDI
HILN
TTSI
SBR
Layer-1
Layer-2
Layer-3
SSC (Transient, Sinusoid, Noise)
Parametric stereo
DST
ALS
Remark

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ISO/IEC 14496-3:2005/Amd.2:2006(E)
In Part 3: Audio, Subpart 1, replace Table 1.3 (Audio Profiles definition) with the following table:
Table 1.3 – Audio Profiles definition

Mobile
High High
High Low
AAC
Main Scalable Speech Syntheti Natural Audio
Object Audio Object Quality Delay Efficiency Efficiency
Profile
Audio Audio Audio c Audio Audio Internet-
Type ID Type Audio Audio AAC AAC v2
Profile Profile Profile Profile Profile working
Profile Profile Profile Profile
Profile
0 Null
1 AAC main X   X
2 AAC LC X X  X X X X X
3 AAC SSR X   X
4 AAC LTP X X  X X
5 SBR     X X
6 AAC Scalable X X  X X
7 TwinVQ X X   X
8 CELP X X X X X X
9 HVXC X X X  X X
10 (reserved)
11 (reserved)
12 TTSI X X X X X X
13 Main X  X
synthetic
14 Wavetable
synthesis
15 General MIDI
16 Algorithmic
Synthesis and
Audio FX
17 ER AAC LC   X X X
18 (reserved)
19 ER AAC LTP   X X
20 ER AAC   X X X
Scalable
21 ER TwinVQ    X X
22 ER BSAC    X X
23 ER AAC LD   X X X
24 ER CELP   X X X
25 ER HVXC   X X
26 ER HILN    X
27 ER    X
Parametric
28 SSC
29 PS      X
30 (reserved)
31 (escape)
32 Layer-1
33 Layer-2
34 Layer-3
35 DST
36 ALS

In Part 3: Audio, Subpart 1, subclause 1.5.2.3 (Levels within the profiles), add at the end:
• Levels for the High Efficiency AAC v2 Profile
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ISO/IEC 14496-3:2005/Amd.2:2006(E)
Table 1.11A - Levels for the High Efficiency AAC v2 Profile
Level Max. Max. AAC
Max. AAC Max. SBR Max. PCU Max. RCU Max. PCU Max. RCU
channels/ sampling sampling sampling rate HQ / LP HQ / LP
object rate, SBR not rate, SBR [kHz] (in/out) SBR SBR
present [kHz] present [kHz] (Note 5) (Note 5)
1 NA NA NA NA NA NA NA NA
2 2 48 24 24/48 (Note 9 10 9 10
1)
3 2 48 24/48 (Note 48/48 (Note 15 10 15 10
3) 2)
4 5 48 24/48 (Note 48/48 (Note 25 28 20 23
4) 2)
5 5 96 48 48/96 49 28 39 23
Note 1: A level 2 HE AAC v2 Profile decoder implements the baseline version of the parametric stereo tool.
Higher level decoders shall not be limited to the baseline version of the parametric stereo tool.
Note 2: For level 3 and level 4 decoders, it is mandatory to operate the SBR tool in downsampled mode if the
sampling rate of the AAC core is higher than 24kHz. Hence, if the SBR tool operates on a 48kHz AAC signal,
the internal sampling rate of the SBR tool will be 96kHz, however, the output signal will be downsampled by
the SBR tool to 48kHz.
Note 3: If Parametric Stereo data is present the maximum AAC sampling rate is 24kHz, if Parametric Stereo
data is not present the maximum AAC sampling rate is 48kHz.
Note 4: For one or two channels the maximum AAC sampling rate, with SBR present, is 48kHz. For more
than two channels the maximum AAC sampling rate, with SBR present, is 24kHz.
Note 5: The PCU/RCU number are given for a decoder operating the LP SBR tool whenever applicable.

A HE AAC v2 Profile decoder of a certain level shall operate the HQ SBR tool for streams containing
Parametric Stereo data. For streams not containing Parametric Stereo data, the HE AAC v2 Profile decoder
may operate the HQ SBR tool, or the LP SBR tool.

In Part 3: Audio, Subpart 1, subclause 1.5.2.4 (Table 1.12 - audioProfileLevelIndication Values), replace the
row:
0x30-0x7F reserved for ISO use -

with:
0x28 AAC Profile L1
0x29 AAC Profile L2
0x2A AAC Profile L4
0x2B AAC Profile L5
0x2C High Efficiency AAC Profile L2
0x2D High Efficiency AAC Profile L3
0x2E High Efficiency AAC Profile L4
0x2F High Efficiency AAC Profile L5
0x30 High Efficiency AAC v2 Profile L2
0x31 High Efficiency AAC v2 Profile L3
0x32 High Efficiency AAC v2 Profile L4
0x33 High Efficiency AAC v2 Profile L5
0x34-0x7F reserved for ISO use -

4 © ISO/IEC 2006 – All rights reserved

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ISO/IEC 14496-3:2005/Amd.2:2006(E)
In Part 3: Audio, Subpart 1, in subclause 1.6.2.1 AudioSpecificConfig, replace table 1.13 with the table below:
Table 1.13 — Syntax of AudioSpecificConfig()
Syntax No. of bits Mnemonic
AudioSpecificConfig ()
{
audioObjectType = GetAudioObjectType();
samplingFrequencyIndex; 4 bslbf
if ( samplingFrequencyIndex == 0xf ) {
 samplingFrequency; 24 uimsbf
}
channelConfiguration; 4 bslbf

sbrPresentFlag = -1;
psPresentFlag = -1;
if ( audioObjectType == 5 ||
 audioObjectType == 29) {
 extensionAudioObjectType = 5;
 sbrPresentFlag = 1;
 if ( audioObjectType == 29 ) {
  psPresentFlag = 1;
 }
 extensionSamplingFrequencyIndex; 4 uimsbf
 if ( extensionSamplingFrequencyIndex == 0xf ) {
  extensionSamplingFrequency; 24 uimsbf
 }
 audioObjectType = GetAudioObjectType();
}
else {
 extensionAudioObjectType = 0;
}
switch (audioObjectType) {
case 1:
case 2:
case 3:
case 4:
case 6:
case 7:
case 17:
case 19:
case 20:
case 21:
case 22:
case 23:
 GASpecificConfig();
 break:
case 8:
 CelpSpecificConfig();
 break;
case 9:
 HvxcSpecificConfig();
 break:
case 12:
 TTSSpecificConfig();

 break;

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ISO/IEC 14496-3:2005/Amd.2:2006(E)
case 13:

case 14:
case 15:
case 16:
 StructuredAudioSpecificConfig();

 break;

case 24:

 ErrorResilientCelpSpecificConfig();
 break;
case 25:
 ErrorResilientHvxcSpecificConfig();
 break;
case 26:
case 27:
 ParametricSpecificConfig();
 break;
case 28:
 SSCSpecificConfig();
 break;
case 32:
case 33:
case 34:
 MPEG_1_2_SpecificConfig();
 break;
case 35:
 DSTSpecificConfig();
 break;
case 36:
 ALSSpecificConfig();
 break;
default:

 /* reserved */

}
switch (audioObjectType) {
case 17:
case 19:
case 20:
case 21:
case 22:
case 23:
case 24:
case 25:
case 26:
case 27:
 epConfig; 2 bslbf
 if ( epConfig == 2 || epConfig == 3 ) {
  ErrorProtectionSpecificConfig();
 }
 if ( epConfig == 3 ) {
  directMapping; 1 bslbf
  if ( ! directMapping ) {
  /* tbd */
  }
 }
}
if ( extensionAudioObjectType != 5 && bits_to_decode() >= 16 ) {
 syncExtensionType; 11 bslbf
 if (syncExtensionType == 0x2b7) {
 extensionAudioObjectType = GetAudioObjectType();
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ISO/IEC 14496-3:2005/Amd.2:2006(E)
  if ( extensionAudioObjectType == 5 ) {
  sbrPresentFlag; 1 uimsbf
  if (sbrPresentFlag == 1) {
   extensionSamplingFrequencyIndex; 4 uimsbf
   if ( extensionSamplingFrequencyIndex == 0xf ) {
   extensionSamplingFrequency; 24 uimsbf
   }
   if ( bits_to_decode() >= 12 ) {

   syncExtensionType; 11 bslbf
   if (syncExtensionType == 0x548) {

    psPresentFlag; 1 uimsbf
   }
   }
  }
  }
 }
}
}


In Part 3: Audio, Subpart 1, in subclause 1.6.2.1 AudioSpecificConfig, add:
1.6.2.1.12 ALSSpecificConfig
Defined in ISO/IEC 14496-3 subpart 11.

In Part 3: Audio, Subpart 1, in subclause 1.6.2.2.1 Overview, replace table 1.15 by the following table:
Table 1.15 – Audio Object Types
Audio Object Type Object definition of elementary stream Mapping of audio payloads to
Type ID payloads and detailed syntax access units and elementary
streams
AAC MAIN 1 ISO/IEC 14496-3 subpart 4 see subclause 1.6.2.2.2.1.2
AAC LC 2 ISO/IEC 14496-3 subpart 4 see subclause 1.6.2.2.2.1.2
AAC SSR 3 ISO/IEC 14496-3 subpart 4 see subclause 1.6.2.2.2.1.2
AAC LTP 4 ISO/IEC 14496-3 subpart 4 see subclause 1.6.2.2.2.1.2
SBR 5 ISO/IEC 14496-3 subpart 4
AAC scalable 6 ISO/IEC 14496-3 subpart 4 see subclause 1.6.2.2.2.1.3
TwinVQ 7 ISO/IEC 14496-3 subpart 4
CELP 8 ISO/IEC 14496-3 subpart 3
HVXC 9 ISO/IEC 14496-3 subpart 2
TTSI 12 ISO/IEC 14496-3 subpart 6
Main synthetic 13 ISO/IEC 14496-3 subpart 5
Wavetable synthesis 14 ISO/IEC 14496-3 subpart 5
General MIDI 15 ISO/IEC 14496-3 subpart 5
Algorithmic Synthesis 16 ISO/IEC 14496-3 subpart 5
and Audio FX
ER AAC LC 17 ISO/IEC 14496-3 subpart 4 see subclause 1.6.2.2.2.1.4
ER AAC LTP 19 ISO/IEC 14496-3 subpart 4 see subclause 1.6.2.2.2.1.4
ER AAC scalable 20 ISO/IEC 14496-3 subpart 4 see subclause 1.6.2.2.2.1.4
ER Twin VQ 21 ISO/IEC 14496-3 subpart 4
ER BSAC 22 ISO/IEC 14496-3 subpart 4
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ISO/IEC 14496-3:2005/Amd.2:2006(E)
ER AAC LD 23 ISO/IEC 14496-3 subpart 4 see subclause 1.6.2.2.2.1.4
ER CELP 24 ISO/IEC 14496-3 subpart 3
ER HVXC 25 ISO/IEC 14496-3 subpart 2
ER HILN 26 ISO/IEC 14496-3 subpart 7
ER Parametric 27 ISO/IEC 14496-3 subpart 2 and 7
SSC 28 ISO/IEC 14496-3 subpart 8
PS 29 ISO/IEC 14496-3 subpart 8
(reserved) 30
(escape) 31
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
DST 35 ISO/IEC 14496-3 subpart 10
ALS 36 ISO/IEC 14496-3 subpart 11


In Part 3: Audio, Subpart 1, under 1.6.3 Semantics, after 1.6.3.13 extensionAudioObjectType add:
1.6.3.14 psPresentFlag
A one bit field indicating the presence or absence of Parametric Stereo data. The value –1 indicates that the
psPresentFlag was not conveyed in the AudioSpecificConfig(). In this case, a High Efficiency AAC v2 Profile
decoder shall support implicit signaling (see subclause 1.6.6).

In Part 3: Audio, Subpart 1, after 1.6.5 Signaling of SBR, add the following subclause:
1.6.6 Signaling of Parametric Stereo (PS)
1.6.6.1 Generating and Signaling HE AAC + PS Content
The PS tool in combination with the HE AAC coder enables good stereo quality at very low bitrates. At the
same time it allows for compatibility with existing HE AAC-only decoders. However, the output from a HE AAC
decoder will only be mono for a HE AAC v2 stream carrying PS data.
Therefore, depending on the application, a content provider or content creator may want to choose between
the two alternatives given below. In general, the PS data is always embedded in the HE AAC stream in a HE
AAC compatible way (in the sbr_extension element), and PS is a pure post processing step in the decoder.
Therefore, compatibility can be achieved. However, by means of different signaling the content creator can
select between the full-quality mode and the backward compatibility mode as outlined in 1.6.6.1.1 and
1.6.6.1.2.
For the hierarchical profiles, a profile higher in the profile hierarchy is of course able to decode the content of a
profile lower in the profile hierarchy. In Figure 1.0A the hierarchical structure of the AAC, HE AAC and HE
AAC v2 Profile is displayed. The figure shows that a HE AAC Profile decoder is fully capable of decoding any
AAC-Profile stream, given that the HE AAC Profile decoder is of the same or a higher level as indicated in the
AAC Profile stream. Similarly the HE AAC v2 decoder can handle all HE AAC Profile streams as well as all
AAC Profile streams.
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ISO/IEC 14496-3:2005/Amd.2:2006(E)
AAC SBR PS
AAC Profile
High Efficiency AAC Profile
High Efficiency AAC v2 Profile

Figure 1.0A – Hierarchical structure of AAC, HE AAC and HE AAC v2 Profile,
and compatibility between them.

1.6.6.1.1 Ensuring Full Audio Quality of AAC+SBR+PS for the Listener
To ensure that listeners get the full audio quality of AAC+SBR+PS, the stream should indicate the HE AAC v2
Profile and use the explicit, hierarchical signaling (signaling 2.A. as described below), so that it is played by
HE AAC v2 Profile decoders, i.e., PS capable decoders. With regard to HE AAC-only streams or AAC-only
streams, an HE AAC v2 Profile decoder will decode all HE AAC Profile streams and AAC Profile streams of
the appropriate level, as the HE AAC v2 Profile is a superset of the HE AAC Profile and the AAC Profile.
1.6.6.1.2 Achieving Backward Compatibility with Existing HE AAC and AAC Decoders
The aim of this mode is to get all AAC-based and HE AAC-based decoders to play the stream, even if they do
not support the PS tool. Compatible streams can be created using the following two signaling methods:
a) indicate a profile containing SBR (e.g. the HE AAC Profile), but not the HE AAC v2 Profile, and use
the explicit backward compatible signalling (2.B. as described below). This method is recommended
for all MPEG-4 based systems in which the length of the AudioSpecificConfig() is known in the
decoder. As this is not the case for LATM with audioMuxVersion==0 (see clause 1.7), this method
cannot be used for LATM with audioMuxVersion==0. In explicit backward compatible signaling, PS-
specific configuration data is added at the end of the AudioSpecificConfig(). Decoders that do not
know about PS will ignore these parts, while HE AAC v2 Profile decoders will detect its presence and
configure the decoder accordingly.
b) indicate a profile containing SBR (e.g. the HE AAC Profile), but not the HE AAC v2 Profile, and use
implicit signalling. In this mode, there is no explicit indication of the presence of PS data. Instead, HE
AAC v2 Profile decoders shall open two output channels for a stream containing SBR data with
channelConfiguration==1, i.e., a mono stream using a single channel element, and check the
presence of PS data while decoding the stream and use the PS tool if PS data is found. This is
possible because PS can be decoded without PS-specific configuration data if a certain way of
handling decoder number of output channels is obeyed, as described below for HE AAC v2 Profile
decoders.
Both methods lead to the result that, provided that the profile indication indicates a profile supported by the
decoder, the AAC+SBR part of an AAC+SBR+PS streams will be decoded by HE AAC-only decoders, and the
AAC part of an AAC+SBR+PS stream will be decoded by AAC-only decoders. HE AAC v2 decoders will
detect the presence of PS and decode the full quality AAC+SBR+PS stream.
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ISO/IEC 14496-3:2005/Amd.2:2006(E)
1.6.6.2 Implicit and Explicit Signaling of Parametric Stereo
This subclause outlines the different signaling methods of PS, and the decoder behavior for different types of
signaling.
There are several ways to signal the presence of PS data:
1. implicit signaling: If bs_extension_id equals EXTENSION_ID_PS, PS data is present in the
sbr_extension element, and this implicitly signals the presence of PS data. The ability to detect and
decode implicitly signaled PS is mandatory for all High Efficiency AAC v2 Profile (HE AAC v2 Profile)
decoders.
2. explicit signaling: The presence of PS data is signaled explicitly by means of the PS Audio Object
Type and the psPresentFlag in the AudioSpecificConfig(). When explicit signaling of PS is used,
implicit signaling of PS shall not occur. Two different types of explicit signaling are available:
2.A. hierarchical signaling: If the first audioObjectType (AOT) signaled is the PS AOT, the
extensionAudioObjectType is set to SBR, and a second audio object type is signaled which indicates
the underlying audio object type. This signaling method is not backward compatible. This method
may be needed in systems that do not convey the length of the AudioSpecificConfig(), such as LATM
with audioMuxVersion==0, and content authors are encouraged to use it only when thus needed.
2.B. backward compatible signaling: If the extensionAudioObjectType SBR is signaled at the end of
the AudioSpecificConfig(), a psPresentFlag is transmitted at the end of the backward compatible
explicit SBR signaling, indicating the presence or absence of PS data. This method shall only be
used in systems that convey the length of the AudioSpecificConfig(). Hence, it shall not be used for
LATM with audioMuxVersion==0.
For all types of parametric stereo signaling, the channelConfiguration in the audioSpecifcConfig indicates the
number of channels of the underlying AAC coded stream. Hence, if parametric stereo data is available, the
channelConfiguration will be one, indicating a single channel element, while the parametric stereo tool will
produce two output channels based on the single channel element and the parametric stereo data.
Table 1.22A shows the decoder behavior depending on profile and audio object type indication when implicit
or explicit signaling is used.
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ISO/IEC 14496-3:2005/Amd.2:2006(E)
Table 1.22A – PS Signaling and Corresponding Decoder Behavior
Bitstream characteristics Decoder behavior
Profile PS signaling psPresent raw_data_block HE AAC HE AAC v2
indication Flag Profile Profile
Decoders Decoders
High signaling 1, implicit -1 AAC+SBR Play AAC+SBR Play AAC+SBR
Efficiency signaling (Note 1)
AAC Profile (first AOT != PS)
AAC+SBR+PS Play AAC+SBR Play at least
AAC+SBR,
should play
AAC+SBR+PS
(Note 1)
signaling 2.B, 0 AAC+SBR Play AAC+SBR Play AAC+SBR
backwards (Note 2)
compatible explicit
1 AAC+SBR+PS Play AAC+SBR Play at least
signaling
AAC+SBR,
(second AOT ==
should play
SBR)
AAC+SBR+PS
(Note 3)
High signaling 2.A, non- 1 AAC+SBR+PS Undefined Play
Efficiency backwards AAC+SBR+PS
AAC v2 compatible (Note 3)
Profile signaling
(first AOT == PS)
signaling 2.B, 1 AAC+SBR+PS Undefined Play
backwards AAC+SBR+PS
compatible signling (Note 3)
(second AOT ==
SBR)
Note 1: Implicit signaling, assume the presence of PS data in the payload, giving two output channels
for a single channel element.
Note 2: Explicitly signals that there is no PS data, hence no implicit signaling is present.
Note 3: Number of output channels is two for a single channel element containing AAC+SBR+PS
data.

The upper part of Table 1.22A displays bitstream characteristics and decoder behavior if the profile indication
is the High Efficiency AAC Profile. The lower part displays bitstream characteristics and decoder behavior if
the profile indication is the High Efficiency AAC v2 Profile.
1.6.6.3 HE AAC v2 Profile Decoder Behavior in Case of Implicit Signaling
If the presence of PS data is backward compatible implicitly signaled (signaling 1, in the list above) the first
AudioObjectType signaled is not the PS AOT, and the psPresentFlag is not read from the
AudioSpecificConfig(). Hence, the psPresentFlag is set to –1, indicating that implicit signaling of parametric
stereo may occur.
Since a received mono stream will result in a stereo output if Parametric Stereo data is present in the stream,
the HE AAC v2 Profile decoder shall assume that PS data is available and decide the number of output
channels to be two for a single channel element containing SBR data, and thus also possibly PS data. If no
PS data is found the mono output shall be mapped to the two opened channels for every single channel
element.
© ISO/IEC 2006 – All rights reserved 11

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ISO/IEC 14496-3:2005/Amd.2:2006(E)
1.6.6.4 HE AAC v2 Profile Decoder Behavior in Case of Explicit Signaling
If the presence of PS data is explicitly signaled (signaling 2, in the list above) the presence of PS data is
backward compatible explicitly signaled (signaling 2.B) or non-backward compatible explicitly signaled
(signaling 2.A).
For the backward compatible explicit signaled (signaling 2.B) the extensionAudioObjectType signaled is the
SBR AOT. The explicit signaling of PS is done by means of the psPresentFlag that can be either zero or one.
If the psPresentFlag is zero, this indicates that PS data is not present, and hence the HE AAC v2 Profile
decoder should not make assumptions on the number of output channels in anticipation of PS data (as in case
of implicit signaling of PS) and instead employ the original channelConfiguration. If the psPresentFlag is one,
PS data is present and the HE AAC v2 Profile decoder shall operate the PS Tool.
For the non-backward compatible explicit signaling of PS (signaling 2.A) the first AudioObjectType signaled is
the PS AOT. The extensionAudioObjectType is assigned the SBR AOT. For this hierarchical explicit signaling,
the psPresentFlag is set to one if the first signaled AOT is the PS AOT. The psPresentFlag is not transmitted
and hence it is not possible to explicitly signal the absence of implicit signaling. Hence, for the hierarchical
explicit signaling of parametric stereo, PS data is always present and the HE AAC v2 Profile decoder shall
operate the PS Tool.

In Part 3: Audio, Subpart 4, in subclause 4.4.2.6 Payloads for the audio object type ER BSAC, replace table
4.33 bsac_raw_data_block with the following table:
Table 4.33 – Syntax of bsac_raw_data_block()
No. of bits Mnemonic
• Syntax
bsac_raw_data_block()
{
 bsac_base_element();

layer=slayer_size;
while(data_available() && layer<(top_layer+slayer_size)) {
    bsac_layer_element(layer);

 layer++;
}
byte_alignment();


   if (data_available())
...