ISO/IEC 14496-3:2005/Amd 5:2007
(Amendment)Information technology — Coding of audio-visual objects — Part 3: Audio — Amendment 5: BSAC extensions and transport of MPEG Surround
Information technology — Coding of audio-visual objects — Part 3: Audio — Amendment 5: BSAC extensions and transport of MPEG Surround
Technologies de l'information — Codage des objets audiovisuels — Partie 3: Codage audio — Amendement 5: Extensions BSAC et transport d'ambiance MPEG
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Standards Content (Sample)
INTERNATIONAL ISO/IEC
STANDARD 14496-3
Third edition
2005-12-01
AMENDMENT 5
2007-07-15
Information technology — Coding of
audio-visual objects —
Part 3:
Audio
AMENDMENT 5: BSAC extensions and
transport of MPEG Surround
Technologies de l'information — Codage des objets audiovisuels —
Partie 3: Codage audio
AMENDEMENT 5: Extensions BSAC et transport d'ambiance MPEG
Reference number
ISO/IEC 14496-3:2005/Amd.5:2007(E)
©
ISO/IEC 2007
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ISO/IEC 14496-3:2005/Amd.5:2007(E)
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ii © ISO/IEC 2007 – All rights reserved
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ISO/IEC 14496-3:2005/Amd.5:2007(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 5 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 normative syntax of the integration of ER BSAC and the SBR tool and the
corresponding decoding process. An informative encoder description is given in the Annex. Furthermore, this
Amendment specifies the transport and embedding of MPEG Surround (ISO/IEC 23003-1) side information in
MPEG-4 AAC bitstreams and MPEG-4 Audio environments.
© ISO/IEC 2007 – All rights reserved iii
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ISO/IEC 14496-3:2005/Amd.5:2007(E)
Information technology — Coding of audio-visual objects —
Part 3:
Audio
AMENDMENT 5: BSAC extensions and transport of MPEG
Surround
In the following, changes to existing text and Tables are highlighted by gray background.
In the fourth paragraph of subclause 0.3.2.2 General audio coding tools, replace:
It operates at up to 48 kHz sampling rate and uses a frame length of 512 or 480 samples, compared to the
1024 or 960 samples used in standard MPEG-2/4 AAC to enable coding of general audio signals with an
algorithmic delay not exceeding 20 ms.
with:
To enable coding of general audio signals with an algorithmic delay not exceeding 20 ms at 48 kHz, it uses a
frame length of 512 or 480 samples (compared to the 1024 or 960 samples used in standard MPEG-2/4 AAC).
In Part 3: Audio, Subpart 1, in subclause 1.2 Normative references, add:
ISO/IEC 14496-23, Information technology — Coding of audio-visual objects — Part 23: Symbolic Music
Representation
ISO/IEC 23003-1, Information technology — MPEG audio technologies — Part 1: MPEG Surround
In Part 3: Audio, Subpart 1, in subclause 1.3 Terms and definitions, add:
PS: Parametric Stereo
SMR: Symbolic Music Representation
and increase the index-number of subsequent entries.
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ISO/IEC 14496-3:2005/Amd.5:2007(E)
In Part 3: Audio, Subpart 1, in subclause 1.5.1.1 Audio object type definition, amend Table 1.1 with the
updates in the table below:
Tools/
Modules
Audio Object
Type
…
MPEG Surround 30
…
(escape) X 31
…
(reserved) 39
SMR Simple 40
SMR Main 41
...
In Part 3: Audio, Subpart 1, after subclause 1.5.1.2.32 add the following subclauses:
1.5.1.2.33 PS object type
The PS object type contains the PS tool and can be combined with the SBR tool.
1.5.1.2.34 MPEG Surround object type
The MPEG Surround object type conveys MPEG Surround side information (see ISO/IEC 23003-1) in the
MPEG-4 Audio framework.
1.5.1.2.35 SMR Simple object type
The SMR simple object type it is used to transport musical scores to be rendered both audibly and visually.
The encoded data contains information on the main score, the parts (i.e. instrument specific scores), the
possible multilingual lyrics associated with the parts, the visual formatting rules to be used for visual rendering,
fonts to be used for custom musical symbols and synchronization information. The fonts and the
synchronization information are represented as binary data, all the other as XML data. The SMR simple object
type can convey the XML data as plain XML text or as gzip-ped XML (see ISO/IEC 14496-23).
1.5.1.2.36 SMR Main object type
The SMR main object type can transport the musical scores exactly in the same way as the SMR Simple
object type but in this case the XML data can be encoded also using the MPEG-B tools defined in
ISO/IEC 23001-1 (see ISO/IEC 14496-23).
2 © ISO/IEC 2007 – All rights reserved
Remark
Object Type ID
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ISO/IEC 14496-3:2005/Amd.5:2007(E)
In Part 3: Audio, Subpart 1, in subclause 1.5.1.2.6 SBR object type, replace Table 1.2 with the table below:
Table 1.2 — Audio object types that can be combined with SBR
Audio Object Type Object Type ID
AAC main 1
AAC LC 2
AAC SSR 3
AAC LTP 4
AAC Scalable 6
ER AAC LC 17
ER AAC LTP 19
ER AAC scalable 20
ER BSAC 22
In subclause 1.5.2.1, replace Table 1.3 Audio Profiles definition with the table below:
Mobile
High Low High High
AAC
Main Scalable Speech Synthetic Natural Audio
Object Audio Object Quality Delay Efficiency Efficiency
Audio Audio Audio Audio Audio Internet- Profile
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 X* X*
synthesis
15 General MIDI X* X*
16 Algorithmic X* X*
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 MPEG
Surround
31 (escape)
32 Layer-1
33 Layer-2
34 Layer-3
35 DST
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ISO/IEC 14496-3:2005/Amd.5:2007(E)
36 ALS
37 SLS
38 SLS non-core
39 (reserved)
40 SMR Simple
41 SMR Main
*) Subset of Main Synthetic
In subclause 1.6.2.1, extend Table 1.13 — AudioSpecificConfig() as follows:
Table 1.13 — Syntax of AudioSpecificConfig()
Syntax No. of bits Mnemonic
AudioSpecificConfig ()
{
audioObjectType = GetAudioObjectType();
samplingFrequencyIndex; 4 uimsbf
if ( samplingFrequencyIndex==0xf )
samplingFrequency; 24 uimsbf
channelConfiguration; 4 uimsbf
sbrPresentFlag = -1;
psPresentFlag = -1;
if ( audioObjectType == 5 ||
audioObjectType == 29 ) {
extensionAudioObjectType = audioObjectType;
sbrPresentFlag = 1;
if ( audioObjectType == 29 ) {
psPresentFlag = 1;
}
extensionSamplingFrequencyIndex; 4 uimsbf
if ( extensionSamplingFrequencyIndex==0xf )
extensionSamplingFrequency; 24 uimsbf
audioObjectType = GetAudioObjectType();
if ( audioObjectType == 22 )
extensionChannelConfiguration; 4 uimsbf
}
else {
extensionAudioObjectType = 0;
}
switch (audioObjectType) {
…
case 28:
SSCSpecificConfig();
break;
case 30:
sacPayloadEmbedding; 1 uimsbf
SpatialSpecificConfig();
break;
case 32:
case 33:
case 34:
…
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ISO/IEC 14496-3:2005/Amd.5:2007(E)
case 40:
case 41:
SymbolicMusicSpecificConfig()
break;
default:
/* reserved */
}
…
if ( extensionAudioObjectType != 5 &&
bits_to_decode() >= 16 ) {
syncExtensionType; 11 bslbf
if (syncExtensionType == 0x2b7) {
extensionAudioObjectType = GetAudioObjectType();
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
}
}
}
}
if ( extensionAudioObjectType == 22 ) {
sbrPresentFlag; 1 uimsbf
if (sbrPresentFlag == 1) {
extensionSamplingFrequencyIndex; 4 uimsbf
if ( extensionSamplingFrequencyIndex == 0xf )
extensionSamplingFrequency; 24 uimsbf
}
extensionChannelConfiguration; 4 uimsbf
}
}
}
}
After subclause 1.6.2.1.13, add the following new subclauses:
1.6.2.1.14 SpatialSpecificConfig
Defined in ISO/IEC 23003-1:2007, 5.1.
1.6.2.1.15 SymbolicMusicSpecificConfig
1)
Defined in ISO/IEC 14496-23:— , 7.2.1.
1) To be published.
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ISO/IEC 14496-3:2005/Amd.5:2007(E)
In subclause 1.6.2.2.1, extend Table 1.15 — Audio Object Types as follows:
Table 1.15 — Audio Object Types
Object Audio Object definition of elementary stream Mapping of audio payloads to
Type ID Type payloads and detailed syntax access units and elementary
streams
0 NULL
…
29 PS ISO/IEC 14496-3 subpart 8
30 MPEG Surround ISO/IEC 23003-1
31 (escape)
…
39 (reserved)
40 SMR Simple ISO/IEC 14496-23
41 SMR Main ISO/IEC 14496-23
After subclause 1.6.3.15 fillBits, add the following new subclauses:
1.6.3.16 extensionChannelConfiguration
A four bit field indicating the channel configuration of the BSAC extensions. This configuration data is
available in case of explicit signalling for the BSAC extensions. The number of audio output channels is
determined according to Table 1.17 — Channel Configuration.
1.6.3.17 sacPayloadEmbedding
The audio Object Type ID 30 MPEG Surround is used to convey spatial audio coding side information for
MPEG Surround decoding as defined in ISO/IEC 23003-1. Depending on this flag, the MPEG surround data
payload, i.e. SpatialFrame(), is available by different means:
Table 1.19A — sacPayloadEmbedding
sacPayloadEmbedding Meaning
0 One SpatialFrame() is mapped into one access unit.
Subsequent access units form one elementary stream.
That elementary stream will always depend on another
elementary stream that contains the underlying
(downmixed) audio data.
1 The top level payload is multiplexed into the underlying
(downmixed) audio data. The actual multiplexing details
depend on the presentation of the audio data (i.e., usually
on the AOT). Note that this leads to an elementary stream
with no real payload. That elementary stream will always
depend on another elementary stream that contains both,
the underlying (downmixed) audio data and the
multiplexed spatial audio data.
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ISO/IEC 14496-3:2005/Amd.5:2007(E)
In Part 3: Audio, Subpart 1, after 1.6.6 Signaling of Parametric Stereo (PS), add the following new sublcause:
1.6.7 Signalling of BSAC Extension payloads
The implicit signalling method for BSAC extension payloads is similar to that of SBR tool. The BSAC decoder
that can decode the BSAC extension payloads checks if there is an extension type for the SBR tool such as
‘EXT_BSAC_SBR_DATA’ in the bsac_raw_data_block(). The sampling frequency should be updated, when
the extension type is detected and the SBR tool is operated in dual-rate mode.
The BSAC extension decoder checks if there is the extension type for the BSAC channel extension such as
‘EXT_BSAC_CHANNEL’ in the bsac_raw_data_block(). In case where the extension type for multichannel,
the number of channel from the AudioSpecificConfig() for BSAC Audio Object Type is updated depending on
the ‘channel_configu-ration_index’ of each extended_bsac_base_element().
When explicit signalling is used, implicit signalling shall not occur. Two different types of explicit signalling are
available:
1. Explicit Signalling Method 1: hierarchical signalling
If the first audioObjectType (AOT) signalled is the SBR AOT, a second audio object type is
signalled which indicates the ER BSAC AOT. The extensionChannelConfiguration indicates the total
number of channels in the bsac_raw_data_block().
2. Explicit Signalling Method 2 : backward compatible signalling
The extensionAudioObjectType is signalled at the end of the AudioSpecificConfig(). If the
extensionAudioObjectType is the ER BSAC AOT, the extensionChannelConfiguration indicates the
total number of channels in the bsac_raw_data_block(). 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.
Table 1.22B explains the decoder behaviour with SBR and BSAC channel extension signalling.
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ISO/IEC 14496-3:2005/Amd.5:2007(E)
Table 1.22B – SBR and BSAC channel extension signalling and Corresponding Decoder Behaviour
Bitstream characteristics Decoder behaviour
Extension sbrPresentFlag extensionChan raw_data_block BSAC BSAC
AudioObjectType nelConfiguratio decoder Extensions
n decoder
!= ER_BSAC -1 Not available BSAC Play BSAC Play BSAC
( Implicit (Note 1)
BSAC+SBR Play BSAC Play at least
Signalling ) BSAC,
should play
BSAC+SBR
BSAC+MC Play BSAC Play at least
BSAC,
should play
BSAC+MC
BSAC+SBR+MC Play BSAC Play at least
BSAC,
should play
BSAC+SBR
+MC
== ER_BSAC ( 0 == BSAC Play BSAC Play BSAC
Explicit (Note 2) channelConfigu
Signalling ) ration
(Note 4)
!= BSAC + MC Play BSAC Play BSAC+MC
channelConfigu
ration
1 == BSAC+SBR Play BSAC Play
(Note 3) channelConfigu BSAC+SBR
ration
(Note 4)
!= BSAC+SBR+MC Play BSAC Play
channelConfigu BSAC+SBR
ration +MC
Note 1: Implicit signalling, check payload in order to determine output sampling frequency, or assume
the presence of SBR data in the payload, giving an output sampling frequency of twice the sampling
frequency indicated by samplingFrequency in the AudioSpecificConfig() (unless the down sampled
SBR Tool is operated, or twice the sampling frequency indicated by samplingFrequency exceeds the
maximum allowed output sampling frequency of the current level, in which case the output sampling
frequency is the same as indicated by samplingFrequency).
Note 2: Explicitly signals that there is no SBR data, hence no implicit signalling is present, and the
output sampling frequency is given by samplingFrequency in the AudioSpecificConfig().
Note 3: Output sampling frequency is the extensionSamplingFrequency in AudioSpecificConfig().
Note 4: Explicitly signals that there is no BSAC channel extension data, and the number of output
channel is given by channelConfiguration in the AudioSpecificConfig().
8 © ISO/IEC 2007 – All rights reserved
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ISO/IEC 14496-3:2005/Amd.5:2007(E)
Replace the definition of bsac_raw_data_block() in Part 3: Audio, Subpart 4, subclause 4.4.2.6 Payloads for
the audio object type ER BSAC, Table 4.33:
Table 4.33 — Syntax of bsac_raw_data_block()
Syntax No. of bits Mnemonic
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()) {
zero_code 32 bslbf
sync_word 4 bslbf
while( bits_to_decode() > 4 ) {
extension_type 4 bslbf
switch(extension_type) {
case EXT_BSAC_CHANNEL :
extended_bsac_raw_data_block(); Note 1
break;
case EXT_BSAC_SBR_DATA :
extended_bsac_sbr_data(nch, 0);
break;
case EXT_BSAC_SBR_DATA_CRC :
extended_bsac_sbr_data(nch, 1);
break;
case EXT_BSAC_CHANNEL_SBR :
extended_bsac_raw_data_block(); Note 1
extended_bsac_sbr_data(nch, 0);
break;
case EXT_BSAC_CHANNEL_SBR_CRC :
extended_bsac_raw_data_block(); Note 1
extended_bsac_sbr_data(nch, 1);
break;
case EXT_BSAC_SAC_DATA :
extended_bsac_sac_data();
break;
default :
extended_bsac_data();
break;
}
byte_alignment();
}
}
}
Note 1: The byte_alignment() functions in extended_bsac_raw_data_block() are relative to
the start of extended_bsac_raw_data_block().
© ISO/IEC 2007 – All rights reserved 9
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ISO/IEC 14496-3:2005/Amd.5:2007(E)
Renumber Table 4.35 – Syntax of extended_bsac_raw_data_block() and Table 4.36 – Syntax of
extended_bsac_base_element() which were introduced in ISO/IEC 14496-3:2005/Amd.2 as Table 4.43A –
Syntax of extended_bsac_raw_data_block() and Table 4.43B – Syntax of extended_bsac_base_element(),
respectively.
Add the following tables after Table 4.43B – Syntax of extended_bsac_base_element() in Part 3: Audio,
Subpart 4, at the end of subclause 4.4.2.6:
Table 4.43C — Syntax of extended_bsac_sbr_data ()
Syntax No. of bits Mnemonic
extended_bsac_sbr_data(nch, crc_flag)
{
num_sbr_bits = 0;
cnt = count; 4 uimsbf
num_sbr_bits += 4;
if (cnt == 15) {
cnt += esc_count - 1; 8 uimsbf
num_sbr_bits += 8;
}
if (crc_flag) {
bs_sbr_crc_bits; 10 uimsbf
num_sbr_bits += 10;
}
num_sbr_bits += 1;
if (bs_header_flag) 1 uimsbf
num_sbr_bits += sbr_header();
num_sbr_bits += bsac_sbr_data(nch, bs_amp_res);
num_align_bits = (8*cnt - num_sbr_bits);
bs_fill_bits; num_align_ uimsbf
bits
}
Table 4.43D — Syntax of bsac_sbr_data()
Syntax No. of bits Mnemonic
bsac_sbr_data(nch, bs_amp_res)
{
switch (nch) {
case 1 :
sbr_single_channel_element(bs_amp_res)
break;
case 2 :
sbr_channel_pair_element(bs_amp_res)
...
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