ISO/IEC 23008-3:2019/Amd 1:2019

INTERNATIONAL ISO/IEC
STANDARD 23008-3
Second edition
2019-02-20
AMENDMENT 1
2019-06
Information technology — High
efficiency coding and media delivery
in heterogeneous environments —
Part 3:
3D audio
AMENDMENT 1: Audio metadata
enhancements
Technologies de l'information — Codage à haute efficacité et livraison
des medias dans des environnements hétérogènes —
Partie 3: Audio 3D
AMENDEMENT 1: Améliorations de la prise en charge des
métadonnées audio
Reference number
ISO/IEC 23008-3:2019/Amd.1:2019(E)
©
ISO/IEC 2019
ISO/IEC 23008-3:2019/Amd.1:2019(E)

© ISO/IEC 2019
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Published in Switzerland
ii © ISO/IEC 2019 – All rights reserved

ISO/IEC 23008-3:2019/Amd.1:2019(E)

Foreword
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This document was prepared by Technical Committee ISO/IEC JTC 1, Information technology,
Subcommittee SC 29, Coding of audio, picture, multimedia and hypermedia information.
A list of all parts in the ISO/IEC 23008 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
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© ISO/IEC 2019 – All rights reserved iii

ISO/IEC 23008-3:2019/Amd.1:2019(E)
Information technology — High efficiency coding and
media delivery in heterogeneous environments —
Part 3:
3D audio
AMENDMENT 1: Audio metadata enhancements

5.2.2.1 General configuration syntax
In subclause 5.2.2.1 replace Table 14 with:
Table 14 — Syntax of Signals3d()
Syntax No. of bits Mnemonic
Signals3d()
{
numAudioChannels              = 0;
numAudioObjects                = 0;
numSAOCTransportChannels     = 0;
numHOATransportChannels      = 0;

bsNumSignalGroups; 5 uimsbf
for ( grp = 0; grp < bsNumSignalGroups + 1 ; grp++ ) {
signal_groupID[grp] = grp;
differsFromReferenceLayout[grp] = 0;
signalGroupType[grp]; 3 bslbf
bsNumberOfSignals[grp] = escapedValue(5, 8, 16);
if ( SignalGroupType[grp] == SignalGroupTypeChannels ) {
numAudioChannels += bsNumberOfSignals[grp] + 1;
differsFromReferenceLayout[grp]; 1 bslbf
if(differsFromReferenceLayout[grp]) {
audioChannelLayout[grp] = SpeakerConfig3d();
}
else {
audioChannelLayout[grp] = referenceLayout;
}
}
if ( SignalGroupType[grp] == SignalGroupTypeObject ) {
numAudioObjects += bsNumberOfSignals[grp] + 1;
}
if ( SignalGroupType[grp] == SignalGroupTypeSAOC ) {
numSAOCTransportChannels += bsNumberOfSignals[grp] + 1;
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ISO/IEC 23008-3:2019/Amd.1:2019(E)

Table 14 (continued)
Syntax No. of bits Mnemonic
saocDmxLayoutPresent; 1 bslbf
if ( saocDmxLayoutPresent == 1 ) {
saocDmxChannelLayout = SpeakerConfig3d();
}
}
if ( SignalGroupType[grp] == SignalGroupTypeHOA ) {
numHOATransportChannels += bsNumberOfSignals[grp] + 1;
}
}
}
5.2.2.3 Core decoder configuration
In 5.2.2.3 replace Table 23 with:
Table 23 — Syntax of mpegh3daExtElementConfig()
Syntax No. of bits Mnemonic
mpegh3daExtElementConfig()
{
usacExtElementType            = escapedValue(4, 8, 16);
usacExtElementConfigLength   = escapedValue(4, 8, 16);

if (usacExtElementDefaultLengthPresent) { 1 uimsbf
usacExtElementDefaultLength = escapedValue(8, 16, 0) + 1;
} else {
usacExtElementDefaultLength = 0;
}
usacExtElementPayloadFrag; 1 uimsbf

switch (usacExtElementType) {
case ID_EXT_ELE_FILL:
/* No configuration element */
break;
case ID_EXT_ELE_MPEGS:
SpatialSpecificConfig();
break;
case ID_EXT_ELE_SAOC:
SAOCSpecificConfig();
break;
case ID_EXT_ELE_AUDIOPREROLL:
/* No configuration element */
a
The default entry for the usacExtElementType is used for unknown extElementTypes so that legacy
decoders can cope with future extensions.
2 © ISO/IEC 2019 – All rights reserved

ISO/IEC 23008-3:2019/Amd.1:2019(E)

Table 23 (continued)
Syntax No. of bits Mnemonic
break;
case ID_EXT_ELE_UNI_DRC:
mpegh3daUniDrcConfig();
break;
case ID_EXT_ELE_OBJ_METADATA:
ObjectMetadataConfig();
break;
case ID_EXT_ELE_SAOC_3D:
SAOC3DSpecificConfig();
break;
case ID_EXT_ELE_HOA:
HOAConfig();
break;
case ID_EXT_ELE_FMT_CNVRTR
/* No configuration element */
break;
case ID_EXT_ELE_MCT:
MCTConfig();
break;
case ID_EXT_ELE_TCC:
TccConfig();
break;
case ID_EXT_ELE_HOA_ENH_LAYER:
HOAEnhConfig();
break;
case ID_EXT_ELE_HREP:
HREPConfig(current_signal_group);
break;
case ID_EXT_ELE_ENHANCED_OBJ_METADATA:
EnhancedObjectMetadataConfig();
break;
case ID_EXT_ELE_PROD_METADATA:
prodMetadataConfig();
break;
a
default:
while (usacExtElementConfigLength--) {
tmp; 8 uimsbf
}
break;
}
}
a
The default entry for the usacExtElementType is used for unknown extElementTypes so that legacy
decoders can cope with future extensions.

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ISO/IEC 23008-3:2019/Amd.1:2019(E)

5.3.4 Core decoder configuration data elements
In 5.3.4 replace Table 75 with:
Table 75 — Value of usacExtElementType
usacExtElementType Value
ID_EXT_ELE_FILL 0
ID_EXT_ELE_MPEGS 1
ID_EXT_ELE_SAOC 2
ID_EXT_ELE_AUDIOPREROLL 3
ID_EXT_ELE_UNI_DRC 4
ID_EXT_ELE_OBJ_METADATA 5
ID_EXT_ELE_SAOC_3D 6
ID_EXT_ELE_HOA 7
ID_EXT_ELE_FMT_CNVRTR 8
ID_EXT_ELE_MCT 9
ID_EXT_ELE_TCC 10
ID_EXT_ELE_HOA_ENH_LAYER 11
ID_EXT_ELE_HREP 12
ID_EXT_ELE_ENHANCED_OBJ_METADATA 13
ID_EXT_ELE_PROD_METADATA 14
/* reserved for ISO use */ 15-127
/* reserved for use outside of ISO scope */ 128 and higher
NOTE  Application-specific usacExtElementType values are mandated to be in the space reserved for
use outside of ISO scope. These are skipped by a decoder as a minimum of structure is required by
the decoder to skip these extensions.

In 5.3.4 replace Table 76 with:
Table 76 — Interpretation of data blocks for extension payload decoding
usacExtElementType The concatenated usacExtElementSegmentData
represents:
ID_EXT_ELE_FILL Series of fill_byte
ID_EXT_ELE_MPEGS SpatialFrame() as defined in ISO/IEC 23003-1
ID_EXT_ELE_SAOC SAOCFrame() as defined in ISO/IEC 23003-2
ID_EXT_ELE_AUDIOPREROLL AudioPreRoll()
ID_EXT_ELE_UNI_DRC uniDrcGain() as defined in ISO/IEC 23003-4
ID_EXT_ELE_OBJ_METADATA objectMetadataFrame()
ID_EXT_ELE_SAOC_3D Saoc3DFrame()
ID_EXT_ELE_HOA HOAFrame()
ID_EXT_ELE_FMT_CNVRTR FormatConverterFrame()
ID_EXT_ELE_MCT MultichannelCodingFrame()
ID_EXT_ELE_TCC TccGroupOfSegments()
ID_EXT_ELE_HOA_ENH_LAYER HOAEnhFrame()
ID_EXT_ELE_HREP HREPFrame(outputFrameLength, current_signal_group)
ID_EXT_ELE_ENHANCED_OBJ_METADATA EnhancedObjectMetadataFrame()
4 © ISO/IEC 2019 – All rights reserved

ISO/IEC 23008-3:2019/Amd.1:2019(E)

Table 76 (continued)
usacExtElementType The concatenated usacExtElementSegmentData
represents:
ID_EXT_ELE_PROD_METADATA prodMetadataFrame()
unknown Unknown data. The data block shall be discarded.

12.2.1 Configuration of HOA elements
In subclause 12.2.1 replace Table 188 with:
Table 188 — Syntax of HOADecoderConfig()
Syntax No. of bits Mnemonic
HOADecoderConfig(numHOATransportChannels)
{
MinAmbHoaOrder = escapedValue(3,5,0) – 1; 3,8 uimsbf
MinNumOfCoeffsForAmbHOA = (MinAmbHoaOrder + 1)^2;
NumOfAdditionalCoders = numHOATransportChannels –
MinNumOfCoeffsForAmbHOA;
NumLayers = 1;
NumHOAChannelsLayer[0] = numHOATransportChannels;
if(SingleLayer == 0){ 1 bslbf
HOALayerChBits = ceil(log2(NumOfAdditionalCoders));
NumHOAChannelsLayer[0] = codedLayerCh + HOALayerChBits uimsbf
MinNumOfCoeffsForAmbHOA;
remainingCh = numHOATransportChannels –
NumHOAChannelsLayer[0];
while (remainingCh>1) {
HOALayerChBits = ceil(log2(remainingCh));
NumHOAChannelsLayer[NumLayers] = HOALayerChBits uimsbf
NumHOAChannelsLayer[NumLayers-1] +
codedLayerCh + 1;
remainingCh = numHOATransportChannels –
NumHOAChannelsLayer[NumLayers];
NumLayers++;
}
if (remainingCh) {
NumHOAChannelsLayer[NumLayers] =
numHOATransportChannels;
NumLayers++;
}
}
CodedSpatialInterpolationTime; 3 uimsbf
SpatialInterpolationMethod; 1 bslbf
NOTE  MinAmbHoaOrder = 30 … 37 are reserved. HOAFrameLengthIndicator = 3 is reserved. CodedVVecLength = 3 is
reserved.
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ISO/IEC 23008-3:2019/Amd.1:2019(E)

Table 188 (continued)
Syntax No. of bits Mnemonic
CodedVVecLength; 2 uimsbf
MaxGainCorrAmpExp; 3 uimsbf
HOAFrameLengthIndicator; 2 uimsbf

if( MinAmbHoaOrder < HoaOrder ) {
DiffOrderBits = ceil( log2(HoaOrder- MinAmbHoaOrder+1))
MaxHoaOrderToBeTransmitted = DiffOrder + DiffOrderBits uimsbf
MinAmbHoaOrder;
}
else {
MaxHoaOrderToBeTransmitted = HoaOrder;
}
MaxNumOfCoeffsToBeTransmitted =
(MaxHoaOrderToBeTransmitted + 1)^2;
MaxNumAddActiveAmbCoeffs =
MaxNumOfCoeffsToBeTransmitted
- MinNumOfCoeffsForAmbHOA;
VqConfBits = ceil ( log2( ceil( log2( NumOfHoaCoeffs+1 ))));
NumVVecVqElementsBits; VqConfBits uimsbf
if( MinAmbHoaOrder == 1) {
UsePhaseShiftDecorr; 1 bslbf
}
if(SingleLayer==1) {
HOADecoderEnhConfig();
}
AmbAsignmBits = ceil( log2( MaxNumAddActiveAmbCoeffs ) );
ActivePredIdsBits = ceil( log2( NumOfHoaCoeffs ) );
i = 1;
while( i * ActivePredIdsBits
+ ceil( log2( i ) ) < NumOfHoaCoeffs ){
i++;
}
NumActivePredIdsBits = ceil( log2( max( 1, i – 1 ) ) );
GainCorrPrevAmpExpBits = ceil( log2( ceil( log2(
1.5 * NumOfHoaCoeffs ) )
+ MaxGainCorrAmpExp + 1 ) );
for (i=0; i AmbCoeffTransitionState[i] = 3;
}
}
NOTE  MinAmbHoaOrder = 30 … 37 are reserved. HOAFrameLengthIndicator = 3 is reserved. CodedVVecLength = 3 is
reserved.
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ISO/IEC 23008-3:2019/Amd.1:2019(E)

14.2.1 Main MHAS syntax elements
In 14.2.1 replace Table 220 with:
Table 220 — Syntax of MHASPacketPayload()
Syntax No. of bits Mnemonic
MHASPacketPayload(MHASPacketType)
{
switch (MHASPacketType) {
case PACTYP_SYNC:
0xA5;                    /* syncword*/ 8 uimsbf
break;
case PACTYP_MPEGH3DACFG:
mpegh3daConfig();
break;
case PACTYP_MPEGH3DAFRAME:
mpegh3daFrame();
break;
case PACTYP_AUDIOSCENEINFO:
mae_AudioSceneInfo();
break;
case PACTYP_FILLDATA:
for (i=0; i< MHASPacketLength; i++) {
mhas_fill_data_byte(i); 8 bslbf
}
break;
case PACTYP_SYNCGAP:
syncSpacingLength = escapedValue(16,24,24); 16,40,64 uimsbf
break;
case PACTYP_MARKER:
for (i=0; i< MHASPacketLength; i++) {
marker_byte(i); 8 bslbf
}
break;
case PACTYP_CRC16:
mhasParity16Data; 16 bslbf
break;
case PACTYP_CRC32:
mhasParity32Data; 32 bslbf
break;
case PACTYP_GLOBAL_CRC16:
global_CRC_type; 2 bslbf
numProtectedPackets; 6 bslbf
mhasParity16Data; 16 bslbf
break;
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ISO/IEC 23008-3:2019/Amd.1:2019(E)

Table 220 (continued)
Syntax No. of bits Mnemonic
case PACTYP_ GLOBAL_CRC32:
global_CRC_type; 2 bslbf
numProtectedPackets; 6 bslbf
mhasParity32Data; 32 bslbf
break;
case PACTYP_DESCRIPTOR:
for (i=0; i< MHASPacketLength; i++) {
mhas_descriptor_data_byte(i); 8 bslbf
}
break;
case PACTYP_USERINTERACTION:
mpegh3daElementInteraction();
break;
case PACTYP_LOUDNESS_DRC:
mpegh3daLoudnessDrcInterface();
break;
case PACTYP_BUFFERINFO:
mhas_buffer_fullness_present 1 uimsbf
if (mhas_buffer_fullness_present)
mhas_buffer_fullness = escapedValue(15,24,32); 15,39,71 uimsbf
}
break;
case PACTYP_AUDIOTRUNCATION:
audioTruncationInfo();
break;
case PACTYP_GENDATA:
GenDataPayload();
break;
case PACTYP_EARCON:
earconInfo();
break;
case PACTYP_PCMCONFIG:
pcmDataConfig();
break;
case PACTYP_PCMDATA:
pcmDataPayload();
break;
case PACTYP_LOUDNESS:
mpegh3daLoudnessInfoSet();
break;
}
ByteAlign();
}
8 © ISO/IEC 2019 – All rights reserved

ISO/IEC 23008-3:2019/Amd.1:2019(E)

14.3.1 mpeghAudioStreamPacket()
In 14.3.1 replace Table 223 with:
Table 223 — Value of MHASPacketType
MHASPacketType Value
PACTYP_FILLDATA 0
PACTYP_MPEGH3DACFG 1
PACTYP_MPEGH3DAFRAME 2
PACTYP_AUDIOSCENEINFO 3
/* reserved for ISO use */ 4-5
PACTYP_SYNC 6
PACTYP_SYNCGAP 7
PACTYP_MARKER 8
PACTYP_CRC16 9
PACTYP_CRC32 10
PACTYP_DESCRIPTOR 11
PACTYP_USERINTERACTION 12
PACTYP_LOUDNESS_DRC 13
PACTYP_BUFFERINFO 14
PACTYP_GLOBAL_CRC16 15
PACTYP_GLOBAL_CRC32 16
PACTYP_AUDIOTRUNCATION 17
PACTYP_GENDATA 18
PACTYP_EARCON 19
PACTYP_PCMCONFIG 20
PACTYP_PCMDATA 21
PACTYP_LOUDNESS 22
/* reserved for ISO use */ 23-127
/* reserved for use outside of ISO scope */ 128-261
/* reserved for ISO use */ 262-389
/* reserved for use outside of ISO scope */ 390-517
NOTE  Application-specific MHASPacketType values are mandated to be in the space
reserved for use outside of ISO scope. These are skipped by a decoder as a minimum of
structure is required by the decoder to skip these extensions.

14.3.2 MHASPacketPayload()
At the end of subclause 14.3.2 add:
earconInfo() Earcon Info structure as defined in 28.2.
pcmDataConfig() PCM data configuration structure as defined in 28.2.
pcmDataPayload() PCM data payload structure as defined in 28.2.
mpegh3daLoudnessInfoSet() Loudness metadata structure as defined in 6.3.1.

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ISO/IEC 23008-3:2019/Amd.1:2019(E)

14.4 Description of MHASPacketTypes
At the end of subclause 14.4 add:
14.4.15  PACTYP_EARCON
The MHASPacketType PACTYP_EARCON may be used to embed information about the earcons available
in the earconInfo() structure and to feed earcon info data in the form of the earconInfo() structure to
the decoder.
If the earconInfo() structure contains at least one earcon of type PCM (i.e. earconType == 5) the MHAS
stream shall contain at least one MHAS packet of type PACTYP_PCMCONFIG and at least one MHAS
packet of type PACTYP_PCMDATA.
14.4.16  PACTYP_PCMCONFIG
The MHASPacketType PACTYP_PCMCONFIG may be used to carry configuration information for PCM
payload data and to feed the PCM data configuration information in the form of the pcmDataConfig()
structure to the decoder.
If an MHASPacketType PACTYP_PCMCONFIG is present after an MHASPacketType PACTYP_EARCON,
the pcmDataConfig() structure shall be used together with the previous earconInfo() structure. If no
MHASPacketType PACTYP_EARCON is present in the stream the pcmDataConfig() structure shall be
ignored.
14.4.17  PACTYP_PCMDATA
The MHASPacketType PACTYP_PCMDATA may be used to embed PCM payload data corresponding to
the PCM signals defined in the pcmDataConfig() structure and to feed the PCM data in the form of the
pcmDataPayload() structure to the decoder.
If an MHASPacketType PACTYP_ PCMDATA is present after an MHASPacketType PACTYP_ PCMCONFIG,
the pcmDataPayload() structure shall be used together with the previous earconInfo() and
pcmDataConfig() structures. If no MHASPacketType PACTYP_EARCON and MHASPacketType PACTYP_
PCMCONFIG are present in the stream the pcmDataPayload() structure shall be ignored.
14.4.18  PACTYP_LOUDNESS
The MHASPacketType PACTYP_LOUDNESS may be used to embed loudness metadata as defined in
the mpegh3daLoudnessInfoSet() structure. If present and supported by a decoder, it shall take
precedence over the in-stream loudness information conveyed via mpegh3daConfigExtension() as
defined in Table 24.
If present, the MHASPacketType PACTYP_LOUDNESS shall follow PACTYP_MPEGH3DACFG for each
random access point and stream access point.
Updated loudness information may be available for instance after editing. The MHASPacketType
PACTYP_LOUDNESS can be used to convey the updated loudness information to the decoder without
requiring an update of the audio stream.

17.10.3.1 General
In subclause 17.10.3.1, extend paragraphs by:
— Enhanced object metadata;
— diffuseness;
— divergence and divergence azimuth range;
— exclusion sector metadata;
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ISO/IEC 23008-3:2019/Amd.1:2019(E)

— Production Metadata.
17.10.3.2 Syntax of an interface for object-based metadata
In 17.10.3.2 replace Table 265 with:
Table 265 — Syntax of mpegh3da_getObjectAudioAndMetadata()
Syntax No. of bits Mnemonic
mpegh3da_getObjectAudioAndMetadata()
{
/* FRAME CONFIGURATION */
goa_frameLength; 6 uimsbf
goa_audioTruncation; 2 bslbf
if (goa_audioTruncation>0) {
goa_numSamples; 13 uimsbf
} else {
goa_numSamples = goa_frameLength << 6;
}
/* OBJECT METADATA */
goa_numberOfOutputObjects; 9 uimsbf
for ( o = 0; o < goa_numberOfOutputObjects; o++ ) {
goa_elementID[o]; 9 uimsbf
goa_hasDynamicObjectPriority[o]; 1 bslbf
goa_hasUniformSpread[o]; 1 bslbf

/* OAM Data */
goa_numOAMframes[o] 6 uimsbf
for (nf = 0; nf < goa_numOAMframes[o]; nf++) {
goa_objectMetadataPresent; 1 bslbf
if (goa_objectMetadataPresent==1) {
goa_positionAzimuth[o][nf]; 8 uimsbf
goa_positionElevation[o][nf]; 6 uimsbf
goa_positionRadius[o][nf]; 4 uimsbf
goa_objectGainFactor[o][nf]; 7 uimsbf

if (goa_hasDynamicObjectPriority[o]) {
goa_dynamicObjectPriority[o][nf]; 3 uimsbf
}
if ( goa_hasUniformSpread[o] ) {
goa_uniformSpread[o][nf]; 7 uimsbf
} else {
goa_spreadWidth[o][nf]; 7 uimsbf
goa_spreadHeight[o][nf]; 5 uimsbf
goa_spreadDepth[o][nf]; 4 uimsbf
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ISO/IEC 23008-3:2019/Amd.1:2019(E)

Table 265 (continued)
Syntax No. of bits Mnemonic
}
}
}
/* Signal group related data */
goa_fixedPosition[o]; 1 bslbf
goa_groupPriority[o]; 3 uimsbf

/* Enhanced Object Metadata */
goa_diffuseness[o]; 7 uimsbf
goa_divergence[o]; 7 uimsbf
goa_divergenceAzimuthRange[o]; 6 uimsbf
goa_numExclusionSectors[o]; 4 uimsbf
for ( s = 0; s < goa_numExclusionSectors[o]; s++) {
goa_usePredefinedSector[o][s]; 1 bslbf
if ( goa_usePredefinedSector[o][s] ) {
goa_excludeSectorIndex[o][s]; 4 uimsbf
} else {
goa_excludeSectorMinAzimuth[o][s]; 7 uimbsf
goa_excludeSectorMaxAzimuth[o][s]; 7 uimbsf
goa_excludeSectorMinElevation[o][s]; 5 uimbsf
goa_excludeSectorMaxElevation[o][s] 5 uimbsf
}
} /* for ( s = 0; s < goa_numExclusionSectors[o]; s++) */
} /* for ( o = 0; o < goa_numberOfOutputObjects; o++ ) */

/* GOA EXTENSION ELEMENTS */
goa_numberOfExtensionElements; 3 uimsbf

if (goa_numberOfExtensionElements)
{
for ( ext = 0; ext < goa_numberOfExtensionElements; ext++ ) {
goa_extElementType; 3 uimbsf
goa_extElementLength; 10 uimsbf

switch (goa_extElementType) {
case ID_EXT_GOA_PROD_METADATA:
goa_Production_Metadata();
break;
default:
break;
}
}
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ISO/IEC 23008-3:2019/Amd.1:2019(E)

Table 265 (continued)
Syntax No. of bits Mnemonic
}
}
Add new tables after Table 265:
Table AMD1.1 — Syntax of goa_Production_Metadata()
Syntax No. of bits Mnemonic
goa_Production_Metadata()
{
/* PRODUCTION METADATA CONFIGURATION */
goa_ hasObjectDistance; 1 bslbf
if (goa_hasObjectDistance) {
for ( o = 0; o < goa_numberOfOutputObjects; o++ ) {
goa_bsObjectDistance[o]; 9 uimsbf
}
}
}
Table AMD1.2 — Syntax of goa_extElementType
goa_extElementType Value
ID_EXT_GOA_PROD_METADATA 0
/* reserved */ 1-7
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17.10.3.3. Semantics of the interface for object-based metadata
At the end of 17.10.3.3. add:
goa_numberOfExtensionElements Defines the number of extension elements to the GOA output
interface.
goa_extElementType Defines the type of the extension element.
goa_extElementLength Defines the length of the extension element.
goa_hasObjectDistance This flag defines if the object distance parameter is signalled
in the production metadata frame.
goa_bsObjectDistance This field describes the distance of an object. The field can
take values between 0 and 511, which maps to distance
values between 0 m and 177 km. Table AMD1.3 provides the
mapping of goa_bsObjectDistance field to the distance.
Table AMD1.3 — Mapping of position_distance field to the distance
goa_bsObjectDistance distance
0 distance = 0 m
1 − 511 distance = 0.01 * 2^( 0.0472188798661443 * ( goa_bsObjectDistance - 1 ) )

17.10.4.1 General
In subclause 17.10.4.1, replace paragraph 8 with:
If a channel output interface is provided by an implementation, the following metadata shall be provided
via the interface to be evaluated by possible external renderers:
— Number of channels;
— Number of valid PCM samples for the current frame;
— elementIDs for the referenced audio channels;
— Channel configuration;
— “fixed position” flag;
— Static group priority;
— Downmix matrix elements, if transmitted and matching the selected Reproduction Layout (according
to 10.3.1);
— Production metadata.
14 © ISO/IEC 2019 – All rights reserved

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17.10.4.2 Syntax of an interface for channel-based metadata
In subclause 17.10.4.2 replace Table 267 with:
Table 267 — Syntax of mpegh3da_getChannelMetadata()
Syntax No. of bits Mnemonic
mpegh3da_getChannelMetadata()
{
/* FRAME CONFIGURATION */
gca_frameLength; 6 uimsbf
gca_audioTruncation; 2 bslbf
if (gca_audioTruncation>0) {
gca_numSamples; 13 uimsbf
} else {
gca_numSamples = gca_frameLength << 6;
}
/* CHANNEL METADATA */
gca_numberOfOutputChannelGroups; 9 uimsbf
for ( cGrp = 0; cGrp < gca_numberOfOutputChannelGroups; cGrp ++ ) {
gca_numberOfChannels[cGrp]; 16 uimsbf
gca_channelLayout[cGrp] = SpeakerConfig3d();

for ( nChn = 0; nChn < gca_numberOfChannels[cGrp]; nChn++ {
gca_elementID[cGrp][nChn]; 9 uimsbf
}
/* TRACKING-RELATED METADATA */
gca_fixedChannelsPosition[cGrp]; 1 bslbf

/* GROUP-RELATED METADATA */
gca_groupPriority[cGrp]; 3 uimsbf
gca_channelGain[cGrp]; 8 uimsbf

/* DOWNMIX MATRIX ELEMENT */
gca_downmixAvailable; 1 bslbf
if (gca_downmixAvailable) {
gca_downmixConfig();
}
}
/* GCA EXTENSION ELEMENTS */
gca_numberOfExtensionElements; 3 uimsbf

if (gca_numberOfExtensionElements)
{
for ( ext = 0; ext < gca_numberOfExtensionElements; ext++ ) {
© ISO/IEC 2019 – All rights reserved 15

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Table 267 (continued)
Syntax No. of bits Mnemonic
gca_extElementType; 3 uimbsf
gca_extElementLength; 10 uimsbf

switch (gca_extElementType) {
case ID_EXT_GCA_PROD_METADATA:
gca_Production_Metadata();
break;
default:
break;
}
}
}
}
Add new tables following Table 267:
Table AMD1.4 — Syntax of gca_Production_Metadata()
Syntax No. of bits Mnemonic
gca_Production_Metadata()
{
/* PRODUCTION METADATA CONFIGURATION */

for (gp = 0; gp < numChannelGroups; gp++ ) {
gca_directHeadphone[gp] 1 bslbf
}
gca_hasReferenceDistance; 1 bslbf
if (gca_hasReferenceDistance) {
gca_bsReferenceDistance; 7 uimsbf
} else {
gca_bsReferenceDistance = 57;
}
}
Table AMD1.5 — Syntax of gca_extElementType
gca_extElementType Value
ID_EXT_GCA_PROD_METADATA 0
/* reserved */ 1-7
16 © ISO/IEC 2019 – All rights reserved

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17.10.4.3 Semantics of the interface for channel-based metadata
In subclause 17.10.4.3, replace:
gca_groupPriority This field defines the priority of the group to which the current object be-
longs to. It can take integer values between 0 and 7.
with:
gca_groupPriority This field defines the priority of the group to which the current channel
belongs to. It can take integer values between 0 and 7.

At the end of 17.10.4.3 add:
gca_numberOfExtensionElements Defines the number of extension elements to the GCA output
interface.
gca_extElementType Defines the type of the extension element.
gca_extElementLength Defines the length of the extension element.
gca_directHeadphone This flag defines that the corresponding signal group of type
channels goes directly to the headphone output. The signals
are routed to left and right headphone channel. For mono, the
signal is mixed to left and right headphone channel with a gain
factor of 0.707.
gca_hasReferenceDistance This flag defines if the gca_bsReferenceDistance parameter
is signalled in the production metadata config. If it is 0, the
gca_bsReferenceDistance is set to 57, meaning the reference
loudspeaker distance of input layout as 3.1748 m, by default.
gca_bsReferenceDistance This field describes the reference loudspeaker distance of
input layout. The field can take values between 0 and 127,
which maps to reference loudspeaker distance values between
0.5 m and 31.4 m. Table AMD1.6 provides the mapping of
gca_bsReferenceDistance field to the reference loudspeaker
distance.
Table AMD1.6 — Mapping of gca_bsReferenceDistance field to the reference
loudspeaker distance
gca_bsReference reference distance
Distance
0 − 127 reference distance =
0.01 * 2^( 0.0472188798661443 *( gca_bsReferenceDistance + 119 ))

17.10.5.1 General
In subclause 17.10.5.1, replace paragraph 7 with:
If the HOA output interface is provided by an implementation, the following metadata shall be provided
via the interface to be interpreted and acted upon by potential external renderers:
— HOA order;
© ISO/IEC 2019 – All rights reserved 17

ISO/IEC 23008-3:2019/Amd.1:2019(E)

— Number of valid PCM samples for the current frame;
— Signal group related priority and fixedPosition parameter;
— NFC metadata;
— A flag that indicates if HOA content is relative to a screen and if so, the production screen size
information;
— HOA rendering matrix elements, if transmitted and matching the selected reproduction layout;
— Production metadata.
17.10.5.2 Syntax of an interface for HOA metadata
In 17.10.5.2 replace Table 269 with:
Table 269 — Syntax of mpegh3da_getHoaMetadata()
Syntax No. of bits Mnemonic
mpegh3da_getHoaMetadata()
{
/* FRAME CONFIGURATION */
gha_frameLength; 6 uimsbf
gha_audioTruncation; 2 bslbf
if (gha_audioTruncation>0) {
gha_numSamples; 13 uimsbf
} else {
gha_numSamples = gha_frameLength << 6;
}
gha_numberOfHoaGroups; 9 uimsbf
for (hGrp = 0; hGrp < gha_numberOfHoaGroups; hGrp ++ ) {
/* Signal group related data */
gha_fixedPosition[hGrp]; 1 bslbf
gha_groupPriority[hGrp]; 3 uimsbf
/* HOA METADATA */
gha_HoaOrder[hGrp]; 9 uimsbf
gha_UsesNfc[hGrp]; 1 bslbf
if (gha_UsesNfc[hGrp]) {
gha_NfcReferenceDistance[hGrp]; 32 bslbf
}
gha_hasSignalledHoaMatrix[hGrp]; 1 uimsbf
if (gha_hasSignalledHoaMatrix[hGrp]) {
gha_HoaRenderingMatrixSet();
}
gha_isScreenRelative[hGrp]; 1 uimsbf
if (gha_isScreenRelative[hGrp]) {
mae_ProductionScreenSizeData();
mae_ProductionScreenSizeDataExtension();
}
18 © ISO/IEC 2019 – All rights reserved

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Table 269 (continued)
Syntax No. of bits Mnemonic
}
/* GHA EXTENSION ELEMENTS */
gha_numberOfExtensionElements; 3 uimsbf

if (gha_numberOfExtensionElements)
{
for ( ext = 0; ext < gha_numberOfExtensionElements; ext++ ) {
gha_extElementType; 3 uimbsf
gha_extElementLength; 10 uimsbf

switch (gha_extElementType) {
case ID_EXT_GHA_PROD_METADATA:
gha_Production_Metadata();
break;
default:
break;
}
}
}
}
Add new tables following Table 269:
Table AMD1.7 — Syntax of gha_Production_Metadata()
Syntax No. of bits Mnemonic
gha_Production_Metadata()
{
/* PRODUCTION METADATA CONFIGURATION */

gha_hasReferenceDistance; 1 bslbf
if (gha_hasReferenceDistance) {
gha_bsReferenceDistance; 7 uimsbf
}
else {
gha_bsReferenceDistance = 57;
}
}
© ISO/IEC 2019 – All rights reserved 19

ISO/IEC 23008-3:2019/Amd.1:2019(E)

Table AMD1.8 — Syntax of gha_extElementType
gha_extElementType Value
ID_EXT_GHA_PROD_METADATA 0
/* reserved */ 1-7
17.10.5.3 Semantics of the interface for HOA metadata
At the end of subclause 17.10.5.3, add:
gha_fixedPosition This field defines if the HOA soundfield orientation shall be
updated during processing of scene displacement (tracking)
data. If the soundfield orientation shall not be updated, the
flag is set to 1.
gha_groupPriority This field defines the priority of the group to which the
current HOA soundfield belongs to. It can take integer values
between 0 and 7.
gha_numberOfExtensionElements Defines the number of extension elements to the GHA output
interface.
gha_extElementType Defines the type of the extension element.
gha_extElementLength Defines the length of the extension element.
gha_isScreenRelative This element indicates if the HOA representation shall be ren-
dered with respect to the reproduction screen size.
gha_hasReferenceDistance This flag defines if the gha_bsReferenceDistance parameter
is signalled in the production metadata config. If it is 0, the
gha_bsReferenceDistance is set to 57, meaning the reference
loudspeaker distance of input layout as 3.1748 m, by default.
gha_bsReferenceDistance This field describes the reference loudspeaker distance of
input layout. The field can take values between 0 and 127,
which maps to reference loudspeaker distance values between
0.5 m and 31.4 m. Table AMD1.9 provides the mapping of
gha_bsReferenceDistance field to the reference loudspeaker
distance.
Table AMD1.9 — Mapping of gha_bsReferenceDistance field to the reference
loudspeaker distance
gha_bsReferenceDistance reference distance
0 − 127 reference distance =
0.01 * 2^( 0.0472188798661443 *(gha_bsReferenceDistance + 119) )

17.10.6 Audio PCM data
In subclause 17.10.6, replace paragraph 3 with:
The decoder shall signal the offset index of the PCM buffer for the first un-rendered output object and
the offset index of the PCM buffer for the first HOA audio signal.

20 © ISO/IEC 2019 – All rights reserved

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17.10 Interfaces for channel-based, object-based, and HOA metadata and audio data
At the end of subclause 17.10 add:
17.11  Interface for positional scene displacement data
17.11.1  General
For applications which allow small user movements (−25 cm … +25 cm) in the audio scene, the user
position data for the binaural rendering may be provided to the decoder by using the syntax element
mpegh3daPositionalSceneDisplacementData(). This will allow the scene displacement processing to
account for user orientation changes and positional displacement.
17.11.2  Syntax of the positional scene displacement interface
Table AMD1.10 — Syntax of mpegh3daPositionalSceneDisplacementData()
Syntax No. of bits Mnemonic
mpegh3daPositionalSceneDisplacementData()
{
sd_azimuth; 8 uimsbf
sd_elevation; 6 uimsbf
sd_radius; 4 uimsbf
}
17.11.3  Semantics of the positional scene displacement interface
sd_azimuth This field defines the scene displacement azimuth position. This field can take val-
ues from −180 to 180:
az = (sd_azimuth −128) · 1.5
offset
az . = min(max(az , −180), 180)
offset offset
sd_elevation This field defines the scene displacement elevation position. This field can take
values from −90 to 90:
el = (sd_elevation −32) · 3.0
offset
el = min(max(el , −90), 90)
offset offset
sd_radius This field defines the scene displacement radius. This field can take values from 0
and 0.25:
r = sd_radius / 60
offset
© ISO/IEC 2019 – All rights reserved 21

ISO/IEC 23008-3:2019/Amd.1:2019(E)

17.11.4  Processing
When mpegh3daPositionalSceneDisplacementData() is used, the scene displacement defined in 18.8
must be adjusted with the following values:
′
az =+az 90°
offset offset
el′ =°90 −el
offset offset
This results in new position transferred to Cartesian coordinates (x,y,z):
xr=⋅sincel′′⋅ os az +⋅resincla′′⋅ os z
() ()
() ( ))
offset offset offset
′′ ′′
yr=⋅sinsel ⋅ in az +⋅resinsla⋅ in z
() ()
() ( ))
offset offset offset
zr=⋅coscel′′+⋅reos l
()
()
offset offset
20.5.1 Definition
In subclause 20.5.1 replace the following text:
Box Types: ‘mhaC’, ‘mha1’, ‘mha2’
Container: Sample Table Box (‘stbl’)
Mandatory: The mha1 box is mandatory
with:
Box Types: ‘mhaC’, ‘mha1’, ‘mha2’
Container: Sample Table Box (‘stbl’)
Mandatory: No
20.9.5.3 Semantics
In subclause 20.9.5.3 remove:
multiStream
defined in subclause 20.8
Clause 26
Add new Clauses 27 and 28 after Clause 26:
27  Production metadata decoding
27.1  General
Audio metadata originates from production tools and production formats. Audio metadata should be
made available in the bit stream to enable a renderer to perform advanced rendering of immersive
audio. This clause describes the production metadata and the decoding process thereof.
22 © ISO/IEC 2019 – All rights reserved

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27.1.1  Object distance coding
The object distance is signalled as an 9-bit value allowing coding of values from 0 m up to 177 km when
using an exponential mapping. The resolution of the distance is highest for near positions (<1 mm) and
lowest in the far positions (around 5 km). The very low distances, below about 1 cm, are considered less
important, thus the distance coding starts from 1cm for the second quantized value (=1). The lowest
value signals distance =0.
27.1.2  Direct headphone signalling
The directHeadphone flag defines that the corresponding signal group of type channels goes to the
headphone output directly. The channel group can be mono or stereo, i.e. the directHeadphone flag
shall be 0 for all signal groups of type channels, which have a different layout than mono or stereo
assigned to them. For stereo, the two signals are mixed to left and right headphone channel, directly.
For mono:
— the signal is mixed to the left channel directly, if the CICPspeakerIdx == 0,
— the signal is mixed to the right channel directly, if the CICPspeakerIdx == 1,
— the signal is mixed to left and right headphone channel with a gain factor of 0.707, otherwise.
Over loudspeakers, the signals would come out at the speakers indicated in the CICP layout index.
The signals flow for the directHeadphone channels is modified only if a binaural output signal is
generated. For decoding and rendering for loudspeaker playback, no change is needed and the signal is
mixed to the output channels according to the rule set of the format converter.
When using the channel output interface, the directHeadphone signal is provided to the output
interface, as shown in Figure AMD1.1.
Figure AMD1.1 — Signal flow diagram showing the routing of directHeadphone
channel groups to the output
© ISO/IEC 2019 – All rights reserved 23

ISO/IEC 23008-3:2019/Amd.1:2019(E)

In case of binaural rendering, the directHeadphone channels are processed by DRC1 and then bypass
the format converter, mixer and binaural renderer. The sampling rate of the directHeadphone
channels is converted to match the output sampling rate. The directHeadphone channels are delay-
aligned to match the delay introduced to the non-directHeadphone signals by the format converter and
the binaural renderer. The directHeadphone channels are then mixed with the input of DRC2 from the
binaural renderer.
27.1.3  Reference distance coding
The reference loudspeaker distance of input layout is signalled as a 7-bit value allowing coding of
values from 0.5 m up to 31.4 m. The distances below 0.5 m are considered less important in terms of
loudspeaker layout, thus the distance coding starts from 0.5 m for the first quantized value (=0). When
the reference distance is not defined in the bitstream, it is assumed to be 3.1748 m. Note that each
quantized reference distance value is identical to one of t
...