ISO/IEC 23003-3:2020/Amd 2

• Status: Not Published
• 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/WG 6 - MPEG Audio coding
• Current Stage: 6000 - International Standard under publication
• Start Date: 19-Sep-2026
• Completion Date: 26-Sep-2026

• Amends: ISO/IEC 23003-3:2020 - Information technology — MPEG audio technologies — Part 3: Unified speech and audio coding
• Effective Date: 17-May-2025

Overview

ISO/IEC 23003-3:2020/Amd 2 is an amendment to the international standard for unified speech and audio coding under MPEG audio technologies. Managed by ISO/IEC JTC 1/SC 29, this amendment introduces crucial provisions for media authenticity within the MPEG-D Unified Speech and Audio Coding (USAC) framework. Media authenticity serves as a mechanism to verify the integrity and origin of audio media, providing greater trust and resilience for applications where genuine audio content is paramount, such as broadcast, streaming, and archival systems.

This amendment standardizes an optional set of tools and syntax elements for signaling and handling media authenticity data within USAC bitstreams, incorporating recognized identification and cryptographic mechanisms.

Key Topics

• Media Authenticity Metadata
  The amendment specifies syntax and semantics for embedding media authenticity information in USAC audio streams. This includes parameters to manage configuration, digital signatures, timestamps, provider identification, unique identifiers, and resilience levels.

• Support for Standardized Identifiers
  The solution references globally recognized standards like IETF RFC 3986 for Uniform Resource Identifiers (URI) and IETF RFC 9562 for Universally Unique Identifiers (UUIDs). These enable precise linking to media sources and facilitate content identification across media types.

• Authentication Methods
  The specification outlines the use of cryptographic hash algorithms (e.g., SHA-1, SHA-224, SHA-256, SHA-384, SHA-512) for signature generation and verification, ensuring the integrity of audio data.

• Temporal Consistency and Splicing
  The system supports overlapping and non-overlapping authentication sequences, enabling verification across edits or splices while ensuring seamless temporal consistency.

• Resilience and Adaptive Bitrate Scenarios
  By signaling resilience levels and supporting adaptive bitrate schemes, the amendment ensures robust authentication in dynamic streaming environments.

Applications

Implementing media authenticity via this ISO/IEC amendment brings significant practical value to several domains:

• Digital Audio Distribution and Streaming
  Ensures end-to-end integrity of audio streams, helping platforms and broadcasters prove the authenticity of their content to end users and stakeholders.

• Media Archives and Access Control
  Provides cryptographically verifiable records for archival media, essential for legal, journalistic, and historical purposes.

• Forensic and Regulatory Compliance
  Supporting detailed audit trails and tamper-evidence, enabling compliance with legal or regulatory requirements in environments handling sensitive or valuable audio data.

• Cross-Media Asset Management
  By embedding standard-compliant UUIDs and URIs, organizations can efficiently link and manage related assets across audio, video, and metadata systems.

Related Standards

This media authenticity amendment to MPEG unified speech and audio coding references and complements several standards:

• ISO/IEC 23003 (MPEG audio technologies)
  The parent series for advanced audio coding specifications.

• ISO/IEC 14496-3 (MPEG-4 Audio)
  For baseline USAC profile and extended HE AAC profile management.

• IETF RFC 3986
  Specifying the generic URI syntax crucial for content identification.

• IETF RFC 9562
  Defining universally unique IDs (UUIDs) used for audio object identification.

• ISO/IEC 23001-17
  Utilized for time-related identifiers in media authenticity mechanisms.

Adoption of ISO/IEC 23003-3:2020/Amd 2 strengthens trust in digital audio by supporting interoperable, standards-based media authentication, helping organizations build resilient and authoritative multimedia systems.

FINAL DRAFT
Amendment
ISO/IEC
23003-3:2020/
FDAM 2
ISO/IEC JTC 1/SC 29
Information technology — MPEG
Secretariat: JISC
audio technologies —
Voting begins on:
2026-07-24
Part 3:
Unified speech and audio coding
Voting terminates on:
2026-09-18
AMENDMENT 2: Media authenticity
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
WITH THEIR COMMENTS, NOTIFICATION OF ANY
RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE
AND TO PROVIDE SUPPOR TING DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
Reference number
ISO/IEC 23003­3:2020/FDAM 2:2026(en) © ISO/IEC 2026

FINAL DRAFT
ISO/IEC 23003-3:2020/FDAM 2:2026(en)
Amendment
ISO/IEC
23003-3:2020/
FDAM 2
ISO/IEC JTC 1/SC 29
Information technology — MPEG
Secretariat: JISC
audio technologies —
Voting begins on:
Part 3:
Unified speech and audio coding
Voting terminates on:
AMENDMENT 2: Media authenticity
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
WITH THEIR COMMENTS, NOTIFICATION OF ANY
RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE
AND TO PROVIDE SUPPOR TING DOCUMENTATION.
© ISO/IEC 2026
IN ADDITION TO THEIR EVALUATION AS
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
or ISO’s member body in the country of the requester.
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland Reference number
ISO/IEC 23003­3:2020/FDAM 2:2026(en) © ISO/IEC 2026

© ISO/IEC 2026 – All rights reserved
ii
ISO/IEC 23003-3:2020/FDAM 2:2026(en)
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.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of document should be noted. This document was drafted in accordance with the editorial rules of the ISO/
IEC Directives, Part 2 (see www.iso.org/directives or www.iec.ch/members_experts/refdocs).
ISO and IEC draw attention to the possibility that the implementation of this document may involve the
use of (a) patent(s). ISO and IEC take no position concerning the evidence, validity or applicability of any
claimed patent rights in respect thereof. As of the date of publication of this document, ISO and IEC had not
received notice of (a) patent(s) which may be required to implement this document. However, implementers
are cautioned that this may not represent the latest information, which may be obtained from the patent
database available at www.iso.org/patents and https://patents.iec.ch. ISO and IEC shall not be held
responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www.iso.org/iso/foreword.html.
In the IEC, see www.iec.ch/understanding-standards.
This document was prepared by Joint Technical Committee ISO/IEC JTC 1, Information technology,
Subcommittee SC 29, [name of subcommittee].
A list of all parts in the ISO 23003 series can be found on the ISO and IEC websites.
Any feedback or questions on this document should be directed to the user’s national standards
body. A complete listing of these bodies can be found at www.iso.org/members.html and
www.iec.ch/national-committees.

© ISO/IEC 2026 – All rights reserved
iii
ISO/IEC 23003-3:2020/FDAM 2:2026(en)
Information technology — MPEG audio technologies —
Part 3:
Unified speech and audio coding
AMENDMENT 2: Media authenticity

Add the following at the end of Clause 2:
IETF RFC 3986, Uniform Resource Identifier (URI): Generic Syntax
IETF RFC 9562, Universally Unique IDentifiers (UUIDs)

4.4.2
Add the following new subclause:
4.4.2  Audio object types
Currently, this document does not define any audio object types. The range of Object Type ID values 64 to 95
(both 64 and 95 included) is reserved. The data function UsacAotSpecificConfig(audioObjectType) is defined
as empty.
NOTE ISO/IEC 14496-3 defines Object Type ID value 42 and the associated USAC audio object type.

After Clause 4.5.4 add:
4.5.5  audioProfileLevelIndication
Currently, this document does not define any audioProfileLevelIndication values. The range of
audioProfileLevelIndication values 0x70 to 0x7F (both 0x70 and 0x7F included) is reserved.
NOTE ISO/IEC 14496-3 defines audioProfileLevelIndication values for the Baseline USAC Profile and for the
Extended HE AAC Profile.
Replace Table 78 with the following:

© ISO/IEC 2026 – All rights reserved
ISO/IEC 23003-3:2020/FDAM 2:2026(en)
Table 78 — 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
/* reserved for ISO/IEC 23008-3 use */ 5-14
ID_EXT_ELE_AUTH_INFO 15
/* reserved for ISO use */ 16-127
/* 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.

Replace Table 86 with the following:
Table 86 — Interpretation of data blocks for USAC extension payload decoding
usacExtElementType The concatenated usacExtElementSegmentData
represents:
ID_EXT_ELE_FILL Series of fill_byte
ID_EXT_ELE_MPEGS SpatialFrame()
ID_EXT_ELE_SAOC SaocFrame()
ID_EXT_ELE_AUDIOPREROLL AudioPreRoll()
ID_EXT_ELE_UNI_DRC uniDrcGain() as defined in ISO/IEC 23003-4
ID_EXT_ELE_AUTH_INFO authExtension() as defined in 7.19
unknown unknown data. The data block shall be discarded.

Renumber Tables 157 to 189 in ISO/IEC 23003-3 as Tables 171 to 203.

7.19
Add the following new subclause:
7.19  Media Authenticity
7.19.1  General
Media Authenticity is optional. If supported, the corresponding data is carried in syntax elements as defined
in Table 157, Table 158, Table 159, Table 160, Table 161, Table 162 and Table 163.
MPEG-D USAC decoders used in applications which do not support media authentication as described in
the current section shall ignore the auth_extension() element. The process of media authentication and
verification is out of scope for the MPEG-D USAC audio decoder.
7.19.2  Media Authenticity Syntax

© ISO/IEC 2026 – All rights reserved
ISO/IEC 23003-3:2020/FDAM 2:2026(en)
Table 157 — Syntax of authExtension
Syntax No. of bits Mnemonic
authExtension()
{
numAuthExtMinus1 = escapedValue(4,4,4); 4, 8, 12 uimsbf
for (i=0; i <= numAuthExtMinus1; i++) {
authSequence 1 uimsbf
authExtType 3 uimsbf
switch (authExtType) {
case AUTH_START:
authExtConfig();
break;
case AUTH_SIG:
authExtSig();
break;
case AUTH_UUID:
authUUID();
break;
case AUTH_TIME:
authTimestamp();
break;
case AUTH_RESILIENCE:
authResilienceTag ();
break;
case AUTH_SEQUENCE_AU_COUNTER:
authSequenceAUCounter();
break;
default:
break;
}
}
}
Table 158 — Syntax of authExtConfig
Syntax No. of bits Mnemonic
authExtConfig()
{
authID 8 uimsbf
authHashType = escapedValue(4,8,8); 4, 12, 20 uimsbf
authKeyID = escapedValue(3,8,8); 3, 11, 19 uimsbf
authAddExtTypes 1 uimsbf
authProvID = escapedValue(8,8,16); 8, 16, 32 uimsbf
if (authProvID == 0x00) {
authSourceURILengthMinus1 8 uimsbf
for (i=0; i<= authProvIDLengthMinus1; i++) {
authSourceURI[i] 8 bslbf
© ISO/IEC 2026 – All rights reserved
ISO/IEC 23003-3:2020/FDAM 2:2026(en)
TTaabblle 1e 158 58 ((ccoonnttiinnueuedd))
Syntax No. of bits Mnemonic
}
}
authResilienceLevelMax 4 uimsbf
hasAuthSequenceAUCounter 1 uimsbf
isFirstSequence 1 uimsbf
isAuthCRC 1 uimsbf
if (authAddExtTypes){
authAddExtInclusion 1 uimsbf
authAddExtTypeListLengthMinus1 7 uimsbf
for (i=0; i <= authAddExtTypeListLengthMinus1; i++) {
authAddExtConfigExt[i] 1 blsbf
authAddExtType[i] = escapedValue(7,8,16); 7, 15, 31 uimsbf
}
}
}
Table 159 — Syntax of authExtSig
Syntax No. of bits Mnemonic
authExtSig()
{
authID 8 uimsbf
authPartialSig 1 uimsbf
authABREnable 2 uimsbf
numSig = 1;
if (authABREnable) {
authABRBitrateAtMinMax 2 uimsbf

if (authABREnable==1) {
if(authABRBitrateAtMinMax==1) {
numSig = 2;
} else {
numSig = 3;
}
}
if (authABREnable==2) {
if(authABRBitrateAtMinMax==1) {
numSig = 3;
} else if(authABRBitrateAtMinMax==2) {
numSig = 4;
} else {
numSig = 5;
}
}
© ISO/IEC 2026 – All rights reserved
ISO/IEC 23003-3:2020/FDAM 2:2026(en)
TTabablele 1 15599 ((ccoonnttiinnueuedd))
Syntax No. of bits Mnemonic
}
for (m=0; m<=authResilienceLevelMax; m++)
for (n=0; n if (authPartialSig) {
sigSegmentStart 1 uimsbf
sigSegmentStop 1 uimsbf
sigSegmentLengthMinus1 5 uimsbf
sigPartial (sigSegmentLengthMinus1+1) * 8 uimsbf
} else {
sigLengthMinus1 7 uimsbf
sigComplete (sigLengthMinus1+1) * 8 uimsbf
}
}
}
}
Table 160 — Syntax of authUUID
Syntax No. of bits Mnemonic
authUUID()
{
uuidSegmentStart 1 uimsbf
uuidSegmentStop 1 uimsbf
uuidSegmentLengthMinus1 4 uimsbf
uuid (uuidSegmentLengthMinus1+1)*8 uimsbf
}
Table 161 — Syntax of authTimestamp
Syntax No. of bits Mnemonic
authTimestamp()
{
authID 8 uimsbf
authTimeType 7 uimsbf
authTimeOffsetType 1 uimsbf
switch (authTimeType ) {
case authTimeLong:
authTime = escapedValue(12,16,32); 12, 28, 60 uimsbf
authTimeOffset 12 uimsbf
break;
case authTimeShort:
authTimeS = escapedValue(4,8,8); 4, 12, 20 uimsbf
authTimeOffsetS = escapedValue(4,8,8); 4, 12, 20 uimsbf
break;
case authTimeTAI: { /* acc. ISO/IEC 23001-17 */
TAI_timestamp; 64 uimsbf
© ISO/IEC 2026 – All rights reserved
ISO/IEC 23003-3:2020/FDAM 2:2026(en)
TTabablele 1 16611 ((ccoonnttiinnueuedd))
Syntax No. of bits Mnemonic
status_bits; 8 uimsbf
break;
default:
break;
}
}
Table 162 — Syntax of authResilienceTag
Syntax No. of bits Mnemonic
authResilienceTag()
{
authID 8 uimsbf
numLevels 4 uimsbf
for(i=0; i authResilienceLevel 4 uimsbf
}
}
Table 163 — Syntax of authSequenceAUCounter
Syntax No. of bits Mnemonic
authSequenceAUCounter()
{
authID 8 uimsbf
authSequenceAUCounter escapedValue(8,16,16) uimsbf
}
7.19.3  Media Authenticity Semantics
numAuthExtMinus1 Plus 1 indicates the number of signalled authExtType elements.
authSequence Indicates the authentication sequence to which the related authenti-
cation information belongs to.
authExtType Indicates the type of authentication information signalled.
authID Shall be used to identify the combination of authHashType, auth-
ProvID and authKeyID to which the related authentication informa-
tion belongs to. This may be used to enable authentication of one au-
thentication sequence with different authentication configurations.
authHashType Indicates the hashing algorithm to be used according to Table 164 .

© ISO/IEC 2026 – All rights reserved
ISO/IEC 23003-3:2020/FDAM 2:2026(en)
Table 164 — Values and meaning of authHashType
authHashType Value Hashing algorithm
0 SHA-1
1 SHA-224
2 SHA-256
3 SHA-384
4 SHA-512
All other values /* reserved for ISO use */
authKeyID Identifies the authentication key used to calculate the value of the
signature in authExtSig() according to Table 165. The values of au-
thKeyID are dependent on the authentication provider and are not
defined in the present document. This value shall be set to 0 in case
there is no key needed for the underlying hashing function.
Table 165 — Values and meaning of authKeyID
authKeyID Value Key
0 No key
All values /* Authentication Provider key ID */
authProvID Identifies the provider of the authentication system according to
Table 166. In case authProvID equals to 1, there is no provider.
This mode can be used to create a message digest only by using the
method identified by authHashType.
Table 166 — Values and meaning of authProvID
authProvID Value Authentication Provider URI
0 See authSourceURI.
1 Message Digest only
2-… /* Registration Authority */
authSourceURILengthMinus1 Plus 1 indicates the length of the authSourceURI-field in bytes.
authSourceURI Shall contain a URI with syntax and semantics conforming to
IETF RFC 3986.
authResilienceLevelMax The maximum number of resilience levels that is allowed for this
specific authSequence and authID.
hasAuthSequenceAUCounter If set to 1, every access unit belonging to the auth sequence
identified by authID and authSequence shall contain an authSe-
quenceAUCounter() syntax element.
isFirstSequence Indicates if an authentication sequence is a non-overlapping se-
quence or the first authentication sequence of a set of overlapping
authentication sequences. If set to 1, the authentication sequence
is a non-overlapping sequence or the first authentication se-
quence of a set of overlapping authentication sequences. Other-
wise, the authentication sequence is an overlapping authentica-
tion sequence that is not the first authentication sequence of a set
of overlapping authentication sequences.

© ISO/IEC 2026 – All rights reserved
ISO/IEC 23003-3:2020/FDAM 2:2026(en)
isAuthCRC Indicates if an CRC-based authentication method is used. If set to
1, the used verification mechanism shall generate the signature
(sigPartial or sigComplete) utilizing the data resulting from cal-
culating a CRC as defined in 1.8.4.5 (CRC16) of ISO/IEC 14496-3,
using the syntax elements accordi
...

ISO/IEC 23003-3:2020/FDAMFDAmd 2:2026(en)
ISO/IEC JTC 1/SC 29
Secretariat: JISC
Date: 2026-06-1907-09
Information technology — MPEG audio technologies — —
Part 3:
Unified speech and audio coding — Amendment
AMENDMENT 2: Media authenticity
FDIS stage
ISO/IEC 23003-3:2020/FDAmd 2(en)
© ISO/IEC 20252026
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication
may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying,
or posting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO
at the address below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: + 41 22 749 01 11
EmailE-mail: [e-mail]
Website: www.iso.orgwww.iso.org
Published in Switzerland
© ISO/IEC 2026 – All rights reserved
ii
ISO/IEC 23003-3:2020/DAMFDAmd 2:2025(en)
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.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types of
document should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC
Directives, Part 2 (see www.iso.org/directives or www.iec.ch/members_experts/refdocs).
ISO and IEC draw attention to the possibility that the implementation of this document may involve the use of
(a) patent(s). ISO and IEC take no position concerning the evidence, validity or applicability of any claimed
patent rights in respect thereof. As of the date of publication of this document, ISO and IEC had not received
notice of (a) patent(s) which may be required to implement this document. However, implementers are
cautioned that this may not represent the latest information, which may be obtained from the patent database
available at www.iso.org/patents and https://patents.iec.ch. ISO and IEC shall not be held responsible for
identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www.iso.org/iso/foreword.html.
In the IEC, see www.iec.ch/understanding-standards.
This document was prepared by Joint Technical Committee ISO/IEC JTC 1, Information technology,
Subcommittee SC 29, [name of subcommittee].
A list of all parts in the ISO 23003 series can be found on the ISO and IEC websites.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html and www.iec.ch/national-
committees.
© ISO/IEC 20252026 – All rights reserved
iii
ISO/IEC 23003-3:2020/DAM 2:2025(en)
Information technology — MPEG audio technologies — —
Part 3:
Unified speech and audio coding — Amendment
AMENDMENT 2: Media authenticity

Add the following at the end of Clause 2:
IETF RFC 3986, Uniform Resource Identifier (URI): Generic Syntax
IETF RFC 9562, Universally Unique IDentifiers (UUIDs)

4.4.2
Add the following new subclause:
4.4.2  Audio object types
Currently, this document does not define any audio object types. The range of Object Type ID values 64 to 95
(both 64 and 95 included) is reserved. The data function UsacAotSpecificConfig(audioObjectType) is defined
as empty.
NOTE  ISO/IEC 14496-3 defines Object Type ID value 42 and the associated USAC audio object type.

After Clause 4.5.4 add:
4.5.5  audioProfileLevelIndication
Currently, this document does not define any audioProfileLevelIndication values. The range of
audioProfileLevelIndication values 0x70 to 0x7F (both 0x70 and 0x7F included) is reserved.
NOTE  ISO/IEC 14496-3 defines audioProfileLevelIndication values for the Baseline USAC Profile and for the
Extended HE AAC Profile.
Replace Table 78 with the following:
Table 78 — Value of usacExtElementType
usacExtElementType Value
ID_EXT_ELE_FILL 0
ID_EXT_ELE_MPEGS 1
© ISO/IEC 2025 – All rights reserved
ISO/IEC 23003-3:2020/FDAmd 2(en)
usacExtElementType Value
ID_EXT_ELE_SAOC 2
ID_EXT_ELE_AUDIOPREROLL 3
ID_EXT_ELE_UNI_DRC 4
/* reserved for ISO/IEC 23008-3 use */ 5-14
ID_EXT_ELE_AUTH_INFO 15
/* reserved for ISO use */ 16-127
/* 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.

Replace Table 86 with the following:
Table 86 — Interpretation of data blocks for USAC extension payload decoding
usacExtElementType The concatenated
usacExtElementSegmentData represents:
ID_EXT_ELE_FILL Series of fill_byte
ID_EXT_ELE_MPEGS SpatialFrame()
ID_EXT_ELE_SAOC SaocFrame()
ID_EXT_ELE_AUDIOPREROLL AudioPreRoll()
ID_EXT_ELE_UNI_DRC uniDrcGain() as defined in ISO/IEC 23003--4
ID_EXT_ELE_AUTH_INFO authExtension() as defined in 7.19
unknown unknown data. The data block shall be discarded.

Increment numbering of TableRenumber Tables 157 to 189 by 14 (resulting in numbers ranging fromISO/IEC
23003-3 as Tables 171 to 203).

7.19
Add the following new subclause:
7.19  Media Authenticity
7.19.1  General
Media Authenticity is optional. If supported, the corresponding data is carried in syntax elements as defined
in Table 157, Table 158, Table 159, Table 160, Table 161, Table 162 and Table 163.Table 157, Table 158,
Table 159, Table 160, Table 161, Table 162 and Table 163.
© ISO/IEC 2026 – All rights reserved
ISO/IEC 23003-3:2020/DAMFDAmd 2:2026(en)
MPEG-D USAC decoders used in applications which do not support media authentication as described in the
current section shall ignore the auth_extension() element. The process of media authentication and
verification is out of scope for the MPEG-D USAC audio decoder.
7.19.2  Media Authenticity Syntax
Table 157 — Syntax of authExtension
Syntax No. of bits Mnemonic
authExtension()
{
numAuthExtMinus1 = escapedValue(4,4,4); 4, 8, 12 uimsbf
for (i=0; i <= numAuthExtMinus1; i++) {
authSequence 1 uimsbf
authExtType 3 uimsbf
switch (authExtType) {
case AUTH_START:
authExtConfig();
break;
case AUTH_SIG:
authExtSig();
break;
case AUTH_UUID:
authUUID();
break;
case AUTH_TIME:
authTimestamp();
break;
case AUTH_RESILIENCE:
authResilienceTag ();
break;
case AUTH_SEQUENCE_AU_COUNTER:
authSequenceAUCounter();
break;
default:
break;
}
}
}
© ISO/IEC 2026 – All rights reserved
ISO/IEC 23003-3:2020/FDAmd 2(en)
Table 158 — Syntax of authExtConfig
Syntax No. of bits Mnemonic
authExtConfig()
{
authID 8 uimsbf
authHashType = escapedValue(4,8,8); 4, 12, 20 uimsbf
authKeyID = escapedValue(3,8,8); 3, 11, 19 uimsbf
authAddExtTypes 1 uimsbf
authProvID = escapedValue(8,8,16); 8, 16, 32 uimsbf
if (authProvID == 0x00) {
authSourceURILengthMinus1 8 uimsbf
for (i=0; i<= authProvIDLengthMinus1; i++) {
authSourceURI[i] 8 bslbf
}
}
authResilienceLevelMax 4 uimsbf
hasAuthSequenceAUCounter 1 uimsbf
isFirstSequence 1 uimsbf
isAuthCRC 1 uimsbf
if (authAddExtTypes){
authAddExtInclusion 1 uimsbf
authAddExtTypeListLengthMinus1 7 uimsbf
for (i=0; i <= authAddExtTypeListLengthMinus1; i++) {
authAddExtConfigExt[i] 1 blsbf
authAddExtType[i] = escapedValue(7,8,16); 7, 15, 31 uimsbf
}
}
}
Table 159 — Syntax of authExtSig
Syntax No. of bits Mnemonic
authExtSig()
{
authID 8 uimsbf
authPartialSig 1 uimsbf
authABREnable 2 uimsbf
numSig = 1;
© ISO/IEC 2026 – All rights reserved
ISO/IEC 23003-3:2020/DAMFDAmd 2:2026(en)
Syntax No. of bits Mnemonic
if (authABREnable) {
authABRBitrateAtMinMax 2 uimsbf

if (authABREnable==1) {
if(authABRBitrateAtMinMax==1) {
numSig = 2;
} else {
numSig = 3;
}
}
if (authABREnable==2) {
if(authABRBitrateAtMinMax==1) {
numSig = 3;
} else if(authABRBitrateAtMinMax==2) {
numSig = 4;
} else {
numSig = 5;
}
}
}
for (m=0; m<=authResilienceLevelMax; m++)
for (n=0; n if (authPartialSig) {
sigSegmentStart 1 uimsbf
sigSegmentStop 1 uimsbf
sigSegmentLengthMinus1 5 uimsbf
sigPartial (sigSegmentLengthMinus1+1) * 8 uimsbf
} else {
sigLengthMinus1 7 uimsbf
sigComplete (sigLengthMinus1+1) * 8 uimsbf
}
}
}
}
© ISO/IEC 2026 – All rights reserved
ISO/IEC 23003-3:2020/FDAmd 2(en)
Table 160 — Syntax of authUUID
Syntax No. of bits Mnemonic
authUUID()
{
uuidSegmentStart 1 uimsbf
uuidSegmentStop 1 uimsbf
uuidSegmentLengthMinus1 4 uimsbf
uuid (uuidSegmentLengthMinus1+1)*8 uimsbf
}
Table 161 — Syntax of authTimestamp
Syntax No. of bits Mnemonic
authTimestamp()
{
authID 8 uimsbf
authTimeType 7 uimsbf
authTimeOffsetType 1 uimsbf
switch (authTimeType ) {
case authTimeLong:
authTime = escapedValue(12,16,32); 12, 28, 60 uimsbf
authTimeOffset 12 uimsbf
break;
case authTimeShort:
authTimeS = escapedValue(4,8,8); 4, 12, 20 uimsbf
authTimeOffsetS = escapedValue(4,8,8); 4, 12, 20 uimsbf
break;
case authTimeTAI: { /* acc. ISO/IEC 23001-17 */
TAI_timestamp; 64 uimsbf
status_bits; 8 uimsbf
break;
default:
break;
}
}
—Table 162 — Syntax of authResilienceTag
Syntax No. of bits Mnemonic
authResilienceTag()
{
© ISO/IEC 2026 – All rights reserved
ISO/IEC 23003-3:2020/DAMFDAmd 2:2026(en)
Syntax No. of bits Mnemonic
authID 8 uimsbf
numLevels 4 uimsbf
for(i=0; i authResilienceLevel 4 uimsbf
}
}
Table 163 — Syntax of authSequenceAUCounter
Syntax No. of bits Mnemonic
authSequenceAUCounter()
{
authID 8 uimsbf
authSequenceAUCounter escapedValue(8,16,16) uimsbf
}
7.19.3  Media Authenticity Semantics
numAuthExtMinus1 Plus 1 indicates the number of signalled authExtType elements.
authSequence Indicates the authentication sequence to which the related
authentication information belongs to.
authExtType Indicates the type of authentication information signalled.
authID Shall be used to identify the combination of authHashType,
authProvID and authKeyID to which the related authentication
information belongs to. This may be used to enable authentication of
one authentication sequence with different authentication
configurations.
authHashType Indicates the hashing algorithm to be used according to Table 164
.Table 164 .
Table 164 — Values and meaning of authHashType
authHashType Value Hashing algorithm
0 SHA-1
1 SHA-224
2 SHA-256
3 SHA-384
4 SHA-512
All other values /* reserved for ISO use */

© ISO/IEC 2026 – All rights reserved
ISO/IEC 23003-3:2020/FDAmd 2(en)
authKeyID Identifies the authentication key used to calculate the value of the
signature in authExtSig() according to Table 165.Table 165. The
values of authKeyID are dependent on the authentication provider
and are not defined in the present document. This value shall be set
to 0 in case there is no key needed for the underlying hashing
function.
Table 165 — Values and meaning of authKeyID
authKeyID Value Key
0 No key
All values /* Authentication Provider key ID */

authProvID Identifies the provider of the authentication system according to
Table 166.Table 166. In case authProvID equals to 1, there is no
provider. This mode can be used to create a message digest only by
using the method identified by authHashType.
Table 166 — Values and meaning of authProvID
authProvID Value Authentication Provider URI
0 See authSourceURI.
1 Message Digest only
2-… /* Registration Authority */

authSourceURILengthMinus1 Plus 1 indicates the length of the authSourceURI-field in bytes.
authSourceURI Shall contain a URI with syntax and semantics conforming to IETF
RFC 3986.
authResilienceLevelMax The maximum number of resilience levels that is allowed for this
specific authSequence and authID.
hasAuthSequenceAUCounter If set to 1, every access unit belonging to the auth sequence
identified by authID and authSequence shall contain an
authSequenceAUCounter() syntax element.
isFirstSequence Indicates if an authentication sequence is a non-overlapping
sequence or the first authentication sequence of a set of
overlapping authentication sequences. If set to 1, the
authentication sequence is a non-overlapping sequence or the first
authentication sequence of a set of overlapping authentication
sequences. Otherwise, the authentication sequence is an
overlapping authentication sequence that is not the first
authentication sequence of a set of overlapping authentication
sequences.
isAuthCRC Indicates if an CRC-based authentication method is used. If set to
1, the used verification mechanism shall generate the signature
(sigPartial or sigComplete) utilizing the data resulting from
calculating a CRC as defined in 1.8.4.5 (CRC16) of ISO/IEC 14496-
3, using the syntax elements according to 7.19.4.37.19.4.3 as input.
© ISO/IEC 2026 – All rights reserved
ISO/IEC 23003-3:2020/DAMFDAmd 2:2026(en)
authAddExtTypes Indicates if authentication information for additional extension
types is signalled.
authAddExtInclusion If set to 1, all extension types signalled in authAddExtType shall be
included into the calculation of the authentication information,
according to 7.19.4.7.19.4. If set to 0, all extension types signalled
in authAddExtType shall be excluded from the calculation of the
authentication information, according to 7.19.4.7.19.4.
authAddExtTypeListLengthMinus1 Plus 1 indicates the length of the list of authAddExtType.
authAddExtConfigExt Indicates if ext
...