SIST EN IEC 62680-1-7:2020
(Main)Universal serial bus interfaces for data and power - Part 1-7: Common components - USB Audio 3.0 device class definition data formats (IEC 62680-1-7:2019)
Universal serial bus interfaces for data and power - Part 1-7: Common components - USB Audio 3.0 device class definition data formats (IEC 62680-1-7:2019)
IEC 62680-1-7:2019 describes in detail all the Audio Data Formats that are supported by the Audio Device Class. This document is considered an integral part of the Audio Device Class Specification, although subsequent revisions of this document are independent of the revision evolution of the main USB Audio Specification. This is to easily accommodate the addition of new Audio Data Formats without impeding the core USB Audio Specification.
Schnittstellen des Universellen Seriellen Busses für Daten und Energie - Teil 1-7: Gemeinsame Komponenten - USB Audio 3.0 Geräteklassendefinition Datenformate (IEC 62680-1-7:2019)
Interfaces de bus universel en série pour les données et l'alimentation électrique - Partie 1-7: Composants communs - Définition de classes de dispositifs USB Audio 3.0 pour formats de données (IEC 62680-1-7:2019)
L'IEC 62680-1-7:2019 décrit en détail tous les formats de données audio pris en charge par la classe des dispositifs audio. Le présent document est vu comme faisant partie intégrante de la Spécification de classe de dispositifs audio, bien que les révisions ultérieures du présent document soient indépendantes de l'évolution des révisions de la Spécification USB audio principale. L'objectif est de faciliter la prise en compte de l'ajout de nouveaux formats de données audio sans affecter la Spécification USB audio de base.
Vmesniki univerzalnega serijskega vodila za prenos podatkov in napajanje - 1-7. del: Skupne komponente - Definicija tipa naprave USB Avdio 3.0 za podatkovne formate (IEC 62680-1-7:2019)
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
01-julij-2020
Vmesniki univerzalnega serijskega vodila za prenos podatkov in napajanje - 1-7.
del: Skupne komponente - Definicija tipa naprave USB Avdio 3.0 za podatkovne
formate (IEC 62680-1-7:2019)
Universal serial bus interfaces for data and power - Part 1-7: Common components -
USB Audio 3.0 device class definition data formats (IEC 62680-1-7:2019)
Schnittstellen des Universellen Seriellen Busses für Daten und Energie - Teil 1-7:
Gemeinsame Komponenten - USB Audio 3.0 Geräteklassendefinition Datenformate
(IEC 62680-1-7:2019)
Interfaces de bus universel en série pour les données et l'alimentation électrique - Partie
1-7: Composants communs - Définition de classes de dispositifs USB Audio 3.0 pour
formats de données (IEC 62680-1-7:2019)
Ta slovenski standard je istoveten z: EN IEC 62680-1-7:2019
ICS:
35.200 Vmesniška in povezovalna Interface and interconnection
oprema equipment
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EUROPEAN STANDARD EN IEC 62680-1-7
NORME EUROPÉENNE
EUROPÄISCHE NORM
November 2019
ICS 33.160; 35.100.20
English Version
Universal serial bus interfaces for data and power - Part 1-7:
Common components - USB Audio 3.0 device class definition
data formats
(IEC 62680-1-7:2019)
Interfaces de bus universel en série pour les données et Schnittstellen des Universellen Seriellen Busses für Daten
l'alimentation électrique - Partie 1-7: Composants communs und Energie - Teil 1-7: Gemeinsame Komponenten - USB
- Définition de classes de dispositifs USB Audio 3.0 pour Audio 3.0 Geräteklassendefinition Datenformate
formats de données (IEC 62680-1-7:2019)
(IEC 62680-1-7:2019)
This European Standard was approved by CENELEC on 2019-10-24. CENELEC members are bound to comply with the CEN/CENELEC
Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC
Management Centre or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the
same status as the official versions.
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Turkey and the United Kingdom.
European Committee for Electrotechnical Standardization
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CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2019 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN IEC 62680-1-7:2019 E
European foreword
The text of document 100/3159/CDV, future edition 1 of IEC 62680-1-7, prepared by IEC/TC 100
"Audio, video and multimedia systems and equipment" was submitted to the IEC-CENELEC parallel
vote and approved by CENELEC as EN IEC 62680-1-7:2019.
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2020-07-24
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2022-10-24
document have to be withdrawn
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights.
Endorsement notice
The text of the International Standard IEC 62680-1-7:2019 was approved by CENELEC as a
European Standard without any modification.
IEC 62680-1-7 ®
Edition 1.0 2019-09
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Universal serial bus interfaces for data and power –
Part 1-7: Common components – USB Audio 3.0 device class definition data
formats
Interfaces de bus universel en série pour les données et l'alimentation
électrique –
Partie 1-7: Composants communs – Définition de classes de dispositifs USB
Audio 3.0 pour formats de données
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 33.160; 35.100.20 ISBN 978-2-8322-7243-5
– 2 – IEC 62680-1-7–: 2012 – 9
© USB-IF:1997-2016
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
UNIVERSAL SERIAL BUS INTERFACES FOR DATA AND POWER –
Part 1-7: Common components –
USB Audio 3.0 device class definition data formats
FOREWORD
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all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
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9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 62680-1-7 has been prepared by technical area 18: Multimedia
home systems and applications for end-user networks, of IEC technical committee 100: Audio,
video and multimedia systems and equipment.
The text of this standard was prepared by the USB Implementers Forum (USB-IF). The
structure and editorial rules used in this publication reflect the practice of the organization
which submitted it.
The text of this International Standard is based on the following documents:
CDV Report on voting
100/3159/CDV 100/3229/RVC
Full information on the voting for the approval of this International Standard can be found in
the report on voting indicated in the above table.
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IEC– 63 268– 0-1-7:2019 – 3 –
© USB-IF:1997-2016
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
colour printer.
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© USB-IF:1997-2016
INTRODUCTION
The IEC 62680 series is based on a series of specifications that were originally developed by the USB
Implementers Forum (USB-IF). These specifications were submitted to the IEC under the auspices of
a special agreement between the IEC and the USB-IF.
This standard is the USB-IF publication USB Device Class Definition for Audio Data Formats Release
3.0.
The USB Implementers Forum, Inc.(USB-IF) is a non-profit corporation founded by the group of
companies that developed the Universal Serial Bus specification. The USB-IF was formed to provide a
support organization and forum for the advancement and adoption of Universal Serial Bus technology.
The Forum facilitates the development of high-quality compatible USB peripherals (devices), and
promotes the benefits of USB and the quality of products that have passed compliance testing.
ANY USB SPECIFICATIONS ARE PROVIDED TO YOU "AS IS, "WITH NO WARRANTIES
WHATSOEVER, INCLUDING ANY WARRANTY OF MERCHANTABILITY, NON-INFRINGEMENT,
OR FITNESS FOR ANY PARTICULAR PURPOSE. THE USB IMPLEMENTERS FORUM AND THE
AUTHORS OF ANY USB SPECIFICATIONS DISCLAIM ALL LIABILITY, INCLUDING LIABILITY
FOR INFRINGEMENT OF ANY PROPRIETARY RIGHTS, RELATING TO USE OR
IMPLEMENTATION OR INFORMATION IN THIS SPECIFICAITON.
THE PROVISION OF ANY USB SPECIFICATIONS TO YOU DOES NOT PROVIDE YOU WITH ANY
LICENSE, EXPRESS OR IMPLIED, BY ESTOPPEL OR OTHERWISE, TO ANY INTELLECTUAL
PROPERTY RIGHTS.
Entering into USB Adopters Agreements may, however, allow a signing company to participate in a
reciprocal, RAND-Z licensing arrangement for compliant products. For more information, please see:
https://www.usb.org/documents
IEC DOES NOT TAKE ANY POSITION AS TO WHETHER IT IS ADVISABLE FOR YOU TO ENTER
INTO ANY USB ADOPTERS AGREEMENTS OR TO PARTICIPATE IN THE USB IMPLEMENTERS
FORUM.”
Copyright © 1997-2016 USB Implementers Forum, Inc. All rights reserved.
IEC– 65 268– 0-1-7:2019 – 5 –
© USB-IF:1997-2016
UNIVERSAL SERIAL BUS
DEVICE CLASS DEFINITION
FOR
AUDIO DATA FORMATS
Release 3.0
September 22, 2016
Copyright © 1997-2016 USB Implementers Forum, Inc. All rights reserved.
– 6 – IEC 62680-1-7–: 2016 – 9
© USB-IF:1997-2016
SCOPE OF THIS RELEASE
This document is the Release 3.0 of this device class definition.
CONTRIBUTORS
Joe Scanlon Advanced Micro Devices
Rhoads Hollowell Apple Inc.
Girault Jones Apple Inc.
Matthew X. Mora Apple Inc.
Tzung-Dar Tsai C-Media Electronics, Inc.
Brad Lambert Cirrus Logic, Inc.
Dan Bogard Conexant Systems, Inc.
Pete Burgers DisplayLink (UK), Ltd.
David Roh Dolby Laboratories, Inc.
Leng Ooi Google, Inc.
Pierre-Louis Bossart Intel Corporation
David Hines Intel Corporation
Abdul Rahman Ismail (Co-Chair) Intel Corporation
Devon Worrell Intel Corporation
Chandrashekhar Rao Logitech, Inc.
Terry Moore MCCI Corporation
Alex Lin MediaTek, Inc.
Bala Sivakumar Microsoft Corporation
Geert Knapen (Co-Chair & Editor) NXP Semiconductors
PL Mobile Audio
411 E. Plumeria drive
San Jose, CA 95134, USA
E-mail: geert.knapen@nxp.com
James Goel Qualcomm, Inc.
Andre Schevciw Qualcomm, Inc.
Jin-Sheng Wang Qualcomm, Inc.
Morten Christiansen Synopsys
REVISION HISTORY
Revision Date Filename Description
1.0 Mar. 18, 98 Frmts10.pdf Release 1.0
2.0 May. 31, 06 Frmts20 final.pdf Release 2.0
3.0 Sep. 22, 16 Frmts30.pdf Release 3.0
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IEC– 67 268– 0-1-7:2019 – 7 –
© USB-IF:1997-2016
Copyright © 1997-2016 USB Implementers Forum, Inc.
All rights reserved.
INTELLECTUAL PROPERTY DISCLAIMER
A LICENSE IS HEREBY GRANTED TO REPRODUCE THIS SPECIFICATION FOR INTERNAL USE ONLY. NO OTHER
LICENSE, EXPRESS OR IMPLIED, BY ESTOPPEL OR OTHERWISE, IS GRANTED OR INTENDED HEREBY.
USB-IF AND THE AUTHORS OF THIS SPECIFICATION EXPRESSLY DISCLAIM ALL LIABILITY FOR INFRINGEMENT OF
INTELLECTUAL PROPERTY RIGHTS RELATING TO IMPLEMENTATION OF INFORMATION IN THIS SPECIFICATION.
USB-IF AND THE AUTHORS OF THIS SPECIFICATION ALSO DO NOT WARRANT OR REPRESENT THAT SUCH
IMPLEMENTATION(S) WILL NOT INFRINGE THE INTELLECTUAL PROPERTY RIGHTS OF OTHERS.
THIS SPECIFICATION IS PROVIDED “AS IS” AND WITH NO WARRANTIES, EXPRESS OR IMPLIED, STATUTORY OR
OTHERWISE. ALL WARRANTIES ARE EXPRESSLY DISCLAIMED. USB-IF, ITS MEMBERS AND THE AUTHORS OF THIS
SPECIFICATION PROVIDE NO WARRANTY OF MERCHANTABILITY, NO WARRANTY OF NON-INFRINGEMENT, NO
WARRANTY OF FITNESS FOR ANY PARTICULAR PURPOSE, AND NO WARRANTY ARISING OUT OF ANY PROPOSAL,
SPECIFICATION, OR SAMPLE.
IN NO EVENT WILL USB-IF, MEMBERS OR THE AUTHORS BE LIABLE TO ANOTHER FOR THE COST OF PROCURING
SUBSTITUTE GOODS OR SERVICES, LOST PROFITS, LOSS OF USE, LOSS OF DATA OR ANY INCIDENTAL,
CONSEQUENTIAL, INDIRECT, OR SPECIAL DAMAGES, WHETHER UNDER CONTRACT, TORT, WARRANTY, OR
OTHERWISE, ARISING IN ANY WAY OUT OF THE USE OF THIS SPECIFICATION, WHETHER OR NOT SUCH PARTY
HAD ADVANCE NOTICE OF THE POSSIBILITY OF SUCH DAMAGES.
NOTE: VARIOUS USB-IF MEMBERS PARTICIPATED IN THE DRAFTING OF THIS SPECIFICATION. CERTAIN OF
THESE MEMBERS MAY HAVE DECLINED TO ENTER INTO A SPECIFIC AGREEMENT LICENSING INTELLECTUAL
PROPERTY RIGHTS THAT MAY BE INFRINGED IN THE IMPLEMENTATION OF THIS SPECIFICATION. PERSONS
IMPLEMENT THIS SPECIFICATION AT THEIR OWN RISK.
Dolby™, AC-3™, Pro Logic™ and Dolby Surround™ are trademarks of Dolby Laboratories, Inc.
All other product names are trademarks, registered trademarks, or service marks of their respective owners.
Please send comments via electronic mail to audio-chair@usb.org
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© USB-IF:1997-2016
TABLE OF CONTENTS
Scope of This Release . 6
Contributors . 6
Revision History . 6
Table of Contents . 8
List of Tables . 9
List of Figures . 10
1 Introduction . 10
1.1 Related Documents . 11
1.2 Terms and Abbreviations . 11
2 Audio Data Formats . 13
2.1 Transfer Delimiter . 14
2.2 Service Interval and Service Interval Packet Definitions . 14
2.3 Simple Audio Data Formats . 14
2.3.1 Type I Formats . 14
2.3.2 Type III Formats . 18
2.3.3 Type IV Formats . 19
2.4 Extended Audio Data Formats . 19
2.4.1 Extended Type I Formats . 20
2.4.2 Extended Type III Formats . 21
2.5 Class-specific AS Interface Descriptor . 21
3 Auxiliary Protocols . 23
3.1 HDCP Protocol . 23
4 Adding New Audio Data Formats . 24
5 Adding New Side Band Protocols . 25
Appendix A. Additional Audio Device Class Codes . 26
A.1 Audio Data Formats Bit Allocations . 26
A.2 SubHeader Codes . 27
A.3 Audio Format General Constants . 27
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© USB-IF:1997-2016
LIST OF TABLES
Table 2-1: Packetization . 16
Table 2-2: SIPDescriptor Layout . 20
Table 2-3: Class-Specific AS Interface Descriptor . 22
Table 3-1: HDCP SubHeader Layout . 23
Table A-2: Audio Data Formats Bit Allocations in the bmFormats Field and Usage . 26
Table A-3: SubHeader Codes . 27
Table A-4: General Constants. 27
Copyright © 1997-2016 USB Implementers Forum, Inc. All rights reserved.
– 10 – IEC 62680-1–-7 10:201 – 9
© USB-IF:1997-2016
LIST OF FIGURES
Figure 2-1: Type I Audio Stream . 13
Figure 2-2: Extended Type I Format . 21
Figure 2-3: Extended Type III Format . 21
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IEC– 611268 – 0-1-7:2019 – 11 –
© USB-IF:1997-2016
1 INTRODUCTION
The intention of this document is to describe in detail all the Audio Data Formats that are supported by the
Audio Device Class. This document is considered an integral part of the Audio Device Class Specification,
although subsequent revisions of this document are independent of the revision evolution of the main USB
Audio Specification. This is to easily accommodate the addition of new Audio Data Formats without impeding
the core USB Audio Specification.
1.1 RELATED DOCUMENTS
• Universal Serial Bus Specification, Revision 2.0 (referred to in this document as the USB Specification). In
particular, see Chapter 5, “USB Data Flow Model” and Chapter 9, “USB Device Framework.”
• Universal Serial Bus Device Class Definition for Audio Devices (referred to in this document as USB Audio
Device Class).
• Universal Serial Bus Device Class Definition for Terminal Types (referred to in this document as USB Audio
Terminal Types).
• ANSI S1.11-1986 standard.
• MPEG-1 standard ISO/IEC 111172-3 1993. (available from http://www.iso.ch )
• MPEG-2 standard ISO/IEC 13818-3 Feb. 20, 1997. (available from http://www.iso.ch)
• Digital Audio Compression Standard (AC-3), ATSC A/52A Aug. 20, 2001. (available from
http://www.atsc.org )
• Windows Media Audio (WMA) specification. (available from http://www.microsoft.com)
• ANSI/IEEE-754 floating-point standard.
• ISO/IEC 60958 International Standard: Digital Audio Interface and Annexes.
• ISO/IEC 61937 standard.
• ITU G.711 standard.
• ETSI Specification TS 102 114, “DTS Coherent Acoustics; Core and Extensions”. (Available from
http://webapp.etsi.org/action%5CPU/20020827/ts_102114v010101p.pdf)
1.2 TERMS AND ABBREVIATIONS
This section defines terms used throughout this document. For additional terms that pertain to the Universal
Serial Bus, see Chapter 2, “Terms and Abbreviations,” in the USB Specification.
AC-3 Audio compression standard from Dolby Labs.
Audio Slot A collection of audio subslots, each containing a PCM audio
sample of a different physical audio channel, taken at the same
moment in time.
Audio Stream A concatenation of a potentially very large number of audio
slots ordered according to ascending time.
Audio Subslot Holds a single PCM audio sample.
DTS Acronym for Digital Theater Systems.
DVD Acronym for Digital Versatile Disc.
Encoded Audio Bit Stream A concatenation of a potentially very large number of encoded
audio frames, ordered according to ascending time.
Copyright © 1997-2016 USB Implementers Forum, Inc. All rights reserved.
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© USB-IF:1997-2016
Encoded Audio Frame A sequence of bits that contains an encoded representation of
audio samples from one or more physical audio channels taken
over a fixed period of time.
MPEG Acronym for Moving Pictures Expert Group.
PCM Acronym for Pulse Coded Modulation.
Service Interval A grouping of USB (micro)frames or Bus Intervals that are
related.
Service Interval Packet A packet that contains all the audio slots that are transferred
over the bus during a Service Interval.
Transfer Delimiter A unique token that indicates an interruption in an isochronous
data packet stream. Can be either a zero-length data packet or
the absence of an isochronous transfer in a certain USB frame.
WMA Acronym for Windows Media Audio.
Copyright © 1997-2016 USB Implementers Forum, Inc. All rights reserved.
IEC– 613268 – 0-1-7:2019 – 13 –
© USB-IF:1997-2016
2 AUDIO DATA FORMATS
Audio Data formats can be divided in two main groups:
• Simple Audio Data Formats
• Extended Audio Data Formats
Simple Audio Data Formats can then be subdivided into three groups according to type.
The first group, Type I, deals with audio data streams that are transmitted over USB and are constructed on a
sample-by-sample basis. Each audio sample is represented by a single independent symbol, contained in an
audio subslot. Different compression schemes may be used to transform the audio samples into symbols.
Note: This is different from encoding. Compression is considered to take place on a per-audio-sample
base. Each audio sample generates one symbol (e.g. A-law compression where a 16-bit audio
sample is compressed into an 8-bit symbol).
If multiple physical audio channels are formatted into a single audio channel cluster, then samples at time x of
subsequent channels are first contained into audio subslots. These audio subslots are then interleaved,
according to the cluster channel ordering as described in the main USB Audio Specification, and then grouped
into an audio slot. The audio samples, taken at time x+1, are interleaved in the same fashion to generate the
next audio slot and so on. The notion of physical channels is explicitly preserved during transmission. A typical
example of Type I formats is the standard PCM audio data. The following figure illustrates the concept.
Figure 2-1: Type I Audio Stream
The second group, Type III, contains Audio Data Formats that use encapsulation as described in the ISO/IEC
61937 standard before being sent over USB. One or more non-PCM encoded audio data streams are packed
into “pseudo-stereo samples” and transmitted as if they were real stereo PCM audio samples. The sampling
frequency of these pseudo samples (transport sampling frequency, as reported by the Clock Frequency Control
of the associated Clock Source Entity) either matches the sampling frequency of the original non-encoded PCM
audio data streams (native sampling frequency) or there is an integer ratio relationship between them.
Therefore, clock recovery at the receiving end is relatively easy. The drawback is that unless multiple non-PCM
encoded streams are packed into one pseudo stereo stream, more bandwidth than necessary is consumed.
The third group, Type IV, deals with audio streams that are not transmitted over USB. Instead, they interface
with the Audio Function through an AudioStreaming interface that does not contain a USB isochronous IN or
OUT endpoint. These streams typically connect via a digital interface like S/PDIF (or some other means of
connectivity) and may require interaction from the Host before they enter or leave the Audio Function. A
Copyright © 1997-2016 USB Implementers Forum, Inc. All rights reserved.
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© USB-IF:1997-2016
typical example is an external S/PDIF connector that can accept an AC-3 encoded audio stream. This stream is
first processed by an AC-3 decoder before the (decoded) logical audio channels enter the Audio Function
through the Input Terminal that represents this S/PDIF connection.
In addition to the Simple Audio Data Formats described above, Extended Audio Data Formats are defined.
These are based on the Simple Audio Data Formats Type I and III definitions but they provide an optional
packet header and for the Extended Audio Data Format Type I, an optional synchronous (i.e. sample accurate)
control channel. Type IV Audio Data Formats do not have an Extended Audio Data Format definition.
The following sections explain the different Audio Data Formats and Format Types in more detail.
2.1 TRANSFER DELIMITER
Isochronous data streams are continuous in nature, although the actual number of bytes sent per packet may
vary throughout the lifetime of the stream (for rate adaptation purposes for instance). To indicate a temporary
stop in the isochronous data stream without closing the pipe (and thus relinquishing the USB bandwidth), an in-
band Transfer Delimiter needs to be defined. This specification considers two situations to be a Transfer
Delimiter. The first is a zero-length data packet and the second is the absence of an isochronous transfer in a
USB (micro)frame that would normally have an isochronous transfer. Both situations are considered equivalent
and the Audio Function is expected to behave the same. However, the second type consumes less isochronous
USB bandwidth (i.e. zero bandwidth). In both cases, this specification considers a Transfer Delimiter to be an
entity that can be sent over the USB.
2.2 SERVICE INTERVAL AND SERVICE INTERVAL PACKET DEFINITIONS
Note: The USB Audio 2.0 Specification used the terms Virtual Frame and Virtual Frame Packet to
describe the same concepts that were called Service Interval and Service Interval Packet in the
USB 3.0 and higher Specifications. In this specification, the terminology has been consolidated to
use the more general terms of Service Interval and Service Interval Packet instead of the USB
Audio 2.0-specific terminology of Virtual Frame and Virtual Frame Packet. Also, the term Bus
Interval is used instead of USB (micro)frame, wherever applicable.
In the following paragraphs, the packetizing process for audio is described in terms of Service Interval and
Service Interval Packets. This provides a consistent model of ‘one Service Interval Packet (SIP) per Service
Interval (SI)’, irrespe
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