draft-ietf-rtcweb-audio-codecs-for-interop-02.txt   draft-ietf-rtcweb-audio-codecs-for-interop-03.txt 
Network Working Group S. Proust Network Working Group S. Proust
Internet-Draft Orange Internet-Draft Orange
Intended status: Informational E. Berger Intended status: Informational December 2, 2015
Expires: February 8, 2016 Cisco Expires: June 4, 2016
B. Feiten
Deutsche Telekom
B. Burman
Ericsson
K. Bogineni
Verizon Wireless
M. Lei
Huawei
E. Marocco
Telecom Italia
August 7, 2015
Additional WebRTC audio codecs for interoperability. Additional WebRTC audio codecs for interoperability.
draft-ietf-rtcweb-audio-codecs-for-interop-02 draft-ietf-rtcweb-audio-codecs-for-interop-03
Abstract Abstract
To ensure a baseline level of interoperability between WebRTC To ensure a baseline level of interoperability between WebRTC
clients, [I-D.ietf-rtcweb-audio] requires a minimum set of codecs. clients, a minimum set of required codecs is specified. However, to
However, to maximize the possibility to establish the session without maximize the possibility to establish the session without the need
the need for audio transcoding, it is also recommended to include in for audio transcoding, it is also recommended to include in the offer
the offer other suitable audio codecs that are available to the other suitable audio codecs that are available to the browser.
browser.
This document provides some guidelines on the suitable codecs to be This document provides some guidelines on the suitable codecs to be
considered for WebRTC clients to address the most relevant considered for WebRTC clients to address the most relevant
interoperability use cases. interoperability use cases.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on February 8, 2016.
This Internet-Draft will expire on June 4, 2016.
Copyright Notice Copyright Notice
Copyright (c) 2015 IETF Trust and the persons identified as the Copyright (c) 2015 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Definitions . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Definition and abbreviations . . . . . . . . . . . . . . . . 3
3. Rationale for additional WebRTC codecs . . . . . . . . . . . 3 3. Rationale for additional WebRTC codecs . . . . . . . . . . . 3
4. Additional suitable codecs for WebRTC . . . . . . . . . . . . 4 4. Additional suitable codecs for WebRTC . . . . . . . . . . . . 5
4.1. AMR-WB . . . . . . . . . . . . . . . . . . . . . . . . . 5 4.1. AMR-WB . . . . . . . . . . . . . . . . . . . . . . . . . 5
4.1.1. AMR-WB General description . . . . . . . . . . . . . 5 4.1.1. AMR-WB General description . . . . . . . . . . . . . 5
4.1.2. WebRTC relevant use case for AMR-WB . . . . . . . . . 5 4.1.2. WebRTC relevant use case for AMR-WB . . . . . . . . . 5
4.1.3. Guidelines for AMR-WB usage and implementation with 4.1.3. Guidelines for AMR-WB usage and implementation with
WebRTC . . . . . . . . . . . . . . . . . . . . . . . 5 WebRTC . . . . . . . . . . . . . . . . . . . . . . . 5
4.2. AMR . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 4.2. AMR . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
4.2.1. AMR General description . . . . . . . . . . . . . . . 6 4.2.1. AMR General description . . . . . . . . . . . . . . . 6
4.2.2. WebRTC relevant use case for AMR . . . . . . . . . . 6 4.2.2. WebRTC relevant use case for AMR . . . . . . . . . . 6
4.2.3. Guidelines for AMR usage and implementation with 4.2.3. Guidelines for AMR usage and implementation with
WebRTC . . . . . . . . . . . . . . . . . . . . . . . 6 WebRTC . . . . . . . . . . . . . . . . . . . . . . . 7
4.3. G.722 . . . . . . . . . . . . . . . . . . . . . . . . . . 7 4.3. G.722 . . . . . . . . . . . . . . . . . . . . . . . . . . 7
4.3.1. G.722 General description . . . . . . . . . . . . . . 7 4.3.1. G.722 General description . . . . . . . . . . . . . . 7
4.3.2. WebRTC relevant use case for G.722 . . . . . . . . . 7 4.3.2. WebRTC relevant use case for G.722 . . . . . . . . . 7
4.3.3. Guidelines for G.722 usage and implementation . . . . 7 4.3.3. Guidelines for G.722 usage and implementation . . . . 8
4.4. Other codecs . . . . . . . . . . . . . . . . . . . . . . 7 4.4. Other codecs . . . . . . . . . . . . . . . . . . . . . . 8
5. Security Considerations . . . . . . . . . . . . . . . . . . . 8 5. Security Considerations . . . . . . . . . . . . . . . . . . . 8
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 8 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
8.1. Normative references . . . . . . . . . . . . . . . . . . 8 8.1. Normative references . . . . . . . . . . . . . . . . . . 9
8.2. Informative references . . . . . . . . . . . . . . . . . 8 8.2. Informative references . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 11
1. Introduction 1. Introduction
As indicated in [I-D.ietf-rtcweb-overview], it has been anticipated As indicated in [I-D.ietf-rtcweb-overview], it has been anticipated
that WebRTC will not remain an isolated island and that some WebRTC that WebRTC will not remain an isolated island and that some WebRTC
endpoints will need to communicate with devices used in other endpoints will need to communicate with devices used in other
existing networks with the help of a gateway. Therefore, in order to existing networks with the help of a gateway. Therefore, in order to
maximize the possibility to establish the session without the need maximize the possibility to establish the session without the need
for audio transcoding, it is recommended in [I-D.ietf-rtcweb-audio] for audio transcoding, it is recommended in [I-D.ietf-rtcweb-audio]
to include in the offer other suitable audio codecs that are to include in the offer other suitable audio codecs that are
available to the browser. This document provides some guidelines on available to the browser. This document provides some guidelines on
the suitable codecs to be considered for WebRTC clients to address the suitable codecs to be considered for WebRTC clients to address
the most relevant interoperability use cases. the most relevant interoperability use cases.
The codecs considered in this document are recommended to be The codecs considered in this document are recommended to be
supported and included in the Offer only for WebRTC clients for which supported and included in the Offer only for WebRTC clients for which
interoperability with other non WebRTC end points and non WebRTC interoperability with other non-WebRTC endpoints and non-WebRTC based
based services is relevant as described in sections 5.1.2, 5.2.2 and services is relevant as described in Section 4.1.2, Section 4.2.2,
5.3.2. Other use cases may justify offering other additional codecs Section 4.3.2. Other use cases may justify offering other additional
to avoid transcodings. It is the intent of this document to codecs to avoid transcodings.
inventory and document any other additional interoperability use
cases and codecs if needed.
2. Definitions 2. Definition and abbreviations
Legacy networks: In this draft, legacy networks encompass the o Legacy networks: In this document, legacy networks encompass the
conversational networks that are already deployed like the PSTN, the conversational networks that are already deployed like the PSTN,
PLMN, the IMS, H.323 networks. the PLMN, the IP/IMS networks offering VoIP services, including
3GPP "4G" Evolved Packet System[TS23.002] supporting voice over
LTE radio access (VoLTE) [IR.92].
o AMR: Adaptive Multi-Rate.
o AMR-WB: Adaptive Multi-Rate WideBand.
o CAT-iq: Cordless Advanced Technology-internet and quality.
o DECT: Digital Enhanced Cordless Telecommunications
o IMS: IP Multimedia Subsystem
o LTE: Long Term Evolution (3GPP "4G" wireless data transmission
standard)
o MOS: Mean Opinion Score
o PSTN:Public Switched Telephone Network
o PLMN: Public Land Mobile Network
o VoLTE: Voice Over LTE
3. Rationale for additional WebRTC codecs 3. Rationale for additional WebRTC codecs
The mandatory implementation of OPUS [RFC6716] in WebRTC clients can The mandatory implementation of OPUS [RFC6716] in WebRTC clients can
guarantee the codec interoperability (without transcoding) at the guarantee codec interoperability (without transcoding) at state of
state of the art voice quality (better than narrow band "PSTN" the art voice quality (better than narrow band "PSTN" quality)
quality) between WebRTC clients. The WebRTC technology is however between WebRTC clients. The WebRTC technology is also expected to be
expected to be used to communicate with other types of clients using used to communicate with other types of clients using other
other technologies. It can be used for instance as an access technologies. It can be used for instance as an access technology to
technology to 3GPP IMS services (e.g. VoLTE, ViLTE) or to VoLTE services (Voice over LTE as specified in [IR.92]) or to
interoperate with fixed or mobile Circuit Switched or VoIP services interoperate with fixed or mobile Circuit Switched or VoIP services
like mobile 3GPP 3G/2G Circuit Switched voice or DECT based VoIP like mobile Circuit Switched voice over 3GPP 2G/3G mobile networks
telephony. Consequently, a significant number of calls are likely to
occur between terminals supporting WebRTC clients and other terminals [TS23.002] or DECT based VoIP telephony [EN300175-1]. Consequently,
like mobile handsets, fixed VoIP terminals, DECT terminals that do a significant number of calls are likely to occur between terminals
not support WebRTC clients nor implement OPUS. As a consequence, supporting WebRTC clients and other terminals like mobile handsets,
these calls are likely to be either of low narrow band PSTN quality fixed VoIP terminals, DECT terminals that do not support WebRTC
using G.711 at both ends or affected by transcoding operations. The clients nor implement OPUS. As a consequence, these calls are likely
drawbacks of such transcoding operations are recalled below: to be either of low narrow band PSTN quality using G.711 [G.711] at
both ends or affected by transcoding operations. The drawbacks of
such transcoding operations are recalled below:
o Degraded user experience with respect to voice quality: voice o Degraded user experience with respect to voice quality: voice
quality is significantly degraded by transcoding. For instance, quality is significantly degraded by transcoding. For instance,
the degradation is around 0.2 to 0.3 MOS for most of transcoding the degradation is around 0.2 to 0.3 MOS for most of transcoding
use cases with AMR-WB at 12.65 kbit/s and in the same range for use cases with AMR-WB codec (Section 4.1) at 12.65 kbit/s and in
other wideband transcoding cases. It should be stressed that if the same range for other wideband transcoding cases. It should be
G.711 is used as a fall back codec for interoperation, wideband stressed that if G.711 is used as a fall back codec for
voice quality will be lost. Such bandwidth reduction effect down interoperation, wideband voice quality will be lost. Such
to narrow band clearly degrades the user perceived quality of bandwidth reduction effect down to narrow band clearly degrades
service leading to shorter and less frequent calls. Such a switch the user perceived quality of service leading to shorter and less
to G.711 is less than desirable or acceptable choice for frequent calls. Such a switch to G.711 is less than desirable or
customers. If transcoding is performed between OPUS and any other acceptable choice for customers. If transcoding is performed
wideband codec, wideband communication could be maintained but between OPUS and any other wideband codec, wideband communication
with degraded quality (MOS scores of transcoding between AMR-WB could be maintained but with degraded quality (MOS scores of
12.65 kbit/s and OPUS at 16 kbit/s in both directions are transcoding between AMR-WB 12.65 kbit/s and OPUS at 16 kbit/s in
significantly lower than those of AMR-WB at 12.65 kbit/s or OPUS both directions are significantly lower than those of AMR-WB at
at 16 kbit/s). Furthermore, in degraded conditions, the addition 12.65 kbit/s or OPUS at 16 kbit/s). Furthermore, in degraded
of defects, like audio artifacts due to packet losses, and the conditions, the addition of defects, like audio artifacts due to
audio effects resulting from the cascading of different packet packet losses, and the audio effects resulting from the cascading
loss recovery algorithms may result in a quality below the of different packet loss recovery algorithms may result in a
acceptable limit for the customers. quality below the acceptable limit for the customers.
o Degraded user experience with respect to conversational o Degraded user experience with respect to conversational
interactivity: the degradation of conversational interactivity is interactivity: the degradation of conversational interactivity is
due to the increase of end to end latency for both directions that due to the increase of end to end latency for both directions that
is introduced by the transcoding operations. Transcoding requires is introduced by the transcoding operations. Transcoding requires
full de-packetization for decoding of the media stream (including full de-packetization for decoding of the media stream (including
mechanisms of de-jitter buffering and packet loss recovery) then mechanisms of de-jitter buffering and packet loss recovery) then
re-encoding, re-packetization and re-sending. The delays produced re-encoding, re-packetization and re-sending. The delays produced
by all these operations are additive and may increase the end to by all these operations are additive and may increase the end to
end delay beyond acceptable limits like with more than 1s end to end delay beyond acceptable limits like with more than 1s end to
end latency. end latency.
o Additional costs in networks: transcoding places important o Additional costs in networks: transcoding places important
additional costs on network gateways mainly related to codec additional costs on network gateways mainly related to codec
implementation, codecs license, deployments, testing and implementation, codecs license, deployments, testing and
validation costs. It must be noted that transcoding of wideband validation costs. It must be noted that transcoding of wideband
to wideband would require more CPU and be more costly than between to wideband would require more CPU processing and be more costly
narrowband codecs. than between narrowband codecs.
4. Additional suitable codecs for WebRTC 4. Additional suitable codecs for WebRTC
The following codecs are considered as relevant suitable codecs with The following codecs are considered as relevant suitable codecs with
respect to the general purpose described in section 4. This list respect to the general purpose described in Section 3. This list
reflects the current status of WebRTC foreseen use cases. It is not reflects the current status of WebRTC foreseen use cases. It is not
limitative and opened to further inclusion of other codecs for which limitative and opened to further inclusion of other codecs for which
relevant use cases can be identified. These additional codecs are relevant use cases can be identified. These additional codecs are
recommended to be included in the offer in addition to OPUS and G.711 recommended to be included in the offer in addition to OPUS and G.711
according to the foreseen interoperability cases to be addressed. according to the foreseen interoperability cases to be addressed.
4.1. AMR-WB 4.1. AMR-WB
4.1.1. AMR-WB General description 4.1.1. AMR-WB General description
The Adaptive Multi-Rate WideBand (AMR-WB) is a 3GPP defined speech The Adaptive Multi-Rate WideBand (AMR-WB) is a 3GPP defined speech
codec that is mandatory to implement in any 3GPP terminal that codec that is mandatory to implement in any 3GPP terminal that
supports wideband speech communication. It is being used in circuit supports wideband speech communication. It is being used in circuit
switched mobile telephony services and new multimedia telephony switched mobile telephony services and new multimedia telephony
services over IP/IMS and 4G/VoLTE, specified by GSMA as voice IMS services over IP/IMS like for voice over LTE as specified by GSMA in
profile for VoLTE in [IR.92]. More detailed information on AMR-WB [IR.92]. More detailed information on AMR-WB can be found in
can be found in [IR.36]. [IR.36] includes references for all 3GPP [IR.36]. References for AMR-WB related specifications including
AMR-WB related specifications including detailed codec description detailed codec description and Source code are in [TS26.171],
and Source code. [TS26.173], [TS26.190], [TS26.204].
4.1.2. WebRTC relevant use case for AMR-WB 4.1.2. WebRTC relevant use case for AMR-WB
The market of voice personal communication is driven by mobile The market of personal voice communication is driven by mobile
terminals. AMR-WB is now implemented in several hundreds of devices terminals. AMR-WB is now implemented in several hundreds of devices
models and more than 130 HD mobile networks in 80 countries with a models and 145 HD mobile networks in 85 countries with a customer
customer base of more than 300 millions. A high number of calls are base of more than 450 millions. A high number of calls are
consequently likely to occur between WebRTC clients and mobile 3GPP consequently likely to occur between WebRTC clients and mobile 3GPP
terminals. The use of AMR-WB by WebRTC clients would consequently terminals. The use of AMR-WB by WebRTC clients would consequently
allow transcoding free interoperation with all mobile 3GPP wideband allow transcoding free interoperation with all mobile 3GPP wideband
terminal. Besides, WebRTC clients running on mobile terminals terminals. Besides, WebRTC clients running on mobile terminals
(smartphones) may reuse the AMR-WB codec already implemented on these (smartphones) may reuse the AMR-WB codec already implemented on these
devices. devices.
4.1.3. Guidelines for AMR-WB usage and implementation with WebRTC 4.1.3. Guidelines for AMR-WB usage and implementation with WebRTC
Guidelines for implementing and using AMR-WB and ensuring The payload format to be used for AMR-WB is described in [RFC4867]
interoperability with 3GPP mobile services can be found in with bandwidth efficient format and one speech frame encapsulated in
[TS26.114]. In order to ensure interoperability with 4G/VoLTE as each RTP packets. Further guidelines for implementing and using AMR-
specified by GSMA, the more specific IMS profile for voice derived WB and ensuring interoperability with 3GPP mobile services can be
from [TS26.114] should be considered in [IR.92]. In order to found in [TS26.114]. In order to ensure interoperability with 4G/
VoLTE as specified by GSMA, the more specific IMS profile for voice
derived from [TS26.114] should be considered in [IR.92]. In order to
maximize the possibility of successful call establishment for WebRTC maximize the possibility of successful call establishment for WebRTC
client offering AMR-WB it is important that the WebRTC client: client offering AMR-WB it is important that the WebRTC client:
o Offer AMR in addition to AMR-WB with AMR-WB, being a wideband o Offer AMR in addition to AMR-WB with AMR-WB, being a wideband
codec, listed first as preferred payload type with respect to codec, listed first as preferred payload type with respect to
other narrow band codecs (AMR, G.711...)and with Bandwidth other narrow band codecs (AMR, G.711...)and with Bandwidth
Efficient payload format preferred. Efficient payload format preferred.
o Be capable of operating AMR-WB with any subset of the nine codec o Be capable of operating AMR-WB with any subset of the nine codec
modes and source controlled rate operation. Offer at least one modes and source controlled rate operation. Offer at least one
AMR-WB configuration with parameter settings as defined in AMR-WB configuration with parameter settings as defined in
Table 6.1 of [TS 26.114]. In order to maximize the Table 6.1 of [TS26.114]. In order to maximize the
interoperability and quality this offer does not restrict the interoperability and quality this offer does not restrict the
codec modes offered. Restrictions in the use of codec modes may codec modes offered. Restrictions in the use of codec modes may
be included in the answer. be included in the answer.
4.2. AMR 4.2. AMR
4.2.1. AMR General description 4.2.1. AMR General description
Adaptive Multi-Rate (AMR) is a 3GPP defined speech codec that is Adaptive Multi-Rate (AMR) is a 3GPP defined speech codec that is
mandatory to implement in any 3GPP terminal that supports voice mandatory to implement in any 3GPP terminal that supports voice
communication, i.e. several hundred millions of terminals. This communication, i.e. several hundred millions of terminals. This
include both mobile phone calls using GSM and 3G cellular systems as include both mobile phone calls using GSM and 3G cellular systems as
well as multimedia telephony services over IP/IMS and 4G/VoLTE, such well as multimedia telephony services over IP/IMS and 4G/VoLTE, such
as GSMA voice IMS profile for VoLTE in [IR.92]. In addition to as GSMA voice IMS profile for VoLTE in [IR.92]. In addition to
impacts listed above, support of AMR can avoid degrading the high impacts listed above, support of AMR can avoid degrading the high
efficiency over mobile radio access. efficiency over mobile radio access.References for AMR related
specifications including detailed codec description and Source code
are in [TS26.071], [TS26.073], [TS26.090], [TS26.104].
4.2.2. WebRTC relevant use case for AMR 4.2.2. WebRTC relevant use case for AMR
A user of a WebRTC endpoint on a device integrating an AMR module A user of a WebRTC endpoint on a device integrating an AMR module
wants to communicate with another user that can only be reached on a wants to communicate with another user that can only be reached on a
mobile device that only supports AMR. Although more and more mobile device that only supports AMR. Although more and more
terminal devices are now "HD voice" and support AMR-WB; there is terminal devices are now "HD voice" and support AMR-WB; there is
still a high number of legacy terminals supporting only AMR still a high number of legacy terminals supporting only AMR
(terminals with no wideband / HD Voice capabilities) are still used. (terminals with no wideband / HD Voice capabilities) are still used.
The use of AMR by WebRTC client would consequently allow transcoding The use of AMR by WebRTC client would consequently allow transcoding
free interoperation with all mobile 3GPP terminals. Besides, WebRTC free interoperation with all mobile 3GPP terminals. Besides, WebRTC
client running on mobile terminals (smartphones) may reuse the AMR client running on mobile terminals (smartphones) may reuse the AMR
codec already implemented on these devices. codec already implemented on these devices.
4.2.3. Guidelines for AMR usage and implementation with WebRTC 4.2.3. Guidelines for AMR usage and implementation with WebRTC
Guidelines for implementing and using AMR with purpose to ensure The payload format to be used for AMR is described in [RFC4867] with
interoperability with 3GPP mobile services can be found in bandwidth efficient format and one speech frame encapsulated in each
[TS26.114]. In order to ensure interoperability with 4G/VoLTE as RTP packets. Further guidelines for implementing and using AMR with
specified by GSMA, the more specific IMS profile for voice derived purpose to ensure interoperability with 3GPP mobile services can be
from [TS26.114] should be considered in [IR.92]. In order to found in [TS26.114]. In order to ensure interoperability with 4G/
VoLTE as specified by GSMA, the more specific IMS profile for voice
derived from [TS26.114] should be considered in [IR.92]. In order to
maximize the possibility of successful call establishment for WebRTC maximize the possibility of successful call establishment for WebRTC
client offering AMR, it is important that the WebRTC client: client offering AMR, it is important that the WebRTC client:
o Be capable of operating AMR with any subset of the eight codec o Be capable of operating AMR with any subset of the eight codec
modes and source controlled rate operation. modes and source controlled rate operation.
o Offer at least one configuration with parameter settings as o Offer at least one configuration with parameter settings as
defined in Table 6.1 and Table 6.2 of [TS26.114]. In order to defined in Table 6.1 and Table 6.2 of [TS26.114]. In order to
maximize the interoperability and quality this offer shall not maximize the interoperability and quality this offer shall not
restrict AMR codec modes offered. Restrictions in the use of restrict AMR codec modes offered. Restrictions in the use of
codec modes may be included in the answer. codec modes may be included in the answer.
4.3. G.722 4.3. G.722
4.3.1. G.722 General description 4.3.1. G.722 General description
G.722 is an ITU-T defined wideband speech codec. [G.722] was G.722 [G.722] is an ITU-T defined wideband speech codec. G.722 was
approved by ITU-T in 1988. It is a royalty free codec that is common approved by ITU-T in 1988. It is a royalty free codec that is common
in a wide range of terminals and end-points supporting wideband in a wide range of terminals and endpoints supporting wideband speech
speech and requiring low complexity. The complexity of G.722 is and requiring low complexity. The complexity of G.722 is estimated
estimated to 10 MIPS [EN300175-8] which is 2.5 to 3 times lower than to 10 MIPS [EN300175-8] which is 2.5 to 3 times lower than AMR-WB.
AMR-WB. Especially, G.722 has been chosen by ETSI DECT as the Especially, G.722 has been chosen by ETSI DECT as the mandatory
mandatory wideband codec for New Generation DECT with purpose to wideband codec for New Generation DECT with purpose to greatly
greatly increase the voice quality by extending the bandwidth from increase the voice quality by extending the bandwidth from narrow
narrow band to wideband. G.722 is the wideband codec required for band to wideband. G.722 is the wideband codec required for CAT-iq
CAT-iq DECT certified terminal and the V2.0 of CAT-iq specifications DECT certified terminals and the V2.0 of CAT-iq specifications have
have been approved by GSMA as minimum requirements for HD voice logo been approved by GSMA as minimum requirements for HD voice logo usage
usage on "fixed" devices; i.e., broadband connections using the G.722 on "fixed" devices; i.e., broadband connections using the G.722
codec. codec.
4.3.2. WebRTC relevant use case for G.722 4.3.2. WebRTC relevant use case for G.722
G.722 is the wideband codec required for DECT CAT-iq terminals. The G.722 is the wideband codec required for DECT CAT-iq terminals. The
market for DECT cordeless phones including DECT chipset is more than market for DECT cordless phones including DECT chipset is more than
150 Millions per year and CAT-IQ is a registered trade make in 47 150 Millions per year and CAT-IQ is a registered trade make in 47
countries worldwide. G.722 has also been specified by ETSI in countries worldwide. G.722 has also been specified by ETSI in
[TS181005] as mandatory wideband codec for IMS multimedia telephony [TS181005] as mandatory wideband codec for IMS multimedia telephony
communication service and supplementary services using fixed communication service and supplementary services using fixed
broadband access. The support of G.722 would consequently allow broadband access. The support of G.722 would consequently allow
transcoding free IP interoperation between WebRTC client and fixed transcoding free IP interoperation between WebRTC client and fixed
VoIP terminals including DECT / CAT-IQ terminals supporting G.722. VoIP terminals including DECT / CAT-IQ terminals supporting G.722.
Besides, WebRTC client running on fixed terminals implementing G.722 Besides, WebRTC client running on fixed terminals implementing G.722
may reuse the G.722 codec already implemented on these devices. may reuse the G.722 codec already implemented on these devices.
4.3.3. Guidelines for G.722 usage and implementation 4.3.3. Guidelines for G.722 usage and implementation
Guidelines for implementing and using G.722 with purpose to ensure The payload format to be used for G.722 is defined in [RFC3551] with
interoperability with Multimedia Telephony services overs IMS can be each octet of the stream of octets produced by the codec to be octet-
found in section 7 of [TS26.114]. Additional information of G.722 aligned in an RTP packet. The sampling frequency for G.722 is 16 kHz
implementation in DECT can be found in [EN300175-8] and full codec but the rtp clock rate is set to 8000Hz in SDP to stay backward
description and C source code in [G.722]. compatible with an erroneous definition in the original version of
the RTP A/V profile. Further guidelines for implementing and using
G.722 with purpose to ensure interoperability with Multimedia
Telephony services overs IMS can be found in section 7 of [TS26.114].
Additional information of G.722 implementation in DECT can be found
in [EN300175-8] and full codec description and C source code in
[G.722].
4.4. Other codecs 4.4. Other codecs
Other interoperability use cases may justify the use of other codecs. Other interoperability use cases may justify the use of other codecs.
5. Security Considerations 5. Security Considerations
Security considerations for WebRTC Audio Codec and Processing
Requirements can be found in [I-D.ietf-rtcweb-audio]. Implementors
making use of the additional codecs considered in this document are
advised to also report more specifically to the "Security
Considerations" sections of [RFC4867] (for AMR and AMR-WB) and
[RFC3551].
6. IANA Considerations 6. IANA Considerations
None. None.
7. Acknowledgements 7. Acknowledgements
None. Special thanks to Espen Berger, Bernhard Feiten, Bo Burman, Kalyani
Bogineni, Miao Lei, Enrico Marocco, who co-authored the initial
document. Thanks, as well, to Magnus Westerlund and Barry Dingle who
carefully reviewed the document and helped to improve it.
8. References 8. References
8.1. Normative references 8.1. Normative references
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [G.722] ITU, "Recommendation ITU-T G.722 (2012): 7 kHz audio-
Requirement Levels", BCP 14, RFC 2119, coding within 64 kbit/s", 2012-09.
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>. [I-D.ietf-rtcweb-audio]
Valin, J. and C. Bran, "WebRTC Audio Codec and Processing
Requirements", draft-ietf-rtcweb-audio-09 (work in
progress), November 2015.
[IR.92] GSMA, "IMS Profile for Voice and SMS V9.0", April 2015.
[RFC3551] Schulzrinne, H. and S. Casner, "RTP Profile for Audio and
Video Conferences with Minimal Control", STD 65, RFC 3551,
DOI 10.17487/RFC3551, July 2003,
<http://www.rfc-editor.org/info/rfc3551>.
[RFC4867] Sjoberg, J., Westerlund, M., Lakaniemi, A., and Q. Xie,
"RTP Payload Format and File Storage Format for the
Adaptive Multi-Rate (AMR) and Adaptive Multi-Rate Wideband
(AMR-WB) Audio Codecs", RFC 4867, DOI 10.17487/RFC4867,
April 2007, <http://www.rfc-editor.org/info/rfc4867>.
[TS26.071]
3GPP, "3GPP TS 26.071 v12.0.0: Recommendation ITU-T G.722
(2012): "Mandatory Speech Codec speech processing
functions; AMR Speech CODEC; General description".",
2014-09.
[TS26.073]
3GPP, "3GPP TS 26.073 v12.0.0: ANSI C code for the
Adaptive Multi Rate (AMR) speech codec", 2014-09.
[TS26.090]
3GPP, "3GPP TS 26.090 v12.0.0: Mandatory Speech Codec
speech processing functions; Adaptive Multi-Rate (AMR)
speech codec; Transcoding functions.", 2014-09.
[TS26.104]
3GPP, "3GPP TS 26.104 v12.0.0: ANSI C code for the
floating-point Adaptive Multi Rate (AMR) speech codec.",
2014-09.
[TS26.114]
3GPP, "IP Multimedia Subsystem (IMS); Multimedia
telephony; Media handling and interaction V13.0.0", June
2015.
[TS26.171]
3GPP, "3GPP TS 26.071 v12.0.0: Recommendation ITU-T G.722
(2012): "Speech codec speech processing functions;
Adaptive Multi-Rate - Wideband (AMR-WB) speech codec;
General description".", 2014-09.
[TS26.173]
3GPP, "3GPP TS 26.073 v12.1.0: ANSI-C code for the
Adaptive Multi-Rate - Wideband (AMR-WB) speech codec.",
2015-03.
[TS26.190]
3GPP, "3GPP TS 26.090 v12.0.0: Speech codec speech
processing functions; Adaptive Multi-Rate - Wideband (AMR-
WB) speech codec; Transcoding functions.", 2014-09.
[TS26.204]
3GPP, "3GPP TS 26.104 v12.1.0: Speech codec speech
processing functions; Adaptive Multi-Rate - Wideband (AMR-
WB) speech codec; ANSI-C code.", 2015-03.
8.2. Informative references 8.2. Informative references
[EN300175-1]
ETSI, "ETSI EN 300 175-1, Digital Enhanced Cordless
Telecommunications (DECT); Common Interface (CI); Part 1:
Overview v2.5.1", 2009.
[EN300175-8] [EN300175-8]
ETSI, "ETSI EN 300 175-8, v2.5.1: "Digital Enhanced ETSI, "ETSI EN 300 175-8, v2.5.1: Digital Enhanced
Cordless Telecommunications (DECT); Common Interface (CI); Cordless Telecommunications (DECT); Common Interface (CI);
Part 8: Speech and audio coding and transmission".", 2009. Part 8: Speech and audio coding and transmission.", 2009.
[G.722] ITU, "Recommendation ITU-T G.722 (2012): "7 kHz audio-
coding within 64 kbit/s".", 2012.
[I-D.ietf-rtcweb-audio] [G.711] ITU, "Recommendation ITU-T G.711 (2012): Pulse code
Valin, J. and C. Bran, "WebRTC Audio Codec and Processing modulation (PCM) of voice frequencies", 1988-11.
Requirements", draft-ietf-rtcweb-audio-08 (work in
progress), April 2015.
[I-D.ietf-rtcweb-overview] [I-D.ietf-rtcweb-overview]
Alvestrand, H., "Overview: Real Time Protocols for Alvestrand, H., "Overview: Real Time Protocols for
Browser-based Applications", draft-ietf-rtcweb-overview-14 Browser-based Applications", draft-ietf-rtcweb-overview-14
(work in progress), June 2015. (work in progress), June 2015.
[IR.36] GSMA, "Adaptive Multirate Wide Band V3.0", September 2014. [IR.36] GSMA, "Adaptive Multirate Wide Band V3.0", September 2014.
[IR.92] GSMA, "IMS Profile for Voice and SMS V9.0", April 2015.
[RFC6716] Valin, JM., Vos, K., and T. Terriberry, "Definition of the [RFC6716] Valin, JM., Vos, K., and T. Terriberry, "Definition of the
Opus Audio Codec", RFC 6716, DOI 10.17487/RFC6716, Opus Audio Codec", RFC 6716, DOI 10.17487/RFC6716,
September 2012, <http://www.rfc-editor.org/info/rfc6716>. September 2012, <http://www.rfc-editor.org/info/rfc6716>.
[RFC7478] Holmberg, C., Hakansson, S., and G. Eriksson, "Web Real- [RFC7478] Holmberg, C., Hakansson, S., and G. Eriksson, "Web Real-
Time Communication Use Cases and Requirements", RFC 7478, Time Communication Use Cases and Requirements", RFC 7478,
DOI 10.17487/RFC7478, March 2015, DOI 10.17487/RFC7478, March 2015,
<http://www.rfc-editor.org/info/rfc7478>. <http://www.rfc-editor.org/info/rfc7478>.
[TS181005] [TS181005]
ETSI, "Telecommunications and Internet converged Services ETSI, "Telecommunications and Internet converged Services
and Protocols for Advanced Networking (TISPAN); Service and Protocols for Advanced Networking (TISPAN); Service
and Capability Requirements V3.3.1 (2009-12)", 2009. and Capability Requirements V3.3.1 (2009-12)", 2009.
[TS26.114] [TS23.002]
3GPP, "IP Multimedia Subsystem (IMS); Multimedia 3GPP, "3GPP TS 23.002 v13.3.0: Network architecture",
telephony; Media handling and interaction V13.0.0", June 2015-09.
2015.
Authors' Addresses Author's Address
Stephane Proust Stephane Proust
Orange Orange
2, avenue Pierre Marzin 2, avenue Pierre Marzin
Lannion 22307 Lannion 22307
France France
Email: stephane.proust@orange.com Email: stephane.proust@orange.com
Espen Berger
Cisco
Email: espeberg@cisco.com
Bernhard Feiten
Deutsche Telekom
Email: Bernhard.Feiten@telekom.de
Bo Burman
Ericsson
Email: bo.burman@ericsson.com
Kalyani Bogineni
Verizon Wireless
Email: Kalyani.Bogineni@VerizonWireless.com
Miao Lei
Huawei
Email: lei.miao@huawei.com
Enrico Marocco
Telecom Italia
Email: enrico.marocco@telecomitalia.it
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