draft-ietf-rtcweb-audio-05.txt   draft-ietf-rtcweb-audio-06.txt 
Network Working Group JM. Valin Network Working Group JM. Valin
Internet-Draft Mozilla Internet-Draft Mozilla
Intended status: Standards Track C. Bran Intended status: Standards Track C. Bran
Expires: August 17, 2014 Plantronics Expires: March 9, 2015 Plantronics
February 13, 2014 September 5, 2014
WebRTC Audio Codec and Processing Requirements WebRTC Audio Codec and Processing Requirements
draft-ietf-rtcweb-audio-05 draft-ietf-rtcweb-audio-06
Abstract Abstract
This document outlines the audio codec and processing requirements This document outlines the audio codec and processing requirements
for WebRTC client application and endpoint devices. for WebRTC client application and endpoint devices.
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.
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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 August 17, 2014. This Internet-Draft will expire on March 9, 2015.
Copyright Notice Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the Copyright (c) 2014 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 2
3. Codec Requirements . . . . . . . . . . . . . . . . . . . . . 2 3. Codec Requirements . . . . . . . . . . . . . . . . . . . . . 2
4. Audio Level . . . . . . . . . . . . . . . . . . . . . . . . . 3 4. Audio Level . . . . . . . . . . . . . . . . . . . . . . . . . 3
5. Acoustic Echo Cancellation (AEC) . . . . . . . . . . . . . . 4 5. Acoustic Echo Cancellation (AEC) . . . . . . . . . . . . . . 4
6. Legacy VoIP Interoperability . . . . . . . . . . . . . . . . 4 6. Legacy VoIP Interoperability . . . . . . . . . . . . . . . . 5
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
8. Security Considerations . . . . . . . . . . . . . . . . . . . 5 8. Security Considerations . . . . . . . . . . . . . . . . . . . 5
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5
10. Normative References . . . . . . . . . . . . . . . . . . . . 5 10. Normative References . . . . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction 1. Introduction
An integral part of the success and adoption of the Web Real Time An integral part of the success and adoption of the Web Real Time
Communications (WebRTC) will be the voice and video interoperability Communications (WebRTC) will be the voice and video interoperability
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to maximize the possibility to establish the session without the need to maximize the possibility to establish the session without the need
for audio transcoding. for audio transcoding.
WebRTC clients are REQUIRED to implement the following audio codecs: WebRTC clients are REQUIRED to implement the following audio codecs:
o Opus [RFC6716] with the payload format specified in [Opus-RTP]. o Opus [RFC6716] with the payload format specified in [Opus-RTP].
o G.711 PCMA and PCMU with the payload format specified in section o G.711 PCMA and PCMU with the payload format specified in section
4.5.14 of [RFC3551]. 4.5.14 of [RFC3551].
o [RFC3389] comfort noise (CN). Receivers MUST support RFC3389 CN
for streams encoded with G.711 or any other supported codec that
does not provide its own CN. Since Opus provides its own CN
mechanism, the use of RFC3389 CN with Opus is NOT RECOMMENDED.
Use of DTX/CN by senders is OPTIONAL.
o The audio/telephone-event media format as specified in [RFC4733]. o The audio/telephone-event media format as specified in [RFC4733].
WebRTC clients are REQUIRED to be able to generate and consume the WebRTC clients are REQUIRED to be able to generate and consume the
following events: following events:
+------------+--------------------------------+-----------+ +------------+--------------------------------+-----------+
|Event Code | Event Name | Reference | |Event Code | Event Name | Reference |
+------------+--------------------------------+-----------+ +------------+--------------------------------+-----------+
| 0 | DTMF digit "0" | RFC4733 | | 0 | DTMF digit "0" | RFC4733 |
| 1 | DTMF digit "1" | RFC4733 | | 1 | DTMF digit "1" | RFC4733 |
| 2 | DTMF digit "2" | RFC4733 | | 2 | DTMF digit "2" | RFC4733 |
| 3 | DTMF digit "3" | RFC4733 | | 3 | DTMF digit "3" | RFC4733 |
| 4 | DTMF digit "4" | RFC4733 | | 4 | DTMF digit "4" | RFC4733 |
| 5 | DTMF digit "5" | RFC4733 | | 5 | DTMF digit "5" | RFC4733 |
| 6 | DTMF digit "6" | RFC4733 | | 6 | DTMF digit "6" | RFC4733 |
| 7 | DTMF digit "7" | RFC4733 | | 7 | DTMF digit "7" | RFC4733 |
| 8 | DTMF digit "8" | RFC4733 | | 8 | DTMF digit "8" | RFC4733 |
| 9 | DTMF digit "9" | RFC4733 | | 9 | DTMF digit "9" | RFC4733 |
| 10 | DTMF digit "*" | RFC4733 | | 10 | DTMF digit "*" | RFC4733 |
| 11 | DTMF digit "#" | RFC4733 | | 11 | DTMF digit "#" | RFC4733 |
+------------+--------------------------------+-----------+ +------------+--------------------------------+-----------+
For all cases where the client is able to process audio at a sampling For all cases where the client is able to process audio at a sampling
rate higher than 8 kHz, it is RECOMMENDED that Opus be offered before rate higher than 8 kHz, it is RECOMMENDED that Opus be offered before
PCMA/PCMU. For Opus, all modes MUST be supported on the decoder PCMA/PCMU. For Opus, all modes MUST be supported on the decoder
side. The choice of encoder-side modes is left to the implementer. side. The choice of encoder-side modes is left to the implementer.
Clients MAY use the offer/answer mechanism to signal a preference for Clients MAY use the offer/answer mechanism to signal a preference for
a particular mode or ptime. a particular mode or ptime.
4. Audio Level 4. Audio Level
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10. Normative References 10. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3551] Schulzrinne, H. and S. Casner, "RTP Profile for Audio and [RFC3551] Schulzrinne, H. and S. Casner, "RTP Profile for Audio and
Video Conferences with Minimal Control", STD 65, RFC 3551, Video Conferences with Minimal Control", STD 65, RFC 3551,
July 2003. July 2003.
[RFC3389] Zopf, R., "Real-time Transport Protocol (RTP) Payload for
Comfort Noise (CN)", RFC 3389, September 2002.
[RFC4733] Schulzrinne, H. and T. Taylor, "RTP Payload for DTMF [RFC4733] Schulzrinne, H. and T. Taylor, "RTP Payload for DTMF
Digits, Telephony Tones, and Telephony Signals", RFC 4733, Digits, Telephony Tones, and Telephony Signals", RFC 4733,
December 2006. December 2006.
[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, September 2012. Opus Audio Codec", RFC 6716, September 2012.
[RFC6562] Perkins, C. and JM. Valin, "Guidelines for the Use of [RFC6562] Perkins, C. and JM. Valin, "Guidelines for the Use of
Variable Bit Rate Audio with Secure RTP", RFC 6562, March Variable Bit Rate Audio with Secure RTP", RFC 6562, March
2012. 2012.
[Opus-RTP] [Opus-RTP]
Spittka, J., Vos, K., and JM. Valin, "RTP Payload Format Spittka, J., Vos, K., and JM. Valin, "RTP Payload Format
for Opus Codec", August 2013. for Opus Codec", August 2013.
Authors' Addresses Authors' Addresses
Jean-Marc Valin Jean-Marc Valin
Mozilla Mozilla
650 Castro Street 331 E. Evelyn Avenue
Mountain View, CA 94041 Mountain View, CA 94041
USA USA
Email: jmvalin@jmvalin.ca Email: jmvalin@jmvalin.ca
Cary Bran Cary Bran
Plantronics Plantronics
345 Encinial Street 345 Encinial Street
Santa Cruz, CA 95060 Santa Cruz, CA 95060
USA USA
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