draft-ietf-rtcweb-fec-06.txt   draft-ietf-rtcweb-fec-07.txt 
Network Working Group J. Uberti Network Working Group J. Uberti
Internet-Draft Google Internet-Draft Google
Intended status: Standards Track July 3, 2017 Intended status: Standards Track December 10, 2017
Expires: January 4, 2018 Expires: June 13, 2018
WebRTC Forward Error Correction Requirements WebRTC Forward Error Correction Requirements
draft-ietf-rtcweb-fec-06 draft-ietf-rtcweb-fec-07
Abstract Abstract
This document provides information and requirements for how Forward This document provides information and requirements for how Forward
Error Correction (FEC) should be used by WebRTC implementations. Error Correction (FEC) should be used by WebRTC implementations.
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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This Internet-Draft will expire on January 4, 2018. This Internet-Draft will expire on June 13, 2018.
Copyright Notice Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the Copyright (c) 2017 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 . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
skipping to change at page 7, line 16 skipping to change at page 7, line 16
The general FEC mechanism described in The general FEC mechanism described in
[I-D.ietf-payload-flexible-fec-scheme] SHOULD also be supported, as [I-D.ietf-payload-flexible-fec-scheme] SHOULD also be supported, as
mentioned in Section 5. mentioned in Section 5.
Implementations MAY support additional FEC mechanisms if desired, Implementations MAY support additional FEC mechanisms if desired,
e.g. [RFC5109]. e.g. [RFC5109].
8. Adaptive Use of FEC 8. Adaptive Use of FEC
Since use of FEC always causes redundant data to be transmitted, this Because use of FEC always causes redundant data to be transmitted,
will lead to less bandwidth available for the primary encoding when and the total amount of data must remain within any bandwidth limits
in a bandwidth-constrained environment. This is in contrast to indicated by congestion control and the receiver, this will lead to
methods like RTX [RFC4588] or flexfec less bandwidth available for the primary encoding, even when the
[I-D.ietf-payload-flexible-fec-scheme] retransmissions, which only redundant data is not being used. This is in contrast to methods
transmit redundant data when necessary, at the cost of an extra like RTX [RFC4588] or flexfec [I-D.ietf-payload-flexible-fec-scheme]
roundtrip. retransmissions, which only transmit redundant data when necessary,
at the cost of an extra roundtrip.
Given this, WebRTC implementations SHOULD consider using RTX or Given this, WebRTC implementations SHOULD consider using RTX or
flexfec retransmissions instead of FEC when RTT is low, and SHOULD flexfec retransmissions instead of FEC when RTT is low, and SHOULD
only transmit the amount of FEC needed to protect against the only transmit the amount of FEC needed to protect against the
observed packet loss (which can be determined, e.g., by monitoring observed packet loss (which can be determined, e.g., by monitoring
transmit packet loss data from RTCP Receiver Reports [RFC3550]), transmit packet loss data from RTCP Receiver Reports [RFC3550]),
unless the application indicates it is willing to pay a quality unless the application indicates it is willing to pay a quality
penalty to proactively avoid losses. penalty to proactively avoid losses.
Note that when probing bandwidth, i.e., speculatively sending extra Note that when probing bandwidth, i.e., speculatively sending extra
skipping to change at page 8, line 37 skipping to change at page 8, line 37
[I-D.ietf-payload-flexible-fec-scheme] [I-D.ietf-payload-flexible-fec-scheme]
Singh, V., Begen, A., Zanaty, M., and G. Mandyam, "RTP Singh, V., Begen, A., Zanaty, M., and G. Mandyam, "RTP
Payload Format for Flexible Forward Error Correction Payload Format for Flexible Forward Error Correction
(FEC)", draft-ietf-payload-flexible-fec-scheme-05 (work in (FEC)", draft-ietf-payload-flexible-fec-scheme-05 (work in
progress), July 2017. progress), July 2017.
[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, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC2198] Perkins, C., Kouvelas, I., Hodson, O., Hardman, V., [RFC2198] Perkins, C., Kouvelas, I., Hodson, O., Hardman, V.,
Handley, M., Bolot, J., Vega-Garcia, A., and S. Fosse- Handley, M., Bolot, J., Vega-Garcia, A., and S. Fosse-
Parisis, "RTP Payload for Redundant Audio Data", RFC 2198, Parisis, "RTP Payload for Redundant Audio Data", RFC 2198,
DOI 10.17487/RFC2198, September 1997, DOI 10.17487/RFC2198, September 1997,
<http://www.rfc-editor.org/info/rfc2198>. <https://www.rfc-editor.org/info/rfc2198>.
[RFC3264] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model [RFC3264] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model
with Session Description Protocol (SDP)", RFC 3264, with Session Description Protocol (SDP)", RFC 3264,
DOI 10.17487/RFC3264, June 2002, DOI 10.17487/RFC3264, June 2002,
<http://www.rfc-editor.org/info/rfc3264>. <https://www.rfc-editor.org/info/rfc3264>.
[RFC4867] Sjoberg, J., Westerlund, M., Lakaniemi, A., and Q. Xie, [RFC4867] Sjoberg, J., Westerlund, M., Lakaniemi, A., and Q. Xie,
"RTP Payload Format and File Storage Format for the "RTP Payload Format and File Storage Format for the
Adaptive Multi-Rate (AMR) and Adaptive Multi-Rate Wideband Adaptive Multi-Rate (AMR) and Adaptive Multi-Rate Wideband
(AMR-WB) Audio Codecs", RFC 4867, DOI 10.17487/RFC4867, (AMR-WB) Audio Codecs", RFC 4867, DOI 10.17487/RFC4867,
April 2007, <http://www.rfc-editor.org/info/rfc4867>. April 2007, <https://www.rfc-editor.org/info/rfc4867>.
[RFC5956] Begen, A., "Forward Error Correction Grouping Semantics in [RFC5956] Begen, A., "Forward Error Correction Grouping Semantics in
the Session Description Protocol", RFC 5956, the Session Description Protocol", RFC 5956,
DOI 10.17487/RFC5956, September 2010, DOI 10.17487/RFC5956, September 2010,
<http://www.rfc-editor.org/info/rfc5956>. <https://www.rfc-editor.org/info/rfc5956>.
[RFC7587] Spittka, J., Vos, K., and JM. Valin, "RTP Payload Format [RFC7587] Spittka, J., Vos, K., and JM. Valin, "RTP Payload Format
for the Opus Speech and Audio Codec", RFC 7587, for the Opus Speech and Audio Codec", RFC 7587,
DOI 10.17487/RFC7587, June 2015, DOI 10.17487/RFC7587, June 2015,
<http://www.rfc-editor.org/info/rfc7587>. <https://www.rfc-editor.org/info/rfc7587>.
[TS.26114]
3GPP, "IP Multimedia Subsystem (IMS); Multimedia
telephony; Media handling and interaction", 3GPP TS 26.114
15.0.0, September 2017.
12.2. Informative References 12.2. Informative References
[I-D.ietf-mmusic-sdp-bundle-negotiation] [I-D.ietf-mmusic-sdp-bundle-negotiation]
Holmberg, C., Alvestrand, H., and C. Jennings, Holmberg, C., Alvestrand, H., and C. Jennings,
"Negotiating Media Multiplexing Using the Session "Negotiating Media Multiplexing Using the Session
Description Protocol (SDP)", draft-ietf-mmusic-sdp-bundle- Description Protocol (SDP)", draft-ietf-mmusic-sdp-bundle-
negotiation-38 (work in progress), April 2017. negotiation-43 (work in progress), December 2017.
[I-D.ietf-rtcweb-data-channel] [I-D.ietf-rtcweb-data-channel]
Jesup, R., Loreto, S., and M. Tuexen, "WebRTC Data Jesup, R., Loreto, S., and M. Tuexen, "WebRTC Data
Channels", draft-ietf-rtcweb-data-channel-13 (work in Channels", draft-ietf-rtcweb-data-channel-13 (work in
progress), January 2015. progress), January 2015.
[RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V. [RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V.
Jacobson, "RTP: A Transport Protocol for Real-Time Jacobson, "RTP: A Transport Protocol for Real-Time
Applications", STD 64, RFC 3550, DOI 10.17487/RFC3550, Applications", STD 64, RFC 3550, DOI 10.17487/RFC3550,
July 2003, <http://www.rfc-editor.org/info/rfc3550>. July 2003, <https://www.rfc-editor.org/info/rfc3550>.
[RFC3711] Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K. [RFC3711] Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K.
Norrman, "The Secure Real-time Transport Protocol (SRTP)", Norrman, "The Secure Real-time Transport Protocol (SRTP)",
RFC 3711, DOI 10.17487/RFC3711, March 2004, RFC 3711, DOI 10.17487/RFC3711, March 2004,
<http://www.rfc-editor.org/info/rfc3711>. <https://www.rfc-editor.org/info/rfc3711>.
[RFC4588] Rey, J., Leon, D., Miyazaki, A., Varsa, V., and R. [RFC4588] Rey, J., Leon, D., Miyazaki, A., Varsa, V., and R.
Hakenberg, "RTP Retransmission Payload Format", RFC 4588, Hakenberg, "RTP Retransmission Payload Format", RFC 4588,
DOI 10.17487/RFC4588, July 2006, DOI 10.17487/RFC4588, July 2006,
<http://www.rfc-editor.org/info/rfc4588>. <https://www.rfc-editor.org/info/rfc4588>.
[RFC5109] Li, A., Ed., "RTP Payload Format for Generic Forward Error [RFC5109] Li, A., Ed., "RTP Payload Format for Generic Forward Error
Correction", RFC 5109, DOI 10.17487/RFC5109, December Correction", RFC 5109, DOI 10.17487/RFC5109, December
2007, <http://www.rfc-editor.org/info/rfc5109>. 2007, <https://www.rfc-editor.org/info/rfc5109>.
[RFC5763] Fischl, J., Tschofenig, H., and E. Rescorla, "Framework [RFC5763] Fischl, J., Tschofenig, H., and E. Rescorla, "Framework
for Establishing a Secure Real-time Transport Protocol for Establishing a Secure Real-time Transport Protocol
(SRTP) Security Context Using Datagram Transport Layer (SRTP) Security Context Using Datagram Transport Layer
Security (DTLS)", RFC 5763, DOI 10.17487/RFC5763, May Security (DTLS)", RFC 5763, DOI 10.17487/RFC5763, May
2010, <http://www.rfc-editor.org/info/rfc5763>. 2010, <https://www.rfc-editor.org/info/rfc5763>.
[RFC5764] McGrew, D. and E. Rescorla, "Datagram Transport Layer [RFC5764] McGrew, D. and E. Rescorla, "Datagram Transport Layer
Security (DTLS) Extension to Establish Keys for the Secure Security (DTLS) Extension to Establish Keys for the Secure
Real-time Transport Protocol (SRTP)", RFC 5764, Real-time Transport Protocol (SRTP)", RFC 5764,
DOI 10.17487/RFC5764, May 2010, DOI 10.17487/RFC5764, May 2010,
<http://www.rfc-editor.org/info/rfc5764>. <https://www.rfc-editor.org/info/rfc5764>.
[RFC6386] Bankoski, J., Koleszar, J., Quillio, L., Salonen, J., [RFC6386] Bankoski, J., Koleszar, J., Quillio, L., Salonen, J.,
Wilkins, P., and Y. Xu, "VP8 Data Format and Decoding Wilkins, P., and Y. Xu, "VP8 Data Format and Decoding
Guide", RFC 6386, DOI 10.17487/RFC6386, November 2011, Guide", RFC 6386, DOI 10.17487/RFC6386, November 2011,
<http://www.rfc-editor.org/info/rfc6386>. <https://www.rfc-editor.org/info/rfc6386>.
[RFC6464] Lennox, J., Ed., Ivov, E., and E. Marocco, "A Real-time [RFC6464] Lennox, J., Ed., Ivov, E., and E. Marocco, "A Real-time
Transport Protocol (RTP) Header Extension for Client-to- Transport Protocol (RTP) Header Extension for Client-to-
Mixer Audio Level Indication", RFC 6464, Mixer Audio Level Indication", RFC 6464,
DOI 10.17487/RFC6464, December 2011, DOI 10.17487/RFC6464, December 2011,
<http://www.rfc-editor.org/info/rfc6464>. <https://www.rfc-editor.org/info/rfc6464>.
[RFC6465] Ivov, E., Ed., Marocco, E., Ed., and J. Lennox, "A Real- [RFC6465] Ivov, E., Ed., Marocco, E., Ed., and J. Lennox, "A Real-
time Transport Protocol (RTP) Header Extension for Mixer- time Transport Protocol (RTP) Header Extension for Mixer-
to-Client Audio Level Indication", RFC 6465, to-Client Audio Level Indication", RFC 6465,
DOI 10.17487/RFC6465, December 2011, DOI 10.17487/RFC6465, December 2011,
<http://www.rfc-editor.org/info/rfc6465>. <https://www.rfc-editor.org/info/rfc6465>.
[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, <https://www.rfc-editor.org/info/rfc6716>.
[TS.26114]
3GPP, "IP Multimedia Subsystem (IMS); Multimedia
telephony; Media handling and interaction", 3GPP TS 26.114
13.3.0, March 2016.
Appendix A. Change log Appendix A. Change log
Changes in draft -07:
o Clarify how bandwidth management interacts with FEC.
o Make 3GPP reference normative.
Changes in draft -06: Changes in draft -06:
o Discuss how multiple streams can be protected by a single FlexFEC o Discuss how multiple streams can be protected by a single FlexFEC
stream. stream.
o Discuss FEC for bandwidth probing. o Discuss FEC for bandwidth probing.
o Add note about recovery of RTP headers and header extensions. o Add note about recovery of RTP headers and header extensions.
o Add note about FEC/SRTP ordering. o Add note about FEC/SRTP ordering.
 End of changes. 24 change blocks. 
35 lines changed or deleted 42 lines changed or added

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