Internet-Draft RTCP feedback Message Timing Config February 2024
Majali Expires 9 August 2024 [Page]
AVTCORE Working Group
Intended Status:
S. Majali

RTCP feedback Message Timing Configuration


This specification describes configuring the Real-time Transport Control Protocol (RTCP) message feedback send time.

Status of This Memo

This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.

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This Internet-Draft will expire on 9 August 2024.

Table of Contents

1. Introduction

This document proposes controlling specific RTCP message feedback send time. This proposal help sender negotiate RTCP feedback send time, better flexibility in defining application behavior. This document defines a new Session Description Protocol (SDP) parameter to negotiate the timing configuration.

1.1. Requirements Language

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.

2. SDP Definitions

This section defines optional SDP parameters that are used to negotiate RTCP feedback message send time. Time defined is applicable to specific RTCP feedback message only.

An OPTIONAL RTCP feedback specific parameter, "fb-min-time", indicates the minimum period T_fb_min_time in milliseconds between two same RTCP feedback or wait time before sending feedback message.

The syntax is as follows:

a=rtcp-fb:<rtcp-fb-pt> <rtcp-fb-param>;fb-min-time=<fb-min-time-val>

where above parameters are explained in Section 4 of [RFC4585]

= /fmt ; as defined in SDP
= SP "app" [SP byte-string]
/ SP token [SP byte-string]
/ ; empty
= feedback message minimum time value in milliseconds

“fb-min-time” may have an OPTIONAL parameter “sync-counter”, indicates synchronization counter SYNC-CONTER helps synchronize RTCP feedback with RTP timestamp change.

If T0 is start of time, receiver keeps count of change in RTP timestamp as COUNT. Once COUNT is equal to parameter SYNC-CONTER or time elapsed is greater than or equal to T_fb_min_time, receiver sends the RTCP feedback. Receiver resets the counter and time, to determine when the next feedback is to be sent.

2.1. SDP description for RTCP feedback timing configuration

3. IANA Considerations

An OPTIONAL parameters, "fb-min-time", “sync-counter” are defined. See Section 3 for details.

4. Security Considerations

RTP packets using the payload format defined in this specification are subject to the general security considerations discussed in RTP Section 9 of [RFC3550]

5. References

5.1. Normative References

Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, , <>.
Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, , <>.
Ott, J., Wenger, S., Sato, N., Burmeister, C., and J. Rey, "Extended RTP Profile for Real-time Transport Control Protocol (RTCP)-Based Feedback (RTP/AVPF)", RFC 4585, DOI 10.17487/RFC4585, , <>.
Schulzrinne, H., Casner, S., Frederick, R., and V. Jacobson, "RTP: A Transport Protocol for Real-Time Applications", STD 64, RFC 3550, DOI 10.17487/RFC3550, , <>.

Author's Address

Shridhar Majali
2788 San Tomas Expressway
Santa Clara, CA 95051
United States of America