| Internet-Draft | RTCP feedback Message Timing Config | February 2024 |
| Majali | Expires 9 August 2024 | [Page] |
This specification describes configuring the Real-time Transport Control Protocol (RTCP) message feedback send time.¶
This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.¶
Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet-Drafts is at https://datatracker.ietf.org/drafts/current/.¶
Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress."¶
This Internet-Draft will expire on 9 August 2024.¶
Copyright (c) 2024 IETF Trust and the persons identified as the document authors. All rights reserved.¶
This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Revised BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Revised BSD License.¶
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.¶
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.¶
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]¶
“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.¶
Payload specific RTCP feedback PLI (Picture Loss Indication) with minimum interval of 50 milliseconds. Configuration can be used by the receiver to trigger PLI when no decodable unit is available to decode for 50ms.¶
a=rtcp-fb:96 nack pli;fb-min-time=50¶
RTCP feedback Generic NACK with minimum time of 1 milliseconds. Receiver to wait for 1 milliseconds before NACK RTCP feedback message is sent on packet loss.¶
a=rtcp-fb:96 nack;fb-min-time=1¶
RTCP feedback transport-cc with minimum time of 50 milliseconds and synchronization counter set to 3. Receiver to send transport-cc feedback on every 3rd change in RTP timestamp change or 50 milliseconds elapsed, whichever happens earliest.¶
a=rtcp-fb:96 transport-cc ;fb-min-time=50;sync-counter=3¶
An OPTIONAL parameters, "fb-min-time", “sync-counter” are defined. See Section 3 for details.¶
RTP packets using the payload format defined in this specification are subject to the general security considerations discussed in RTP Section 9 of [RFC3550]¶