Internet-Draft | RTCP LNTF | June 2024 |
Majali | Expires 5 December 2024 | [Page] |
Real-time media streams that use RTP, use multiple mechanisms to recover from packet and frame loss. Sender to recover frame loss effectively, it can use information on the last frame receiver successfully decoded and latest packet it received on network. This document describes an RTP Control Protocol (RTCP) feedback message intended to notify the sender with loss details.¶
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This document proposes RTCP feedback message Loss Notification (LNTF) during packet loss, containing information about the latest frame decoded and latest packet received by the receiver. This feedback is beneficial in video streaming; video encoder can use this information to encode future frames by referencing successfully decoded frames.¶
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.¶
LNTF message is identified by payload type defined as Payload-Specific Feedback message (PSFB).¶
The fields V, P, FMT, PT, length and SSRC are defined in the RTP specification Section 6.1 of [RFC4585], the respective meaning being summarized below:¶
This section defines Session Description Protocol (SDP) signaling for LNTF feedback that can be employed by applications.¶
rtcp-fb-syntax = "a=rtcp-fb:" rtcp-fb-pt SP rtcp-fb-val CRLF¶
The literals of the above grammar have the following semantics: Feedback type "lntf": This feedback type indicates loss notification.¶
Upon publication of this document as an RFC (if it is decided to publish it), IANA is requested to register the string "lntf" in its registry of "rtcp-fb" values in the SDP attribute registry group.¶
This is not different from security considerations for any other RTCP message.¶
The authors would like to thank Alfred Heggestad and Harald Alvestrand for their reviews and valuable comments.¶