[webrtc-stats] Confusing round trip time defintion in remoute-outbound-rtp (#659)

k0nserv has just created a new issue for https://github.com/w3c/webrtc-stats:

== Confusing round trip time defintion in remoute-outbound-rtp ==
The definition for `roundTripTime`, `totalRoundTripTime`, and `roundTripTimeMeasurements` in `remote-outbound-rtp` are all, seemingly, incorrect. They refer to the `DLRR` report block of Sender Reports(SR) but reference extended RTCP reports(defined in [RFC3611](https://www.rfc-editor.org/rfc/rfc3611)). This is correct, insofar that DLRR is defined in RFC3611, but as far as I can tell it's not the case that DLRR blocks are contained within Sender Reports as the text implies. Because of this confusion it's unclear how these stats are supposed to be implemented, further I'm not sure if webrtc mandates the use of RTCP XR.


> Estimated round trip time for this [SSRC](https://www.w3.org/TR/webrtc-stats/#dfn-ssrc) based on the latest [RTCP Sender Report](https://www.w3.org/TR/webrtc-stats/#dfn-sender-report) (SR) **that contains a DLRR report block** as defined in [[RFC3611](https://www.w3.org/TR/webrtc-stats/#bib-rfc3611)]. The Calculation of the round trip time is defined in section 4.5. of [[RFC3611](https://www.w3.org/TR/webrtc-stats/#bib-rfc3611)]. If the latest SR does not contain the DLRR report block, or if the last RR timestamp in the DLRR report block is zero, or if the delay since last RR value in the DLRR report block is zero, the round trip time is left undefined.

_Emphasis mine_

It seems like the intention is to use DLRR report blocks an all instances that mention Sender Reports(SR) and that those mentions of SR are errors.

Please advise

Please view or discuss this issue at https://github.com/w3c/webrtc-stats/issues/659 using your GitHub account

Sent via github-notify-ml as configured in https://github.com/w3c/github-notify-ml-config

Received on Monday, 29 August 2022 14:43:07 UTC