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Terminology

The process of freeing a candidate is defined in [[RFC8445]] Section 8.3.

+ +

+ + The following terms are defined in mediacapture-extensions + video timestamp concepts +

+

@@ -1540,6 +1553,46 @@

Event summary

+
+

Timestamp behavior

+

RTCRtpSender timestamp effects on packet NTP and RTP timestamps

+

+ The user agent defines a frame timestamp being the same as the [=capture timestamp=] + of the frame being produced on the {{RTCRtpSender}} {{MediaStreamTrack}} if it is set. + If it is unset the user agent estimates a timestamp from the sent frame's [=presentation timestamp=] together with the + time it was received by the {{RTCRtpSender}}. +

+

+ The NTP and RTP timestamps of the encoded frame corresponding to the frame being produced on the {{RTCRtpSender}} + {{MediaStreamTrack}} are sourced from the [=frame timestamp=]. +

+

+ The [=RTP timestamp=] of frames being produced on the {{RTCRtpSender}} is ignored. +

+

RTCRtpReceiver timestamps

+

Remote capture timestamp

+

+ + For a frame produced in a {{RTCRtpReceiver}} track, the user agent computes a + remote capture timestamp. It is a best-effort estimate of the local capture + time on the sender translated to the receiver clock, and can use methods like using RTCP SR + as specified in [[?RFC3550]] Section 6.4.1, or by other alternative means if use by RTCP SR + isn't feasible. +

+ Each frame's [=capture timestamp=] is set to the [=remote capture timestamp=], if available. +

+

Received RTP timestamp

+

+ For a frame produced in a {{RTCRtpReceiver}} track, the frame's [=RTP timestamp=] is set + from the RTP timestamp of constituent packets of the corresponding received encoded frame. +

+

Receive timestamp

+

+ For a frame produced in a {{RTCRtpReceiver}} track, the [=receive timestamp=] is set + as the time the corresponding encoded frame was received by the platform, i.e. the time at which the + last packet belonging to this frame was received over the network. +

+

Security Considerations