Knowledge Base

packetsReceived

inbound-rtpinboundaudiovideo

Total number of RTP packets received for this SSRC.

Description

Non-negative integer

Total number of RTP packets received for this SSRC. This includes retransmissions.

The boring, spec explanation

At the receiving endpoint, this is calculated as defined in RFC3550 section 6.4.1.

At the sending endpoint the packetsReceived is estimated by subtracting the Cumulative Number of Packets Lost from the Extended Highest Sequence Number Received, both reported in the RTCP Receiver Report, and then subtracting the initial Extended Sequence Number that was sent to this SSRC in a RTCP Sender Report and then adding one, to mirror what is discussed in Appendix A.3 in RFC3550, but for the sender side. If no RTCP Receiver Report has been received yet, then return 0.

Our explanation

Imagine you are sending numbered letters to a friend who sends back a report saying, "The highest number I received was 100, but I am missing 5 letters."

To figure out exactly how many letters actually arrived, you take the total range (from the first number sent to the last one they saw) and simply subtract the number of missing letters.

This calculation allows the sender to estimate successful delivery using only a summary report, rather than needing a confirmation for every single packet individually.

See also