4.10 SDES Private Extension for Media Quality

A host and a mixer can send information to another host to inform it of the media quality that is being sent to it. Some of the information is sent from the host originating the media, and additional information can be added by the mixer.

Figure 16: SDES PRIV extension for media quality

Host1 and Host2 are having a conference call using a mixer. Host1 checks the send and receive network quality and finds that both are good. Host1 fills in m by setting the m bitmask for send and receive network quality as 1 and q bits, with all q bits as zero (0). Host1 sends it to mixer in regular RTCP reports. Mixer detects echo from Host1 and updates the m and q bits. Mixer sends RTCP SDES private extension of media quality to Host2 immediately, because Host1 has not sent SDES PRIV quality state before. After less than 30 seconds, mixer receives another RTCP report from Host1 with the same m and q bits. Because the last report was sent less than 30 seconds before, mixer does not send this extension to Host2. After 30 seconds, mixer sends another RTCP SDES extension for media quality to Host2 with the same m and q bits.

After less than 10 seconds, mixer receives another RTCP report from Host1 with the different m or q bits. Because the last RTCP SDES private extension was sent less than 10 seconds before, mixer does not send the extension to Host2. Within the same 10 seconds, mixer receives another extension from Host1 with different m or q bits. It updates the m and q bits for Host1 and, after 10 seconds, sends the latest m and q bit from Host1 to Host2.