[webrtc-extensions] need API to control audio nack & audio RTX (#119)

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

== need API to control audio nack & audio RTX ==
1.webrtc support audio nack, but its disabled default, currently user can only active this via munging SDP.
most webrtc platform enable audio nack via munging sdp（include google meet also:>）.
2. audio nack does't support rtx which video dose support.

is it necessary to clarify those in extension spec?

Please view or discuss this issue at https://github.com/w3c/webrtc-extensions/issues/119 using your GitHub account


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