Enabling opus discontinuous transmission(DTX) without SDP munging

[bdrtc]

Opus DTX(Discontinuous Transmission )is an extension of the Opus Audio codec, when enabled, it will encode silence at a lower bitrate by reducing the number of frames sent over the network. this optimisation reduces the audio bandwidth used when participants are not speaking, its useful in multi conference scenario which sfu need do selective audio routing, its disabled by default, and can only active this feature via SDP munging.

wonder whether it is possible to be in rtcrtpencodingparameters as an extension.