The RTCRtpSender interface provides the ability to control and obtain details about how a particular MediaStreamTrack is encoded and sent to a remote peer. With it, you can configure the encoding used for the corresponding track, get information about the device's media capabilities, and so forth. You can also obtain access to an RTCDTMFSender which can be used to send DTMF codes to the remote peer.
An RTCDTMFSender which can be used to send DTMF tones using "telephone-event" payloads on the RTP session represented by the RTCRtpSender object. If null, the track and/or the connection doesn't support DTMF. Only audio tracks can support DTMF.
The transport over which Real-time Transport Control Protocol (RTCP) information is exchanged. This value is null before the RTCDtlsTransport object is created. When bundling is in use, more than one RTCRtpSender can share the same transport, sending all RTP and RTCP information over that one transport.
Attempts to replace the track currently being sent by the RTCRtpSender with another track, without performing renegotiation. This method can be used, for example, to toggle between the front- and rear-facing cameras on a device.