Default values for RTCRtpEncodingParameters

[soareschen]

The current definition seems to imply that all fields are optional and have the value undefined if not set. However it seems that at least some of the fields should have default values, e.g. active and priority.

For example, the following examples have different active values:

// sender.encodings[0].active == true
pc.addTransceiver('audio');

// sender.encodings[0].active == true
pc.addTransceiver('audio', { sendEncodings: [] });

// sender.encodings[0].active == undefined
pc.addTransceiver('audio', { sendEncodings: [{}] });