Re: Issue 136: Handling of RTCRtpParameters

I have some questions about how this affects latching rules.

Let us say that we want to specify the Payload Type for an incoming audio or video stream, but don't know the SSRC yet.  Ideally, we would like to be able to receive the first stream without an RtpUnhandled event.

1. By requiring RTCRtpParameters to be "completely filled in", does this mean that there is no longer a way to indicate that "any SSRC" is acceptable (e.g. wildcard)?   If so does this imply that the RtpUnhandled event will be thrown on reception of the first SSRC?   Or is there a way to specify an SSRC wildcard?

2. Assuming that there is a way to specify an SSRC wildcard, presumably there is no RtpUnhandled event, since the stream was delivered to an existing RTCRtpReceiver object.  If so, once the first stream is received on the Payload Type, what happens?  Is this reflected in the RTCRtpParameters object (e.g. SSRC is filled in)?   If not, where/how is the "latching" state reflected?