Webrtcbin - Pre-offer SDP exchange before pipeline setup possible?

Application Development
1

I’ve an application utilising webrtcbin and my intent is to send an SDP before getting the pipeline linked and playing in order to pre-advertise different encodings of the stream and then link the correct pipeline once I get my answer.

I’ve been able to send offers and get answers from the client using both libgstsdp to manually generate and adding the transceivers to webrtcbin then using create-offer but when trying to set-remote-offer I’m getting failures as the transceivers haven’t got a transport stream set up even if I wait until the pipeline has linked and there is data flowing.

When I have a pipeline linked and running then rely on the on-negotiation-needed signal to trigger the create-offer, as in the sendrecv example, everything works ok and we have everything set up.

So can I do this SDP exchange and then hold the answer until after building a running pipeline? If so how can I update the transceivers I used to build the SDP so that they get a transport stream, or should this happen on negotiation/flow?
Do I need to reissue SDP once I have ssrc available?
I can’t seem to find any examples of this so any guidance would be greatly appreciated.

2

It sounds like what you are doing should work just fine. Setting a remote offer with preconfigured transceivers should work fine. Please open an issue upstream with a test case.

3

Thanks for the sanity check. I just wanted to confirm the approach was feasible. I’ll double‑check my logic and timing, and if it’s still failing I’ll put together a minimal test with generic code.

4

Hi there, I’m trying to do something similar to receive video on a Quest3 (Android), and wanted to know if you had any luck.