webrtcbin does not emit pad-added signal

[Michiel Konstapel]

On 09-07-2022 00:37, Alexei Golovko via gstreamer-devel wrote:
> I try to connect webrtcbin to Janus with gstreamer 1.20.1 and python 
> 3.9, but does not receive pad-added signal.
>
> The code is in 
> https://gist.github.com/le-chat/d74457383b6e821666b90e8d5cebcd38#file-webrtc_receiver-py
> This gist provides full self-contained environment (with Nix or 
> Docker) and starts Janus server, virtual RTSP camera (used as video 
> source for Janus) and webrtcbin-based client which tries to connect.
>
> The handler for pad-added is never called, and I don't understand why.
>
> The logs are at https://pastebin.com/raw/RsyKBAfM
> As i can see, webrtcbin establishes connection and receives many RTP 
> packets from Janus.
>
> Regards, Alexei Golovko.

My first guess would be that you're adding the signal handler AFTER the 
pad has already been created, is that possible? I think 
set-remote-description will trigger the creation of the pad. Or do you 
see the same happening when you connect the handler before going into 
PLAYING (uncomment line 35 in your code)?

HTH,
Michiel