I can't link display+speaker, please help about go2rtc

[Barabba11]

I have this error:

what is this github.com/AlexxIi/go2rtc/internal/webrtc/webrtc.80:185 error?
on browser returns "not found"

[Barabba11]

I've tried with ffmpeg trying to collect together random examples, bu i don't know the proper syntax

streams:
  test: ffmpeg:-f gdigrab -framerate 30 -i desktop
ffmpeg:
  bin: c:\ffmpeg.exe

the following command works and output the video with screen grabbed:
ffmpeg -f gdigrab -framerate 30 -i desktop c:log\output.mkv

I have this error:

and this error:

[Barabba11]

I hope somebody can help me, thanks