Forword encoded video by WebRTC

help
1

Intention: Gather local realtime display video by FFmpeg, then forward it to remote by webRTC.
Situation: 1. WebRTC has established 2. video track set 3*.I can send while the other can't receive
Question: WHY or alternative

Detail.

  1. I'm RTC callee. here how i receive offer and create answear.(don't care about param, since RTC has connected) RTC handle offer
  2. Note video track is create by fn start_webrtc_video_stream_on_pc add video track
    3.FFmpegcapture video after video track is created.FFmpeg
  3. Proof of I can &remote can't. proof

Need more,plz tell me, I've stuck here for tooooo long