Try to use gst to encode / decode video (from file now)
Use 2 mpv to play video and audio(autoaudio/video won’t work and i have no idea.)
Also platfrom’s chat room fetcher (not complete yet)

There is it’s pipeline:

filesrc → matroskademux ──(video/x-av1)→ av1parse → av1dec → videoconvert → x264enc → queue → appsink ─→ mpv #1 (H.264)
                        └──(audio/x-opus)→ opusdec → queue → audioconvert → wavenc → appsink ─→ mpv #2 (WAV)