sorry I couldn’t reply until today.
1) In the preview window of Syphon Recorder, I see the stream without dropped frames.
2) I think I checked correctly what you suggested : “open GL scene” set as source in the Syphon Server settings panel and I see nothing on the billboard.
The same setting on “image” = the hdmi stream is seen on the billboard and on the Syphon Recorder Preview window
3) Still no moving “movie” whatever codec or size choices. The duration is correct, the sound is good, but frozen frame…
5) last thing about the MacMini. Ok for the Intel HD 4000, is the Core i5 and 4 Gb RAM strong enough to manage one Prores HD video stream ?