mermaid

https://app.diagrams.net/
https://www.jianshu.com/p/af48cc77b57a

flowchart LR
	subgraph a["motion estimation"]
		direction TB
		i
		g
	end
	subgraph b["motion compression"]
	end
	subgraph c["motion compensation"]
	end
	a-->b
	b-->c

draw.io