Camera stream of Restful API

I’m new to HA, and I want to create an easy camera integration.
I can get the fMP4 stream via my Resful API,
and I want to view the stream on the entity by the minimal implementation.
I had read the document below.
I tried the “stream_source” by using RTSP url which is good running in VLC
without my API, but it doesn’t work.
Please help me to know how to use it, thanks.