How to have rpi4 turn on TV to show RTSP from a camera?

Configuration
1

i have HASS OS running on the rpi4. the TV is connected to the rpi4’s hdmi.
i was able to integrate the Amcrest 410 doorbell. whenever someone push the doorbell, i can see the entity in HA going from OFF to ON. the doorbell also has a RTSP stream that i can view in VLC.

how can tie all of this together? when someone ring the Amcrest, have the rpi4 turn on the TV and show the RTSP from the doorbell cam.

2

Have you looked into this, it might work for you, I have not done it myself: HDMI-CEC - Home Assistant

3

@kdem 's idea is correct, however, if your TV is “smart” and connect to HA, there might be easier alternatives.

As to actually show the RTSP stream, do you have something in mind?
Is your TV actually smart and has an app?
Does the RPI show the HA frontend?
An always-on PC hooked?