How to change video quality in html5?

Question

Video

Good afternoon.
I would like to adjust the video quality in the standard player. We can initially store video in the required resolutions. I will also display the button for the player. But the question arises, how to do auto-tuning? How to find out what download speed a person has?
You need at least an idea where to start digging.

Answer 1

These are two different videos.
Or use ffmpeg but only if the server is dedicated.