Take a look at our program, Tremendum Transcoder, it does all you need and can simplify the way you add media to your sites greatly. 4k videos is not a problem... install it in a powerful server if you need a fast conversion of many videos. For day to day uses, like adding some updates, it can be run from any server alongside with other services with a lower priority, to keep things running smooth.
If you have any questions, feel free to contact me
