I know this is old but if you never found anything then try Splash player. You'll need to change some stuff in the settings before it interpolates to 60 FPS but its a nice player, just not really supported by the devs. Hope this helps you :)
Hey! I'm looking for the same alternative to SVP4 too, and after some research I found https://mirillis.com/free-hd-video-player It's proprietary but it's a free software. I tried to download it and the motion works nicely! Just play the video, then open playback setting, enable and set Motion to maximum (all the way to the right). I wonder why this player is not popular, let me know what do you think about this video player!