Has anyone tried using FFMPEG for converting Slow Motion video captured on an iPhone to something usable on PC?

I was searching for how to move Slow Motion video from my iPhone 7 to my Windows PC. All the answers were coming up using iMovie and other Apple software.

As I was not moving the video to a Mac this was not useful. I did find my old friend FFMPEG could make the move quite nicely. Using the command:

ffmpeg -i SlowMotionVideoFromIphone.mov -vf "setpts=4*PTS" SlowMotionVideoOnPC.mp4

does a nice job with the video, but I’ve not found how to re-sync the audio yet. That’s why I am asking if anyone else has tried this and found a solution for both video and audio?