# How do I set FPS if I don't know what it is?

I recorded a video on my Galaxy Tab E 9.6" (a samsung tablet) and dragged it into the blender video editor. The properties of the video (on windows 8.1) says that it has a frame rate of 30 FPS. I set the FPS in the dimensions tab in the preferences editor to 30 FPS.

I rendered the video (after adding a number of sound files) but the original audio and the video did not sync up and it gradually got worse. When I checked in the editor, the original audio was about 3 frames longer than the video. I then tried to troubleshoot by using a custom frame rate. I didn't know what it was so I tried to figure it out by trial and error I ended up coming up with something like 30.0001 FPS. I rendered again and it was still not synced up and again gradually got worse.

What I need to know is: how else can I troubleshoot this? Is there a way that I can have blender set the FPS to EXACTLY what the video is os it will sync up? Or is there some other method that I need to use so that it'll sync up?

ffprobe yourclipname.mp4