4k video drag play Carton

I'm going to use app（ffplay） to play the 4k video from the iPhone external USB drive, Video is a 4k video recorded in iphone se，play it for a while, drag it forward, and the video will get stuck. But I used ffmpeg -i 20184k.m4v -c copy 20184kcopy.m4v, and in the same situation, I did the same drag (play for a while, drag forward a little bit, the video was smooth, I compared the source video with the converted video. Found that the source video time base is 600, the converted time base becomes 19200, and the discovery is because the source video time base is too small to drag To audio and video synchronization, resulting in the Carton.

My question now is how to make sure that the 4k video is smooth without changing the original 4k video time base

Don't know how to solve it? help me？

thank you