Convert DJI slow motion 120FPS video, to real time 120FPS and merge sound. All without reencoding anything.

remuxDji120Fps

#!/bin/bash
set -e

ffmpeg -i $1.MP4 -c:v copy -c:a copy -f matroska - | ffmpeg -i pipe: -map 0:v -c:v copy -bsf:v hevc_mp4toannexb -f hevc - | ffmpeg -fflags +genpts -r 120 -i pipe: -c:v copy /tmp/_tmp.mp4
ffmpeg -i /tmp/_tmp.mp4 -i $1.aac -c copy $1_remux.mp4
rm /tmp/_tmp.mp4 $1.MP4 $1.aac

# pass file name without extension as parameter, for example: DJI_0020 for DJI_0020.MP4 and DJI_0020.aac pair