[HELP] Video have different time and audio desync after conversion

[Bartoloni]

And i heard it's possible to do this with FFmpeg, but i don't know how to use it

usually on VFR clips i use Kdenlive (that is just an FFMPEG / MLT gui ), placing the VFR clip on the project bin make Kdenlive to request to "convert" to a "friendly" (not VFR)  format using FFMPEG...