How can i use ffmpeg to crop a video
ffmpeg -i in.mp4 -filter:v "crop=500:500:20:20" Vid-out.mp4
ffmpeg -i in.mp4 -filter:v "crop=W_:H_:W_:H_" Vid-out.mp4
what I'm trying to figure out is, how does anyone know where 500:500 is or where 20:20 is in the video or picture, where does 0 or 500 start on a picture or video, and how can i find out easily