Use ffmpeg to center crop and scale an image to 1:1

frames.sh

#Given a video of any aspect ratio this script will extract center cropped thumbnails at 299x299.
#Useful for gathering image training data.
#Assumes ffmpeg 3.3.2
#If you get an error about exact that means you are using an older version of ffmpeg
#Simply remove the :exact=1. 
#This will make it work, but may cause the output size to be off by a pixel
#Script assumes you are downsampling. 

#!/bin/bash

PATH_TO_VID=myvideo.mov
PATH_TO_OUT_DIR=out
ffmpeg -i "$PATH_TO_VID" -y -an -q 0 -vf scale="'if(gt(iw,ih),-1,299):if(gt(iw,ih),299,-1)', crop=299:299:exact=1" $PATH_TO_OUT_DIR/%06d.jpg

That should be what the script does. Just change the OUTPUT_WIDTH to 1920. To be clear that will cause some upscaling since the extra 280 (1080-800) pixels (height) have to come from somewhere. If you don’t want to scale your only other option is letterboxing.

ok ty