FFMPEG
Crop Video
Preview/Crop before Cropping:
ffplay -vf "crop=x:y:w:h" OUTPUT.webm
The x:y is optional but it will default to 0,0 as starting point.
Preview/Crop Specific Time Frame:
ffplay -ss 5 -t 8 -vf "crop=500:500" OUTPUT.webm
Start at 5 second mark and play for 8 seconds.
[! ] Simply replace
ffplaywithffmpeg -i INPUTFILEto get an actual crop.