Blurred Background on All Sides of Vertical Video
ffmpeg -i <input_file> -filter_complex "[0:v]scale=ih*16/9:-1,boxblur=luma_radius=min(h\,w)/20:luma_power=1:chroma_radius=min(cw\,ch)/20:chroma_power=1[bg];[bg][0:v]overlay=(W-w)/2:(H-h)/2,crop=h=iw*9/16" <output_file>
Don’t forget to replace <input_file>
and <output_file>
with the appropriate file names.