FFmpeg: How to convert horizontal video 16:9 to vertical video 9:16, with blurred background on top and bottom sides

Question

I know there is a post to do the contrary: FFmpeg: How to convert vertical video with black sides, to video 16:9, with blurred background sides

but i can\'t figure o

Answer 1

I adapted solution proposed by Mulvya

here is the final result:

ffmpeg -i input.mp4 -lavfi "[0:v]scale=256/81*iw:256/81*ih,boxblur=luma_radius=min(h\,w)/40:luma_power=3:chroma_radius=min(cw\,ch)/40:chroma_power=1[bg];[bg][0:v]overlay=(W-w)/2:(H-h)/2,setsar=1,crop=w=iw*81/256"  output.mp4