To convert a video to 16x9 or 9x16 by adding black bars use ffmpeg as follows
ffmpeg -i film1.mp4 -vf "scale=1920:1080:force_original_aspect_ratio=decrease,pad=1920:1080:(ow-iw)/2:(oh-ih)/2,setsar=1" film1_bars.mp4
This add bars to the top and bottom, flip both of the 1920:1080
to 1080:1920
for horizontal bars (better for computer monitors, TV etc)
Note IGTV also requires h.264 and a max of 30fps.