Rotate video with 90 degrees using ffmpeg

rotate_vid_90d_ffmpeg.ps1

# rotate video with 90 degrees
# reference: https://stackoverflow.com/questions/3937387/rotating-videos-with-ffmpeg
$input = Read-Host -Prompt "input file name"
$output = Read-Host -Prompt "output file name"
if ([string]::IsNullOrEmpty($output)) {
  $output = "output.mp4" 
}

# run ffmpeg
ffmpeg.exe -i $input -vf "transpose=1" $output