convert any source video to fixed size flv with coloured letterboxes

convert.sh

# params: $input, $output, $width, $height, $color

# for landscape (normal) orientation
ffmpeg -y -i $input -vcodec flv1 -vf "scale=iw*min($width/iw\,$height/ih):ih*min($width/iw\,$height/ih), pad=$width:$height:($width-iw*min($width/iw\,$height/ih))/2:($height-ih*min($width/iw\,$height/ih))/2:color=$color" -vb 4000k -acodec mp3 -ar 44100 -ab 320k -vsync 1 -async 1 $output

# for portrait orientation
ffmpeg -y -i $input -vcodec flv1 -vf "transpose=1, scale=iw*min($width/iw\,$height/ih):ih*min($width/iw\,$height/ih), pad=$width:$height:($width-iw*min($width/iw\,$height/ih))/2:($height-ih*min($width/iw\,$height/ih))/2:color=$color" -vb 4000k -acodec mp3 -ar 44100 -ab 320k -vsync 1 -async 1 $output