ffmpeg drawtext how to set direction right to left

问题

i write arabic text to videos and it works fine but the issue is that the arabic language is written from right to left so the text must align right not left i get the text like this
and it should be like this

my code

ffmpeg -y -i input.mp4 -vf "drawtext=text_shaping=1:fontfile=C\/:/Windows/Fonts/tradbdo.ttf:\
textfile=text-new.txt:fontcolor=white:fontsize=40:x=w-tw:y=h-50*t:" -c:v libx264 output.mp4

来源：https://stackoverflow.com/questions/47931448/ffmpeg-drawtext-how-to-set-direction-right-to-left