FFMPEG目录和可变数据

Question

运行此操作会产生错误。我做错了什么？

read YYYY MM DD <<<$(date +'%Y %m %d')
for f in "$@"
do
  /usr/local/bin/ffmpeg -i "$f" -vf fps=1/8 "/Volumes/Backup/VideoFrames/$YYYY $MM $DD/${f%.*}Frame55Grab%d.png"
done