Using FFMPEG to splice a bumper onto an excerpt of a movie

bumper.sh

#!/bin/bash

in="$1"
bumper_img="$2"
seek="$3" # "hh:mm:ss" or # of seconds
length="$4" # "hh:mm:ss" or # of seconds

ffmpeg \
  -f image2pipe -vcodec ppm -i <(
    ffmpeg \
      -v 0 \
      -loop 1 -f image2 -i "${bumper_img}" \
      -f image2pipe -vcodec ppm \
      -r 29.97 -t 5 -an \
      -y /dev/stdout;
    ffmpeg \
      -v 0 \
      -ss "${seek}" -t "${length}" \
      -i "${in}" \
      -f image2pipe -vcodec ppm \
      -r 29.97 -an \
      -y /dev/stdout
  ) \
  -f mov -vcodec libx264 \
  -r 29.97 -an \
  -y /tmp/concated.mov

exit $?