Making a film color DNA

#!/bin/bash
# film name
FILM=$1
# the api key to access my api to update my database
APIKEY=$2

# some of this may not be relevant for you
BUCKET="gs://MY_BUCKET/"
PFX="MY_DESTINATION_GCS_FOLDER/"
FX="MY_VIDEO_SOURCE_GCS_FOLDER/"
API="https://MY_API_ENDPOINT"


if [ -z $FILM ]; then
  echo "Arg 1 should be the film name"
  exit 1
fi
echo "...doing film ${FILM}"
if [ -z $STRIP ]; then
  echo "Arg 2 should be the strip name"
  exit 1
fi
echo "...creating strip ${STRIP}"
if [ -z $FPS ]; then
  echo "Arg 3 should be the new fps to generate the required number of images"
  exit 1
fi
echo "...new FPS is ${FPS}"
if [ -z $FOLDER ]; then
  echo "Arg 4 should be the folder for the final result png"
  exit 1
fi

## get the md5 of the film
## eg 0006c7fe42adaa132c21324e121c304c.mp4 = 0006c7fe42adaa132c21324e121c304c
MD5="${FILM%.*}"
echo "...working on md5 ${MD5}"

# this is my small app to pick up the ID in my database that matches the film MD5
# you'll have to replace this however you are going to record the image color strip produced
FILMMASTER=$(node index.mjs -v false -a ${API} -k ${APIKEY} -m ${MD5})
echo "...FILMMASTER ${FILMMASTER}"

## get film from gcs
gsutil cp "${BUCKET}${FX}${FILM}" ./

# get the current number of frames
# ffprobe gets installed with ffmpeg
FPS=$(ffprobe -v error -select_streams v:0 -show_entries stream=avg_frame_rate -of default=noprint_wrappers=1:nokey=1 "${FILM}" |  sed -E "s/\/1//" | bc -l)

if [ -z $FPS ]; then
  echo "Couldnt get the frame rate"
  exit 1
fi

# now get the duration in secs
S=$(ffprobe -v error -show_entries format=duration -of default=noprint_wrappers=1:nokey=1 "${FILM}" | bc -l)
if [ -z $S ]; then
  echo "Couldnt get the duration"
  exit 1
fi

# we want a standard number of images no matter the fps or duration
# so in other words change the frame rate
# the new framerate needs to be the duration in secs/number of images required
IMAGES=256
FPS=$(echo "$S / $IMAGES" | bc -l)

echo "...${FILM} (seconds:${S} total frames:${TF} new FPS ${FPS} for ${IMAGES} images)"
FOLDER="strips/"
STRIP=$(basename ${FILM})

echo "...result will be in ${FOLDER}${STRIP}"
SCRATCH="./tmp/"
PREFIX="${MD5}"-
EXT=".png"

# make the series of images
BITS="${SCRATCH}${PREFIX}d${EXT}"
FINAL="${FOLDER}${STRIP}${EXT}"

# clean the previous stuff in case there's any around
rm -f -- "${SCRATCH}${PREFIX}*${EXT}"
rm -f -- "${FINAL}"

# this will cut the film into a standard number of images and take the average color
ffmpeg -i "${FILM}" -hide_banner -loglevel error -vf tblend=all_mode=average,scale=1:1,fps=1/${FPS} "${BITS}" < /dev/null

# number of files created
NFILES=$(ls ${SCRATCH} | tail -n 1 | sed  "s/${PREFIX}//" | sed "s/.png//" | bc)
echo "...${NFILES} created in ${SCRATCH}" < /dev/null

# get the files created and combine
ffmpeg -i "${BITS}" -hide_banner -loglevel error -filter_complex scale=3:75,tile="${NFILES}x1",avgblur=sizeX=2 -update true "${FINAL}" < /dev/null

# clean tmp files
rm "${SCRATCH}"*
echo "...final result is ${FINAL}"

# now move to gcs
DEST="${BUCKET}${PFX}/"
gsutil cp "${FINAL}" "${DEST}"

# delete the film
rm "${FILM}"

# do the mutation
# this is my small app to update my database
# you'll have some other way of recording the result location on cloud storage
node index.mjs -v true -a ${API} -k ${APIKEY} -f ${FILMMASTER} -s ${STRIP}${EXT}

BUCKET="gs://MY_BUCKET/"
gsutil ls "${BUCKET}MY_VIDEO_FOLDER" > films.lst
cat films.lst | sed -E "s/.*\///g" | sort > vids.lst
gsutil ls "${BUCKET}MY_IMAGE_FOLDER" | sed "s/.png//g" | sed -E "s/.*\///g" | sort > strips.lst
## files vids without strips
comm -3 vids.lst strips.lst > work.lst

KEY=MY_API_KEY
while IFS= read -r LINE; do
  echo $LINE
  bash strip.sh "${LINE}" ${KEY}
done < w.lst