A simple shell script to calculate duration of some videos in the current directory with *.MP4 extension

calculate_MP4_duration.sh

#!/usr/bin/env zsh

pad_zero() {
  local NUMBER=$1
  if [[ $NUMBER -lt 10 ]]; then echo 0$NUMBER; else echo $NUMBER; fi
}

convert_seconds_to_hours() {
  local SECONDS=$1
  HOURS=$(expr $SECONDS / 3600)
  MINUTES=$(expr $SECONDS % 3600 / 60)
  SECONDS=$(expr $SECONDS % 3600 % 60)
  echo "$(pad_zero $HOURS):$(pad_zero $MINUTES):$(pad_zero $SECONDS)"
}

calculate_MP4_seconds() {
  local TOTAL_SUM=0
  for file in *.MP4; do
    SECONDS=$(ffmpeg -i $file 2>&1 | grep Duration | cut -d ' ' -f 4 | sed s/,// | sed 's@\..*@@g' | awk '{ split($1, A, ":"); split(A[3], B, "."); print 3600*A[1] + 60*A[2] + B[1] }')
    TOTAL_SUM=$(expr $TOTAL_SUM + $SECONDS)
  done
  convert_seconds_to_hours $TOTAL_SUM
}

calculate_MP4_seconds