Stich PNGs in directories to MP4

stitch_pngs.sh

#!/bin/bash

mindepth=0
maxdepth=0
original_dir=$(pwd)

print_help() {
  echo "Usage: $0 [OPTION]..."
  echo "Create videos from PNG files in directories."
  echo
  echo "Options:"
  echo "-r    search subdirectories recursively"
  echo "-s    only search subdirectories (not this directory)"
  echo "-h    display this help and exit"
}

while getopts ":srh" opt; do
  case ${opt} in
    s ) 
      mindepth=1
      maxdepth=1
      ;;
    r ) 
      maxdepth=10
      ;;
    h ) 
      print_help
      exit 0
      ;;
    \? ) 
      echo "Invalid option: -$OPTARG" 1>&2
      print_help
      exit 1
      ;;
  esac
done

while IFS= read -r -d '' D; do
    cd "${D}" 
    if [ "$(ls -A *.png 2>/dev/null)" ]; then
        if [ "${D}" = "." ]; then
            video_name=$(basename "${original_dir}")
        else
            video_name=$(basename "${D}")
        fi
        if [ -f framerate ]; then
            framerate=$(cat framerate)
        else
            framerate=1/5
        fi
        find . -maxdepth 1 -name "*.png" -print0 | sort -zV | xargs -0 cat | ffmpeg -framerate "${framerate}" -i - -r 10 "${video_name}.mp4"
    fi
    cd "${original_dir}"
done < <(find . -mindepth ${mindepth} -maxdepth ${maxdepth} -type d -print0)