make_crossfade_ffmpeg_video_from_images.sh

#!/bin/bash

# Anh Nguyen <[email protected]>
# 2016-04-30
# Susanne Oberhauser-Hirschoff <[email protected]>

# MIT License

# This script takes in same-size images from a folder and make a crossfade video from the images using ffmpeg.
# Make sure you have ffmpeg installed before running.

# The output command looks something like the below, but for as many images as you have in the folder.
# See the answer by LordNeckbeard at:
# http://superuser.com/questions/833232/create-video-with-5-images-with-fadein-out-effect-in-ffmpeg/1071748#1071748
#
#
# ffmpeg \
# -loop 1 -t 1 -i 001.png \
# -loop 1 -t 1 -i 002.png \
# -loop 1 -t 1 -i 003.png \
# -loop 1 -t 1 -i 004.png \
# -loop 1 -t 1 -i 005.png \
# -filter_complex \
# "[1:v][0:v]blend=all_expr='A*(if(gte(T,0.5),1,T/0.5))+B*(1-(if(gte(T,0.5),1,T/0.5)))'[b1v]; \
# [2:v][1:v]blend=all_expr='A*(if(gte(T,0.5),1,T/0.5))+B*(1-(if(gte(T,0.5),1,T/0.5)))'[b2v]; \
# [3:v][2:v]blend=all_expr='A*(if(gte(T,0.5),1,T/0.5))+B*(1-(if(gte(T,0.5),1,T/0.5)))'[b3v]; \
# [4:v][3:v]blend=all_expr='A*(if(gte(T,0.5),1,T/0.5))+B*(1-(if(gte(T,0.5),1,T/0.5)))'[b4v]; \
# [0:v][b1v][1:v][b2v][2:v][b3v][3:v][b4v][4:v]concat=n=9:v=1:a=0,format=yuv420p[v]" -map "[v]" out.mp4
#set -o xtrace
#----------------------------------------------------------------
# SETTINGS
: ${input_dir:=.}
: ${input_glob:="*.png"}
files=(${input_dir}/${input_glob})  # Change the file type to the correct type of your images
n_files=$((${#files[@]}))                        # Replace this by a number of images
#: ${output_size:=2560:1440}
: ${output_size:=3840:2160}
: ${output_basename:=video}
: ${output_type:=gif}
: ${output_file:=${output_basename}-${output_size/:/x}.${output_type}}           # Name of output video
: ${crossfade:=0.75}                     # Crossfade duration between two images
: ${first_extra_rep=2}
: ${last_extra_rep=8}
#----------------------------------------------------------------

# Making an ffmpeg script...
input=()
loop_filters=()
blend_filters=()

function L_i_stay_N () {
    i=$1 N=$2
    eval echo "[L${i}stay{1..$N}]"
}


first_extra_rep_L=($(L_i_stay_N 0 $first_extra_rep))
concat_filter=${first_extra_rep_L[*]}

 

last_file=$((n_files - 1))
last_extra_rep_L=($(L_i_stay_N $last_file $last_extra_rep))

i=0
for f in "${files[@]}"; do
    input+=("\\\\
  -f image2 -i '$f'")
#
  loop_filters+=("\
  [${i}:v] scale=${output_size},loop=loop=50:size=1,trim=duration=${crossfade},")
  
  if [ $i -eq 0 ]
  then
      loop_filters+=("split=$((first_extra_rep + 2))" ${first_extra_rep_L[*]} "[L${i}stay][L${i}down];
")
  elif [ $i -eq $last_file ]
  then
      loop_filters+=("split=$((2 + last_extra_rep)) [L${last_file}up][L${last_file}stay]"  ${last_extra_rep_L[*]} ";
")
  else
      loop_filters+=("split=3 [L${i}up][L${i}stay][L${i}down];
")     
  fi

  next=$((i+1))

  if [ "${i}" -ne "$last_file" ]; then
      blend_filters+=("\
  [L${next}up][L${i}down] blend=all_expr='A*(if(gte(T,${crossfade}),1,T/${crossfade}))+B*(1-(if(gte(T,${crossfade}),1,T/${crossfade})))' [blend${i}_${next}];
")
      concat_filter+=("
[L${i}stay]
  [blend${i}_${next}]")
  fi

  i=$((i+1))
done
concat_filter+=("
[L${last_file}stay]
" ${last_extra_rep_L[*]})
concat_filter+=("
concat=unsafe=1:n=$((last_file * 2 + 1 + first_extra_rep + last_extra_rep)):v=1:a=0,format=yuv420p[v]")

script="ffmpeg ${input[*]} \\\\
-filter_complex \"
 ${loop_filters[*]}
 ${blend_filters[*]}
 ${concat_filter[*]}
\" \\\\
    -map \"[v]\" $@ ${output_file}"

printf "${script}\n"

# Run it
#eval "${script}"