A simple service that will take a .mov and search through every frame looking for differences between that frame and the previous and create a gif with 1 frame for every _changed_ image (visually)

mov_to_gif.sh

#!/bin/bash

# Default values
FRAME_RATE=4      # Default frame rate (every nth frame)
SSIM_THRESHOLD=0.98  # Threshold below which frames are considered different
TARGET_WIDTH=""   # Target width for frames in the GIF, empty means original width
TARGET_HEIGHT=""  # Target height for frames in the GIF, empty means original height
input_file=""     # Input filename
output_gif=""     # Output filename

progress_bar() {
    local total=$1
    local current=$2
    local width=50  # Width of the progress bar
    local percent=$((current * 100 / total))
    local count=$((width * current / total))
    printf "\r["
    for ((i=0; i<count; i++)); do
        printf "#"
    done
    for ((i=count; i<width; i++)); do
        printf " "
    done
    printf "] %d%%" $percent
}

# Parse command-line arguments for customization
while [[ "$#" -gt 0 ]]; do
    case $1 in
        -f|--frame-rate) FRAME_RATE="$2"; shift ;;
        -s|--ssim) SSIM_THRESHOLD="$2"; shift ;;
        -w|--width) TARGET_WIDTH="$2"; shift ;;
        -h|--height) TARGET_HEIGHT="$2"; shift ;;
        -i|--input) input_file="$2"; shift ;;
        -o|--output) output_gif="$2"; shift ;;
        *) echo "Unknown parameter passed: $1"; exit 1 ;;
    esac
    shift
done

# Check if input and output filenames are provided
if [[ -z "$input_file" || -z "$output_gif" ]]; then
    echo "Both input and output filenames must be provided."
    exit 1
fi

# Create the resize filter string based on provided dimensions
if [[ -z "$TARGET_WIDTH" && -z "$TARGET_HEIGHT" ]]; then
    RESIZE_FILTER=""
elif [[ -z "$TARGET_HEIGHT" ]]; then
    RESIZE_FILTER=",scale=$TARGET_WIDTH:-1"
elif [[ -z "$TARGET_WIDTH" ]]; then
    RESIZE_FILTER=",scale=-1:$TARGET_HEIGHT"
else
    RESIZE_FILTER=",scale=$TARGET_WIDTH:$TARGET_HEIGHT"
fi

# Create a directory to hold the frames
mkdir -p frames

# Extract every nth frame from the MOV file based on FRAME_RATE and the RESIZE_FILTER
ffmpeg -i "$input_file" -vf "select=not(mod(n\,$FRAME_RATE)),setpts=N/FRAME_RATE/TB$RESIZE_FILTER" frames/frame%04d.png
echo "Executing: ffmpeg -i $input_file -vf ""select=not(mod(n\,$FRAME_RATE)),setpts=N/FRAME_RATE/TB$RESIZE_FILTER"" frames/frame%04d.png"

# Initialize previous frame and time variables

prev_frame=""
prev_frame_number=0
prev_frame_number_ref=0
frame=""
frame_number=0
frame_number_ref=0

# Lists to hold the frames and delays for the final GIF
frames_list=()
delays_list=()

frame_count=$(ls frames | wc -l)
current_frame=0
current_delay=0
skipped_frames=0
# Loop through the frames and compare to the previous
for frame in frames/frame*.png; do
    if [ ! -z "$prev_frame" ]; then
        # Get the SSIM value
        ssim=$(ffmpeg -i "$prev_frame" -i "$frame" -filter_complex ssim -an -f null - 2>&1 | grep 'SSIM' | awk '{print $5}' | cut -d: -f2)
        # Check if SSIM indicates a significant change based on SSIM_THRESHOLD
        if (( $(echo "$ssim < $SSIM_THRESHOLD" | bc -l) )); then
            # Calculate the delay based on frame numbers (in hundredths of a second)
            frame_number=$(echo "$frame" | grep -o '[0-9]\+' | head -1)
            frame_number_ref=$((10#$frame_number))
            delay=$(( $current_delay * $FRAME_RATE  ))
            prev_frame="$frame"
            prev_frame_number=$frame_number
            prev_frame_number_ref=$frame_number_ref
            current_delay=0
            # Skip the frame if the delay is zero
            if [ "$delay" -ne 0 ]; then
                frames_list+=("$frame")
                delays_list+=("-delay $delay")
                
            fi
        else
            skipped_frames=$((skipped_frames + 1))
        fi
    else
        prev_frame="$frame" 
    fi
    
    
    progress_bar $frame_count $current_frame
    current_frame=$((current_frame + 1))
    current_delay=$((current_delay + 1))
done

# Generate the GIF
cmd_args=()
for i in "${!frames_list[@]}"; do
    cmd_args+=("${delays_list[$i]}" "${frames_list[$i]}")
done
echo "Executing: convert ""${cmd_args[@]}"" -loop 0 -layers Optimize ""$output_gif"""
convert ${cmd_args[@]} -loop 0 -layers Optimize "$output_gif"
echo "Total frames: $current_frame. Skipped frames: $skipped_frames"
# Cleanup
rm -r frames