Generate slideshow from photos using FFMPEG

generate_slideshow_command.py

import natsort
import os
from PIL import Image
import sys

INPUT_DIR = "/Users/aaron/Desktop/pictures"
OUTPUT_DIR = "/Users/aaron/Desktop/pictures-processed"

OUTPUT_WIDTH = 1920
OUTPUT_HEIGHT = 1080

FFMPEG_IMAGE_DURATION = 5

def fetch_sorted_files(dirname):
    files = natsort.natsorted(os.listdir(dirname))
    return files


if __name__=="__main__":
    # clear the output directory

    for file in os.listdir(OUTPUT_DIR):
        file_path = os.path.join(OUTPUT_DIR, file)
        os.remove(file_path)

    # process the images

    input_files = fetch_sorted_files(INPUT_DIR)

    idx = 0
    for file in input_files:
        if ".DS_Store" in file:
            continue

        input_path = os.path.join(INPUT_DIR, file)
        output_path = os.path.join(OUTPUT_DIR, "{}.jpg".format(idx))

        image = Image.open(input_path)
        image_width = float(image.size[0])
        image_height = float(image.size[1])
        scaling_factor = min(OUTPUT_WIDTH / image_width, OUTPUT_HEIGHT / image_height)

        image_width *= scaling_factor
        image_height *= scaling_factor

        image = image.resize((int(image_width), int(image_height)), Image.Resampling.LANCZOS)

        output_image = Image.new("RGB", (OUTPUT_WIDTH, OUTPUT_HEIGHT), color="black")
        output_image.paste(image, (
            int((OUTPUT_WIDTH - image_width) / 2), 
            int((OUTPUT_HEIGHT - image_height) / 2)
        ))
        output_image.save(output_path, format="jpeg")

        idx += 1

    # print the command

    print("ffmpeg \\")

    output_files = fetch_sorted_files(OUTPUT_DIR)
    for file in output_files:
        file_path = os.path.join(OUTPUT_DIR, file)
        print("-i \"{}\" \\".format(file_path))

    print("-filter_complex \"\\")

    for idx in range(0, len(output_files)):
        line = "[{}]scale={}:-2,setsar=1:1[out];[out]crop={}:{}[out];[out]scale=8000:-1,zoompan=z='zoom+0.0005':x=iw/2-(iw/zoom/2):y=ih/2-(ih/zoom/2):d={}:s={}x{}:fps=25".format(idx, OUTPUT_WIDTH, OUTPUT_WIDTH, OUTPUT_HEIGHT, 25 * FFMPEG_IMAGE_DURATION, OUTPUT_WIDTH, OUTPUT_HEIGHT)
        if idx > 0:
            line += ",fade=d=1:t=in:alpha=1,setpts=PTS-STARTPTS+{}/TB".format(idx * FFMPEG_IMAGE_DURATION - 1)
        line += "[f{}];\\".format(idx)
        print(line)

    idx = 0
    output_string = "[f0]"
    for idx in range(1, len(output_files)):
        if idx > 1:
            output_string += "[bg{}]".format(idx - 1)

        output_string += "[f{}]overlay".format(idx)
        if idx + 1 < len(output_files):
            output_string += "[bg{}],".format(idx)\

    print("{},format=yuv420p[v]\" \\".format(output_string))
    print("-map \"[v]\" -r 25 output.mp4")