turn a timelapse into a sliced timelapse

lapser.py

from skimage import io
import argparse
import glob
import numpy as np
import os


def make_frames(files, outdir, n=8, prefix="composite"):
    split = int(len(files) / n)
    pathstart = os.path.join(outdir, prefix)
    for i in range(split):
        print("%d / %d ~ %2.3f%%" % (i+1, split, 100.0* (i+1) / split))

        imgs = files[i:len(files):split]
        img = compose(imgs)
        io.imsave("%s-%04d.png" % (pathstart, i), img)


def compose(filenames):
    imgs = [io.imread(f) for f in filenames]
    h, w, _ = imgs[0].shape # (2060, 3662, 3)
    pxw = int(w / len(filenames))
    canvas = np.zeros_like(imgs[0])
    x = 0
    for i, img in enumerate(imgs):
        canvas[:,x:x+pxw,:] = img[:,x:x+pxw,:]
        x += pxw
    return canvas


def main(indir, outdir):
    """assumes `ffmpeg -r 1 -i file.mp4 -r 1 "lapse/title-%04d.png`
        has already been run to dump the frames out.
    """
    os.makedirs(outdir, exist_ok=True)

    files = sorted(glob.glob(indir + "/*"))
    make_frames(files, outdir)

    print("""turn this into a movie playable on iphone via:
    ffmpeg -i out/composite-%d.png -s 1920x1080 -c:v libx264 -pix_fmt yuv420p -profile:v baseline -level 4.2 -crf 15 -movflags +faststart output.mp4
    """)


if __name__ == '__main__':
    ap = argparse.ArgumentParser()
    ap.add_argument("-i", "--input_directory", required=False,
        default="/Users/jsundram/Downloads/lapse",
        help="Path to lapse images")
    ap.add_argument("-o", "--output_directory", required=False,
        default="/Users/jsundram/Downloads/out",
        help="Path to store output images")

    args = vars(ap.parse_args())
    main(args['input_directory'], args['output_directory'])