Run ffmpeg to generate a libx264 .mp4.

ffmpeg_tools.py

# Douglas Myers-Turnbull wrote this for the Kokel Lab, which has released it under the Apache Software License, Version 2.0
# See the license file here: https://gist.github.com/dmyersturnbull/bfa1c3371e7449db553aaa1e7cd3cac1
# The list of copyright owners is unknown

from plumbum import local
import os

def make_video_from_frames(input_dir: str, video_path: str, framerate: str='10/1', ffmpeg_path: str='ffmpeg', input_image_extension: str='.jpg') -> None:
    """Runs ffmpeg on all selected files in a directory to generates an x264-encoded video in an MP4 container.
    Warnings:
        - Make sure that the frames are sorted in the correct order.
        - Overwrites the output video file without warning.
    video_path: the full path of the video file, which MUST end in .mp4
    framerate: a rational number in the format a/b (ex: 4/5 is 4 frames per every 5 seconds)
    input_image_extension: The extension of the images in the directory to use as input; must start with a dot (.)
    """
    assert input_image_extension.startswith('.')
    assert video_path.endswith('.mp4')
    ffmpeg = local[ffmpeg_path]
    ffmpeg['-r', framerate,
                '-y',                                           # overwrites
                '-pattern_type', 'glob',
                '-i', os.path.join(input_dir, '*' + input_image_extension),
                '-vf', 'scale=trunc(iw/2)*2:trunc(ih/2)*2',     # needed because: https://stackoverflow.com/questions/24961127/ffmpeg-create-video-from-images
                '-c:v', 'libx264',
                '-pix_fmt', 'yuv420p',                          # needed because most video players can only use the 264 pixel format, but it's not default
                video_path]()