timelapse.py

#!/usr/bin/env python3

import argparse
import re
import subprocess

def parse_args():
    parser = argparse.ArgumentParser()
    parser.add_argument(
        "output_file",
    )
    parser.add_argument(
        "-i", "--input-fps",
        help="frames per second of the input stream",
        type=float,
        default=1,
    )
    parser.add_argument(
        "-o", "--output-fps",
        help="frames per second of the output stream",
        type=int,
        default=30,
    )
    parser.add_argument(
        "-r", "--resolution",
        help="resolution of the video, defaults to '1920x1080'",
        default="1920x1080",
    )
    parser.add_argument(
        "-d", "--display-name",
        help="X11 display name, of the format: 'hostname:display_number.screen_number', defaults to ':0.0'",
        default=":0.0",
    )

    parser.add_argument(
        "--big",
        help="Override resolution to 1920x2130 for recording in 'big' configuration, i. e. external screen attached",
        action="store_true",
    )

    return parser.parse_args()


def record(display_name, input_fps, output_fps, resolution, output_file):
    args = ["ffmpeg"]
    args.extend(["-framerate", f"{input_fps}"])
    if resolution is not None:
        args.extend(["-s", resolution])
    args.extend(["-f", "x11grab"])
    args.extend(["-i", display_name])
    args.extend(["-vf", f"settb=1/{output_fps},setpts=N"])
    args.extend(["-r", f"{output_fps}"])
    args.extend(["-vcodec", "libx264", "-crf", "0", "-preset", "ultrafast", "-threads", "0"])
    args.append(output_file)

    print("Running:", args)
    subprocess.run(args)

def main():
    args = parse_args()

    if args.big:
        args.resolution = "1920x2130"

    if args.resolution is not None and not re.fullmatch(r"\d+x\d+", args.resolution):
        print("Resolution format incorrect")
        exit(2)

    if not re.fullmatch(r"\S*:\d+\.\d+", args.display_name):
        print("Display name format incorrect")
        exit(3)

    print("Starting recording. To stop recording, just use Ctrl+C.")
    try:
        record(args.display_name, args.input_fps, args.output_fps, args.resolution, args.output_file)
    except KeyboardInterrupt:
        print()
        print("Stopped recording. Goodbye!")

if __name__ == "__main__":
    main()