Doctor Who audio synced intro

dw_intro.py

import subprocess
from collections import namedtuple
from pathlib import Path

Timewarp = namedtuple("Timewarp", ["start", "end", "rate"])


def font_filter(stream: str, text: str):
    return ":".join(
        [
            f"[{stream}]drawtext=fontfile=roboto.ttf",
            f"text='{text}'",
            "fontcolor=white",
            "bordercolor=black",
            "borderw=5",
            "x=(w-text_w)/2",
            f"y=10[{stream}]",
        ]
    )


def create_intro(
    input_file: Path,
    output_file: Path,
    start_time: float,
    comparison=False,
):
    command = ["ffmpeg", "-hide_banner", "-v", "error", "-stats", "-y"]

    command.extend(["-i", str(input_file)])

    filters = [
        f"[0:v]trim={start_time}:duration=42.5,setpts=PTS-STARTPTS[intro]",
    ]

    timewarps = [
        Timewarp(0, 8, 0.75),
        Timewarp(8, 23, 0.9),
        Timewarp(23, 26, 0.6),
        Timewarp(26, 29.7, 1.2),
        Timewarp(29.7, 34.8, 0.8),
        Timewarp(34.8, 36, 1.75),
        Timewarp(36, 42, 1),
    ]
    parts = "".join(f"[part{part}]" for part, _ in enumerate(timewarps))
    filters.append(f"[intro]split={len(timewarps)}{parts}")

    for part_num, timewarp in enumerate(timewarps):
        filter_data = [
            f"[part{part_num}]trim={timewarp.start}:{timewarp.end}",
            "setpts=PTS-STARTPTS",
            f"setpts={timewarp.rate}*PTS[part{part_num}]",
        ]
        filters.append(",".join(filter_data))

    filters.append(f"{parts}concat=n={len(timewarps)},setpts=PTS-STARTPTS[vout]")
    filters.append(f"[0:a]atrim={start_time}:duration=37.5,asetpts=PTS-STARTPTS[aout]")

    if comparison:
        filters.append(
            f"[0:v]trim={start_time}:duration=37.5,setpts=PTS-STARTPTS[vout_top]"
        )
        if Path("roboto.ttf").exists():
            filters.extend(
                [
                    font_filter("vout_top", "Original"),
                    font_filter("vout", "Audio synced"),
                ]
            )
        filters.append(
            "[vout_top][vout]vstack[vout]",
        )

    # Theoretically not needed, but I messed up so here is the fix
    filters.append(
        "[vout]fps=23.98,setpts=PTS-STARTPTS,trim=0.7:37.5,setpts=PTS-STARTPTS[vout]"
    )
    filters.append("[aout]atrim=0.7:37.5,asetpts=PTS-STARTPTS[aout]")

    command.extend(["-filter_complex", ";".join(filters)])

    command.extend(["-map", "[vout]"])
    command.extend(["-map", "[aout]"])
    command.extend([str(output_file)])

    subprocess.run(command)


def main():
    import argparse

    parser = argparse.ArgumentParser(
        prog="dw_intro.py",
        description="Creates a timewarped Doctor Who intro synced with the audio. "
        + "Designed to be used with Season 9 Episode 3. ",
        epilog="Be careful using this, it might break.",
    )

    parser.add_argument(
        "-i",
        "--input",
        type=Path,
        required=True,
        help="the input file from which to take the intro.",
    )
    parser.add_argument(
        "-o",
        "--output",
        type=Path,
        help="the output file. Defaults to either `synced.mp4` or `comparison.mp4`",
    )
    parser.add_argument(
        "-s",
        "--start",
        type=float,
        default=185.3,
        help="the time in seconds at which the intro starts. Defaults to 185.3s",
    )
    parser.add_argument(
        "-c",
        "--comparison",
        action="store_true",
        help="create a comparison instead of only the synced intro",
    )

    args = parser.parse_args()
    if args.output is None:
        args.output = Path("comparison.mp4" if args.comparison else "synced.mp4")

    create_intro(args.input, args.output, args.start, args.comparison)


if __name__ == "__main__":
    try:
        main()
    except KeyboardInterrupt:
        pass