Calculate video bitrate to achieve a given filesize and duration

video_bitrate.pyw

"""Calculate the video bitrate for video compression software
to achieve a given filesize and duration.

Intended for use with HandBrake: https://handbrake.fr/
Result bitrate should be copied to your constant/average bitrate.
Note that input filesize is in megabytes, not mebibytes.

"""

import re
import sys
from tkinter import Misc, StringVar, Tk
from tkinter.ttk import Entry, Frame, Label, LabelFrame, Spinbox


def main() -> None:
    def refresh_output() -> None:
        try:
            filesize = float(video_filesize.var.get()) * 8000
            duration = parse_video_duration(video_length.var.get())
            audio = float(audio_bitrate.var.get())
        except ValueError:
            return output_bitrate.var.set("")

        output_bitrate_num = (filesize - audio * duration) / duration
        if output_bitrate_num <= 0:
            return output_bitrate.var.set("Video too long")

        output_bitrate.var.set(str(int(output_bitrate_num)))

    enable_windows_dpi_awareness()
    app = Tk()
    app.title("HandBrake Video Bitrate Calculator")
    app.geometry("854x200")

    content = Frame(app, padding=10)
    content.pack(expand=True, fill="both")
    content.grid_columnconfigure(0, weight=3)
    content.grid_columnconfigure(1, weight=1)
    content.grid_rowconfigure(0, weight=1)

    inputs = Frame(content)
    inputs.grid(row=0, column=0, sticky="nesw")
    inputs.grid_columnconfigure(0, weight=1)
    inputs.grid_rowconfigure(0, weight=3)
    inputs.grid_rowconfigure(1, weight=1)

    outputs = Frame(content)
    outputs.grid(row=0, column=1, sticky="nesw")
    outputs.grid_anchor("center")

    video = LabelFrame(inputs, text="Video", padding=10)
    video.grid(row=0, column=0, sticky="nesw")
    video.grid_anchor("center")
    video.grid_columnconfigure(0, weight=1)
    video_filesize = LabelSpinbox(video, label="Desired filesize (MB):", value="50")
    video_filesize.grid(sticky="ew")
    video_length = LabelEntry(video, label="Length (mm:ss):", value="3:00")
    video_length.grid(sticky="ew")

    audio = LabelFrame(inputs, text="Audio", padding=10)
    audio.grid(row=1, column=0, sticky="nesw")
    audio.grid_anchor("center")
    audio.grid_columnconfigure(0, weight=1)
    audio_bitrate = LabelSpinbox(audio, label="Bitrate (kbps):", value="96")
    audio_bitrate.grid(sticky="ew")

    output_bitrate = LabelEntry(outputs, label="Result bitrate (kbps):")
    output_bitrate.grid(sticky="ew")

    video_filesize.var.trace_add("write", lambda *_: refresh_output())
    video_length.var.trace_add("write", lambda *_: refresh_output())
    audio_bitrate.var.trace_add("write", lambda *_: refresh_output())
    refresh_output()

    app.mainloop()


def parse_video_duration(s: str) -> int:
    s = s.strip()
    m = re.match(r"(?:(\d+):)?(?:(\d+):)?(\d+)", s)
    if m is None:
        raise ValueError(f"Invalid duration: {s}")

    hours = int(m[1] or 0)
    minutes = int(m[2] or 0)
    seconds = int(m[3] or 0)

    if m[1] is not None and m[2] is None:
        hours, minutes = 0, hours

    return hours * 3600 + minutes * 60 + seconds


def enable_windows_dpi_awareness() -> None:
    if sys.platform == "win32":
        from ctypes import windll

        windll.shcore.SetProcessDpiAwareness(2)


class LabelEntry(Frame):
    def __init__(self, parent: Misc, *, label: str, value: str = "") -> None:
        super().__init__(parent)
        self.parent = parent
        self.grid_columnconfigure(1, weight=1)
        self.label = Label(self, text=label)
        self.label.grid(row=0, column=0, sticky="w")

        self.var = StringVar(self, value=value)
        self.entry = Entry(self, textvariable=self.var)
        self.entry.grid(row=0, column=1, sticky="ew", padx=(5, 0))


class LabelSpinbox(Frame):
    def __init__(self, parent: Misc, *, label: str, value: str = "", **kwargs) -> None:
        super().__init__(parent)
        self.parent = parent
        self.grid_columnconfigure(1, weight=1)
        self.label = Label(self, text=label)
        self.label.grid(row=0, column=0, sticky="w")

        self.var = StringVar(self, value=value)
        self.entry = Spinbox(self, from_=0, to=9999, textvariable=self.var)
        self.entry.grid(row=0, column=1, sticky="ew", padx=(5, 0))


if __name__ == "__main__":
    main()