shrinker.py

from enum import Enum
import subprocess
import json
import time
import sys


FILE_SIZE_LIMIT_IN_BYTES = 10485760 # 10 * 1024 * 1024
FILE_SIZE_LIMIT_STR = f'{FILE_SIZE_LIMIT_IN_BYTES // 1024 // 1024}mb'
FileSizeLimit = Enum('FileSizeLimit', ['OVER', 'UNDER'])

def get_file_path():

    return sys.argv[1]


def get_data(file_path):
    stdout = subprocess.run(f'.\\ffprobe.exe -i "{file_path}" -v quiet -print_format json -show_streams -show_format', capture_output=True, encoding='UTF-8').stdout
    data_json = json.loads(stdout)
    
    return data_json


def check_file_size(file_path):
    data = get_data(file_path)
    if int(data['format']['size']) < FILE_SIZE_LIMIT_IN_BYTES:
        return FileSizeLimit.UNDER

    return FileSizeLimit.OVER


def split_video(file_path, output_path, output_file_video, output_file_audio):
    subprocess.run(f'.\\ffmpeg.exe -i "{file_path}" -y -c:v copy -an "{output_path + output_file_video}" -c:a copy -vn "{output_path + output_file_audio}"')


def merge_video(file_path_1, file_path_2, output_path, output_file_name):
    subprocess.run(f'.\\ffmpeg.exe -i "{file_path_1}" -i "{file_path_2}" -y -c copy "{output_path + output_file_name}"')


def determine_target_bitrate(video_file_path, audio_file_path):
    video_data = get_data(video_file_path)
    audio_data = get_data(audio_file_path)
    reduction_coefficient = int(video_data['format']['size']) / (FILE_SIZE_LIMIT_IN_BYTES - int(audio_data['format']['size']))
    target_bitrate = int(video_data['streams'][0]['bit_rate']) / reduction_coefficient

    return target_bitrate


def change_bitrate(file_path, output_path, output_file_name, target_bitrate):
    subprocess.run(f'.\\ffmpeg.exe -i "{file_path}" -y -b:v {target_bitrate} -maxrate:v {target_bitrate} -bufsize 750K "{output_path + output_file_name}"')


def main():
    original_file_path = get_file_path()

    try:
        if check_file_size(original_file_path) == FileSizeLimit.UNDER:
            print(f'\nFile is already under {FILE_SIZE_LIMIT_STR}.')
            time.sleep(2)
            sys.exit(0)
    except KeyError as e:
        print('\nInvalid file format.')
        time.sleep(2)
        sys.exit(1)

    split_video(original_file_path, '.\\tmp\\', 'video_only.mp4', 'audio_only.mp4')

    target_bitrate = determine_target_bitrate('.\\tmp\\video_only.mp4', '.\\tmp\\audio_only.mp4')
    change_bitrate('.\\tmp\\video_only.mp4', '.\\tmp\\', 'changed_bitrate.mp4', target_bitrate)
    merge_video('.\\tmp\\changed_bitrate.mp4', '.\\tmp\\audio_only.mp4', original_file_path, f'_{FILE_SIZE_LIMIT_STR}.mp4')

if __name__ == "__main__":
    main()