python下载mp4

import requests
from tqdm import tqdm
import os

def download_from_url(url, dst):
    response = requests.get(url, stream=True)
    file_size = int(response.headers['content-length'])
    if os.path.exists(dst):
        first_byte = os.path.getsize(dst)
    else:
        first_byte = 0
    if first_byte >= file_size:
        return file_size
    header = {"Range": f"bytes={first_byte}-{file_size}"}
    pbar = tqdm(
        total=file_size, initial=first_byte,
        unit='B', unit_scale=True, desc=dst)
    req = requests.get(url, headers=header, stream=True)
    with(open(dst, 'ab')) as f:
        for chunk in req.iter_content(chunk_size=1024):
            if chunk:
                f.write(chunk)
                pbar.update(1024)
    pbar.close()
    return file_size


if __name__ == '__main__':
    url = "xxxx.mp4"
    download_from_url(url, "1.mp4")