视频下载

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 >= first_byte:
        return file_size
    header = {"Range": f"bytes={first_byte}-{file_size}"}
    bar = tqdm(total=file_size, initail=first_byte, unit='B', unit_sc=True, desc=dst)
    re = requests.get(url, header=header, stream=True)
    with(open(dst, 'ab')) as f:
        for chunk in re.iter_content(chunk_size=1024):
            if chunk:
                f.write(chunk)
                bar.update(1024)
    bar.close()
    return file_size