python基于http下载视频或音频

import os
import requests

def do_load_media(url, path):
  try:
    headers = {
      "User-Agent": "Mozilla/5.0 (Windows NT 6.2; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Maxthon/4.3.2.1000 Chrome/30.0.1599.101 Safari/537.36"}
    pre_content_length = 0
    # 循环接收视频数据
    while True:
      # 若文件已经存在，则断点续传，设置接收来需接收数据的位置
      if os.path.exists(path):
        headers['Range'] = 'bytes=%d-' % os.path.getsize(path)
      res = requests.get(url, stream=True, headers=headers)

      content_length = int(res.headers['content-length'])
      # 若当前报文长度小于前次报文长度，或者已接收文件等于当前报文长度，则可以认为视频接收完成
      if content_length