Get video from hikvision cam

可用于下载海康dvr视频，支持多线程下载，代码中已经封装好了下载接口，直接调用开始下载、获取下载速度、下载进度等接口，就可以实现dvr录像下载-Hik dvr video is available for download, support for multi-threaded download, the code has a good package download interface, direct call to start the download, get the download