在线视频测试链接：
http://clips.vorwaerts-gmbh.de/big_buck_bunny.mp4
http://vjs.zencdn.net/v/oceans.mp4
https://media.w3.org/2010/05/sintel/trailer.mp4
http://mirror.aarnet.edu.au/pub/TED-talks/911Mothers_2010W-480p.mp4
在线其它格式视频资源下载，MP4, flv, mkv, 3gp 等
https://www.sample-videos.com/index.php#sample-mp4-video
原文： https://blog.csdn.net/weixin_41010198/article/details/88055078
在线图片测试链接：
http://static.runoob.com/images/demo/demo2.jpg
http://image.nbd.com.cn/uploads/articles/images/673466/500352700_banner.jpg
http://lorempixel.com/200/200/people/1
https://images.unsplash.com/photo-1586097384184-79ba1cec7881?ixlib=rb-1.2.1&q=80&fm=jpg&crop=entropy&cs=tinysrgb&w=400&fit=max&ixid=eyJhcHBfaWQiOjE0NTg5fQ