<html><body><h1>video poster 属性</h1><video width="640" height="360" poster="/i/logo/w3v.png" controls> <source src="/i/video/shanghai.mp4" type="video/mp4"> <source src="/i/video/shanghai.ogg" type="video/ogg"> 您的浏览器不支持 video 标签。</video></body></html>