title: How to tell Vimeo which video size to deliver responsive
body: <p>It's pretty easy to embed Vimeo's iframe in a responsive manner, so that the player changes in size.</p>
  
  <p>BUT: <strong>Does Vimeo actually deliver the video in a correct size then?</strong></p>
  
  <p>First I assumed wrongly that they would check for bandwidth and progressively enhance quality or resolution, but <a href="https://vimeo.com/blog/post/adaptive-streaming-and-4k-coming-soon-for-your-vid" rel="nofollow">Adaptive Streaming apparently is a thing for the future</a>.</p>
  
  <p>Do they at least downscale videos?</p>
  
  <p>F.e. when uploading a video in 3000 px width and embedding it on a site in the responsive player, the video always seems to have a much lower resolution.</p>