title: Safari doesn't play HEVC 4k/UHD HLS stream
body: <p>As part of testing and debugging, I'm trying to play a 4k HLS stream encoded in HEVC in Safari on a mid-2015 MacBook Pro with High Sierra 10.13.6.</p>
  
  <p>But Safari refuses to select the 4k quality, it only plays 1080p and lower. I encoded a stream with only one quality in 4k, and then Safari says "unsupported plugin".</p>
  
  <p>The streams are encoded with a professional grade commercial product and they play in ffplay. The codec string in the manifest is hvc1.1.6.L150.B0 and the bitrate is around 9 Mbit/s, which I believe falls within Apple's constraints.</p>
  
  <p>Apple is very obtuse in providing information. Will Safari NEVER play a HEVC 4k stream on my laptop? Is there some setup where I definitely should be able to play this stream at 4k, such as casting to an AppleTv4k or plugging in a 4k capable TV and running Safari fullscreen? What exactly are the conditions here?</p>