title: What HEVC codec tag to use with fMP4, hvc1 or hev1?
body: <p>How does one choose the correct codec tag to use (<code>hvc1</code> or <code>hev1</code>) when muxing HEVC video into fragmented MP4 for streaming with MPEG-DASH/HLS?</p>
  <p>I reckon there's a slight difference in muxing depending on the tag according to <code>ISO/IEC FDIS 14496-15</code>:</p>
  <blockquote>
  <p>When the sample entry name is 'hvc1', the default and mandatory value of array_completeness is 1 for arrays of all types of parameter sets, and 0 for all other arrays. When the sample entry name is 'hev1', the default value of array_completeness is 0 for all arrays.</p>
  </blockquote>
  <p>Is there anything else apart from this?</p>
  <p>Why are there two tags and what is the criteria to choose between the two?</p>
  <p>Side note: Apple prefers <code>hvc1</code> according to their <a href="https://developer.apple.com/documentation/http_live_streaming/hls_authoring_specification_for_apple_devices#2969487" rel="noreferrer">HLS Authoring spec</a> for some reason.</p>