title: HEVC/H.265 interlaced format support in ffmpeg or VLC
body: <p>&quot;Music Box Russia&quot; channel over satellite transmits in HEVC 1920x1080 25fps <strong>interlaced</strong> - and after recording VLC recognizes file as 50 fps, and resolution 1920x540 - half a height. But on satellite tuner the player works fine - it plays a file as 1920x1080 25fps... When we can expect support for HEVC/H.265 interlaced? <a href="https://www.xsistema.lt/file-manager/downloads/737847e8-a0b8-4ffe-9411-30c383c1508f_20201127%201612%20-%20RUSSIAN%20MUSICBOX%20HD%20-%20%D0%9C%D1%83%D0%B7%D0%9A%D0%B0%D1%87%20_%2016%2B.mp4" rel="nofollow noreferrer">Here</a> is recorded file (Garry Grey &amp; Eva Miller - wtf). Also - a lot of lost frames in VLC player statistics..</p>
  <p><strong>EDIT:</strong></p>
  <p>I found some interesting info how in HEVC the interlace video content can be indicated <a href="https://www.ramugedia.com/interlace-support-in-hevc" rel="nofollow noreferrer">here</a>:</p>
  <blockquote>
  <p>Unlike to H.264/AVC, interlace-dedicated coding in HEVC is not exist:</p>
  <ul>
  <li>No mixed frame-field interaction (like PAFF in H.264/AVC)</li>
  <li>No interlace scanning of transform coefficients</li>
  <li>No correction MVX[1] (or y-component of MV) if current and reference pictures are in different polarity (top-bottom or
  bottom-top).</li>
  </ul>
  <p>However, in HEVC the interlace video content can be indicated
  (signaled in VPS/SPS and <code>pic_timing</code> SEI messages the latter are
  transmitted for every picture in the sequence).  Interlace-related
  setting:</p>
  <ul>
  <li><p>in VPS/SPS set <code>general_interlaced_source_flag=1</code> and <code>general_progressive_source_flag=0</code>. Indeed, the HEVC standard says:</p>
  <p><em>if <code>general_progressive_source_flag</code> is equal to <code>0</code> and
  <code>general_interlaced_source_flag</code> is equal to <code>1</code>, the source scan type of
  the pictures in the CVS should be interpreted as interlaced only.</em></p>
  </li>
  <li><p>in VPS/SPS set <code>general_frame_only_constraint_flag=0</code></p>
  </li>
  <li><p>in SPS VUI set <code>field_seq_flag=1</code> and <code>frame_field_info_present_flag=1</code>. Notice that if these flags are ON
  then picture timing SEIs shall be present for each picture.</p>
  </li>
  <li><p>transmission of Picture Timing SEI per picture with the following parameters:</p>
  <p><code>source_scan_type = 0</code>  to indicate interlace mode
  for top field picture signal <code>pict_struct=1</code> and for bottom field picture <code>pict_struct=2</code></p>
  </li>
  </ul>
  </blockquote>
  <p>Perhaps it is possible to pass these parameters to ffmpeg/vlc before playing a file?</p>