gentoo-overlay/media-video/smplayer/metadata.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE pkgmetadata SYSTEM "http://www.gentoo.org/dtd/metadata.dtd">
<pkgmetadata>
  <herd>qt</herd>
  <herd>video</herd>
  <use>
    <flag name='autoshutdown'>
      Enable the option to shutdown your computer after finishing the playlist.
      This requires <pkg>dev-qt/qtdbus</pkg> as dependency.
    </flag>
	<flag name='streaming'>Support for streaming video sites through
      <pkg>net-misc/youtube-dl</pkg> (MPV only).
    </flag>
  </use>
</pkgmetadata>