title: What are bitstream filters in ffmpeg?
body: <p>After careful reading of <a href="https://www.ffmpeg.org/ffmpeg-bitstream-filters.html" rel="noreferrer">FFmpeg Bitstream Filters Documentation</a>, I still do not understand what they are really for.</p>
  
  <p>The document states that the filter:</p>
  
  <blockquote>
    <p><strong>performs bitstream level modifications without performing decoding</strong></p>
  </blockquote>
  
  <p>Could anyone further explain that to me? A use case would greatly clarify things. Also, there are clearly different filters. How do they differ?</p>