title: Lossless transparent image format with animation support in c#?
body: <p>I need an animation format to store transparent (RGBA) images used in C#. Requirements:</p>
  <ul>
  <li>Alpha channel support</li>
  <li>Random access to frames</li>
  <li>C# support ideally</li>
  </ul>
  <p>I've checked WebP and APNG, but there is no random access (because of the &quot;relative-to-previous&quot; frame rendering). And I can't use any video format because I need to playback faster/slower and the loading of video  takes ages (can't play immediately after load).</p>
  <p>Edit 1:
  I need to play the animation at variable speed (that's why need random access).</p>