title: Frame synchronization with AVPlayer
body: <p>I'm having an issue syncing external content in a <code>CALayer</code> with an <code>AVPlayer</code> at high precision. </p>
  
  <p>My first thought was to lay out an array of frames (equal to the number of frames in the video) within a <code>CAKeyframeAnimation</code> and sync with an <code>AVSynchronizedLayer</code>. However, upon stepping through the video frame-by-frame, it appears that <code>AVPlayer</code> and Core Animation redraw on different cycles, as there is a slight (but noticeable) delay between them before they sync up.</p>
  
  <p>Short of processing and displaying through Core Video, is there a way to accurately sync with an <code>AVPlayer</code> on the frame level?</p>
  
  <p><strong>Update: February 5, 2012</strong></p>
  
  <p>So far the best way I've found to do this is to pre-render through <code>AVAssetExportSession</code> coupled with <code>AVVideoCompositionCoreAnimationTool</code> and a <code>CAKeyFrameAnimation</code>. </p>
  
  <p>I'm still very interested in learning of any real-time ways to do this, however.</p>