title: How many frames in CMSampleBuffer?
body: <p>This might be a dumb question, but I am just starting to learn about media formats and AVFoundation, so bear with me.</p>
  
  <p>I've been trying to figure out whether a CMSampleBuffer from AVCaptureVideoDataOutput can have more than one frame in it.  From the documentation, it seems possible, however, most sample code I've seen seem to due with the CMSampleBuffer as if it is a single frame.  Am I just misunderstanding this?</p>
  
  <p>If there can be more than one frame per buffer, is it possible to get at the individual frames and determine if it is a key frame?</p>
  
  <p>Thanks</p>