title: Is there a quality difference between output of AVCaptureMovieFileOutput and AVCaptureVideoDataOutput?
body: <p>In the process of capturing a light trail photo, I noticed that for fast moving objects, there is slightly more discontinuity between successive frames if I use the sample buffers from AVCaptureVideoDataOutput compared to if I record a movie and extract frames and run the same algo.</p>
  
  <p>Is there a refresh rate/frame rate difference if the two modes are used?</p>
  
  <p>A colleague who has experience in professional photography claims that there is a visible lag even in Apple's default camera app when comparing the preview in Photo mode and Video mode but it is not something very obvious to me.</p>
  
  <p>Furthermore, I am actually capturing video at a low frame rate (close to highest exposure)</p>
  
  <p>To conclude these experiments, I need to know if there is any definitive proof to confirm or disprove the same</p>