              self.faces.num_faces_detected += 1
              self.faces.faces_detected[os.path.basename(filename)] = faces
  
      def process_single_image(self, filename):
          """ Detect faces in an image. Rotate the image the specified amount
              until at least one face is found, or until image rotations are
 
</s>
            frame_no += 1
            if frame_no == self.save_interval:
                self.write_alignments()
                frame_no = 0
              self.faces.num_faces_detected += 1
              self.faces.faces_detected[os.path.basename(filename)] = faces
            frame_no += 1
            if frame_no == self.save_interval:
                self.write_alignments()
                frame_no = 0
  
      def process_single_image(self, filename):
          """ Detect faces in an image. Rotate the image the specified amount
              until at least one face is found, or until image rotations are
keep add keep keep keep keep
 alignments.json save interval for extracting (#477)

* implement save interval
scripts/extract.py