def framerate_aspect(self, file):
        """
        read framerate and aspect ratio
        """
        file.seek(self.sequence_header_offset + 7, 0)
        v = struct.unpack('>B', file.read(1))[0]
        try:
            fps = FRAME_RATE[v & 0xf]
        except IndexError:
            fps = None
        if v >> 4 < len(ASPECT_RATIO):
            aspect = ASPECT_RATIO[v >> 4]
        else:
            aspect = None
        return fps, aspect