'read framerate and aspect ratio'

def framerate_aspect(self, file):

    file.seek((self.sequence_header_offset + 7), 0)
    v = struct.unpack(u'>B', file.read(1))[0]
    try:
        fps = FRAME_RATE[(v & 15)]
    except IndexError:
        fps = None
    if ((v >> 4) < len(ASPECT_RATIO)):
        aspect = ASPECT_RATIO[(v >> 4)]
    else:
        aspect = None
    return (fps, aspect)
