Content revocation is achieved by disabling licenses issued to a computing device for the content. The rotor is mounted within the housing, and has a first leading edge and a first trailing edge. Furthermore, the encoder describe the past encoding parameters into the encoded bitstream as the history information so as to reuse the history information in advance encoding process. Light that has passed through the three lenses is directed to the second imaging optical system, and the first and second imaging optical systems are disposed along a common optical axis.