A data processing apparatus is capable of executing a plurality of signal processes. The data processing apparatus switches processes of a pre-processing portion, a data processing portion, and a post-processing portion with a control signal supplied from a function controlling portion corresponding to a command supplied from the outside. Thus, the data processing apparatus executes for example processes for increasing the resolution, generating a picture dedicated for a right eye and a picture dedicated for a left-eye, generating a luminance signal and color difference signals, changing the aspect ratio, generating pictures having difference resolutions, and converting the frame rate for input data corresponding to a request and outputs picture data generated as the processed result to an external device (for example, a displaying device and a record and reproduction device).