Abstract: A method of playing back media data in a single operating system that supports a smart service and digital television (DTV) service is provided. The method includes loading the single operating system that supports the smart service and the DTV service, receiving, by a default media player included in the single operating system from an application, a request for playback of a target media data, determining a type of an identifier (ID) of the target media data, selecting, based on the type of the ID of the target media data, one player from among a video-on-demand (VOD) player and a DTV player different from the default media player, and playing back the target media data by the selected player.

Abstract: A smart set-top box (STB) that provides a smart service and a digital television (DTV) service using a single operating system may be provided. The STB may load applications designed based on an application programming interface (API) of a framework corresponding to the operating system, may load a DTV stack including a DTV service function and a security service function, and may allow communication between at least one of the applications and the DTV stack when the at least one of the applications uses a binder driver included in a kernel of the operating system so as to access the DTV service function included in the DTV stack.