Abstract: A set top box (STB), which communicates with a display device and a number of audio-visual apparatuses, comprises one or more media processors, a video multiplexer, an audio multiplexer, and a transmitting module. The media processors receive a number of program channels selected by a number of users and identities corresponding to the audio-visual apparatuses, and demodulate the program channels into video streams and corresponding audio streams. The video multiplexer composes the video streams into an integrated video stream and the audio multiplexer composes the audio streams into an integrated audio stream. The STB transmits the integrated video stream and the integrated audio stream to the audio-visual apparatuses.