Abstract: A node device switches from a sleep mode to a wake-up mode when the node device needs to transmit information. The node device transmits a synchronization signal to the another node device based on the information and determines whether an acknowledgement signal is received. The node device transmits the key-frames to the another node device when the acknowledgement signal is received.

Abstract: A node device switches from a sleep mode to a wake-up mode when the node device needs to transmit information. The node device transmits a synchronization signal to the another node device based on the information and determines whether an acknowledgement signal is received. The node device transmits the key-frames to the another node device when the acknowledgement signal is received.

Abstract: A set top box includes a central processing unit, which generates the first accompaniment signals according to a music file, when voice signals is received, they will be converted into stereo voice signals, and the stereo voice signals is converted into digital voice signals, and the set top box adjusts the first accompaniment signals to output second accompaniment signals, mixes the second accompaniment signals and the digital voice signals to output mixing audio signals to the central processing unit, at last converts the mixing audio signals into digital stereo signals, and outputs the digital stereo signals.