| 摘要 |
PURPOSE: An automatic volume controller of a digital audio system and a controlling method thereof are provided to prevent the damage of the digital audio system by controlling automatically the volume of the digital audio system. CONSTITUTION: An automatic volume controller of a digital audio system includes an audio decoder(201), a controller(203), a volume control(204), and a D/A converter(205). The audio decoder(201) is used for decoding an inputted digital audio bit stream according to a PCM(Pulse Code Modulation) method. The controller(203) senses an on/off state of an audio signal and outputs a volume control signal according to a sensed result. The volume control(204) increases or reduces the volume of PCM signals of the audio decoder according to the volume control signal of the controller. The D/A converter(205) is used for converting the PCM signals to analog signals and outputting the analog signals to a speaker.
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