Abstract: The present invention is an audio reproducing apparatus in a video and audio system, comprising a digital signal generator, a de-multiplexer, a Dolby decoder, a pulse width modulator, and an audio player. The digital signal generator generates a first digital signal. The de-multiplexer connected to the digital signal generator receives the first digital signal to generate a selection signal. The Dolby decoder connected to the de-multiplexer is used for receiving the selection signal, for transforming the selection signal into a first processing signal, and for further transforming the first processing signal into a second processing signal after a transformation operation. The pulse width modulator connected to the Dolby decoder receives the second processing signal and generates a modulated signal. The audio player connected to the pulse width modulator receives the modulated signal and transforms the modulated signal into an audio signal.