Digital decoder box with multi-channel audio source format indentification function

A digital decoder box, suitable for connecting to a multi-channel earphone, the digital decoder box comprising:

• a digital signal processor, for receiving a digital audio source signal and outputting a decoded signal after a decoding process being performed on the digital audio source signal;
• a multi-channel digital to analog converter, connected to the digital signal processor, for receiving the decoded signal and converting the decoded signal to an analog signal;
• a multi-channel earphone amplifier, connected to the multi-channel digital to analog converter, for receiving the analog signal and accordingly outputting a set of front channel signals, a set of surround channel signals, a center channel signal, and a sub woofer signal;
• an input format detector, connected to the multi-channel digital to analog converter to detect the format of the decoded signal and accordingly output a control signal;
• a delay circuit, used to receive the set of front channel signals, the set of surround channel signals, the center channel signal, and the sub woofer signal, perform delay processing, and then output the signals to the multi-channel earphone to prevent damage to eardrums of a user due to the impact sound when the earphone is turned on;
• and
• a sub/front speaker select switch, connected to the input format detector and the delay circuit to receive the set of front channel signals and the sub woofer signal output from the delay circuit and switch between the front channel signals and the sub woofer signal according to the control signal, wherein when only the front channel signals but no surround channel signals or sub woofer signal are received, the sub/front speaker select switch turns off the sub woofer output and outputs the front channel signals to the left and right sub woofer speakers in the multi-channel earphone respectively to enhance the stereo sound effects.