How an oversampling CD player works?

What is oversampling?

Oversampling is used for recording process and playback process. Oversampling during recording process through A/D conversion takes more samples as need for the nyquist rate. For example, human hearing ranges from 20 Hz to 22 kHz. Therefore, we will need to have sample rate of 44 kHz to satisfy the nyquist theorem. If we were to oversample this 44 kHz by 4 times more sampling rate, we will be sampling a signal at 4x44 kHz = 176 kHz. Oversampling during the playback process through D/A conversion is mostly done in CD players. The main concept is to average and create the extra points in between samples to make a smoother signal curve. We can also call this interpolation. Some people think non oversampling CD players sound better than a oversampling CD player.

How an oversampling CD player works?

Basicly, an oversampling CD player utilized a digital signal processor (DSP). It takes the audio samples from the CD and perform all kinds of operations to it such as digital filtering. DSP is nice because it is fairly precise compare to analog components which will possiblely be hard to acheive the same performance as DSP can do. DSP takes the audio samples and perform an oversampling process by interpolating each audio samples to produce additional sample points in between. Inside the DSP, these new samples are produced by using a shift register (for delay), coefficent multipliers and an adder.