An analogue-to-digital converter, or ADC as it’s more commonly called, is a device that converts analogue signals into digital signals. ADCs are integral to current music reproduction technology. Since much music production is done on computers, when an analogue recording is used, an ADC is needed to create the PCM data stream that goes onto a compact disc or digital music file. A common use of analogue-to-digital converters is generation of audio signals from digital information in music players.
LPCM stands for Linear Pulse Code Modulation. Sometimes you will see "20 bit LPCM" or "24-bit LPCM" or "24 bit uncompressed” on the disc cases. The more bits, the higher the resolution and the better the sound. It encodes a single sound channel. It supports uncompressed 2-channel LPC digital audio signal output.