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What is LPCM (PCM)

Rob Parsons Updated on Apr 15, 2022 4:22 PM


PCM (Pulse Code Modulation) is a encoding method to stand for analog signal whose magnitude is sampled and quantized to a series of digital signal for audio without any compression. It's often refer to the format used in WAV and AIFF audio container formats. More sampled points translate into more accuracy on the listening end. It is mainly applied in the sphere of DVD, Blu-ray discs, digital telephony and other digital audio applications that demand for high quality sound. Two factors play a key role in deciding on the PCM's stream's fidelity: the sampling rate and bit depth.


LPCM (acronym for Linear Pulse Code Modulation) is uncompressed audio encoding which employs a combination of values like sample sizes, sample rate, number of channels, etc. LPCM is referred to as PCM Plus. As a particular kind of PCM, LPCM's quantization levels are linearly uniform, using PCM with linear quantization. By comparison, the quantization levels of PCM change with amplitude. LPCM is a lossless audio coding that delivers CD quality sound, so it occupies huge disc space. LPCM is used to transmit uncompressed digital audio information via HDMI (High-Definition Multimedia Interface).

Note: The principle for LPCM and PCM are the same except in sample rate and quantization precision.

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Audio formats that use LPCM codec consist of AU Audio, raw audio, WAV, AC3 (Dolby Digital), AIFF (Audio Interchange File Format), AES3, RF64, MPEG audio. LPCM constitutes a part of DVD and Blu-ray audio standard as well.

LPCM (PCM) signal is either passed through optical or coaxial / HDMI connection or via analog audio connection from Blu-ray disc to the home theater receiver.

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