Pulse-code modulation: Difference between revisions

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{{Modulation techniques}}

'''Pulse-code modulation''' ('''PCM''') is a method used to [[Digital signal (signal processing)|digitally]] represent [[analog signal]]s. ItThe PCM method is the standard form of [[digital audio]] in computers, [[compact disc]]s, [[digital telephony]] and other digital audio applications. In a PCM [[Stream (computing)|stream]], the [[amplitude]] of the analog signal is [[Sampling (signal processing)|sampled]] at uniform intervals, and each sample is [[Quantization (signal processing)|quantizedquantisized]] to the nearest value within a range of digital steps.

'''Linear pulse-code modulation''' ('''LPCM''') is a specific type of PCM inmethod whichwherein the quantization levels are linearlyuniformly uniformlinear.<ref name="LOC_LPCM" /> This uniform encoding is in contrast to PCM encodings inwherein which quantizationthe levels of quantization vary as a function of amplitude, (as withe.g. the [[A-law|A-law algorithm]] orand the [[μ-law|μ-law algorithm]]). ThoughAlthough ''PCM''a isgeneral, atechnical moreusage, generalthe term, it''PCM'' isalso oftenis used to describe data encoded as LPCM.

A PCM stream has two basic properties that determine the stream's fidelity to the original analog signal: (i) the [[sampling rate]], which is the number of times per second that samples are taken; and (ii) the [[Audio bit depth|bit depth]], which determines the number of possible digital values that can be used to represent each sample.

==History==