Reference
What is PCM audio?
PCM (Pulse Code Modulation) represents an audio waveform as a sequence of numerical sample values. Sample rate says how often the waveform is sampled; bit depth says how each sample value is represented.
PCM is a representation, not one file extension. PCM audio can appear in WAV, AIFF, CAF and many professional containers, or as an intermediate signal inside software and hardware.
The main PCM properties
| Property | What it means | Examples |
|---|---|---|
| Sample rate | Samples per second per channel | 44.1, 48, 96, 192 kHz |
| Bit depth / precision | How sample amplitude is represented | 16, 20, 24, 32-bit integer; 32/64-bit float in many workflows |
| Channels | Independent audio streams/positions | Mono, stereo, 5.1, 7.1 and beyond depending on container/system |
| Compression | PCM itself is normally uncompressed | FLAC/ALAC can losslessly compress PCM-derived audio |
How uncompressed PCM bitrate is calculated
sample rate × bits per sample × channels. CD audio is 44,100 × 16 × 2 = 1,411,200 bit/s, or 1411.2 kbps before file/container overhead.
PCM is not WAV
WAV is a RIFF-based container. PCM is one of the most common payload formats inside WAV, but WAV can describe other encodings too. Likewise, PCM can be stored somewhere other than WAV. See What is WAV?.