PCM (Pulse Code Modulation) is the standard digital audio method of measuring a continuous sound waveform at regular intervals and recording it as numbers. In music production it is most familiar as the uncompressed audio data inside the WAV and AIFF files you record, edit, and bounce. PCM is not a file extension but a form of audio data.
How sound becomes numbers
Analog sound changes continuously, but PCM measures the waveform at fixed time intervals and stores the magnitude at each point as a number. How many times per second it measures is the sample rate; how finely the numbers are divided relates to the bit depth.
Relationship to WAV and AIFF
WAV and AIFF are file formats that hold audio data. In typical production you put linear PCM inside them. With PCM at the same sample rate, bit depth, and channel count, the audio content does not change simply because the container is WAV rather than AIFF. Deliver in whichever format the recipient specifies.
Uncompressed and lossless compression
PCM is generally treated as uncompressed audio data: large in size, but easy to edit. Lossless compression such as FLAC packs PCM data efficiently and returns it to its original state on decoding. The difference from lossy compression like MP3 and AAC is whether you can get back to the original exactly.
Why to keep PCM in production
For handing off to mixing and mastering, editing later, and exporting to other formats, keeping PCM WAV or AIFF as your reference is the safe approach. Converting an MP3 or AAC to WAV does not recover information that is already gone. Create each file you need for sharing individually from the original PCM.
Check before exporting
When exporting PCM, confirm the sample rate, bit depth, and channel count the destination requires. Rather than raising numbers for no reason, it matters more to match your project and the delivery specification. To convert to WAV, AIFF, FLAC, and other formats as needed, use the audio format converter.
