What is PCM?
PCM, or pulse code modulation, is a form of raw sound data. It is not encoded like mp3, or compressed in any fashion.
If you find yourself with a .pcm file, you may realize that it is difficult to find an audio player that supports the PCM format. Trying to find a converter is equally as frustrating. In my experience, Linux and Windows don’t have a simple converter, unless, of course, you want to buy one. I didn’t go that far. I’m determined to keep things free.
(As a side note, FFMPEG claimed to be able to convert it but kept telling me that pcm is an unsupported format.)
How To Convert It
Audacity is a free sound editor that can open pcm files and save them to mp3, and many other formats.
Simply open Audacity, click “File”, “Import”, “Raw Data”. Select the PCM file and then choose the sampling rate. The default is 44100. If this plays your sound at high speed then knock it down to 22050 (half) and try it again.
After that is done, you are free to manipulate the sound or export it as mp3. You can do that by going to “File”, “Export”. Then choose “mp3” as the format in which to save.
If you try to open a file in Audacity the normal way, whether by dragging it to the application or selecting file-> open, you will get an error. The error message reminds you how to open a raw audio file.