Files are generally assessed on their bitrate. A 320kbps MP3 is obviously better than a 128kbps version, right? Ordinarily, yes. But it’s not hard to bluff the bitrate and mislead listeners through “upscaling.” In fact, upscaling can sometimes damage audio quality.

Audio encoding is a complex process, and Stack Overflow user “vaxquis” provides an intricate explanation of how it works. If you find the subject interesting, his explanation is one of the clearest available.

How do you sort the wheat from the chaff?

Full article here:
How to Check the True Bitrate of Your Audio Files (Make Tech Easier)