Mediacenter includes a library tool called Analyze Audio that populates a number of fields in a files tags with information about the file. For example, analyze audio will assess the files loudness, dynamic range, and beats per minute. These tags are used by Mediacenter for certain DSP functions, like volume leveling and adaptive volume, and can also be a source of useful information.
How to Find Un-Analyzed Files
The default smartlist titled "Audio -- Task -- Needs audio analysis" will display tracks that require the Audio Analyze tool to be run against them.