When Adobe Media Encoder imports video and audio in some formats, it processes and caches versions of these items that it can readily access. Imported audio files are each conformed to a new .cfa file, and MPEG files are indexed to a new .mpgindex file.
A database retains links to each of the cached media files. This media cache database is shared with Adobe Media Encoder, Adobe Premiere Pro, Encore, After Effects, and Soundbooth, so each of these applications can each read from and write to the same set of cached media files. If you change the location of the database from within any of these applications, the location is updated for the other applications, too. Each application can use its own cache folder, but the same database keeps track of them all.
You can change the locations of the media cache database and the cached files using settings in the Media category of preferences. (See Preferences.)
To change the location of the media cache database or the media cache itself, click one of the Browse buttons in the Media preferences.
To remove conformed and indexed files from the cache and to remove their entries from the database, click Clean. This command only removes files associated with items for which the source file is no longer available.