Plugins are external components that help device publishers provide extra media-related information.

Note: The plugins are useful only in systems that support media playback and external devices. If your system has no plugins installed, this doesn't cause an error; instead, the device publishers just write fewer data fields to the mount objects.

The plugin manager is integrated into all device publishers. At startup, publishers initialize the plugin manager by providing their type (for instance, publisher-usb) and the path of the plugin directory. The plugin manager loads, from the specified directory, all installed plugins that support the device publisher type and then builds a list of available plugins, sorted by rating. This last action allows the plugin manager to forward information requests to plugins with higher ratings first. Plugins with lower ratings are invoked only when the higher-rated plugins can't provide the requested information.

Here are the available plugins:
Reads volume names and generates volume IDs from the name and other fields (for instance, serial number). Supports all device types and reads WMPInfo.xml (if it's available on the filesystem).
Obtains the names and IDs of iPod devices. (The ipod plugin is available in a separate package.)
Obtains the names and IDs of Media FS devices.
Extracts Table of Contents (TOC) and CD-Text information from audio CDs to fill in fields such as artist and album name.
Gets the region code for the disc and generates a disc ID, which cdpub or usblauncher_otg can then publish through PPS.