This is the dev documentation for an unreleased version of MPF!

This is the documentation for MPF 0.53+, which is the “dev” (next) release of MPF that is a work-in-progress. Unless you’re specifically looking for this version, you probably want to use the version of documentation called “latest” which is for the latest released version of MPF. That documentation is at docs.missionpinball.org/en/latest.


Assets are files that your machine uses that are loaded from disk, such as show YAML files, images, and sound files. MPF has lots of flexibility for how assets are loaded and unloaded. (For example, if you’re running MPF on a machine that doesn’t have a lot of memory, you may not be able to load all the assets at startup and may instead have to dynamically load and unload assets throughout the game.)

MPF also has the ability to automatically “discover” various types of assets in your machine folder, meaning you don’t have to manually type every single asset file name into your config files. You can even set asset properties based on what folder and/or subfolder they’re in. (For example, audio files in /sounds/fx are automatically played on the sound effects track, while sound files in /sounds/voice are played on the voice track.

As of MPF 0.33, assets can be in nested subfolders too. For example:


MPF also supports “asset pools” for sound and image assets which allow you to group multiple asset files into a single asset name that you use in MPF. This lets you add “variation” to assets during game play. For example, if you have a laser sound when a pop bumper is hit, you could actually have four different laser sound files that are each slightly different which you pool into the “laser” asset which is associate with the pop bumper, and then each time the pop bumper is hit you get one of the four sounds played at random instead of the same sound over and over.