Cardio is a library that can play back many different audio files (MP3, FLAC, WV, MOD, etc.). It handles both the input (reading files) and output (writing audio). Cardio is extensible via plugins, many of which are available at the Cardio Web site.
Bocfel is an interpreter for the Z-machine, which means that it can be used to play Infocom games as well as other games based on the Z-machine. It is compliant with version 1.1 of the Z-Machine Standards Document for all Z-machine versions other than 6.