AdlMIDI is a command line program that plays MIDI files using software OPL3 emulation (FM synthesis). It has a console UI. It features a built-in selection of 50 patch sets, most of which are General MIDI compatible, but some of which are customized for playing original background music soundtracks of select PC games.
Desfonema Sequencer is a tracker-inspired MIDI sequencer. It uses a pattern oriented design, with n tracks by pattern. It offers a piano roll editor for tracks, and a tabbed track interface for patterns. It features convenient keyboard shortcuts, a virtual keyboard, step and live editing, MIDI input (ALSA), and a text-based file format that is easy to edit manually or merge and better suited for version systems like Subversion.
hexter is a software synthesizer that models the sound generation of a Yamaha DX7 synthesizer. It can easily load most DX7 patch bank files, edit those patches via a built-in editor or MIDI sys-ex messages, and recreate the sound of the DX7 with greater accuracy than any previous open source emulation (that the author is aware of). It operates as a plugin for the DSSI Soft Synth Interface.
Given a chord progression and a music style, JChordBox generates a song. It is a library tool that can generate backing tracks from a chord progression and a music style. It contains several command line processes detailed in the user guide. It also contains a MIDI song player that can loop, play, pause, stop, rewind, forward, mute, or solo tracks, display transport information, and much more. It runs in a terminal.
The ALSA MIDI Filter application consists of a main script, named midifilter, and supporting Perl modules, configuration files, and documentation. It runs as an ALSA MIDI client that can receive input from a source (such as a MIDI keyboard connected to the computer), perform various filtering and other functionality based on the type and content of the MIDI input, and send the result to one or more other MIDI clients.