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.
Ecasound is a software package designed for multitrack audio processing. It can be used for simple tasks like audio playback, recording, and format conversions, as well as for multitrack effect processing, mixing, recording and signal recycling. It supports a wide range of audio inputs, outputs, and effect algorithms. Effects and audio objects can be combined in various ways, and their parameters can be controlled by operator objects like oscillators and MIDI-CCs. A versatile console-mode user interface is included in the package.