Shotcut supports many video, audio and image formats thanks to FFmpeg.
It uses a timeline for non-linear editing of multiple tracks, which can consist of different file formats.

A MIDI file player/game that displays the musical notes AND teaches you how to play the piano.

PianoBooster is a fun way of playing along with a musical accompaniment and at the same time learning the basics of reading musical notation.
The difference between playing along to a CD or a standard MIDI file is that PianoBooster listens and reacts to what you are playing on a MIDI keyboard.

To run Piano Booster you need a MIDI Piano Keyboard and a MIDI interface for the PC. If you don't have a MIDI keyboard you can still try out PianoBooster, using the PC keyboard ('x' is middle C), but a MIDI piano is really recommended.

qStopMotion - creating frame-by-frame animated films from images imported from a camera or computer.

The resulting animation can be exported to various video formats, such as mpeg or avi.

MuseScore is a WYSIWYG editor with the ability to quickly enter notes from both the computer keyboard and an external MIDI keyboard. Supports import and export of data in MIDI, MusicXML, LilyPond formats, as well as import of files in MusE, Capella and Band-in-a-Box formats. In addition, the program can export scores to PDF, SVG and PNG files, or to LilyPond documents for further fine-tuning of the score.

FluidSynth is a real-time software synthesizer based on the SoundFont 2 specifications and has become widely used. FluidSynth itself does not have a graphical user interface, but thanks to its powerful API, several applications use it and it has even found its way into embedded systems and some mobile applications.

Qsynth - GUI for FluidSynth.

This is an easy-to-use, yet powerful audio file editor.
It works with a mixer built into a personal computer system, as well as external audio media.
It provides for the integration of effects: reversal, echo, phase vibrato (phaser), dynamic timbre change (wahwah).
In the editor, you can remove defects from the audio track: hiss, static noise, hum, and also adjust the pitch and tempo.
Works with formats: WAV, Ogg Vorbis, AIFF, AU, MP3, MPEG.

OpenShot is a very easy-to-use video editor that anyone can understand. A large number of video and audio formats are supported, it is possible to insert transitions and use effects, both video (brightness, contrast, white balance, sepia, old film effect, etc.) and sound. It is possible to insert 3D titles created in Blender. The program easily integrates into the GNOME environment; files can be added to the project by simply dragging and dropping. Exporting files makes it easy to have ready-made profiles.

This is an alternative to commercial programs like FL Studio (R), which allow you to create music on your computer.
It includes creating melodies and beats, synthesizing and mixing sounds, and organizing samples.
You can have fun with the MIDI keyboard and much more, all in a convenient and modern interface.

Hydrogen is an advanced drum machine (step sequencer). The main goal is to create a professional yet simple and intuitive instrument based on drum programming patterns.

Krita is an application for working with raster images. It allows you to both create images from scratch and work with ready-made images. You can work from photos or scans, or start from scratch. Krita directly supports most graphics tablets.