This demo shows how to change audio pitch by semitones, using Piano as an example.
It contains only one audio sample - which is note "C", and all others are played using "magical formula" - pitchShift = power(2, semitone/12), where semitone is number of semitones from default sound (for example D is +2 semitones). Works with negative numbers too.
As it uses additional params added recently in audio_play_sound, may not work in some GM versions from 2022 (and earlier).
You can check live demo on: https://gnysek.itch.io/gamemaker-piano
You can watch demo on youtube: https://www.youtube.com/watch?v=HgYJ12VPtU0
Made with <3 for https://gmclan.org