MIDI playback in a game engine

I created some more (simple) instruments, and added pitch wheel support. There are over 100 instruments in the spec, but I ended up with 6 instruments that vaguely sound like the ones they’re named after: piano, trumpet, guitar, violin, flute, and snare drum. I did add support for a low pass filter, which helped the instruments sound less buzzy, but there are some slightly more sophisticated things that could be done to better simulate the instruments.

I completed what I set out to do: the culmination of the project can be heard here. (imgur doesn’t allow videos over 60s. Also, BEWARE the high pitched noises in the second tune and at the end). It is a version of onestop.mid (which is on every Windows computer) played back in my MIDI engine.

I am happy with the results; you can really here the pitch bending in some of the guitar parts. If I have time I will go back and add more instruments and make them sound better (add an ADSR envelope to the low pass filter, add a low frequency oscillator, etc.) but for now I am content to call the project complete.

I tried to find an editor online for generating instrument sounds with only additive synthesis, but I couldn’t find one. So I decided to try to make a simple instrument sound editor myself:

imgur link (turn audio on)

I think I will be able to come up with some passable keyboard and woodwind sounds, but I’m not sure I can get things like brass instruments working without adding more complexity to the synthesizer. So I’m going to stick with just these simple instrument sounds and work on getting the MIDI playback to switch instruments and handle more MIDI events (maybe pitch wheel support?).

I managed to get simple MIDI playback working. It only can make piano sounds, all at the same volume:

imgur link (audio only)

I found a reference on the MIDI spec here. I implemented code to read the header and track information, and enough of the meta events to set the tempo and detect when tracks end. But I’ve only implemented “note on” and “note off” events, and none of the other voice and control events.

I’ve also reused some piano sound synthesis code from a previous project. So the next step will be implementing some more of the voice events and coming up with more synthesized instruments.

I won’t get a chance to work on the MIDI project for a little while, but I did implement loading/saving files with a file dialog in windows and in browsers. I implemented it for a hitbox editor, but I think I can reuse it to interactively load MIDI files.