edau

WARNING: discussions on Ebitengine's discord led me to publish this earlier than intended. Don't expect much yet.

edau stands for Ebitengine Digital Audio Utils. As the name implies, it's a collection of types, interfaces and utilities to work with audio on Ebitengine, the game engine written in Golang by Hajime Hoshi.

This is currently a loosely scoped, exploratory project for personal use mostly. If any of its parts end up evolving into something bigger, I may separate them into a more focused repository.

Current utilities include:

• SpeedShifter, which can be used to play audio at different speeds, with a few interpolation functions available.
• A tight Looper that unlike Ebitengine's InfiniteLoop doesn't do any fading between end and start loop points nor requires any padding after the end loop point. See also apps/loop_finder for a loop point finder utility.
• A handful of low-level helper functions for audio streams and samples.

General advice for audio in Ebitengine

• Use the .ogg format for all your audio. The implementation used for Ebitengine is around twice as performant as .mp3, it doesn't have random padding at the start and end of the audio like mp3, and given the same file size quality is better than mp3 too.
• If you have only a few SFX's, load the audio as bytes from an Ebitengine audio stream with io.ReadAll and use audio.NewPlayerFromBytes to play them. Keeping multiple players reading from underlying compressed streams can be quite taxing, especially on WASM.
• Consider using audio#Player.SetBufferSize if you need responsive effects or lower latency audio. For desktops, you can typically go slightly below time.Millisecond*20. For browsers I don't recommend going below time.Millisecond*50.

Pending work

Future plans include:

• Transitions for effects and the speed shifter. This is currently an open problem that I'm still trying to figure out, as applying transitions as early as possible leads to inconsistent transition timing, and trying to apply a consistent latency seems tricky (if possible at all).
• Better support for .ogg and a mono player, mostly intended for SFX's and saving some space.
• Effects and effect chains, with programmable and automatable parameters and a simple descriptive UI model to be able to integrate plugins into a DAW-like program.
• A few audio synths. Maybe even some light format to create SFX's programmatically.
• Maybe more sophisticated loopers for more complex song structures with repetitions and multiple sections, though this can already be built on top of the existing looper.

See also...

• SolarLune's resound library, which already includes multiple effects like volume, delay, low-pass filtering, panning, distortion, etc.
• Transition, my incomplete 2023 Ebitengine game jam entry. The code on src/audio implements float32 processing chains for truly smooth transitions (both fades and crossfades) and mixing multiple audio sources.