Suggestion: Replace FMOD with SDL_mixer for an open-source 2D audio backend

[DevTwilight]

Overview

I believe the engine currently uses FMOD through its FNA backend. While FMOD is a robust audio middleware solution, it is proprietary and not fully compatible with an open-source licensing model.

Since Murder Engine is a 2D pixel-art ECS game engine, a simpler and open-source-friendly audio backend such as SDL_mixer (accessed via SDL2-CS bindings) would be a more natural fit.

Motivation

1. Licensing and Openness

• FMOD is closed-source and requires a license for commercial use.
• SDL_mixer is open source, distributed under the zlib license, which is highly permissive and compatible with Murder’s open-source nature.
• SDL2-CS, the official C# bindings for SDL2 (and SDL_mixer), is also open source and maintained under the zlib license.

2. Technical and Architectural Fit

• Murder is built on FNA, which itself uses SDL2 for input, windowing, and platform abstraction.
• Integrating SDL_mixer would therefore align perfectly with the existing SDL-based ecosystem.
• SDL_mixer is designed for 2D game audio — it provides:
  • Simple APIs for playing sound effects and music.
  • Support for multiple formats (WAV, OGG, MP3, MOD, FLAC, etc.).
  • Built-in mixing and volume controls without the complexity of 3D audio.
• This would reduce dependencies on proprietary libraries while maintaining excellent cross-platform support.

3. Maintenance and Accessibility

• Using SDL_mixer simplifies build and distribution pipelines since all components remain open source.
• Developers can easily build, debug, and modify the audio layer without dealing with FMOD’s proprietary SDK.
• It lowers barriers for community contributions and helps ensure long-term sustainability.

References

• SDL_mixer
  Repository: https://github.com/libsdl-org/SDL_mixer
  License: zlib License

• SDL2-CS (C# bindings for SDL2 and SDL_mixer)
  Repository: https://github.com/flibitijibibo/SDL2-CS
  License: zlib License

Summary

Replacing FMOD with SDL_mixer (via SDL2-CS) would:

• Ensure the entire Murder Engine audio stack remains open source.
• Eliminate proprietary licensing dependencies.
• Provide a lightweight, simple, and efficient solution for 2D audio.
• Align perfectly with FNA’s existing SDL-based architecture.

This change would make the engine more transparent, accessible, and community-friendly while retaining all the functionality required for 2D games.