A small Unreal Engine 5 plugin lab that integrates JUCE as a custom audio/MIDI backend to explore ultra-low-latency device I/O (primarily via ASIO on Windows).
This is a technical code sample / experiment, not in any way a production-ready usable replacement for Unreal’s audio pipeline.

• Stack: Unreal Engine 5 plugin (C++), JUCE static library (external), CMake/Projucer build for JUCE
• Focus: real-time audio callbacks, buffer negotiation, MIDI event handling, clean ThirdParty linkage

Related music-tech demos (YouTube):
These clips show other parts of my broader UE/JUCE music framework that aren’t in this repo.

• Quartz-synchronized MetaSounds music system demo – beat-accurate playback + gameplay-driven transitions.
• Real-time MIDI input and Sample demo – low-latency MIDI capture and instrument routing.

• The JUCE device callback path is working and can achieve very low latency with ASIO.
• The Unreal integration layer and module linking are stable for Win64.

Known issue (important):

• When running audio through this backend over asio, Unreal’s native audio manager / sound class routing is currently disrupted.
  In other words, ACO/JUCE output does not participate cleanly in Unreal’s normal SoundClass/SoundMix/AudioMixer control.
  A proper solution will likely require a controlled bridge back into UE’s mixer or a hybrid routing approach.

• JUCE linkage & platform config: UltraLowLatencyAudio.Build.cs
• Unreal ↔ JUCE boundary / includes: Private/JUCEPCH.h
• Audio device + callback core: Private/Audio/AudioEngine.*
• MIDI handling: Private/Audio/MidiCallback.*, Private/MIDIThread/*
• Unreal integration entrypoint: Private/Subsystem/*

JUCE is not included in this repo. Build it separately and place it in ThirdParty/.

Download and unpack JUCE from the official site:
https://juce.com

Using Projucer, create a static library containing the JUCE modules you need.

Modules expected by this plugin (see JUCEPCH.h):

• juce_core
• juce_events
• juce_audio_basics
• juce_audio_devices
• juce_audio_processors
• juce_audio_utils

Expected layout:

JUCE/ Includes/ modules/ <-- JUCE module headers Libraries/ Release/ JUCEStaticLib.lib <-- your built static lib (Win64) 

If your library name/path differs, update UltraLowLatencyAudio.Build.cs accordingly.

To use ASIO:

1. Install ASIO drivers on your system.
2. In Projucer, enable ASIO support in juce_audio_devices before building the static library.

• RTTI and exceptions are enabled in Build.cs to match JUCE requirements.
• WITH_JUCE_BINDING is used to guard compilation when JUCE is not present.

1. Add the plugin to a UE5 project.
2. Ensure JUCE is linked (setup above).
3. Launch editor / PIE.
4. The subsystem initializes JUCE audio + MIDI, and AudioEngine drives the callback/render path.
5. Use the Blueprint exposed functions from the subsystem to interact with JUCE