⚡ KeyASIO.Net

The Ultimate Low-Latency Audio Middleware for osu!

Experience audio latency as low as 0.6ms.
"I was hearing clicks before I even tapped." — Top Player Feedback

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🚀 Why KeyASIO?

While osu!'s audio system suffers from a typical latency of 30~40ms, KeyASIO bypasses the Windows mixer entirely using an external ASIO / WASAPI Exclusive backend.

• ⚡ Extreme Performance: Achieves ~0.6ms latency on high-end hardware (Verified by EmertxE). Even on generic hardware, expect 8-15ms.
• 🎮 True Game Integration: Uses ReadProcessMemory to read memory safely. It's not just "pressing a key makes a sound" — it's real-time game state synchronization.
• 🎧 Rich Audio Support: Fully supports custom hitsounds, storyboard samples, dynamic volume, and skin overrides.
• 🎹 Mania Optimization: Per-key sound processing, identical to native game behavior.

📸 Screenshots

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⚙️ Configuration Guide

KeyASIO offers two main modes. Choose the one that fits your hardware.

🚩 Which mode should I choose?

• I have a dedicated Soundcard (Audio Interface) / Mixer: 👉 Hardware Mix (Recommended). Lowest latency, requires hardware setup.
• I use a Laptop / Integrated Audio / No Mixer: 👉 Software Mix (FullMode). Easier setup, requires VB-CABLE.

🔧 Option A: Hardware Mix (FullMode DISABLED) - Recommended

Target: Users with >1 audio outputs (e.g., PC Line-out + dedicated soundcard) AND a physical mixer.

1. Prerequisites:
   • Install your Soundcard's ASIO driver or ASIO4ALL.
   • A physical mixer to combine audio from osu! (Music) and KeyASIO (Hitsounds).
2. Setup:
   • Route osu! music to Device A (e.g., Motherboard Line-out).
   • Route KeyASIO hitsounds to Device B (e.g., External Soundcard).
   • Combine A and B into your mixer, then to your headphones.
3. In KeyASIO:
   • Select your ASIO device in the GUI.
   • Set Realtime Mode to TRUE.
   • Set FullMode (EnableMusicFunctions) to FALSE.
4. In osu!:
   • Set Effect Volume to 0.
   • Adjust your audio offset (likely below -40ms) to sync the audio.

💻 Option B: Software Mix (FullMode ENABLED)

Target: Users with a single soundcard (Laptops/Desktops without mixer).

1. Prerequisites:
   • Install VB-CABLE.
2. Setup:
   • Set osu! output device to VB-Cable Input.
   • (Optional) If you stream, capture VB-Cable Output in OBS.
3. In KeyASIO:
   • Select your actual output device (Headphones/Speakers) in the GUI.
   • Set FullMode (EnableMusicFunctions) to TRUE.
   • Note: This mode completely replaces osu!'s audio engine.

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Full options in appsettings.yaml: (Modify after program closed)

Item	Description
Debugging	Show debug logs.
Device	Device configuration (Recommend to configure in GUI).
HitsoundPath	Default hitsound path (relative or absolute) for playing.
Keys	Triggering keys. See https://docs.microsoft.com/en-us/dotnet/api/system.windows.forms.keys?view=windowsdesktop-6.0 for more inforamtion.
RealtimeMode	If true, the software will enable memory scanning and play the right hitsounds of beatmaps.
RealtimeMode.AudioOffset	The offset when RealtimeMode is true (allow adjusting in GUI).
RealtimeMode.BalanceFactor	Balance factor.
RealtimeMode.IgnoreBeatmapHitsound	Ignore beatmap's hitsound and force using user skin instead.
RealtimeMode.IgnoreComboBreak	Ignore combo break sound.
RealtimeMode.IgnoreSliderTicksAndSlides	Ignore slider's ticks and slides.
RealtimeMode.IgnoreStoryboardSamples	Ignore beatmap's storyboard samples.
RealtimeMode.SliderTailPlaybackBehavior	Slider tail's playback behavior. Normal: Force to play slider tail's sounds; KeepReverse: Play only if a slider with multiple reverses; Ignore: Ignore slider tail's sounds.
SampleRate	Device's sample rate (allow adjusting in GUI).
SkinFolder	The skin folder when RealtimeMode is true.
VolumeEnabled	Software volume control. Disable for extremely low latency when RealtimeMode is false
Volume	Configured device volume.

❓ FAQ

Is this safe for my osu! account?

KeyASIO uses a passive memory reader (similar to StreamCompanion or Gosumemory) which is generally considered safe and approved by peppy for other tools. However, use at your own risk.

Why do I hear no sound in Auto mod?

If you are using Exclusive Mode, osu!'s internal clock might desync because it loses control of the audio device. This is normal behavior when bypassing the Windows Mixer. So you need to select another audio device in osu!

🚧 Roadmap (v4 Preview)

We are currently working on a complete rewrite (KeyASIO v4).

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Made with ❤️ for the osu! community.