Grafit Pro

Visual programming for real-time data processing

Author

Mārtiņš Dāboliņš
work.dabolins@gmail.com

Technology

Grafit Pro is a native macOS application built with Swift 6, Metal, SwiftUI, and AppKit. All GPU rendering uses the Metal framework. The app is optimized for Apple Silicon and requires no external runtime or cloud services.

Signal Processing

All signal processing algorithms in Grafit Pro — including FFT spectral analysis, Welch's method for power spectral density estimation, magnitude-squared coherence, hemispheric asymmetry index, and IIR filtering — are original implementations written in Swift and Metal compute shaders. These algorithms are based on standard digital signal processing methods documented in academic literature:

Welch's Method — P. D. Welch, "The use of fast Fourier transform for the estimation of power spectra," IEEE Transactions on Audio and Electroacoustics, 1967
EEG Band Powers — Standard frequency band definitions (Delta 0.5–4 Hz, Theta 4–8 Hz, Alpha 8–12 Hz, Beta 12–30 Hz, Gamma 30–100 Hz) as used across clinical and research neuroscience
Coherence — Standard magnitude-squared coherence formula: Coh_xy(f) = |S_xy(f)|² / (S_xx(f) · S_yy(f))
Asymmetry Index — Standard hemispheric asymmetry: AI = (R − L) / (R + L)
IIR Filters — Butterworth and notch filters using Audio EQ Cookbook biquad formulas, processed via Apple's Accelerate framework (vDSP)

No third-party signal processing libraries are used. The GPU compute path implements a Cooley-Tukey Radix-2 DIT FFT in Metal shading language.

Open Source Acknowledgments

VGER

2D GPU rendering library used for the node graph editor canvas, cable drawing, and UI primitives.
Copyright (c) 2021 Audulus LLC

MIT License

MIT License

Copyright (c) 2021 Audulus LLC

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.

Legal

Grafit Pro and the Grafit logo are trademarks of Mārtiņš Dāboliņš. macOS, Metal, Swift, SwiftUI, AppKit, Apple Silicon, and App Store are trademarks of Apple Inc.