KFR - Fast, modern C++ DSP framework

https://www.kfr.dev

KFR is an open source C++ DSP framework that contains high performance building blocks for DSP, audio, scientific and other applications. It is distributed under dual GPLv2/v3 and commercial license.

Installation

Compiler support:

KFR has no external dependencies except a C++17 compatible standard C++ library. CMake is used as build system.

Clang is highly recommended and proven to provide the best performance for KFR. You can use clang as a drop-in replacement of both GCC on Linux and MSVC on Windows. On macOS clang is the default compiler and included in the official Xcode toolchain.

Note: Building DFT module requires Clang at this moment due to internal compiler errors and lack of optimization in GCC and MSVC.

➡️ See Installation for more details

Features

FFT/DFT

• Optimized DFT implementation for any size (non-power of two sizes are supported)
• DFT performance is on par with the most performant implementation currently available See Benchmarks
• Real Forward and Inverse DFT
• Discrete Cosine Transform type II (and its inverse, also called DCT type III)
• Convolution using FFT
• Convolution filter

➡️ See also How to apply FFT with KFR

DSP

• IIR filter design
  • Butterworth
  • Chebyshev type I and II
  • Bessel
  • Lowpass, highpass, bandpass and bandstop filters
  • Conversion of arbitrary filter from {Z, P, K} to SOS format (suitable for biquad function and filter)
• Biquad filter See Benchmarks
• Simple biquad filter design
• FIR filter design using window method
• Loudness measurement according to EBU R128
• Window functions: Triangular, Bartlett, Cosine, Hann, Bartlett-Hann, Hamming, Bohman, Blackman, Blackman-Harris, Kaiser, Flattop, Gaussian, Lanczos, Rectangular
• Sample rate conversion with configurable quality and linear phase
• Oscillators, fast incremental sine/cosine generation, Goertzel algorithm, fractional delay

Base

• Tensors (multidimensional arrays)
• Statistical functions
• Random number generation
• Template expressions (See examples)
• Ring (Circular) buffer

Math

• Mathematical functions such as sin, log and cosh built on top of SIMD primitives
• Most of the standard library functions are re-implemented to support vector of any length and data type

SIMD

• vec<T, N> class and related functions that abstracts cpu-specific intrinsics
• All code in the library is optimized for Intel, AMD (SSE2, SSE3, SSE4.x, AVX and AVX2 and AVX512) and ARM, AArch64 (NEON) processors
• All data types are supported including complex numbers
• All vector lengths are also supported. vec<float,1>, vec<unsigned,3>, vec<complex<float>, 11> all are valid vector types in KFR
• Sorting

IO

• Audio file reading/writing
• WAV
• FLAC
• MP3

C API

C API is available and includes a subset of KFR features including FFT and filter processing.

Benchmark results

DFT

Powers of 2, from 16 to 16777216 (Higher is better)

Prime numbers from 17 to 127 (Higher is better)

Small numbers from 18 to 119 (Higher is better)

Random sizes from 120 to 30720000 (Higher is better)

See fft benchmark for details about benchmarking process.

Biquad

(Higher is better)

Documentation

Documentation home:

KFR 5 (latest) https://www.kfrlib.com/docs/latest/

KFR 4 https://www.kfrlib.com/docs/v4/

Built with

• cxxdox - generates markdown docs from C++
• mkdocs - static documentation generator
• mkdocs-material - material theme for mkdocs

Branches

dev - current development version. Pull requests should go to dev.

master - current stable version passing all compiler/architecture tests.

v4 - previous version of KFR (no new features here, fixes only)

License

KFR is dual-licensed, available under both commercial and open-source GPL 2+ license.

If you want to use KFR in a commercial product or a closed-source project, you need to purchase a Commercial License