# kfrlib/kfr

Fast, modern C++ DSP framework, FFT, Sample Rate Conversion, FIR/IIR/Biquad Filters (SSE, AVX, AVX-512, ARM NEON, RISC-V RVV)

Repository: https://github.com/kfrlib/kfr
Canonical: https://ross.abutalabs.com/products/kfr
Homepage: https://www.kfrlib.com
Language: C++
License: GPL-2.0
License Family: copyleft
Topics: avx, fft, simd, cpp14, audio, dsp, dft, header-only, avx512, digital-signal-processing, audio-processing, cpp17, fast-fourier-transform, discrete-fourier-transform, clang, cxx, cplusplus, cplusplus-14, cplusplus-17, risc-v
Last push: 2026-08-19T17:28:01+00:00

## Health v2 (maintenance only)
Score: 94/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 98, release rhythm 86, longevity 100
- inputs: {"age_days": 3717, "days_push": 14, "days_rel": 15, "gap_med": 52, "n_releases_24m": 10}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1917, forks 281 (observed 2026-08-28T04:05:53.917182+00:00)

## What it is
KFR is a fast, modern C++ digital signal processing framework providing FFT/DFT, FIR/IIR/biquad filter design and processing, sample rate conversion, convolution, and audio file I/O. It uses a SIMD abstraction layer (SSE, AVX, AVX-512, ARM NEON, RISC-V RVV) for high performance and is available under GPLv2+ or a commercial license.

## Use cases
- compute FFT of audio or scientific signals in C++
- design and apply biquad, FIR, and IIR filters
- resample audio with high-quality sample rate conversion
- read and write WAV, FLAC, AIFF, MP3 audio files
- build audio plugins with fast SIMD-optimized DSP
- process gravitational-wave or sensor data with fast DFT
- implement convolution reverb in an audio application

## When to choose
- you need high-performance FFT or filtering in C++ with SIMD acceleration
- you target multiple architectures (x86, ARM, RISC-V) from one codebase
- you want a header-friendly DSP library with no heavy runtime dependencies
- you need audio file encoding/decoding plus DSP in one library

## When to avoid
- your project is not GPL-compatible and you cannot purchase a commercial license
- you need a DSP library in a language other than C++
- you only need simple one-off FFTs where a lighter library suffices
- you target RISC-V CPUs with VLEN < 128 or non-Linux RISC-V systems

## Facets
- artifact type: library
- maturity: stable
- function: audio-processing, math, image-processing, sdk
- domain: developer-tools
- platform: cross-platform, windows, cpp, wasm
- tags: dsp, fft, simd, sample-rate-conversion, filters, header-only, audio-codecs, avx, neon, risc-v, audio, signal-processing, scientific-computing, linux, macos, ios, android

## Member repositories
- kfrlib/kfr (main) score 94

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:05:53.917182+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-30T03:10:09.135652+00:00, confidence not recorded.
  - readme: https://github.com/kfrlib/kfr (fetched 2026-08-28T04:05:53.917182+00:00, sha 49d1ec52305c)
  - homepage: https://www.kfrlib.com (fetched 2026-08-29T10:49:32.558639+00:00, sha a0cda21cdce8)
  - site_page: https://www.kfrlib.com/docs/latest (fetched 2026-08-29T10:49:32.568062+00:00, sha 566b3015e334)
  - site_page: https://www.kfrlib.com/getting-started (fetched 2026-08-29T10:49:32.572505+00:00, sha a656fa7fa9fa)
  - site_page: https://www.kfrlib.com/docs/latest/dft (fetched 2026-08-29T10:49:32.576121+00:00, sha 202ab4483268)
  - site_page: https://www.kfrlib.com/purchase (fetched 2026-08-29T10:49:32.570506+00:00, sha cc718b1cd926)
  - site_page: https://www.kfrlib.com/blog/kfr-6 (fetched 2026-08-29T10:49:32.574410+00:00, sha 2cb289b3cce2)
- Data as of 2026-08-30T08:39:29.467469+00:00.