
bqfft
=====

A small library wrapping various FFT implementations for some common
audio processing use cases. Note this is not a general FFT interface,
as it handles only real inputs.

Transforms of any length are supported, but if you request a length
that bqfft does not know how to calculate using any of the libraries
that have been compiled in, a simple slow DFT will be used instead. A
warning will be printed to stderr if this happens.

Of the most commonly used libraries, Accelerate and IPP support
power-of-two FFT lengths only, KissFFT supports any multiple of two
(because we only use the real-input interface), and FFTW supports any
length. You can compile in more than one library, so for example if
you compile in Accelerate and KissFFT, the former will be used for
powers of two and the latter for other even lengths.

Requires the bqvec library.

This code originated as part of the Rubber Band Library written by the
same authors (see https://hg.sr.ht/~breakfastquay/rubberband/).
It has been pulled out into a separate library and relicensed under a
more permissive licence.

C++ standard required: C++98 (does not use C++11 or newer features)

 * To compile on Linux: Edit Makefile to select implementation, then make.
   Do read the notes in the Makefile, and don't attempt to use the default
   implementation, which is very slow
   
 * To compile on macOS: make -f build/Makefile.osx

 * To build and run tests: as above, but add the "test" target -
   requires Boost test headers installed

[![Build Status](https://travis-ci.org/breakfastquay/bqfft.svg?branch=master)](https://travis-ci.org/breakfastquay/bqfft)

Copyright 2007-2019 Particular Programs Ltd. See the file COPYING for
(BSD/MIT-style) licence terms.
