Chris@23: /* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */
Chris@23: 
Chris@23: /*
Chris@23:     Vamp
Chris@23: 
Chris@23:     An API for audio analysis and feature extraction plugins.
Chris@23: 
Chris@23:     Centre for Digital Music, Queen Mary, University of London.
Chris@23:     Copyright 2006-2012 Chris Cannam and QMUL.
Chris@23:   
Chris@23:     Permission is hereby granted, free of charge, to any person
Chris@23:     obtaining a copy of this software and associated documentation
Chris@23:     files (the "Software"), to deal in the Software without
Chris@23:     restriction, including without limitation the rights to use, copy,
Chris@23:     modify, merge, publish, distribute, sublicense, and/or sell copies
Chris@23:     of the Software, and to permit persons to whom the Software is
Chris@23:     furnished to do so, subject to the following conditions:
Chris@23: 
Chris@23:     The above copyright notice and this permission notice shall be
Chris@23:     included in all copies or substantial portions of the Software.
Chris@23: 
Chris@23:     THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
Chris@23:     EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
Chris@23:     MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
Chris@23:     NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR
Chris@23:     ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
Chris@23:     CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
Chris@23:     WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
Chris@23: 
Chris@23:     Except as contained in this notice, the names of the Centre for
Chris@23:     Digital Music; Queen Mary, University of London; and Chris Cannam
Chris@23:     shall not be used in advertising or otherwise to promote the sale,
Chris@23:     use or other dealings in this Software without prior written
Chris@23:     authorization.
Chris@23: */
Chris@23: 
Chris@23: #ifndef _VAMP_FFT_H_
Chris@23: #define _VAMP_FFT_H_
Chris@23: 
Chris@23: #include "plugguard.h"
Chris@23: _VAMP_SDK_PLUGSPACE_BEGIN(FFT.h)
Chris@23: 
Chris@23: namespace Vamp {
Chris@23: 
Chris@23: /**
Chris@23:  * A simple FFT implementation provided for convenience of plugin
Chris@23:  * authors.
Chris@23:  * 
Chris@23:  * This class provides double-precision FFTs in power-of-two sizes
Chris@23:  * only. It is slower than more sophisticated library
Chris@23:  * implementations. If these requirements aren't suitable, make other
Chris@23:  * arrangements.
Chris@23:  *
Chris@23:  * The inverse transform is scaled by 1/n.
Chris@23:  *
Chris@23:  * The implementation is from Don Cross's public domain FFT code.
Chris@23:  */
Chris@23: class FFT
Chris@23: {
Chris@23: public:
Chris@23:     /**
Chris@23:      * Calculate a forward transform of size n.
Chris@23:      *
Chris@23:      * ri and ii must point to the real and imaginary component arrays
Chris@23:      * of the input. For real input, ii may be NULL.
Chris@23:      *
Chris@23:      * ro and io must point to enough space to receive the real and
Chris@23:      * imaginary component arrays of the output.
Chris@23:      *
Chris@23:      * All input and output arrays are of size n.
Chris@23:      */
Chris@23:     static void forward(unsigned int n,
Chris@23:                         const double *ri, const double *ii,
Chris@23:                         double *ro, double *io);
Chris@23: 
Chris@23:     /**
Chris@23:      * Calculate an inverse transform of size n.
Chris@23:      *
Chris@23:      * ri and ii must point to the real and imaginary component arrays
Chris@23:      * of the input. For real input, ii may be NULL.
Chris@23:      *
Chris@23:      * ro and io must point to enough space to receive the real and
Chris@23:      * imaginary component arrays of the output. The output is scaled
Chris@23:      * by 1/n. The output pointers may not be NULL, even if the output
Chris@23:      * is expected to be real.
Chris@23:      *
Chris@23:      * All input and output arrays are of size n.
Chris@23:      */
Chris@23:     static void inverse(unsigned int n,
Chris@23:                         const double *ri, const double *ii,
Chris@23:                         double *ro, double *io);
Chris@23: };
Chris@23: 
Chris@23: }
Chris@23: 
Chris@23: _VAMP_SDK_PLUGSPACE_END(FFT.h)
Chris@23: 
Chris@23: #endif