annotate vamp-sdk/FFT.h @ 338:c0914307b0df

FFT: make functions static

/* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */

/*
    Vamp

    An API for audio analysis and feature extraction plugins.

    Centre for Digital Music, Queen Mary, University of London.
    Copyright 2006-2012 Chris Cannam and QMUL.
  
    Permission is hereby granted, free of charge, to any person
    obtaining a copy of this software and associated documentation
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    of the Software, and to permit persons to whom the Software is
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    The above copyright notice and this permission notice shall be
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    Except as contained in this notice, the names of the Centre for
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*/

#ifndef _VAMP_FFT_H_
#define _VAMP_FFT_H_

#include "plugguard.h"
_VAMP_SDK_PLUGSPACE_BEGIN(FFT.h)

namespace Vamp {

/**
 * A simple FFT implementation provided for convenience of plugin
 * authors.
 * 
 * This class provides double-precision FFTs in power-of-two sizes
 * only. It is slower than more sophisticated library
 * implementations. If these requirements aren't suitable, make other
 * arrangements.
 *
 * The inverse transform is scaled by 1/n.
 *
 * The implementation is from Don Cross's public domain FFT code.
 */
class FFT
{
public:
    /**
     * Calculate a forward transform of size n.
     *
     * ri and ii must point to the real and imaginary component arrays
     * of the input. For real input, ii may be NULL.
     *
     * ro and io must point to enough space to receive the real and
     * imaginary component arrays of the output.
     *
     * All input and output arrays are of size n.
     */
    static void forward(unsigned int n,
                        const double *ri, const double *ii,
                        double *ro, double *io);

    /**
     * Calculate an inverse transform of size n.
     *
     * ri and ii must point to the real and imaginary component arrays
     * of the input. For real input, ii may be NULL.
     *
     * ro and io must point to enough space to receive the real and
     * imaginary component arrays of the output. The output is scaled
     * by 1/n. The output pointers may not be NULL, even if the output
     * is expected to be real.
     *
     * All input and output arrays are of size n.
     */
    static void inverse(unsigned int n,
                        const double *ri, const double *ii,
                        double *ro, double *io);
};

}

_VAMP_SDK_PLUGSPACE_END(FFT.h)

#endif