annotate vamp-sdk/hostext/PluginInputDomainAdapter.h @ 62:fe5486ee1c70 host-factory-stuff

* Documentation

/* -*- 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 Chris Cannam.
  
    Permission is hereby granted, free of charge, to any person
    obtaining a copy of this software and associated documentation
    files (the "Software"), to deal in the Software without
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    of the Software, and to permit persons to whom the Software is
    furnished to do so, subject to the following conditions:

    The above copyright notice and this permission notice shall be
    included in all copies or substantial portions of the Software.

    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
    EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
    MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
    NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR
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    Except as contained in this notice, the names of the Centre for
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*/

#ifndef _VAMP_PLUGIN_INPUT_DOMAIN_ADAPTER_H_
#define _VAMP_PLUGIN_INPUT_DOMAIN_ADAPTER_H_

#include "PluginWrapper.h"

namespace Vamp {

namespace HostExt {

/**
 * PluginInputDomainAdapter is a Vamp plugin adapter that converts
 * time-domain input into frequency-domain input for plugins that need
 * it.  This permits a host to use time- and frequency-domain plugins
 * interchangeably without needing to handle the conversion itself.
 *
 * This adapter uses a basic Hanning windowed FFT that supports
 * power-of-two block sizes only.  If a frequency domain plugin
 * requests a non-power-of-two blocksize, the adapter will adjust it
 * to a nearby power of two instead.  Thus, getPreferredBlockSize()
 * will always return a power of two if the wrapped plugin is a
 * frequency domain one.  If the plugin doesn't accept the adjusted
 * power of two block size, initialise() will fail.
 *
 * The adapter provides no way for the host to discover whether the
 * underlying plugin is actually a time or frequency domain plugin
 * (except that if the preferred block size is not a power of two, it
 * must be a time domain plugin).
 *
 * The FFT implementation is simple and self-contained, but unlikely
 * to be the fastest available: a host can usually do better if it
 * cares enough.
 *
 * In every respect other than its input domain handling, the
 * PluginInputDomainAdapter behaves identically to the plugin that it
 * wraps.  The wrapped plugin will be deleted when the wrapper is
 * deleted.
 */

class PluginInputDomainAdapter : public PluginWrapper
{
public:
    PluginInputDomainAdapter(Plugin *plugin); // I take ownership of plugin
    virtual ~PluginInputDomainAdapter();
    
    bool initialise(size_t channels, size_t stepSize, size_t blockSize);

    InputDomain getInputDomain() const;

    size_t getPreferredStepSize() const;
    size_t getPreferredBlockSize() const;

    FeatureSet process(const float *const *inputBuffers, RealTime timestamp);

protected:
    size_t m_channels;
    size_t m_blockSize;
    float **m_freqbuf;
    double *m_ri;
    double *m_ro;
    double *m_io;

    void fft(unsigned int n, bool inverse,
             double *ri, double *ii, double *ro, double *io);

    size_t makeBlockSizeAcceptable(size_t) const;
};

}

}

#endif