annotate vamp-hostsdk/PluginInputDomainAdapter.h @ 433:f8a3bd2d86cb

Emscripten Makefile -- not done yet. Also need to factorise out all these common lists of source files.

/* -*- 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 2006-2009 Chris Cannam and QMUL.
  
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    The above copyright notice and this permission notice shall be
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*/

#ifndef _VAMP_PLUGIN_INPUT_DOMAIN_ADAPTER_H_
#define _VAMP_PLUGIN_INPUT_DOMAIN_ADAPTER_H_

#include "hostguard.h"
#include "PluginWrapper.h"

_VAMP_SDK_HOSTSPACE_BEGIN(PluginInputDomainAdapter.h)

namespace Vamp {

namespace HostExt {

/**
 * \class PluginInputDomainAdapter PluginInputDomainAdapter.h <vamp-hostsdk/PluginInputDomainAdapter.h>
 * 
 * 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 windowed FFT (using Hann window by
 * default) 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.
 *
 * The window shape for the FFT frame can be set using setWindowType
 * and the current shape retrieved using getWindowType.  (This was
 * added in v2.3 of the SDK.)
 *
 * 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.
 *
 * \note This class was introduced in version 1.1 of the Vamp plugin SDK.
 */

class PluginInputDomainAdapter : public PluginWrapper
{
public:
    /**
     * Construct a PluginInputDomainAdapter wrapping the given plugin.
     * The adapter takes ownership of the plugin, which will be
     * deleted when the adapter is deleted.
     */
    PluginInputDomainAdapter(Plugin *plugin);
    virtual ~PluginInputDomainAdapter();
    
    bool initialise(size_t channels, size_t stepSize, size_t blockSize);
    void reset();

    InputDomain getInputDomain() const;

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

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

    /**
     * ProcessTimestampMethod determines how the
     * PluginInputDomainAdapter handles timestamps for the data passed
     * to the process() function of the plugin it wraps, in the case
     * where the plugin is expecting frequency-domain data.
     *
     * The Vamp specification requires that the timestamp passed to
     * the plugin for frequency-domain input should be that of the
     * centre of the processing block, rather than the start as is the
     * case for time-domain input.
     *
     * Since PluginInputDomainAdapter aims to be transparent in use,
     * it needs to handle this timestamp adjustment itself.  However,
     * some control is available over the method used for adjustment,
     * by means of the ProcessTimestampMethod setting.
     *
     * If ProcessTimestampMethod is set to ShiftTimestamp (the
     * default), then the data passed to the wrapped plugin will be
     * calculated from the same input data block as passed to the
     * wrapper, but the timestamp passed to the plugin will be
     * advanced by half of the window size.
     * 
     * If ProcessTimestampMethod is set to ShiftData, then the
     * timestamp passed to the wrapped plugin will be the same as that
     * passed to the process call of the wrapper, but the data block
     * used to calculate the input will be shifted back (earlier) by
     * half of the window size, with half a block of zero padding at
     * the start of the first process call.  This has the advantage of
     * preserving the first half block of audio without any
     * deterioration from window shaping.
     * 
     * If ProcessTimestampMethod is set to NoShift, then no adjustment
     * will be made and the timestamps will be incorrect.
     */
    enum ProcessTimestampMethod {
        ShiftTimestamp,
        ShiftData,
        NoShift
    };

    /**
     * Set the method used for timestamp adjustment in plugins taking
     * frequency-domain input.  See the ProcessTimestampMethod
     * documentation for details.
     *
     * This function must be called before the first call to
     * process().
     */
    void setProcessTimestampMethod(ProcessTimestampMethod);

    /**
     * Retrieve the method used for timestamp adjustment in plugins
     * taking frequency-domain input.  See the ProcessTimestampMethod
     * documentation for details.
     */
    ProcessTimestampMethod getProcessTimestampMethod() const;

    /**
     * Return the amount by which the timestamps supplied to process()
     * are being incremented when they are passed to the plugin's own
     * process() implementation.
     *
     * The Vamp API mandates that the timestamp passed to the plugin
     * for time-domain input should be the time of the first sample in
     * the block, but the timestamp passed for frequency-domain input
     * should be the timestamp of the centre of the block.
     *
     * The PluginInputDomainAdapter adjusts its timestamps properly so
     * that the plugin receives correct times, but in some
     * circumstances (such as for establishing the correct timing of
     * implicitly-timed features, i.e. features without their own
     * timestamps) the host may need to be aware that this adjustment
     * is taking place.
     *
     * If the plugin requires time-domain input or the
     * PluginInputDomainAdapter is configured with its
     * ProcessTimestampMethod set to ShiftData instead of
     * ShiftTimestamp, then this function will return zero.
     *
     * The result of calling this function before initialise() has
     * been called is undefined.
     */
    RealTime getTimestampAdjustment() const;

    /**
     * The set of supported window shapes.
     */
    enum WindowType {

        RectangularWindow    = 0,

        BartlettWindow       = 1, /// synonym for RectangularWindow
        TriangularWindow     = 1, /// synonym for BartlettWindow

        HammingWindow        = 2,

        HanningWindow        = 3, /// synonym for HannWindow
        HannWindow           = 3, /// synonym for HanningWindow

        BlackmanWindow       = 4,

        NuttallWindow        = 7,

        BlackmanHarrisWindow = 8
    };

    /**
     * Return the current window shape.  The default is HanningWindow.
     */
    WindowType getWindowType() const;
    
    /**
     * Set the current window shape.
     */
    void setWindowType(WindowType type);


protected:
    class Impl;
    Impl *m_impl;
};

}

}

_VAMP_SDK_HOSTSPACE_END(PluginInputDomainAdapter.h)

#endif