annotate vamp-sdk/PluginBase.h @ 140:a6cfe3d9f752

* Load plugins with RTLD_GLOBAL -- otherwise Vampy plugins will be unable to
  load additional modules (for some reason I don't fully understand)

/* -*- 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
    restriction, including without limitation the rights to use, copy,
    modify, merge, publish, distribute, sublicense, and/or sell copies
    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
    ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
    CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
    WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

    Except as contained in this notice, the names of the Centre for
    Digital Music; Queen Mary, University of London; and Chris Cannam
    shall not be used in advertising or otherwise to promote the sale,
    use or other dealings in this Software without prior written
    authorization.
*/

#ifndef _VAMP_PLUGIN_BASE_H_
#define _VAMP_PLUGIN_BASE_H_

#include <string>
#include <vector>

#define VAMP_SDK_VERSION "1.2"

namespace Vamp {

/**
 * A base class for plugins with optional configurable parameters,
 * programs, etc.  The Vamp::Plugin is derived from this, and
 * individual Vamp plugins should derive from that.
 *
 * This class does not provide the necessary interfaces to instantiate
 * or run a plugin.  It only specifies an interface for retrieving
 * those controls that the host may wish to show to the user for
 * editing.  It could meaningfully be subclassed by real-time plugins
 * or other sorts of plugin as well as Vamp plugins.
 */

class PluginBase 
{
public:
    virtual ~PluginBase() { }

    /**
     * Get the Vamp API compatibility level of the plugin.
     */
    virtual unsigned int getVampApiVersion() const { return 1; }

    /**
     * Get the computer-usable name of the plugin.  This should be
     * reasonably short and contain no whitespace or punctuation
     * characters.  It may only contain the characters [a-zA-Z0-9_-].
     * This is the authoritative way for a program to identify a
     * plugin within a given library.
     *
     * This text may be visible to the user, but it should not be the
     * main text used to identify a plugin to the user (that will be
     * the name, below).
     *
     * Example: "zero_crossings"
     */
    virtual std::string getIdentifier() const = 0;

    /**
     * Get a human-readable name or title of the plugin.  This
     * should be brief and self-contained, as it may be used to
     * identify the plugin to the user in isolation (i.e. without also
     * showing the plugin's "identifier").
     *
     * Example: "Zero Crossings"
     */
    virtual std::string getName() const = 0;

    /**
     * Get a human-readable description for the plugin, typically
     * a line of text that may optionally be displayed in addition
     * to the plugin's "name".  May be empty if the name has said
     * it all already.
     *
     * Example: "Detect and count zero crossing points"
     */
    virtual std::string getDescription() const = 0;
    
    /**
     * Get the name of the author or vendor of the plugin in
     * human-readable form.  This should be a short identifying text,
     * as it may be used to label plugins from the same source in a
     * menu or similar.
     */
    virtual std::string getMaker() const = 0;

    /**
     * Get the copyright statement or licensing summary for the
     * plugin.  This can be an informative text, without the same
     * presentation constraints as mentioned for getMaker above.
     */
    virtual std::string getCopyright() const = 0;

    /**
     * Get the version number of the plugin.
     */
    virtual int getPluginVersion() const = 0;


    struct ParameterDescriptor
    {
	/**
	 * The name of the parameter, in computer-usable form.  Should
	 * be reasonably short, and may only contain the characters
	 * [a-zA-Z0-9_-].
	 */
	std::string identifier;

	/**
	 * The human-readable name of the parameter.
	 */
	std::string name;

	/**
	 * A human-readable short text describing the parameter.  May be
         * empty if the name has said it all already.
	 */
	std::string description;

	/**
	 * The unit of the parameter, in human-readable form.
	 */
	std::string unit;

	/**
	 * The minimum value of the parameter.
	 */
	float minValue;

	/**
	 * The maximum value of the parameter.
	 */
	float maxValue;

	/**
	 * The default value of the parameter.  The plugin should
	 * ensure that parameters have this value on initialisation
	 * (i.e. the host is not required to explicitly set parameters
	 * if it wants to use their default values).
	 */
	float defaultValue;
	
	/**
	 * True if the parameter values are quantized to a particular
	 * resolution.
	 */
	bool isQuantized;

	/**
	 * Quantization resolution of the parameter values (e.g. 1.0
	 * if they are all integers).  Undefined if isQuantized is
	 * false.
	 */
	float quantizeStep;

        /**
         * Names for the quantized values.  If isQuantized is true,
         * this may either be empty or contain one string for each of
         * the quantize steps from minValue up to maxValue inclusive.
         * Undefined if isQuantized is false.
         *
         * If these names are provided, they should be shown to the
         * user in preference to the values themselves.  The user may
         * never see the actual numeric values unless they are also
         * encoded in the names.
         */
        std::vector<std::string> valueNames;
    };

    typedef std::vector<ParameterDescriptor> ParameterList;

    /**
     * Get the controllable parameters of this plugin.
     */
    virtual ParameterList getParameterDescriptors() const {
	return ParameterList();
    }

    /**
     * Get the value of a named parameter.  The argument is the identifier
     * field from that parameter's descriptor.
     */
    virtual float getParameter(std::string) const { return 0.0; }

    /**
     * Set a named parameter.  The first argument is the identifier field
     * from that parameter's descriptor.
     */
    virtual void setParameter(std::string, float) { } 

    
    typedef std::vector<std::string> ProgramList;

    /**
     * Get the program settings available in this plugin.  A program
     * is a named shorthand for a set of parameter values; changing
     * the program may cause the plugin to alter the values of its
     * published parameters (and/or non-public internal processing
     * parameters).  The host should re-read the plugin's parameter
     * values after setting a new program.
     *
     * The programs must have unique names.
     */
    virtual ProgramList getPrograms() const { return ProgramList(); }

    /**
     * Get the current program.
     */
    virtual std::string getCurrentProgram() const { return ""; }

    /**
     * Select a program.  (If the given program name is not one of the
     * available programs, do nothing.)
     */
    virtual void selectProgram(std::string) { }

    /**
     * Get the type of plugin.  This is to be implemented by the
     * immediate subclass, not by actual plugins.  Do not attempt to
     * implement this in plugin code.
     */
    virtual std::string getType() const = 0;
};

}

#endif