annotate vamp-hostsdk/PluginLoader.h @ 458:eb30742e5e43 vampipe

pluginData -> plugins like the schema

/* -*- 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.
  
    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
    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
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    Except as contained in this notice, the names of the Centre for
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*/

#ifndef _VAMP_PLUGIN_LOADER_H_
#define _VAMP_PLUGIN_LOADER_H_

#include <vector>
#include <string>
#include <map>

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

_VAMP_SDK_HOSTSPACE_BEGIN(PluginLoader.h)

namespace Vamp {

class Plugin;

namespace HostExt {

/**
 * \class PluginLoader PluginLoader.h <vamp-hostsdk/PluginLoader.h>
 * 
 * Vamp::HostExt::PluginLoader is a convenience class for discovering
 * and loading Vamp plugins using the typical plugin-path, library
 * naming, and categorisation conventions described in the Vamp SDK
 * documentation.  This class is intended to greatly simplify the task
 * of becoming a Vamp plugin host for any C++ application.
 * 
 * Hosts are not required by the Vamp specification to use the same
 * plugin search path and naming conventions as implemented by this
 * class, and are certainly not required to use this actual class.
 * But we do strongly recommend it.
 *
 * This class is not thread-safe; use it from a single application
 * thread, or guard access to it with a mutex.
 *
 * \note This class was introduced in version 1.1 of the Vamp plugin SDK.
 */

class PluginLoader
{
public:
    /**
     * Obtain a pointer to the singleton instance of PluginLoader.
     * Use this to obtain your loader object.
     */
    static PluginLoader *getInstance();

    /**
     * PluginKey is a string type that is used to identify a plugin
     * uniquely within the scope of "the current system".  It consists
     * of the lower-cased base name of the plugin library, a colon
     * separator, and the identifier string for the plugin.  It is
     * only meaningful in the context of a given plugin path (the one
     * returned by PluginHostAdapter::getPluginPath()).
     *
     * Use composePluginKey() to construct a plugin key from a known
     * plugin library name and identifier.
     *
     * Note: the fact that the library component of the key is
     * lower-cased implies that library names are matched
     * case-insensitively by the PluginLoader class, regardless of the
     * case sensitivity of the underlying filesystem.  (Plugin
     * identifiers _are_ case sensitive, however.)  Also, it is not
     * possible to portably extract a working library name from a
     * plugin key, as the result may fail on case-sensitive
     * filesystems.  Use getLibraryPathForPlugin() instead.
     */
    typedef std::string PluginKey;

    /**
     * PluginKeyList is a sequence of plugin keys, such as returned by
     * listPlugins().
     */
    typedef std::vector<PluginKey> PluginKeyList;

    /**
     * PluginCategoryHierarchy is a sequence of general->specific
     * category names, as may be associated with a single plugin.
     * This sequence describes the location of a plugin within a
     * category forest, containing the human-readable names of the
     * plugin's category tree root, followed by each of the nodes down
     * to the leaf containing the plugin.
     *
     * \see getPluginCategory()
     */
    typedef std::vector<std::string> PluginCategoryHierarchy;

    /**
     * Search for all available Vamp plugins, and return a list of
     * them in the order in which they were found.
     */
    PluginKeyList listPlugins();

    /**
     * Search for all available Vamp plugins, and return a list of
     * static data about each plugin in the order in which they were
     * found. This is slower but returns more comprehensive
     * information than listPlugins().
     *
     * \see ListResponse, PluginStaticData
     */
    ListResponse listPluginData();

    /**
     * AdapterFlags contains a set of values that may be OR'd together
     * to indicate in which circumstances PluginLoader should use a
     * plugin adapter to make a plugin easier to use for a host that
     * does not want to cater for complex features.
     *
     * The available flags are:
     * 
     * ADAPT_INPUT_DOMAIN - If the plugin expects frequency domain
     * input, wrap it in a PluginInputDomainAdapter that automatically
     * converts the plugin to one that expects time-domain input.
     * This enables a host to accommodate time- and frequency-domain
     * plugins without needing to do any conversion itself.
     *
     * ADAPT_CHANNEL_COUNT - Wrap the plugin in a PluginChannelAdapter
     * to handle any mismatch between the number of channels of audio
     * the plugin can handle and the number available in the host.
     * This enables a host to use plugins that may require the input
     * to be mixed down to mono, etc., without having to worry about
     * doing that itself.
     *
     * ADAPT_BUFFER_SIZE - Wrap the plugin in a PluginBufferingAdapter
     * permitting the host to provide audio input using any block
     * size, with no overlap, regardless of the plugin's preferred
     * block size (suitable for hosts that read from non-seekable
     * streaming media, for example).  This adapter introduces some
     * run-time overhead and also changes the semantics of the plugin
     * slightly (see the PluginBufferingAdapter header documentation
     * for details).
     *
     * ADAPT_ALL_SAFE - Perform all available adaptations that are
     * meaningful for the plugin and "safe".  Currently this means to
     * ADAPT_INPUT_DOMAIN if the plugin wants FrequencyDomain input;
     * ADAPT_CHANNEL_COUNT always; and ADAPT_BUFFER_SIZE never.
     * 
     * ADAPT_ALL - Perform all available adaptations that are
     * meaningful for the plugin.
     * 
     * See PluginInputDomainAdapter, PluginChannelAdapter and
     * PluginBufferingAdapter for more details of the classes that the
     * loader may use if these flags are set.
     */
    enum AdapterFlags {

        ADAPT_INPUT_DOMAIN  = 0x01,
        ADAPT_CHANNEL_COUNT = 0x02,
        ADAPT_BUFFER_SIZE   = 0x04,

        ADAPT_ALL_SAFE      = 0x03,

        ADAPT_ALL           = 0xff
    };

    /**
     * Load a Vamp plugin, given its identifying key.  If the plugin
     * could not be loaded, returns 0.
     *
     * The returned plugin should be deleted (using the standard C++
     * delete keyword) after use.
     *
     * \param adapterFlags a bitwise OR of the values in the AdapterFlags
     * enumeration, indicating under which circumstances an adapter should be
     * used to wrap the original plugin.  If adapterFlags is 0, no
     * optional adapters will be used.  Otherwise, the returned plugin
     * may be of an adapter class type which will behave identically
     * to the original plugin, apart from any particular features
     * implemented by the adapter itself.
     * 
     * \see AdapterFlags, PluginInputDomainAdapter, PluginChannelAdapter
     */
    Plugin *loadPlugin(PluginKey key,
                       float inputSampleRate,
                       int adapterFlags = 0);

    /**
     * Load a Vamp plugin, given its key, inputSampleRate and the
     * adapter flags, bundled into a LoadRequest structure. The loaded
     * plugin is returned along with its static data and default
     * configuration in a LoadResponse.
     * 
     * \see AdapterFlags, PluginInputDomainAdapter, PluginChannelAdapter, LoadRequest, LoadResponse
     */
    LoadResponse loadPlugin(LoadRequest req);

    /**
     * Configure and initialise a Vamp plugin. This applies the
     * parameter and program settings found in the PluginConfiguration
     * part of the supplied ConfigurationRequest and initialises the
     * plugin. (Many hosts will prefer to do this themselves in
     * stages, by calling methods on the plugin directly.)
     *
     * Return a ConfigurationResponse containing the result of calling
     * getOutputDescriptors() on the configured and initialised
     * plugin, representing the outputs of the plugin following
     * configuration (since output ranges etc can depend on the
     * parameters). If initialisation fails, returns an empty list.
     *
     * \see PluginConfiguration, ConfigurationRequest, ConfigurationResponse
     */
    ConfigurationResponse configurePlugin(ConfigurationRequest req);
    
    /**
     * Given a Vamp plugin library name and plugin identifier, return
     * the corresponding plugin key in a form suitable for passing in to
     * loadPlugin().
     */
    PluginKey composePluginKey(std::string libraryName,
                               std::string identifier);

    /**
     * Return the category hierarchy for a Vamp plugin, given its
     * identifying key.
     *
     * If the plugin has no category information, return an empty
     * hierarchy.
     *
     * \see PluginCategoryHierarchy
     */
    PluginCategoryHierarchy getPluginCategory(PluginKey plugin);

    /**
     * Return the file path of the dynamic library from which the
     * given plugin will be loaded (if available).
     */
    std::string getLibraryPathForPlugin(PluginKey plugin);

protected:
    PluginLoader();
    virtual ~PluginLoader();

    class Impl;
    Impl *m_impl;

    static PluginLoader *m_instance;
};

}

}

_VAMP_SDK_HOSTSPACE_END(PluginLoader.h)

#endif