comparison vamp-sdk/Plugin.h @ 3:0133b3513e2b

* Renamed sdk to vamp-sdk

+/* -*- 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 X CONSORTIUM 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_H_
+#define _VAMP_PLUGIN_H_
+
+#include "PluginBase.h"
+#include "RealTime.h"
+
+#include <string>
+#include <vector>
+#include <map>
+
+namespace Vamp {
+
+/**
+ * Vamp::Plugin is a base class for plugin instance classes
+ * that provide feature extraction from audio or related data.
+ *
+ * In most cases, the input will be audio and the output will be a
+ * stream of derived data at a lower sampling resolution than the
+ * input.
+ *
+ * Note that this class inherits several abstract methods from
+ * PluginBase, that must be implemented by the subclass.
+ */
+
+/**
+ * Plugin Lifecycle
+ * ================
+ *
+ * Feature extraction plugins are managed differently from real-time
+ * plugins (such as VST effects).  The main difference is that the
+ * parameters for a feature extraction plugin are configured before
+ * the plugin is used, and do not change during use.
+ *
+ * 1. Host constructs the plugin, passing it the input sample rate.
+ * The plugin may do basic initialisation, but should not do anything
+ * computationally expensive at this point.
+ *
+ * 2. Host may query the plugin's available outputs.
+ *
+ * 3. Host queries programs and parameter descriptors, and may set
+ * some or all of them.  Parameters that are not explicitly set should
+ * take their default values as specified in the parameter descriptor.
+ * When a program is set, the parameter values may change and the host
+ * will re-query them to check.
+ *
+ * 4. Host queries the preferred step size, block size, number of
+ * channels, and the number of values per feature for the plugin's
+ * outputs.  These may all vary depending on the parameter values.
+ * (Note however that you cannot make the number of distinct outputs
+ * dependent on parameter values; nor can you make any of these depend
+ * on the number of input channels.)
+ *
+ * 5. Plugin is properly initialised with a call to initialise.  This
+ * fixes the step size, block size, and number of channels, as well as
+ * all of the parameter and program settings.  If the values passed in
+ * to initialise do not match the plugin's advertised preferred values
+ * from step 4, the plugin may refuse to initialise and return false
+ * (although if possible it should accept the new values).
+ *
+ * 6. Host will repeatedly call the process method to pass in blocks
+ * of input data.  This method may return features extracted from that
+ * data (if the plugin is causal).
+ *
+ * 7. Host will call getRemainingFeatures exactly once, after all the
+ * input data has been processed.  This may return any non-causal or
+ * leftover features.
+ *
+ * 8. At any point after initialise was called, the host may
+ * optionally call the reset method and restart processing.  (This
+ * does not mean it can change the parameters, which are fixed from
+ * initialise until destruction.)
+ *
+ * A plugin does not need to handle the case where setParameter or
+ * selectProgram is called after initialise has been called.  It's the
+ * host's responsibility not to do that.
+ */
+
+class Plugin : public PluginBase
+{
+public:
+    /**
+     * Initialise a plugin to prepare it for use with the given number
+     * of input channels, step size (window increment, in sample
+     * frames) and block size (window size, in sample frames).
+     *
+     * The input sample rate should have been already specified at
+     * construction time.
+     * 
+     * Return true for successful initialisation, false if the number
+     * of input channels, step size and/or block size cannot be
+     * supported.
+     */
+    virtual bool initialise(size_t inputChannels,
+			    size_t stepSize,
+			    size_t blockSize) = 0;
+
+    /**
+     * Reset the plugin after use, to prepare it for another clean
+     * run.  Not called for the first initialisation (i.e. initialise
+     * must also do a reset).
+     */
+    virtual void reset() = 0;
+
+    enum InputDomain { TimeDomain, FrequencyDomain };
+    
+    /**
+     * Get the plugin's required input domain.  If this is TimeDomain,
+     * the samples provided to the process() function (below) will be
+     * in the time domain, as for a traditional audio processing
+     * plugin.  If this is FrequencyDomain, the host will carry out a
+     * windowed FFT of size equal to the negotiated block size on the
+     * data before passing the frequency bin data in to process().
+     * The plugin does not get to choose the window type -- the host
+     * will either let the user do so, or will use a Hanning window.
+     */
+    virtual InputDomain getInputDomain() const = 0;
+
+    /**
+     * Get the preferred step size (window increment -- the distance
+     * in sample frames between the start frames of consecutive blocks
+     * passed to the process() function) for the plugin.  This should
+     * be called before initialise().
+     */
+    virtual size_t getPreferredStepSize() const = 0;
+
+    /**
+     * Get the preferred block size (window size -- the number of
+     * sample frames passed in each block to the process() function).
+     * This should be called before initialise().
+     */
+    virtual size_t getPreferredBlockSize() const { return getPreferredStepSize(); }
+
+    /**
+     * Get the minimum supported number of input channels.
+     */
+    virtual size_t getMinChannelCount() const { return 1; }
+
+    /**
+     * Get the maximum supported number of input channels.
+     */
+    virtual size_t getMaxChannelCount() const { return 1; }
+
+    struct OutputDescriptor
+    {
+	/**
+	 * The name of the output, in computer-usable form.  Should be
+	 * reasonably short and without whitespace or punctuation.
+	 */
+	std::string name;
+
+	/**
+	 * The human-readable name of the output.
+	 */
+	std::string description;
+
+	/**
+	 * The unit of the output, in human-readable form.
+	 */
+	std::string unit;
+
+	/**
+	 * True if the output has the same number of values per result
+	 * for every output result.  Outputs for which this is false
+	 * are unlikely to be very useful in a general-purpose host.
+	 */
+	bool hasFixedValueCount;
+
+	/**
+	 * The number of values per result of the output.  Undefined
+	 * if hasFixedValueCount is false.  If this is zero, the output
+	 * is point data (i.e. only the time of each output is of
+	 * interest, the value list will be empty).
+	 *
+	 * Note that this gives the number of values of a single
+	 * output result, not of the output stream (which has one more
+	 * dimension: time).
+	 */
+	size_t valueCount;
+
+	/**
+	 * The names of each of the values, if appropriate.  This is
+	 * always optional.
+	 */
+	std::vector<std::string> valueNames;
+
+	/**
+	 * True if the results in the output have a fixed numeric
+	 * range (minimum and maximum values).  Undefined if
+	 * valueCount is zero.
+	 */
+	bool hasKnownExtents;
+
+	/**
+	 * Minimum value of the results in the output.  Undefined if
+	 * hasKnownExtents is false or valueCount is zero.
+	 */
+	float minValue;
+
+	/**
+	 * Maximum value of the results in the output.  Undefined if
+	 * hasKnownExtents is false or valueCount is zero.
+	 */
+	float maxValue;
+
+	/**
+	 * True if the output values are quantized to a particular
+	 * resolution.  Undefined if valueCount is zero.
+	 */
+	bool isQuantized;
+
+	/**
+	 * Quantization resolution of the output values (e.g. 1.0 if
+	 * they are all integers).  Undefined if isQuantized is false
+	 * or valueCount is zero.
+	 */
+	float quantizeStep;
+
+	enum SampleType {
+
+	    /// Results from each process() align with that call's block start
+	    OneSamplePerStep,
+
+	    /// Results are evenly spaced in time (sampleRate specified below)
+	    FixedSampleRate,
+
+	    /// Results are unevenly spaced and have individual timestamps
+	    VariableSampleRate
+	};
+
+	/**
+	 * Positioning in time of the output results.
+	 */
+	SampleType sampleType;
+
+	/**
+	 * Sample rate of the output results.  Undefined if sampleType
+	 * is OneSamplePerStep.
+	 *
+	 * If sampleType is VariableSampleRate and this value is
+	 * non-zero, then it may be used to calculate a resolution for
+	 * the output (i.e. the "duration" of each value, in time).
+	 * It's recommended to set this to zero if that behaviour is
+	 * not desired.
+	 */
+	float sampleRate;
+    };
+
+    typedef std::vector<OutputDescriptor> OutputList;
+
+    /**
+     * Get the outputs of this plugin.  An output's index in this list
+     * is used as its numeric index when looking it up in the
+     * FeatureSet returned from the process() call.
+     */
+    virtual OutputList getOutputDescriptors() const = 0;
+
+    struct Feature
+    {
+	/**
+	 * True if an output feature has its own timestamp.  This is
+	 * mandatory if the output has VariableSampleRate, and is
+	 * likely to be disregarded otherwise.
+	 */
+	bool hasTimestamp;
+
+	/**
+	 * Timestamp of the output feature.  This is mandatory if the
+	 * output has VariableSampleRate, and is likely to be
+	 * disregarded otherwise.  Undefined if hasTimestamp is false.
+	 */
+	RealTime timestamp;
+	
+	/**
+	 * Results for a single sample of this feature.  If the output
+	 * hasFixedValueCount, there must be the same number of values
+	 * as the output's valueCount count.
+	 */
+	std::vector<float> values;
+
+	/**
+	 * Label for the sample of this feature.
+	 */
+	std::string label;
+    };
+
+    typedef std::vector<Feature> FeatureList;
+    typedef std::map<int, FeatureList> FeatureSet; // key is output no
+
+    /**
+     * Process a single block of input data.
+     * 
+     * If the plugin's inputDomain is TimeDomain, inputBuffers will
+     * point to one array of floats per input channel, and each of
+     * these arrays will contain blockSize consecutive audio samples
+     * (the host will zero-pad as necessary).
+     *
+     * If the plugin's inputDomain is FrequencyDomain, inputBuffers
+     * will point to one array of floats per input channel, and each
+     * of these arrays will contain blockSize/2 consecutive pairs of
+     * real and imaginary component floats corresponding to bins
+     * 0..(blockSize/2-1) of the FFT output.
+     *
+     * The timestamp is the real time in seconds of the start of the
+     * supplied block of samples.
+     *
+     * Return any features that have become available after this
+     * process call.  (These do not necessarily have to fall within
+     * the process block, except for OneSamplePerStep outputs.)
+     */
+    virtual FeatureSet process(float **inputBuffers,
+			       RealTime timestamp) = 0;
+
+    /**
+     * After all blocks have been processed, calculate and return any
+     * remaining features derived from the complete input.
+     */
+    virtual FeatureSet getRemainingFeatures() = 0;
+
+    virtual std::string getType() const { return "Feature Extraction Plugin"; }
+
+protected:
+    Plugin(float inputSampleRate) :
+	m_inputSampleRate(inputSampleRate) { }
+
+    float m_inputSampleRate;
+};
+
+}
+
+#endif
+
+
+