view transform/FeatureWriter.h @ 1376:d9511f9e04d7 dev/refactor-piper-related

Introduce some POD structs for describing an external server application and the desired libraries to load from it, and disambiguating between empty list request and invalid list request. This allows for overriding PiperVampPluginFactory behaviour for using a PluginScan to populate the list request.

/* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */

/*
    Sonic Visualiser
    An audio file viewer and annotation editor.

    Sonic Annotator
    A utility for batch feature extraction from audio files.

    Mark Levy, Chris Sutton and Chris Cannam, Queen Mary, University of London.
    Copyright 2007-2008 QMUL.

    This program is free software; you can redistribute it and/or
    modify it under the terms of the GNU General Public License as
    published by the Free Software Foundation; either version 2 of the
    License, or (at your option) any later version.  See the file
    COPYING included with this distribution for more information.
*/

#ifndef _FEATURE_WRITER_H_
#define _FEATURE_WRITER_H_

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

#include <QString>

#include "Transform.h"

#include <vamp-hostsdk/Plugin.h>

using std::string;
using std::map;
using std::vector;

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

    virtual string getDescription() const = 0;

    struct Parameter { // parameter of the writer, not the plugin
        Parameter() : hasArg(false), mandatory(false) { }
        string name;
        string description;
        bool hasArg;
        bool mandatory;
    };
    typedef vector<Parameter> ParameterList;
    virtual ParameterList getSupportedParameters() const {
        return ParameterList();
    }

    virtual void setParameters(map<string, string> &) {
        return;
    }

    struct TrackMetadata {
        QString title;
        QString maker;
        RealTime duration;
    };
    virtual void setTrackMetadata(QString /* trackid */, TrackMetadata) { }

    class FailedToOpenOutputStream : virtual public std::exception
    {
    public:
        FailedToOpenOutputStream(QString trackId, QString transformId) throw() :
            m_trackId(trackId),
            m_transformId(transformId)
        { }
        virtual ~FailedToOpenOutputStream() throw() { }
        virtual const char *what() const throw() {
            return QString("Failed to open output stream for track id \"%1\", transform id \"%2\"")
                .arg(m_trackId).arg(m_transformId).toLocal8Bit().data();
        }            
        
    protected:
        QString m_trackId;
        QString m_transformId;
    };

    /**
     * Notify the writer that we are about to start extraction for
     * input file N of M (where N is 1..M). May be useful when writing
     * multiple outputs into a single file where some syntactic
     * element is needed to connect them.
     */
    virtual void setNofM(int /* N */, int /* M */) { }

    // may throw FailedToOpenFile or other exceptions
    virtual void write(QString trackid,
                       const Transform &transform,
                       const Vamp::Plugin::OutputDescriptor &output,
                       const Vamp::Plugin::FeatureList &features,
                       std::string summaryType = "") = 0;

    /**
     * Throw FailedToOpenOutputStream if we can already tell that we
     * will be unable to write to the output file.  This is called to
     * test the output stream before processing begins.  The writer
     * may legitimately succeed here but still fail later -- this is
     * really an optimisation to ensure that easy-to-recognise failure
     * cases fail early.
     */
    virtual void testOutputFile(QString /* trackId */, TransformId) { }

    virtual void flush() { } // whatever the last stream was

    virtual void finish() = 0;

    virtual QString getWriterTag() const = 0;
};

#endif