view rdf/RDFFeatureWriter.cpp @ 1520:954d0cf29ca7 import-audio-data

Switch the normalisation option in WritableWaveFileModel from normalising on read to normalising on write, so that the saved file is already normalised and therefore can be read again without having to remember to normalise it

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

/*
    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.
*/

#include <fstream>

#include "base/Exceptions.h"

#include "RDFFeatureWriter.h"
#include "RDFTransformFactory.h"
#include "PluginRDFIndexer.h"

#include <QTextStream>
#include <QTextCodec>
#include <QUrl>
#include <QFileInfo>
#include <QRegExp>

using namespace std;
using Vamp::Plugin;
using Vamp::PluginBase;

RDFFeatureWriter::RDFFeatureWriter() :
    FileFeatureWriter(SupportOneFilePerTrackTransform |
                      SupportOneFilePerTrack |
                      SupportOneFileTotal |
                      SupportStdOut,
                      "n3"),
    m_plain(false),
    m_network(false),
    m_networkRetrieved(false),
    m_count(0)
{
}

RDFFeatureWriter::~RDFFeatureWriter()
{
}

string
RDFFeatureWriter::getDescription() const
{
    return "Write output in Audio Features Ontology RDF/Turtle format.";
}

RDFFeatureWriter::ParameterList
RDFFeatureWriter::getSupportedParameters() const
{
    ParameterList pl = FileFeatureWriter::getSupportedParameters();
    Parameter p;

    p.name = "plain";
    p.description = "Use \"plain\" RDF even if transform metadata is available.";
    p.hasArg = false;
    pl.push_back(p);

    p.name = "audiofile-uri";
    p.description = "Link the output RDF to the given audio file URI instead of its actual location.";
    p.hasArg = true;
    pl.push_back(p);

    p.name = "track-uri";
    p.description = "Link the output RDF to the given track URI.";
    p.hasArg = true;
    pl.push_back(p);

    p.name = "maker-uri";
    p.description = "Link the track in the output RDF to the given foaf:maker URI.";
    p.hasArg = true;
    pl.push_back(p);

    p.name = "network";
    p.description = "Attempt to retrieve RDF descriptions of plugins from network, if not available locally";
    p.hasArg = false;
    pl.push_back(p);
    
    return pl;
}

void
RDFFeatureWriter::setParameters(map<string, string> &params)
{
    FileFeatureWriter::setParameters(params);

    for (map<string, string>::iterator i = params.begin();
         i != params.end(); ++i) {
        if (i->first == "plain") {
            m_plain = true;
        }
        if (i->first == "audiofile-uri") {
            m_userAudioFileUri = i->second.c_str();
        }
        if (i->first == "track-uri") {
            m_userTrackUri = i->second.c_str();
        }
        if (i->first == "maker-uri") {
            m_userMakerUri = i->second.c_str();
        }
        if (i->first == "network") {
            m_network = true;
        }
    }
}

void
RDFFeatureWriter::setTrackMetadata(QString trackId,
                                   TrackMetadata metadata)
{
//    cerr << "setTrackMetadata: title = " << metadata.title << ", maker = " << metadata.maker << endl;
    m_metadata[trackId] = metadata;
}

void
RDFFeatureWriter::setFixedEventTypeURI(QString uri)
{
    m_fixedEventTypeURI = uri;
}

void
RDFFeatureWriter::write(QString trackId,
                        const Transform &transform,
                        const Plugin::OutputDescriptor& output,
                        const Plugin::FeatureList& features,
                        std::string summaryType)
{
    QString pluginId = transform.getPluginIdentifier();

    if (m_rdfDescriptions.find(pluginId) == m_rdfDescriptions.end()) {

        if (m_network && !m_networkRetrieved) {
            PluginRDFIndexer::getInstance()->indexConfiguredURLs();
            m_networkRetrieved = true;
        }

        m_rdfDescriptions[pluginId] = PluginRDFDescription(pluginId);

        if (m_rdfDescriptions[pluginId].haveDescription()) {
            SVCERR << "NOTE: Have RDF description for plugin ID \""
                 << pluginId << "\"" << endl;
        } else {
            SVCERR << "NOTE: No RDF description for plugin ID \""
                 << pluginId << "\"" << endl;
            if (!m_network) {
                SVCERR << "      Consider using the --rdf-network option to retrieve plugin descriptions"  << endl;
                SVCERR << "      from the network where possible." << endl;
            }
        }
    }

    // Need to select appropriate output file for our track/transform
    // combination

    QTextStream *stream = getOutputStream(trackId, transform.getIdentifier(),
                                          QTextCodec::codecForName("UTF-8"));
    if (!stream) {
        throw FailedToOpenOutputStream(trackId, transform.getIdentifier());
    }

    if (m_startedStreamTransforms.find(stream) ==
        m_startedStreamTransforms.end()) {
//        cerr << "This stream is new, writing prefixes" << endl;
        writePrefixes(stream);
        if (m_singleFileName == "" && !m_stdout) {
            writeSignalDescription(stream, trackId);
        }
    }

    if (m_startedStreamTransforms[stream].find(transform) ==
        m_startedStreamTransforms[stream].end()) {
        m_startedStreamTransforms[stream].insert(transform);
        writeLocalFeatureTypes
            (stream, transform, output, m_rdfDescriptions[pluginId],
             summaryType);
    }

    if (m_singleFileName != "" || m_stdout) {
        if (m_startedTrackIds.find(trackId) == m_startedTrackIds.end()) {
            writeSignalDescription(stream, trackId);
            m_startedTrackIds.insert(trackId);
        }
    }

    QString timelineURI = m_trackTimelineURIs[trackId];
    
    if (timelineURI == "") {
        SVCERR << "RDFFeatureWriter: INTERNAL ERROR: writing features without having established a timeline URI!" << endl;
        exit(1);
    }

    if (summaryType != "") {

        writeSparseRDF(stream, transform, output, features,
                       m_rdfDescriptions[pluginId], timelineURI);

    } else if (m_rdfDescriptions[pluginId].haveDescription() &&
               m_rdfDescriptions[pluginId].getOutputDisposition
               (output.identifier.c_str()) == 
               PluginRDFDescription::OutputDense) {

        QString signalURI = m_trackSignalURIs[trackId];

        if (signalURI == "") {
            SVCERR << "RDFFeatureWriter: INTERNAL ERROR: writing dense features without having established a signal URI!" << endl;
            exit(1);
        }

        writeDenseRDF(stream, transform, output, features,
                      m_rdfDescriptions[pluginId], signalURI, timelineURI);

    } else if (!m_plain &&
               m_rdfDescriptions[pluginId].haveDescription() &&
               m_rdfDescriptions[pluginId].getOutputDisposition
               (output.identifier.c_str()) ==
               PluginRDFDescription::OutputTrackLevel &&
               m_rdfDescriptions[pluginId].getOutputFeatureAttributeURI
               (output.identifier.c_str()) != "") {

        QString signalURI = m_trackSignalURIs[trackId];

        if (signalURI == "") {
            SVCERR << "RDFFeatureWriter: INTERNAL ERROR: writing track-level features without having established a signal URI!" << endl;
            exit(1);
        }

        writeTrackLevelRDF(stream, transform, output, features,
                           m_rdfDescriptions[pluginId], signalURI);

    } else {

        writeSparseRDF(stream, transform, output, features,
                       m_rdfDescriptions[pluginId], timelineURI);
    }
}

void
RDFFeatureWriter::writePrefixes(QTextStream *sptr)
{
    QTextStream &stream = *sptr;

    stream << "@prefix dc: <http://purl.org/dc/elements/1.1/> .\n"
           << "@prefix mo: <http://purl.org/ontology/mo/> .\n"
           << "@prefix af: <http://purl.org/ontology/af/> .\n"
           << "@prefix foaf: <http://xmlns.com/foaf/0.1/> . \n"
           << "@prefix event: <http://purl.org/NET/c4dm/event.owl#> .\n"
           << "@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .\n"
           << "@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .\n"
           << "@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .\n"
           << "@prefix tl: <http://purl.org/NET/c4dm/timeline.owl#> .\n"
           << "@prefix vamp: <http://purl.org/ontology/vamp/> .\n"
           << "@prefix : <#> .\n\n";
}

void
RDFFeatureWriter::reviewFileForAppending(QString filename)
{
    // Appending to an RDF file is tricky, because we need to ensure
    // that our URIs differ from any already in the file.  This is a
    // dirty grubby low-rent way of doing that.  This function is
    // called by FileFeatureWriter::getOutputFile when in append mode.

//    cerr << "reviewFileForAppending(" << filename << ")" << endl;

    QFile file(filename);

    // just return, don't report failure -- function that called us will do that
    if (!file.open(QIODevice::ReadOnly)) return;

    QTextStream in(&file);

    QRegExp localObjectUriWithDigits(":[^ ]+_([0-9]+) a ");

    while (!in.atEnd()) {
        QString line = in.readLine();
        if (line.length() > 120) { // probably data
            continue;
        }
        if (localObjectUriWithDigits.indexIn(line) > -1) {
            QString numeric = localObjectUriWithDigits.cap(1);
            int number = numeric.toInt();
            if (number >= m_count) m_count = number + 1;
        }
    }

    file.close();
}

void
RDFFeatureWriter::writeSignalDescription(QTextStream *sptr,
                                         QString trackId)
{
//    SVDEBUG << "RDFFeatureWriter::writeSignalDescription" << endl;

    QTextStream &stream = *sptr;

    /*
     * Describe signal we're analysing (AudioFile, Signal, TimeLine, etc.)
     */
    
    QUrl url(trackId, QUrl::StrictMode);
    QString scheme = url.scheme().toLower();
    bool local = (scheme == "" || scheme == "file" || scheme.length() == 1);

    if (local) {
        if (scheme == "") {
            url.setScheme("file");
            url.setPath(QFileInfo(url.path()).absoluteFilePath());
        } else if (scheme.length() == 1) { // DOS drive letter!
            url.setScheme("file");
            url.setPath(scheme + ":" + url.path());
        }
    }

    // Note reviewFileForAppending above (when opening in append mode)

    unsigned long signalCount = m_count++;

    if (m_trackSignalURIs.find(trackId) == m_trackSignalURIs.end()) {
        m_trackSignalURIs[trackId] = QString(":signal_%1").arg(signalCount);
    }
    QString signalURI = m_trackSignalURIs[trackId];
   
    if (m_trackTrackURIs.find(trackId) == m_trackTrackURIs.end()) {
        m_trackTrackURIs[trackId] = QString(":track_%1").arg(signalCount);
    }
    QString trackURI = m_trackTrackURIs[trackId];

    bool userSpecifiedTrack = false;
    if (m_userTrackUri != "") {
        trackURI = "<" + m_userTrackUri + ">";
        m_trackTrackURIs[trackId] = trackURI;
        userSpecifiedTrack = true;
    }
    
    if (m_trackTimelineURIs.find(trackId) == m_trackTimelineURIs.end()) {
        m_trackTimelineURIs[trackId] = QString(":signal_timeline_%1").arg(signalCount);
    }
    QString timelineURI = m_trackTimelineURIs[trackId];

    QString afURI = url.toEncoded().data();
    if (m_userAudioFileUri != "") afURI = m_userAudioFileUri;

    bool wantTrack = (userSpecifiedTrack ||
                      (m_userMakerUri != "") ||
                      haveTitleArtistMetadata(trackId));

//    cerr << "wantTrack = " << wantTrack << " (userSpecifiedTrack = "
//         << userSpecifiedTrack << ", m_userMakerUri = " << m_userMakerUri << ", have metadata = " << (m_metadata.find(trackId) != m_metadata.end()) << ")" << endl;

    if (wantTrack) {
        // We only write a Track at all if we have some title/artist
        // metadata to put in it, or if the user has requested a
        // specific track URI.  Otherwise we can't be sure that what
        // we have is a Track, in the publication sense -- it may just
        // be a fragment, a test file, whatever.  Since we'd have no
        // metadata to associate with our Track, the only effect of
        // including a Track would be to assert that this was one,
        // which is the one thing we wouldn't know...
        TrackMetadata tm;
        if (haveTitleArtistMetadata(trackId)) {
            tm = m_metadata[trackId];
        }
        stream << trackURI << " a mo:Track ";
        if (tm.title != "") {
            stream << ";\n    dc:title \"\"\"" << tm.title << "\"\"\" ";
        }
        if (m_userMakerUri != "") {
            stream << ";\n    foaf:maker <" << m_userMakerUri << "> ";
        } else if (tm.maker != "") {
            stream << ";\n    foaf:maker [ a mo:MusicArtist; foaf:name \"\"\"" << tm.maker << "\"\"\" ] ";
        }
        if (afURI != "") {
            stream << ";\n    mo:available_as <" << afURI << "> ";
        }
        stream << ".\n\n";
    }

    if (afURI != "") {
        stream << "<" << afURI << "> a mo:AudioFile ;\n";
        stream << "    mo:encodes " << signalURI << ".\n\n";
    }

    stream << signalURI << " a mo:Signal ;\n";

    stream << "    mo:time [\n"
           << "        a tl:Interval ;\n"
           << "        tl:onTimeLine "
           << timelineURI << "\n    ] .\n\n";

    stream << timelineURI << " a tl:Timeline .\n\n";
} 

void
RDFFeatureWriter::writeLocalFeatureTypes(QTextStream *sptr,
                                         const Transform &transform,
                                         const Plugin::OutputDescriptor &od,
                                         PluginRDFDescription &desc, 
                                         std::string summaryType)
{
    QString outputId = od.identifier.c_str();
    QTextStream &stream = *sptr;

    // There is no "needFeatureType" for track-level outputs, because
    // we can't meaningfully write a feature at all if we don't know
    // what property to use for it.  If the output is track level but
    // there is no feature type given, we have to revert to events.

    bool needEventType = false;
    bool needSignalType = false;

    //!!! bin names, extents and so on can be written out using e.g. vamp:bin_names ( "a" "b" "c" ) 

    if (summaryType == "" &&
        desc.getOutputDisposition(outputId) == 
        PluginRDFDescription::OutputDense) {

        // no feature events, so may need signal type but won't need
        // event type

        if (m_plain) {

            needSignalType = true;

        } else if (desc.getOutputSignalTypeURI(outputId) == "") {
            
            needSignalType = true;
        }

    } else if (desc.getOutputDisposition(outputId) ==
               PluginRDFDescription::OutputTrackLevel) {

        // see note above -- need to generate an event type if no
        // feature type given, or if in plain mode

        if (m_plain) {
        
            needEventType = true;

        } else if (desc.getOutputFeatureAttributeURI(outputId) == "") {
    
            if (desc.getOutputEventTypeURI(outputId) == "") {

                needEventType = true;
            }
        }

    } else {

        // may need event type but won't need signal type

        if (m_plain) {
        
            needEventType = true;
    
        } else if (desc.getOutputEventTypeURI(outputId) == "") {

            needEventType = true;
        }
    }

    QString transformUri;
    if (m_transformURIs.find(transform) != m_transformURIs.end()) {
        transformUri = m_transformURIs[transform];
    } else {
        transformUri = QString(":transform_%1_%2").arg(m_count++).arg(outputId);
        m_transformURIs[transform] = transformUri;
    }

    if (transform.getIdentifier() != "") {
        stream << endl
               << RDFTransformFactory::writeTransformToRDF(transform, transformUri)
               << endl;
    }

    if (needEventType && m_fixedEventTypeURI == "") {

        QString uri;
        if (m_syntheticEventTypeURIs.find(transform) !=
            m_syntheticEventTypeURIs.end()) {
            uri = m_syntheticEventTypeURIs[transform];
        } else {
            uri = QString(":event_type_%1").arg(m_count++);
            m_syntheticEventTypeURIs[transform] = uri;
        }

        stream << uri
               << " rdfs:subClassOf event:Event ;" << endl
               << "    dc:title \"" << od.name.c_str() << "\" ;" << endl
               << "    dc:format \"" << od.unit.c_str() << "\" ;" << endl
               << "    dc:description \"" << od.description.c_str() << "\" ."
               << endl << endl;
    }

    if (needSignalType) {

        QString uri;
        if (m_syntheticSignalTypeURIs.find(transform) !=
            m_syntheticSignalTypeURIs.end()) {
            uri = m_syntheticSignalTypeURIs[transform];
        } else {
            uri = QString(":signal_type_%1").arg(m_count++);
            m_syntheticSignalTypeURIs[transform] = uri;
        }

        stream << uri
               << " rdfs:subClassOf af:Signal ;" << endl
               << "    dc:title \"" << od.name.c_str() << "\" ;" << endl
               << "    dc:format \"" << od.unit.c_str() << "\" ;" << endl
               << "    dc:description \"" << od.description.c_str() << "\" ."
               << endl << endl;
    }
}

void
RDFFeatureWriter::writeSparseRDF(QTextStream *sptr,
                                 const Transform &transform,
                                 const Plugin::OutputDescriptor& od,
                                 const Plugin::FeatureList& featureList,
                                 PluginRDFDescription &desc,
                                 QString timelineURI)
{
//    SVDEBUG << "RDFFeatureWriter::writeSparseRDF: have " << featureList.size() << " features" << endl;

    if (featureList.empty()) return;
    QTextStream &stream = *sptr;
        
    bool plain = (m_plain || !desc.haveDescription());

    QString outputId = od.identifier.c_str();

    // iterate through FeatureLists
        
    for (int i = 0; i < (int)featureList.size(); ++i) {

        const Plugin::Feature &feature = featureList[i];
        unsigned long featureNumber = m_count++;

        stream << ":event_" << featureNumber << " a ";

        if (m_fixedEventTypeURI != "") {
            stream << m_fixedEventTypeURI << " ;\n";
        } else {
            QString eventTypeURI = desc.getOutputEventTypeURI(outputId);
            if (plain || eventTypeURI == "") {
                if (m_syntheticEventTypeURIs.find(transform) != 
                    m_syntheticEventTypeURIs.end()) {
                    stream << m_syntheticEventTypeURIs[transform] << " ;\n";
                } else {
                    stream << ":event_type_" << outputId << " ;\n";
                }
            } else {
                stream << "<" << eventTypeURI << "> ;\n";
            }
        }

        QString timestamp = feature.timestamp.toString().c_str();
        timestamp.replace(QRegExp("^ +"), "");

        if (feature.hasDuration && feature.duration > Vamp::RealTime::zeroTime) {

            QString duration = feature.duration.toString().c_str();
            duration.replace(QRegExp("^ +"), "");

            stream << "    event:time [ \n"
                   << "        a tl:Interval ;\n"
                   << "        tl:onTimeLine " << timelineURI << " ;\n"
                   << "        tl:beginsAt \"PT" << timestamp
                   << "S\"^^xsd:duration ;\n"
                   << "        tl:duration \"PT" << duration
                   << "S\"^^xsd:duration ;\n"
                   << "    ] ";

        } else {

            stream << "    event:time [ \n"
                   << "        a tl:Instant ;\n" //location of the event in time
                   << "        tl:onTimeLine " << timelineURI << " ;\n"
                   << "        tl:at \"PT" << timestamp
                   << "S\"^^xsd:duration ;\n    ] ";
        }

        if (transform.getIdentifier() != "") {
            stream << ";\n";
            stream << "    vamp:computed_by " << m_transformURIs[transform] << " ";
        }

        if (feature.label.length() > 0) {
            stream << ";\n";
            stream << "    rdfs:label \"\"\"" << feature.label.c_str() << "\"\"\" ";
        }

        if (!feature.values.empty()) {
            stream << ";\n";
            //!!! named bins?
            stream << "    af:feature \"" << feature.values[0];
            for (int j = 1; j < (int)feature.values.size(); ++j) {
                stream << " " << feature.values[j];
            }
            stream << "\" ";
        }

        stream << ".\n";
    }
}

void
RDFFeatureWriter::writeTrackLevelRDF(QTextStream *sptr,
                                     const Transform &,
                                     const Plugin::OutputDescriptor& od,
                                     const Plugin::FeatureList& featureList,
                                     PluginRDFDescription &desc,
                                     QString signalURI)
{
    if (featureList.empty()) return;
    QTextStream &stream = *sptr;
        
//    bool plain = (m_plain || !desc.haveDescription());

    QString outputId = od.identifier.c_str();
    QString featureUri = desc.getOutputFeatureAttributeURI(outputId);

    if (featureUri == "") {
        SVDEBUG << "RDFFeatureWriter::writeTrackLevelRDF: ERROR: No feature URI available -- this function should not have been called!" << endl;
        return;
    }

    for (int i = 0; i < (int)featureList.size(); ++i) {

        const Plugin::Feature &feature = featureList[i];

        if (feature.values.empty()) {

            if (feature.label == "") continue;

            stream << signalURI << " " << featureUri << " \"\"\""
                   << feature.label.c_str() << "\"\"\" .\n";

        } else {

            stream << signalURI << " " << featureUri << " \""
                   << feature.values[0] << "\"^^xsd:float .\n";
        }
    }
}

void
RDFFeatureWriter::writeDenseRDF(QTextStream *sptr,
                                const Transform &transform,
                                const Plugin::OutputDescriptor& od,
                                const Plugin::FeatureList& featureList,
                                PluginRDFDescription &desc,
                                QString signalURI, 
                                QString timelineURI)
{
    if (featureList.empty()) return;

    StringTransformPair sp(signalURI, transform);

    if (m_openDenseFeatures.find(sp) == m_openDenseFeatures.end()) {

        StreamBuffer b(sptr, "");
        m_openDenseFeatures[sp] = b;
        
        QString &str(m_openDenseFeatures[sp].second);
        QTextStream stream(&str);

        bool plain = (m_plain || !desc.haveDescription());
        QString outputId = od.identifier.c_str();

        unsigned long featureNumber = m_count++;

        // need to write out feature timeline map -- for this we need
        // the sample rate, window length and hop size from the
        // transform

        stream << "\n:feature_timeline_" << featureNumber << " a tl:DiscreteTimeLine .\n\n";

        sv_samplerate_t sampleRate;
        int stepSize, blockSize;

        // If the output is FixedSampleRate, we need to draw the
        // sample rate and step size from the output descriptor;
        // otherwise they come from the transform

        if (od.sampleType == Plugin::OutputDescriptor::FixedSampleRate) {

            sampleRate = od.sampleRate;
            stepSize = 1;
            blockSize = 1;

        } else {

            sampleRate = transform.getSampleRate();
            if (sampleRate == 0.f) {
                SVCERR << "RDFFeatureWriter: INTERNAL ERROR: writing dense features without having set the sample rate properly!" << endl;
                return;
            }

            stepSize = transform.getStepSize();
            if (stepSize == 0) {
                SVCERR << "RDFFeatureWriter: INTERNAL ERROR: writing dense features without having set the step size properly!" << endl;
                return;
            }

            blockSize = transform.getBlockSize();
            if (blockSize == 0) {
                SVCERR << "RDFFeatureWriter: INTERNAL ERROR: writing dense features without having set the block size properly!" << endl;
                return;
            }
        }

        stream << ":feature_timeline_map_" << featureNumber
               << " a tl:UniformSamplingWindowingMap ;\n"
               << "    tl:rangeTimeLine :feature_timeline_" << featureNumber << " ;\n"
               << "    tl:domainTimeLine " << timelineURI << " ;\n"
               << "    tl:sampleRate \"" << sampleRate << "\"^^xsd:float ;\n"
               << "    tl:windowLength \"" << blockSize << "\"^^xsd:int ;\n"
               << "    tl:hopSize \"" << stepSize << "\"^^xsd:int .\n\n";

        stream << signalURI << " af:signal_feature :feature_"
               << featureNumber << " ." << endl << endl;

        stream << ":feature_" << featureNumber << " a ";

        QString signalTypeURI = desc.getOutputSignalTypeURI(outputId);
        if (plain || signalTypeURI == "") {
            if (m_syntheticSignalTypeURIs.find(transform) !=
                m_syntheticSignalTypeURIs.end()) {
                stream << m_syntheticSignalTypeURIs[transform] << " ;\n";
            } else {
                stream << ":signal_type_" << outputId << " ;\n";
            }
        } else {
            stream << "<" << signalTypeURI << "> ;\n";
        }

        stream << "    mo:time ["
               << "\n        a tl:Interval ;"
               << "\n        tl:onTimeLine :feature_timeline_" << featureNumber << " ;";

        RealTime startrt = transform.getStartTime();
        RealTime durationrt = transform.getDuration();

        sv_frame_t start = RealTime::realTime2Frame
            (startrt, sampleRate) / stepSize;
        sv_frame_t duration = RealTime::realTime2Frame
            (durationrt, sampleRate) / stepSize;

        if (start != 0) {
            stream << "\n        tl:start \"" << start << "\"^^xsd:int ;";
        }
        if (duration != 0) {
            stream << "\n        tl:duration \"" << duration << "\"^^xsd:int ;";
        }

        stream << "\n    ] ;\n";

        if (transform.getIdentifier() != "") {
            stream << "    vamp:computed_by " << m_transformURIs[transform] << " ;\n";
        }

        if (od.hasFixedBinCount) {
            // We only know the height, so write the width as zero
            stream << "    af:dimensions \"" << od.binCount << " 0\" ;\n";
        }

        stream << "    af:value \"";
    }

    QString &str = m_openDenseFeatures[sp].second;
    QTextStream stream(&str);

    for (int i = 0; i < (int)featureList.size(); ++i) {

        const Plugin::Feature &feature = featureList[i];

        for (int j = 0; j < (int)feature.values.size(); ++j) {
            stream << feature.values[j] << " ";
        }
    }
}

void RDFFeatureWriter::finish()
{
//    SVDEBUG << "RDFFeatureWriter::finish()" << endl;

    // close any open dense feature literals

    for (map<StringTransformPair, StreamBuffer>::iterator i =
             m_openDenseFeatures.begin();
         i != m_openDenseFeatures.end(); ++i) {
//        SVDEBUG << "closing a stream" << endl;
        StreamBuffer &b = i->second;
        *(b.first) << b.second << "\" ." << endl;
    }

    m_openDenseFeatures.clear();
    m_startedStreamTransforms.clear();

    FileFeatureWriter::finish();
}