# HG changeset patch
# User Chris Cannam
# Date 1589375458 -3600
# Node ID 4c91c95e146a782f854a44429f8bfcc145d01350
# Parent  da57ab54f0e8c7aaddfdc22f83249abadf0ccb21# Parent  83ae68de440101d8cd9c8b24fb571c458cec5281
Merge

diff -r 83ae68de4401 -r 4c91c95e146a align/Align.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/align/Align.cpp	Wed May 13 14:10:58 2020 +0100
@@ -0,0 +1,143 @@
+/* -*- 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.
+    Centre for Digital Music, Queen Mary, University of London.
+    
+    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 "Align.h"
+#include "TransformAligner.h"
+#include "ExternalProgramAligner.h"
+#include "framework/Document.h"
+
+#include <QSettings>
+#include <QTimer>
+
+void
+Align::alignModel(Document *doc,
+                  ModelId reference,
+                  ModelId toAlign)
+{
+    addAligner(doc, reference, toAlign);
+    m_aligners[toAlign]->begin();
+}
+
+void
+Align::scheduleAlignment(Document *doc,
+                         ModelId reference,
+                         ModelId toAlign)
+{
+    addAligner(doc, reference, toAlign);
+    int delay = 500 + 500 * int(m_aligners.size());
+    if (delay > 3500) {
+        delay = 3500;
+    }
+    SVCERR << "Align::scheduleAlignment: delaying " << delay << "ms" << endl;
+    QTimer::singleShot(delay, m_aligners[toAlign].get(), SLOT(begin()));
+}
+
+void
+Align::addAligner(Document *doc,
+                  ModelId reference,
+                  ModelId toAlign)
+{
+    bool useProgram;
+    QString program;
+    getAlignerPreference(useProgram, program);
+    
+    std::shared_ptr<Aligner> aligner;
+
+    {
+        // Replace the aligner with a new one. This also stops any
+        // previously-running alignment, when the old entry is
+        // replaced and its aligner destroyed.
+        
+        QMutexLocker locker(&m_mutex);
+    
+        if (useProgram && (program != "")) {
+            m_aligners[toAlign] =
+                std::make_shared<ExternalProgramAligner>(doc,
+                                                         reference,
+                                                         toAlign,
+                                                         program);
+        } else {
+            m_aligners[toAlign] =
+                std::make_shared<TransformAligner>(doc,
+                                                   reference,
+                                                   toAlign);
+        }
+
+        aligner = m_aligners[toAlign];
+    }
+
+    connect(aligner.get(), SIGNAL(complete(ModelId)),
+            this, SLOT(alignerComplete(ModelId)));
+
+    connect(aligner.get(), SIGNAL(failed(ModelId, QString)),
+            this, SLOT(alignerFailed(ModelId, QString)));
+}
+
+void
+Align::getAlignerPreference(bool &useProgram, QString &program)
+{
+    QSettings settings;
+    settings.beginGroup("Preferences");
+    useProgram = settings.value("use-external-alignment", false).toBool();
+    program = settings.value("external-alignment-program", "").toString();
+    settings.endGroup();
+}
+
+bool
+Align::canAlign() 
+{
+    bool useProgram;
+    QString program;
+    getAlignerPreference(useProgram, program);
+
+    if (useProgram) {
+        return ExternalProgramAligner::isAvailable(program);
+    } else {
+        return TransformAligner::isAvailable();
+    }
+}
+
+void
+Align::alignerComplete(ModelId alignmentModel)
+{
+    removeAligner(sender());
+    emit alignmentComplete(alignmentModel);
+}
+
+void
+Align::alignerFailed(ModelId toAlign, QString error)
+{
+    removeAligner(sender());
+    emit alignmentFailed(toAlign, error);
+}
+
+void
+Align::removeAligner(QObject *obj)
+{
+    Aligner *aligner = qobject_cast<Aligner *>(obj);
+    if (!aligner) {
+        SVCERR << "ERROR: Align::removeAligner: Not an Aligner" << endl;
+        return;
+    }
+
+    QMutexLocker locker (&m_mutex);
+
+    for (auto p: m_aligners) {
+        if (aligner == p.second.get()) {
+            m_aligners.erase(p.first);
+            break;
+        }
+    }
+}
+
diff -r 83ae68de4401 -r 4c91c95e146a align/Align.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/align/Align.h	Wed May 13 14:10:58 2020 +0100
@@ -0,0 +1,121 @@
+/* -*- 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.
+    Centre for Digital Music, Queen Mary, University of London.
+    
+    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 SV_ALIGN_H
+#define SV_ALIGN_H
+
+#include <QString>
+#include <QObject>
+#include <QProcess>
+#include <QMutex>
+#include <set>
+
+#include "Aligner.h"
+
+class AlignmentModel;
+class Document;
+
+class Align : public QObject
+{
+    Q_OBJECT
+    
+public:
+    Align() { }
+
+    /**
+     * Align the "other" model to the reference, attaching an
+     * AlignmentModel to it. Alignment is carried out by the method
+     * configured in the user preferences (either a plugin transform
+     * or an external process) and is done asynchronously. 
+     *
+     * Any errors are reported by firing the alignmentFailed
+     * signal. Note that the signal may be fired during the call to
+     * this function, if the aligner fails to start at all.
+     *
+     * If alignment starts successfully, then an AlignmentModel has
+     * been constructed and attached to the toAlign model, and you can
+     * query that model to discover the alignment progress, eventual
+     * outcome, and also (separately from the alignmentFailed signal
+     * here) any error message generated during alignment.
+     *
+     * A single Align object may carry out many simultanous alignment
+     * calls -- you do not need to create a new Align object each
+     * time, nor to wait for an alignment to be complete before
+     * starting a new one.
+     * 
+     * The Align object must survive after this call, for at least as
+     * long as the alignment takes. The usual expectation is that the
+     * Align object will simply share the process or document
+     * lifespan.
+     */
+    void alignModel(Document *doc,
+                    ModelId reference,
+                    ModelId toAlign);
+
+    /**
+     * As alignModel, except that the alignment does not begin
+     * immediately, but is instead placed behind an event callback
+     * with a small delay. Useful to avoid an unresponsive GUI when
+     * firing off alignments while doing something else as well. Any
+     * error is reported by firing the alignmentFailed signal.
+     *
+     * Scheduled alignments are not queued or serialised - many could
+     * happen at once. They are just delayed a little for UI
+     * responsiveness.
+     */
+    void scheduleAlignment(Document *doc,
+                           ModelId reference,
+                           ModelId toAlign);
+    
+    /**
+     * Return true if the alignment facility is available (relevant
+     * plugin installed, etc).
+     */
+    static bool canAlign();
+
+signals:
+    /**
+     * Emitted when an alignment is successfully completed. The
+     * reference and other models can be queried from the alignment
+     * model.
+     */
+    void alignmentComplete(ModelId alignmentModel); // an AlignmentModel
+
+    /**
+     * Emitted when an alignment fails. The model is the toAlign model
+     * that was passed to the call to alignModel or scheduleAlignment.
+     */
+    void alignmentFailed(ModelId toAlign, QString errorText);
+
+private slots:
+    void alignerComplete(ModelId alignmentModel); // an AlignmentModel
+    void alignerFailed(ModelId toAlign, QString errorText);
+    
+private:
+    QMutex m_mutex;
+
+    // maps toAlign -> aligner for ongoing alignment - note that
+    // although we can calculate alignments with different references,
+    // we can only have one alignment on any given toAlign model, so
+    // we don't key this on the whole (reference, toAlign) pair
+    std::map<ModelId, std::shared_ptr<Aligner>> m_aligners;
+
+    void addAligner(Document *doc, ModelId reference, ModelId toAlign);
+    void removeAligner(QObject *);
+
+    static void getAlignerPreference(bool &useProgram, QString &program);
+};
+
+#endif
+
diff -r 83ae68de4401 -r 4c91c95e146a align/Aligner.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/align/Aligner.h	Wed May 13 14:10:58 2020 +0100
@@ -0,0 +1,45 @@
+/* -*- 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.
+    Centre for Digital Music, Queen Mary, University of London.
+    
+    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 SV_ALIGNER_H
+#define SV_ALIGNER_H
+
+#include <QString>
+
+#include "data/model/Model.h"
+
+class Aligner : public QObject
+{
+    Q_OBJECT
+
+public:
+    virtual ~Aligner() { }
+
+public slots:
+    virtual void begin() = 0;
+
+signals:
+    /**
+     * Emitted when alignment is successfully completed. The reference
+     * and toAlign models can be queried from the alignment model.
+     */
+    void complete(ModelId alignmentModel); // an AlignmentModel
+
+    /**
+     * Emitted when alignment fails.
+     */
+    void failed(ModelId toAlign, QString errorText); // the toAlign model
+};
+
+#endif
diff -r 83ae68de4401 -r 4c91c95e146a align/DTW.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/align/DTW.h	Wed May 13 14:10:58 2020 +0100
@@ -0,0 +1,192 @@
+/* -*- 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.
+    Centre for Digital Music, Queen Mary, University of London.
+    
+    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 SV_DTW_H
+#define SV_DTW_H
+
+#include <vector>
+#include <functional>
+
+template <typename Value>
+class DTW
+{
+public:
+    DTW(std::function<double(const Value &, const Value &)> distanceMetric) :
+        m_metric(distanceMetric) { }
+
+    std::vector<size_t> alignSeries(std::vector<Value> s1,
+                                    std::vector<Value> s2) {
+
+        // Return the index into s2 for each element in s1
+        
+        std::vector<size_t> alignment(s1.size(), 0);
+
+        if (s1.empty() || s2.empty()) {
+            return alignment;
+        }
+
+        auto costs = costSeries(s1, s2);
+
+        size_t j = s1.size() - 1;
+        size_t i = s2.size() - 1;
+
+        while (j > 0 && i > 0) {
+
+            alignment[j] = i;
+            
+            cost_t a = costs[j-1][i];
+            cost_t b = costs[j][i-1];
+            cost_t both = costs[j-1][i-1];
+
+            if (a < b) {
+                --j;
+                if (both < a) {
+                    --i;
+                }
+            } else {
+                --i;
+                if (both < b) {
+                    --j;
+                }
+            }
+        }
+
+        return alignment;
+    }
+
+private:
+    std::function<double(const Value &, const Value &)> m_metric;
+    
+    typedef double cost_t;
+
+    struct CostOption {
+        bool present;
+        cost_t cost;
+    };
+
+    cost_t choose(CostOption x, CostOption y, CostOption d) {
+        if (x.present && y.present) {
+            if (!d.present) {
+                throw std::logic_error("if x & y both exist, so must diagonal");
+            }
+            return std::min(std::min(x.cost, y.cost), d.cost);
+        } else if (x.present) {
+            return x.cost;
+        } else if (y.present) {
+            return y.cost;
+        } else {
+            return 0.0;
+        }
+    }
+
+    std::vector<std::vector<cost_t>> costSeries(std::vector<Value> s1,
+                                                std::vector<Value> s2) {
+
+        std::vector<std::vector<cost_t>> costs
+            (s1.size(), std::vector<cost_t>(s2.size(), 0.0));
+
+        for (size_t j = 0; j < s1.size(); ++j) {
+            for (size_t i = 0; i < s2.size(); ++i) {
+                cost_t c = m_metric(s1[j], s2[i]);
+                costs[j][i] = choose
+                    (
+                        { j > 0,
+                          j > 0 ? c + costs[j-1][i] : 0.0
+                        },
+                        { i > 0,
+                          i > 0 ? c + costs[j][i-1] : 0.0
+                        },
+                        { j > 0 && i > 0,
+                          j > 0 && i > 0 ? c + costs[j-1][i-1] : 0.0
+                        });
+            }
+        }
+
+        return costs;
+    }
+};
+
+class MagnitudeDTW
+{
+public:
+    MagnitudeDTW() : m_dtw(metric) { }
+
+    std::vector<size_t> alignSeries(std::vector<double> s1,
+                                    std::vector<double> s2) {
+        return m_dtw.alignSeries(s1, s2);
+    }
+
+private:
+    DTW<double> m_dtw;
+
+    static double metric(const double &a, const double &b) {
+        return std::abs(b - a);
+    }
+};
+
+class RiseFallDTW
+{
+public:
+    enum class Direction {
+        None,
+        Up,
+        Down
+    };
+    
+    struct Value {
+        Direction direction;
+        double distance;
+    };
+
+    RiseFallDTW() : m_dtw(metric) { }
+
+    std::vector<size_t> alignSeries(std::vector<Value> s1,
+                                    std::vector<Value> s2) {
+        return m_dtw.alignSeries(s1, s2);
+    }
+
+private:
+    DTW<Value> m_dtw;
+
+    static double metric(const Value &a, const Value &b) {
+        
+        auto together = [](double c1, double c2) {
+                            auto diff = std::abs(c1 - c2);
+                            return (diff < 1.0 ? -1.0 :
+                                    diff > 3.0 ?  1.0 :
+                                    0.0);
+                        };
+        auto opposing = [](double c1, double c2) {
+                            auto diff = c1 + c2;
+                            return (diff < 2.0 ? 1.0 :
+                                    2.0);
+                        };
+
+        if (a.direction == Direction::None || b.direction == Direction::None) {
+            if (a.direction == b.direction) {
+                return 0.0;
+            } else {
+                return 1.0;
+            }
+        } else {
+            if (a.direction == b.direction) {
+                return together (a.distance, b.distance);
+            } else {
+                return opposing (a.distance, b.distance);
+            }
+        }
+    }
+};
+
+#endif
diff -r 83ae68de4401 -r 4c91c95e146a align/ExternalProgramAligner.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/align/ExternalProgramAligner.cpp	Wed May 13 14:10:58 2020 +0100
@@ -0,0 +1,231 @@
+/* -*- 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.
+    Centre for Digital Music, Queen Mary, University of London.
+    
+    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 "ExternalProgramAligner.h"
+
+#include <QFileInfo>
+#include <QApplication>
+
+#include "data/model/ReadOnlyWaveFileModel.h"
+#include "data/model/SparseTimeValueModel.h"
+#include "data/model/AlignmentModel.h"
+
+#include "data/fileio/CSVFileReader.h"
+
+#include "framework/Document.h"
+
+ExternalProgramAligner::ExternalProgramAligner(Document *doc,
+                                               ModelId reference,
+                                               ModelId toAlign,
+                                               QString program) :
+    m_document(doc),
+    m_reference(reference),
+    m_toAlign(toAlign),
+    m_program(program),
+    m_process(nullptr)
+{
+}
+
+ExternalProgramAligner::~ExternalProgramAligner()
+{
+    delete m_process;
+}
+
+bool
+ExternalProgramAligner::isAvailable(QString program)
+{
+    QFileInfo file(program);
+    return file.exists() && file.isExecutable();
+}
+
+void
+ExternalProgramAligner::begin()
+{
+    // Run an external program, passing to it paths to the main
+    // model's audio file and the new model's audio file. It returns
+    // the path in CSV form through stdout.
+
+    auto reference = ModelById::getAs<ReadOnlyWaveFileModel>(m_reference);
+    auto other = ModelById::getAs<ReadOnlyWaveFileModel>(m_toAlign);
+    if (!reference || !other) {
+        SVCERR << "ERROR: ExternalProgramAligner: Can't align non-read-only models via program (no local filename available)" << endl;
+        return;
+    }
+
+    while (!reference->isReady(nullptr) || !other->isReady(nullptr)) {
+        qApp->processEvents();
+    }
+    
+    QString refPath = reference->getLocalFilename();
+    if (refPath == "") {
+        refPath = FileSource(reference->getLocation()).getLocalFilename();
+    }
+    
+    QString otherPath = other->getLocalFilename();
+    if (otherPath == "") {
+        otherPath = FileSource(other->getLocation()).getLocalFilename();
+    }
+
+    if (refPath == "" || otherPath == "") {
+        emit failed(m_toAlign,
+                    tr("Failed to find local filepath for wave-file model"));
+        return;
+    }
+
+    auto alignmentModel =
+        std::make_shared<AlignmentModel>(m_reference, m_toAlign, ModelId());
+
+    m_alignmentModel = ModelById::add(alignmentModel);
+    other->setAlignment(m_alignmentModel);
+
+    m_process = new QProcess;
+    m_process->setProcessChannelMode(QProcess::ForwardedErrorChannel);
+
+    connect(m_process,
+            SIGNAL(finished(int, QProcess::ExitStatus)),
+            this,
+            SLOT(programFinished(int, QProcess::ExitStatus)));
+
+    QStringList args;
+    args << refPath << otherPath;
+
+    SVCERR << "ExternalProgramAligner: Starting program \""
+           << m_program << "\" with args: ";
+    for (auto a: args) {
+        SVCERR << "\"" << a << "\" ";
+    }
+    SVCERR << endl;
+
+    m_process->start(m_program, args);
+
+    bool success = m_process->waitForStarted();
+
+    if (!success) {
+        
+        SVCERR << "ERROR: ExternalProgramAligner: Program did not start" << endl;
+        emit failed(m_toAlign,
+                    tr("Alignment program \"%1\" did not start")
+                    .arg(m_program));
+        
+        other->setAlignment({});
+        ModelById::release(m_alignmentModel);
+        delete m_process;
+        m_process = nullptr;
+        
+    } else {
+        m_document->addNonDerivedModel(m_alignmentModel);
+    }
+}
+
+void
+ExternalProgramAligner::programFinished(int  exitCode, QProcess::ExitStatus status)
+{
+    SVCERR << "ExternalProgramAligner::programFinished" << endl;
+    
+    QProcess *process = qobject_cast<QProcess *>(sender());
+
+    if (process != m_process) {
+        SVCERR << "ERROR: ExternalProgramAligner: Emitting process " << process
+               << " is not my process!" << endl;
+        return;
+    }
+
+    auto alignmentModel = ModelById::getAs<AlignmentModel>(m_alignmentModel);
+    if (!alignmentModel) {
+        SVCERR << "ExternalProgramAligner: AlignmentModel no longer exists"
+               << endl;
+        return;
+    }
+    
+    if (exitCode == 0 && status == 0) {
+
+        CSVFormat format;
+        format.setModelType(CSVFormat::TwoDimensionalModel);
+        format.setTimingType(CSVFormat::ExplicitTiming);
+        format.setTimeUnits(CSVFormat::TimeSeconds);
+        format.setColumnCount(2);
+        // The output format has time in the reference file first, and
+        // time in the "other" file in the second column. This is a
+        // more natural approach for a command-line alignment tool,
+        // but it's the opposite of what we expect for native
+        // alignment paths, which map from "other" file to
+        // reference. These column purpose settings reflect that.
+        format.setColumnPurpose(1, CSVFormat::ColumnStartTime);
+        format.setColumnPurpose(0, CSVFormat::ColumnValue);
+        format.setAllowQuoting(false);
+        format.setSeparator(',');
+
+        CSVFileReader reader(process, format, alignmentModel->getSampleRate());
+        if (!reader.isOK()) {
+            SVCERR << "ERROR: ExternalProgramAligner: Failed to parse output"
+                   << endl;
+            QString error = tr("Failed to parse output of program: %1")
+                .arg(reader.getError());
+            alignmentModel->setError(error);
+            emit failed(m_toAlign, error);
+            goto done;
+        }
+
+        //!!! to use ById?
+        
+        Model *csvOutput = reader.load();
+
+        SparseTimeValueModel *path =
+            qobject_cast<SparseTimeValueModel *>(csvOutput);
+        if (!path) {
+            SVCERR << "ERROR: ExternalProgramAligner: Output did not convert to sparse time-value model"
+                   << endl;
+            QString error =
+                tr("Output of alignment program was not in the proper format");
+            alignmentModel->setError(error);
+            delete csvOutput;
+            emit failed(m_toAlign, error);
+            goto done;
+        }
+                       
+        if (path->isEmpty()) {
+            SVCERR << "ERROR: ExternalProgramAligner: Output contained no mappings"
+                   << endl;
+            QString error = 
+                tr("Output of alignment program contained no mappings");
+            alignmentModel->setError(error);
+            delete path;
+            emit failed(m_toAlign, error);
+            goto done;
+        }
+
+        SVCERR << "ExternalProgramAligner: Setting alignment path ("
+             << path->getEventCount() << " point(s))" << endl;
+
+        auto pathId =
+            ModelById::add(std::shared_ptr<SparseTimeValueModel>(path));
+        alignmentModel->setPathFrom(pathId);
+
+        emit complete(m_alignmentModel);
+
+        ModelById::release(pathId);
+        
+    } else {
+        SVCERR << "ERROR: ExternalProgramAligner: Aligner program "
+               << "failed: exit code " << exitCode << ", status " << status
+               << endl;
+        QString error = tr("Aligner process returned non-zero exit status");
+        alignmentModel->setError(error);
+        emit failed(m_toAlign, error);
+    }
+
+done:
+    delete m_process;
+    m_process = nullptr;
+}
diff -r 83ae68de4401 -r 4c91c95e146a align/ExternalProgramAligner.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/align/ExternalProgramAligner.h	Wed May 13 14:10:58 2020 +0100
@@ -0,0 +1,55 @@
+/* -*- 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.
+    Centre for Digital Music, Queen Mary, University of London.
+    
+    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 SV_EXTERNAL_PROGRAM_ALIGNER_H
+#define SV_EXTERNAL_PROGRAM_ALIGNER_H
+
+#include "Aligner.h"
+
+#include <QProcess>
+#include <QString>
+
+class AlignmentModel;
+class Document;
+
+class ExternalProgramAligner : public Aligner
+{
+    Q_OBJECT
+
+public:
+    ExternalProgramAligner(Document *doc,
+                           ModelId reference,
+                           ModelId toAlign,
+                           QString program);
+
+    // Destroy the aligner, cleanly cancelling any ongoing alignment
+    ~ExternalProgramAligner();
+
+    void begin() override;
+
+    static bool isAvailable(QString program);
+
+private slots:
+    void programFinished(int, QProcess::ExitStatus);
+
+private:
+    Document *m_document;
+    ModelId m_reference;
+    ModelId m_toAlign;
+    ModelId m_alignmentModel;
+    QString m_program;
+    QProcess *m_process;
+};
+
+#endif
diff -r 83ae68de4401 -r 4c91c95e146a align/TransformAligner.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/align/TransformAligner.cpp	Wed May 13 14:10:58 2020 +0100
@@ -0,0 +1,404 @@
+/* -*- 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.
+    Centre for Digital Music, Queen Mary, University of London.
+    
+    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 "TransformAligner.h"
+
+#include "data/model/SparseTimeValueModel.h"
+#include "data/model/RangeSummarisableTimeValueModel.h"
+#include "data/model/AlignmentModel.h"
+#include "data/model/AggregateWaveModel.h"
+
+#include "framework/Document.h"
+
+#include "transform/TransformFactory.h"
+#include "transform/ModelTransformerFactory.h"
+#include "transform/FeatureExtractionModelTransformer.h"
+
+#include <QSettings>
+
+TransformAligner::TransformAligner(Document *doc,
+                                   ModelId reference,
+                                   ModelId toAlign) :
+    m_document(doc),
+    m_reference(reference),
+    m_toAlign(toAlign),
+    m_tuningFrequency(440.f),
+    m_incomplete(true)
+{
+}
+
+TransformAligner::~TransformAligner()
+{
+    if (m_incomplete) {
+        auto other =
+            ModelById::getAs<RangeSummarisableTimeValueModel>(m_toAlign);
+        if (other) {
+            other->setAlignment({});
+        }
+    }
+
+    ModelById::release(m_tuningDiffProgressModel);
+    ModelById::release(m_tuningDiffOutputModel);
+    ModelById::release(m_pathOutputModel);
+}
+
+QString
+TransformAligner::getAlignmentTransformName()
+{
+    QSettings settings;
+    settings.beginGroup("Alignment");
+    TransformId id =
+        settings.value("transform-id",
+                       "vamp:match-vamp-plugin:match:path").toString();
+    settings.endGroup();
+    return id;
+}
+
+QString
+TransformAligner::getTuningDifferenceTransformName()
+{
+    QSettings settings;
+    settings.beginGroup("Alignment");
+    bool performPitchCompensation =
+        settings.value("align-pitch-aware", false).toBool();
+    QString id = "";
+    if (performPitchCompensation) {
+        id = settings.value
+            ("tuning-difference-transform-id",
+             "vamp:tuning-difference:tuning-difference:tuningfreq")
+            .toString();
+    }
+    settings.endGroup();
+    return id;
+}
+
+bool
+TransformAligner::isAvailable()
+{
+    TransformFactory *factory = TransformFactory::getInstance();
+    TransformId id = getAlignmentTransformName();
+    TransformId tdId = getTuningDifferenceTransformName();
+    return factory->haveTransform(id) &&
+        (tdId == "" || factory->haveTransform(tdId));
+}
+
+void
+TransformAligner::begin()
+{
+    auto reference =
+        ModelById::getAs<RangeSummarisableTimeValueModel>(m_reference);
+    auto other =
+        ModelById::getAs<RangeSummarisableTimeValueModel>(m_toAlign);
+
+    if (!reference || !other) return;
+
+    // This involves creating a number of new models:
+    //
+    // 1. an AggregateWaveModel to provide the mixdowns of the main
+    // model and the new model in its two channels, as input to the
+    // MATCH plugin. We just call this one aggregateModel
+    //
+    // 2a. a SparseTimeValueModel which will be automatically created
+    // by FeatureExtractionModelTransformer when running the
+    // TuningDifference plugin to receive the relative tuning of the
+    // second model (if pitch-aware alignment is enabled in the
+    // preferences). This is m_tuningDiffOutputModel.
+    //
+    // 2b. a SparseTimeValueModel which will be automatically created
+    // by FeatureExtractionPluginTransformer when running the MATCH
+    // plugin to perform alignment (so containing the alignment path).
+    // This is m_pathOutputModel.
+    //
+    // 2c. a SparseTimeValueModel used solely to provide faked
+    // completion information to the AlignmentModel while a
+    // TuningDifference calculation is going on. We call this
+    // m_tuningDiffProgressModel.
+    //
+    // 3. an AlignmentModel, which stores the path and carries out
+    // alignment lookups on it. This one is m_alignmentModel.
+    //
+    // Models 1 and 3 are registered with the document, which will
+    // eventually release them. We don't release them here except in
+    // the case where an activity fails before the point where we
+    // would otherwise have registered them with the document.
+    //
+    // Models 2a (m_tuningDiffOutputModel), 2b (m_pathOutputModel) and
+    // 2c (m_tuningDiffProgressModel) are not registered with the
+    // document, because they are not intended to persist, and also
+    // Model 2c (m_tuningDiffProgressModel) is a bodge that we are
+    // embarrassed about, so we try to manage it ourselves without
+    // anyone else noticing. These have to be released by us when
+    // finished with, but their lifespans do not extend beyond the end
+    // of the alignment procedure, so this should be ok.
+
+    AggregateWaveModel::ChannelSpecList components;
+    components.push_back
+        (AggregateWaveModel::ModelChannelSpec(m_reference, -1));
+
+    components.push_back
+        (AggregateWaveModel::ModelChannelSpec(m_toAlign, -1));
+
+    auto aggregateModel = std::make_shared<AggregateWaveModel>(components);
+    m_aggregateModel = ModelById::add(aggregateModel);
+    m_document->addNonDerivedModel(m_aggregateModel);
+
+    auto alignmentModel = std::make_shared<AlignmentModel>
+        (m_reference, m_toAlign, ModelId());
+    m_alignmentModel = ModelById::add(alignmentModel);
+
+    TransformId tdId = getTuningDifferenceTransformName();
+
+    if (tdId == "") {
+        
+        if (beginAlignmentPhase()) {
+            other->setAlignment(m_alignmentModel);
+            m_document->addNonDerivedModel(m_alignmentModel);
+        } else {
+            QString error = alignmentModel->getError();
+            ModelById::release(alignmentModel);
+            emit failed(m_toAlign, error);
+            return;
+        }
+
+    } else {
+
+        // Have a tuning-difference transform id, so run it
+        // asynchronously first
+        
+        TransformFactory *tf = TransformFactory::getInstance();
+
+        Transform transform = tf->getDefaultTransformFor
+            (tdId, aggregateModel->getSampleRate());
+
+        transform.setParameter("maxduration", 60);
+        transform.setParameter("maxrange", 6);
+        transform.setParameter("finetuning", false);
+    
+        SVDEBUG << "TransformAligner: Tuning difference transform step size " << transform.getStepSize() << ", block size " << transform.getBlockSize() << endl;
+
+        ModelTransformerFactory *mtf = ModelTransformerFactory::getInstance();
+
+        QString message;
+        m_tuningDiffOutputModel = mtf->transform(transform,
+                                                 m_aggregateModel,
+                                                 message);
+
+        auto tuningDiffOutputModel =
+            ModelById::getAs<SparseTimeValueModel>(m_tuningDiffOutputModel);
+        if (!tuningDiffOutputModel) {
+            SVCERR << "Align::alignModel: ERROR: Failed to create tuning-difference output model (no Tuning Difference plugin?)" << endl;
+            ModelById::release(alignmentModel);
+            emit failed(m_toAlign, message);
+            return;
+        }
+
+        other->setAlignment(m_alignmentModel);
+        m_document->addNonDerivedModel(m_alignmentModel);
+    
+        connect(tuningDiffOutputModel.get(),
+                SIGNAL(completionChanged(ModelId)),
+                this, SLOT(tuningDifferenceCompletionChanged(ModelId)));
+
+        // This model exists only so that the AlignmentModel can get a
+        // completion value from somewhere while the tuning difference
+        // calculation is going on
+        auto progressModel = std::make_shared<SparseTimeValueModel>
+            (aggregateModel->getSampleRate(), 1);
+        m_tuningDiffProgressModel = ModelById::add(progressModel);
+        progressModel->setCompletion(0);
+        alignmentModel->setPathFrom(m_tuningDiffProgressModel);
+    }
+}
+
+void
+TransformAligner::tuningDifferenceCompletionChanged(ModelId tuningDiffOutputModelId)
+{
+    if (m_tuningDiffOutputModel.isNone()) {
+        // we're done, this is probably a spurious queued event
+        return;
+    }
+        
+    if (tuningDiffOutputModelId != m_tuningDiffOutputModel) {
+        SVCERR << "WARNING: TransformAligner::tuningDifferenceCompletionChanged: Model "
+               << tuningDiffOutputModelId
+               << " is not ours! (ours is "
+               << m_tuningDiffOutputModel << ")" << endl;
+        return;
+    }
+
+    auto tuningDiffOutputModel =
+        ModelById::getAs<SparseTimeValueModel>(m_tuningDiffOutputModel);
+    if (!tuningDiffOutputModel) {
+        SVCERR << "WARNING: TransformAligner::tuningDifferenceCompletionChanged: Model "
+               << tuningDiffOutputModelId
+               << " not known as SparseTimeValueModel" << endl;
+        return;
+    }
+
+    auto alignmentModel = ModelById::getAs<AlignmentModel>(m_alignmentModel);
+    if (!alignmentModel) {
+        SVCERR << "WARNING: TransformAligner::tuningDifferenceCompletionChanged:"
+               << "alignment model has disappeared" << endl;
+        return;
+    }
+    
+    int completion = 0;
+    bool done = tuningDiffOutputModel->isReady(&completion);
+
+    SVDEBUG << "TransformAligner::tuningDifferenceCompletionChanged: model "
+            << m_tuningDiffOutputModel << ", completion = " << completion
+            << ", done = " << done << endl;
+    
+    if (!done) {
+        // This will be the completion the alignment model reports,
+        // before the alignment actually begins. It goes up from 0 to
+        // 99 (not 100!) and then back to 0 again when we start
+        // calculating the actual path in the following phase
+        int clamped = (completion == 100 ? 99 : completion);
+        auto progressModel =
+            ModelById::getAs<SparseTimeValueModel>(m_tuningDiffProgressModel);
+        if (progressModel) {
+            progressModel->setCompletion(clamped);
+        }
+        return;
+    }
+
+    m_tuningFrequency = 440.f;
+    
+    if (!tuningDiffOutputModel->isEmpty()) {
+        m_tuningFrequency = tuningDiffOutputModel->getAllEvents()[0].getValue();
+        SVCERR << "TransformAligner::tuningDifferenceCompletionChanged: Reported tuning frequency = " << m_tuningFrequency << endl;
+    } else {
+        SVCERR << "TransformAligner::tuningDifferenceCompletionChanged: No tuning frequency reported" << endl;
+    }    
+    
+    ModelById::release(tuningDiffOutputModel);
+    m_tuningDiffOutputModel = {};
+    
+    alignmentModel->setPathFrom({}); // replace m_tuningDiffProgressModel
+    ModelById::release(m_tuningDiffProgressModel);
+    m_tuningDiffProgressModel = {};
+
+    beginAlignmentPhase();
+}
+
+bool
+TransformAligner::beginAlignmentPhase()
+{
+    TransformId id = getAlignmentTransformName();
+    
+    SVDEBUG << "TransformAligner::beginAlignmentPhase: transform is "
+            << id << endl;
+    
+    TransformFactory *tf = TransformFactory::getInstance();
+
+    auto aggregateModel =
+        ModelById::getAs<AggregateWaveModel>(m_aggregateModel);
+    auto alignmentModel =
+        ModelById::getAs<AlignmentModel>(m_alignmentModel);
+
+    if (!aggregateModel || !alignmentModel) {
+        SVCERR << "TransformAligner::alignModel: ERROR: One or other of the aggregate & alignment models has disappeared" << endl;
+        return false;
+    }
+    
+    Transform transform = tf->getDefaultTransformFor
+        (id, aggregateModel->getSampleRate());
+
+    transform.setStepSize(transform.getBlockSize()/2);
+    transform.setParameter("serialise", 1);
+    transform.setParameter("smooth", 0);
+    transform.setParameter("zonewidth", 40);
+    transform.setParameter("noise", true);
+    transform.setParameter("minfreq", 500);
+
+    int cents = 0;
+    
+    if (m_tuningFrequency != 0.f) {
+        transform.setParameter("freq2", m_tuningFrequency);
+
+        double centsOffset = 0.f;
+        int pitch = Pitch::getPitchForFrequency(m_tuningFrequency,
+                                                &centsOffset);
+        cents = int(round((pitch - 69) * 100 + centsOffset));
+        SVCERR << "TransformAligner: frequency " << m_tuningFrequency
+               << " yields cents offset " << centsOffset
+               << " and pitch " << pitch << " -> cents " << cents << endl;
+    }
+
+    alignmentModel->setRelativePitch(cents);
+    
+    SVDEBUG << "TransformAligner: Alignment transform step size "
+            << transform.getStepSize() << ", block size "
+            << transform.getBlockSize() << endl;
+
+    ModelTransformerFactory *mtf = ModelTransformerFactory::getInstance();
+
+    QString message;
+    m_pathOutputModel = mtf->transform
+        (transform, m_aggregateModel, message);
+
+    if (m_pathOutputModel.isNone()) {
+        transform.setStepSize(0);
+        m_pathOutputModel = mtf->transform
+            (transform, m_aggregateModel, message);
+    }
+
+    auto pathOutputModel =
+        ModelById::getAs<SparseTimeValueModel>(m_pathOutputModel);
+
+    //!!! callers will need to be updated to get error from
+    //!!! alignment model after initial call
+        
+    if (!pathOutputModel) {
+        SVCERR << "TransformAligner: ERROR: Failed to create alignment path (no MATCH plugin?)" << endl;
+        alignmentModel->setError(message);
+        return false;
+    }
+
+    pathOutputModel->setCompletion(0);
+    alignmentModel->setPathFrom(m_pathOutputModel);
+
+    connect(alignmentModel.get(), SIGNAL(completionChanged(ModelId)),
+            this, SLOT(alignmentCompletionChanged(ModelId)));
+
+    return true;
+}
+
+void
+TransformAligner::alignmentCompletionChanged(ModelId alignmentModelId)
+{
+    if (alignmentModelId != m_alignmentModel) {
+        SVCERR << "WARNING: TransformAligner::alignmentCompletionChanged: Model "
+               << alignmentModelId
+               << " is not ours! (ours is "
+               << m_alignmentModel << ")" << endl;
+        return;
+    }
+
+    auto alignmentModel = ModelById::getAs<AlignmentModel>(m_alignmentModel);
+
+    if (alignmentModel && alignmentModel->isReady()) {
+
+        m_incomplete = false;
+        
+        ModelById::release(m_pathOutputModel);
+        m_pathOutputModel = {};
+
+        disconnect(alignmentModel.get(),
+                   SIGNAL(completionChanged(ModelId)),
+                   this, SLOT(alignmentCompletionChanged(ModelId)));
+        emit complete(m_alignmentModel);
+    }
+}
diff -r 83ae68de4401 -r 4c91c95e146a align/TransformAligner.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/align/TransformAligner.h	Wed May 13 14:10:58 2020 +0100
@@ -0,0 +1,61 @@
+/* -*- 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.
+    Centre for Digital Music, Queen Mary, University of London.
+    
+    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 SV_TRANSFORM_ALIGNER_H
+#define SV_TRANSFORM_ALIGNER_H
+
+#include "Aligner.h"
+
+class AlignmentModel;
+class Document;
+
+class TransformAligner : public Aligner
+{
+    Q_OBJECT
+
+public:
+    TransformAligner(Document *doc,
+                     ModelId reference,
+                     ModelId toAlign);
+
+    // Destroy the aligner, cleanly cancelling any ongoing alignment
+    ~TransformAligner();
+
+    void begin() override;
+
+    static bool isAvailable();
+
+private slots:
+    void alignmentCompletionChanged(ModelId);
+    void tuningDifferenceCompletionChanged(ModelId);
+
+private:
+    static QString getAlignmentTransformName();
+    static QString getTuningDifferenceTransformName();
+
+    bool beginAlignmentPhase();
+    
+    Document *m_document;
+    ModelId m_reference;
+    ModelId m_toAlign;
+    ModelId m_aggregateModel; // an AggregateWaveModel
+    ModelId m_alignmentModel; // an AlignmentModel
+    ModelId m_tuningDiffProgressModel; // SparseTimeValueModel, unreg'd with doc
+    ModelId m_tuningDiffOutputModel; // SparseTimeValueModel, unreg'd with doc
+    ModelId m_pathOutputModel; // SparseTimeValueModel, unreg'd with doc
+    float m_tuningFrequency;
+    bool m_incomplete;
+};
+
+#endif
diff -r 83ae68de4401 -r 4c91c95e146a files.pri
--- a/files.pri	Mon May 11 17:29:17 2020 +0100
+++ b/files.pri	Wed May 13 14:10:58 2020 +0100
@@ -1,5 +1,9 @@
 
 SVAPP_HEADERS += \
+           align/Align.h \
+           align/Aligner.h \
+           align/ExternalProgramAligner.h \
+           align/TransformAligner.h \
            audio/AudioCallbackPlaySource.h \
            audio/AudioCallbackRecordTarget.h \
            audio/AudioGenerator.h \
@@ -8,7 +12,6 @@
            audio/EffectWrapper.h \
            audio/PlaySpeedRangeMapper.h \
            audio/TimeStretchWrapper.h \
-           framework/Align.h \
 	   framework/Document.h \
            framework/MainWindowBase.h \
            framework/OSCScript.h \
@@ -17,6 +20,9 @@
            framework/VersionTester.h
 
 SVAPP_SOURCES += \
+	   align/Align.cpp \
+           align/ExternalProgramAligner.cpp \
+           align/TransformAligner.cpp \
            audio/AudioCallbackPlaySource.cpp \
            audio/AudioCallbackRecordTarget.cpp \
            audio/AudioGenerator.cpp \
@@ -25,7 +31,6 @@
            audio/EffectWrapper.cpp \
            audio/PlaySpeedRangeMapper.cpp \
            audio/TimeStretchWrapper.cpp \
-	   framework/Align.cpp \
 	   framework/Document.cpp \
            framework/MainWindowBase.cpp \
            framework/SVFileReader.cpp \
diff -r 83ae68de4401 -r 4c91c95e146a framework/Align.cpp
--- a/framework/Align.cpp	Mon May 11 17:29:17 2020 +0100
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,673 +0,0 @@
-/* -*- 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.
-    Centre for Digital Music, Queen Mary, University of London.
-    
-    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 "Align.h"
-#include "Document.h"
-
-#include "data/model/WaveFileModel.h"
-#include "data/model/ReadOnlyWaveFileModel.h"
-#include "data/model/AggregateWaveModel.h"
-#include "data/model/RangeSummarisableTimeValueModel.h"
-#include "data/model/SparseTimeValueModel.h"
-#include "data/model/AlignmentModel.h"
-
-#include "data/fileio/CSVFileReader.h"
-
-#include "transform/TransformFactory.h"
-#include "transform/ModelTransformerFactory.h"
-#include "transform/FeatureExtractionModelTransformer.h"
-
-#include <QProcess>
-#include <QSettings>
-#include <QApplication>
-
-bool
-Align::alignModel(Document *doc, ModelId ref, ModelId other, QString &error)
-{
-    QSettings settings;
-    settings.beginGroup("Preferences");
-    bool useProgram = settings.value("use-external-alignment", false).toBool();
-    QString program = settings.value("external-alignment-program", "").toString();
-    settings.endGroup();
-
-    if (useProgram && (program != "")) {
-        return alignModelViaProgram(doc, ref, other, program, error);
-    } else {
-        return alignModelViaTransform(doc, ref, other, error);
-    }
-}
-
-QString
-Align::getAlignmentTransformName()
-{
-    QSettings settings;
-    settings.beginGroup("Alignment");
-    TransformId id =
-        settings.value("transform-id",
-                       "vamp:match-vamp-plugin:match:path").toString();
-    settings.endGroup();
-    return id;
-}
-
-QString
-Align::getTuningDifferenceTransformName()
-{
-    QSettings settings;
-    settings.beginGroup("Alignment");
-    bool performPitchCompensation =
-        settings.value("align-pitch-aware", false).toBool();
-    QString id = "";
-    if (performPitchCompensation) {
-        id = settings.value
-            ("tuning-difference-transform-id",
-             "vamp:tuning-difference:tuning-difference:tuningfreq")
-            .toString();
-    }
-    settings.endGroup();
-    return id;
-}
-
-bool
-Align::canAlign() 
-{
-    TransformFactory *factory = TransformFactory::getInstance();
-    TransformId id = getAlignmentTransformName();
-    TransformId tdId = getTuningDifferenceTransformName();
-    return factory->haveTransform(id) &&
-        (tdId == "" || factory->haveTransform(tdId));
-}
-
-void
-Align::abandonOngoingAlignment(ModelId otherId)
-{
-    auto other = ModelById::getAs<RangeSummarisableTimeValueModel>(otherId);
-    if (!other) {
-        return;
-    }
-
-    ModelId alignmentModelId = other->getAlignment();
-    if (alignmentModelId.isNone()) {
-        return;
-    }
-
-    SVCERR << "Align::abandonOngoingAlignment: An alignment is ongoing for model "
-           << otherId << " (alignment model id " << alignmentModelId
-           << "), abandoning it..." << endl;
-    
-    other->setAlignment({});
-
-    for (auto pp: m_pendingProcesses) {
-        if (alignmentModelId == pp.second) {
-            QProcess *process = pp.first;
-            m_pendingProcesses.erase(process);
-            SVCERR << "Align::abandonOngoingAlignment: Killing external "
-                   << "alignment process " << process << "..." << endl;
-            delete process; // kills the process itself
-            break;
-        }
-    }
-
-    if (m_pendingAlignments.find(alignmentModelId) !=
-        m_pendingAlignments.end()) {
-        SVCERR << "Align::abandonOngoingAlignment: Releasing path output model "
-               << m_pendingAlignments[alignmentModelId]
-               << "..." << endl;
-        ModelById::release(m_pendingAlignments[alignmentModelId]);
-        SVCERR << "Align::abandonOngoingAlignment: Dropping alignment model "
-               << alignmentModelId
-               << " from pending alignments..." << endl;
-        m_pendingAlignments.erase(alignmentModelId);
-    }
-
-    for (auto ptd: m_pendingTuningDiffs) {
-        if (alignmentModelId == ptd.second.alignment) {
-            SVCERR << "Align::abandonOngoingAlignment: Releasing preparatory model "
-                   << ptd.second.preparatory << "..." << endl;
-            ModelById::release(ptd.second.preparatory);
-            SVCERR << "Align::abandonOngoingAlignment: Releasing pending tuning-diff model "
-                   << ptd.first << "..." << endl;
-            ModelById::release(ptd.first);
-            SVCERR << "Align::abandonOngoingAlignment: Dropping tuning-diff model "
-                   << ptd.first
-                   << " from pending tuning diffs..." << endl;
-            m_pendingTuningDiffs.erase(ptd.first);
-            break;
-        }
-    }
-
-    SVCERR << "Align::abandonOngoingAlignment: done" << endl;
-}
-
-bool
-Align::alignModelViaTransform(Document *doc,
-                              ModelId referenceId,
-                              ModelId otherId,
-                              QString &error)
-{
-    QMutexLocker locker (&m_mutex);
-
-    auto reference =
-        ModelById::getAs<RangeSummarisableTimeValueModel>(referenceId);
-    auto other =
-        ModelById::getAs<RangeSummarisableTimeValueModel>(otherId);
-
-    if (!reference || !other) return false;
-
-    // There may be an alignment already happening; we should stop it,
-    // which we can do by discarding the output models for its
-    // transforms
-    abandonOngoingAlignment(otherId);
-    
-    // This involves creating a number of new models:
-    //
-    // 1. an AggregateWaveModel to provide the mixdowns of the main
-    // model and the new model in its two channels, as input to the
-    // MATCH plugin. We just call this one aggregateModel
-    //
-    // 2a. a SparseTimeValueModel which will be automatically created
-    // by FeatureExtractionModelTransformer when running the
-    // TuningDifference plugin to receive the relative tuning of the
-    // second model (if pitch-aware alignment is enabled in the
-    // preferences). We call this tuningDiffOutputModel.
-    //
-    // 2b. a SparseTimeValueModel which will be automatically created
-    // by FeatureExtractionPluginTransformer when running the MATCH
-    // plugin to perform alignment (so containing the alignment path).
-    // We call this one pathOutputModel.
-    //
-    // 2c. a SparseTimeValueModel used solely to provide faked
-    // completion information to the AlignmentModel while a
-    // TuningDifference calculation is going on. We call this
-    // preparatoryModel.
-    //
-    // 3. an AlignmentModel, which stores the path and carries out
-    // alignment lookups on it. We just call this one alignmentModel.
-    //
-    // Models 1 and 3 are registered with the document, which will
-    // eventually release them. We don't release them here except in
-    // the case where an activity fails before the point where we
-    // would otherwise have registered them with the document.
-    //
-    // Models 2a (tuningDiffOutputModel), 2b (pathOutputModel) and 2c
-    // (preparatoryModel) are not registered with the document. Model
-    // 2b (pathOutputModel) is not registered because we do not have a
-    // stable reference to the document at the point where it is
-    // created. Model 2c (preparatoryModel) is not registered because
-    // it is a bodge that we are embarrassed about, so we try to
-    // manage it ourselves without anyone else noticing. Model 2a is
-    // not registered for symmetry with the other two. These have to
-    // be released by us when finished with, but their lifespans do
-    // not extend beyond the end of the alignment procedure, so this
-    // should be ok.
-
-    AggregateWaveModel::ChannelSpecList components;
-
-    components.push_back
-        (AggregateWaveModel::ModelChannelSpec(referenceId, -1));
-
-    components.push_back
-        (AggregateWaveModel::ModelChannelSpec(otherId, -1));
-
-    auto aggregateModel = std::make_shared<AggregateWaveModel>(components);
-    auto aggregateModelId = ModelById::add(aggregateModel);
-    doc->addNonDerivedModel(aggregateModelId);
-
-    auto alignmentModel = std::make_shared<AlignmentModel>
-        (referenceId, otherId, ModelId());
-    auto alignmentModelId = ModelById::add(alignmentModel);
-
-    TransformId tdId = getTuningDifferenceTransformName();
-
-    if (tdId == "") {
-        
-        if (beginTransformDrivenAlignment(aggregateModelId,
-                                          alignmentModelId)) {
-            other->setAlignment(alignmentModelId);
-            doc->addNonDerivedModel(alignmentModelId);
-        } else {
-            error = alignmentModel->getError();
-            ModelById::release(alignmentModel);
-            return false;
-        }
-
-    } else {
-
-        // Have a tuning-difference transform id, so run it
-        // asynchronously first
-        
-        TransformFactory *tf = TransformFactory::getInstance();
-
-        Transform transform = tf->getDefaultTransformFor
-            (tdId, aggregateModel->getSampleRate());
-
-        transform.setParameter("maxduration", 60);
-        transform.setParameter("maxrange", 6);
-        transform.setParameter("finetuning", false);
-    
-        SVDEBUG << "Align::alignModel: Tuning difference transform step size " << transform.getStepSize() << ", block size " << transform.getBlockSize() << endl;
-
-        ModelTransformerFactory *mtf = ModelTransformerFactory::getInstance();
-
-        QString message;
-        ModelId tuningDiffOutputModelId = mtf->transform(transform,
-                                                         aggregateModelId,
-                                                         message);
-
-        auto tuningDiffOutputModel =
-            ModelById::getAs<SparseTimeValueModel>(tuningDiffOutputModelId);
-        if (!tuningDiffOutputModel) {
-            SVCERR << "Align::alignModel: ERROR: Failed to create tuning-difference output model (no Tuning Difference plugin?)" << endl;
-            error = message;
-            ModelById::release(alignmentModel);
-            return false;
-        }
-
-        other->setAlignment(alignmentModelId);
-        doc->addNonDerivedModel(alignmentModelId);
-    
-        connect(tuningDiffOutputModel.get(),
-                SIGNAL(completionChanged(ModelId)),
-                this, SLOT(tuningDifferenceCompletionChanged(ModelId)));
-
-        TuningDiffRec rec;
-        rec.input = aggregateModelId;
-        rec.alignment = alignmentModelId;
-        
-        // This model exists only so that the AlignmentModel can get a
-        // completion value from somewhere while the tuning difference
-        // calculation is going on
-        auto preparatoryModel = std::make_shared<SparseTimeValueModel>
-            (aggregateModel->getSampleRate(), 1);
-        auto preparatoryModelId = ModelById::add(preparatoryModel);
-        preparatoryModel->setCompletion(0);
-        rec.preparatory = preparatoryModelId;
-        alignmentModel->setPathFrom(rec.preparatory);
-        
-        m_pendingTuningDiffs[tuningDiffOutputModelId] = rec;
-
-        SVDEBUG << "Align::alignModelViaTransform: Made a note of pending tuning diff output model id " << tuningDiffOutputModelId << " with input " << rec.input << ", alignment model " << rec.alignment << ", preparatory model " << rec.preparatory << endl;
-    }
-
-    return true;
-}
-
-void
-Align::tuningDifferenceCompletionChanged(ModelId tuningDiffOutputModelId)
-{
-    QMutexLocker locker(&m_mutex);
-
-    if (m_pendingTuningDiffs.find(tuningDiffOutputModelId) ==
-        m_pendingTuningDiffs.end()) {
-        SVDEBUG << "NOTE: Align::tuningDifferenceCompletionChanged: Model "
-                << tuningDiffOutputModelId
-                << " not found in pending tuning diff map, presuming "
-                << "completed or abandoned" << endl;
-        return;
-    }
-
-    auto tuningDiffOutputModel =
-        ModelById::getAs<SparseTimeValueModel>(tuningDiffOutputModelId);
-    if (!tuningDiffOutputModel) {
-        SVCERR << "WARNING: Align::tuningDifferenceCompletionChanged: Model "
-               << tuningDiffOutputModelId
-               << " not known as SparseTimeValueModel" << endl;
-        return;
-    }
-
-    TuningDiffRec rec = m_pendingTuningDiffs[tuningDiffOutputModelId];
-
-    auto alignmentModel = ModelById::getAs<AlignmentModel>(rec.alignment);
-    if (!alignmentModel) {
-        SVCERR << "WARNING: Align::tuningDifferenceCompletionChanged:"
-               << "alignment model has disappeared" << endl;
-        return;
-    }
-    
-    int completion = 0;
-    bool done = tuningDiffOutputModel->isReady(&completion);
-
-    if (!done) {
-        // This will be the completion the alignment model reports,
-        // before the alignment actually begins. It goes up from 0 to
-        // 99 (not 100!) and then back to 0 again when we start
-        // calculating the actual path in the following phase
-        int clamped = (completion == 100 ? 99 : completion);
-        auto preparatoryModel =
-            ModelById::getAs<SparseTimeValueModel>(rec.preparatory);
-        if (preparatoryModel) {
-            preparatoryModel->setCompletion(clamped);
-        }
-        return;
-    }
-
-    float tuningFrequency = 440.f;
-    
-    if (!tuningDiffOutputModel->isEmpty()) {
-        tuningFrequency = tuningDiffOutputModel->getAllEvents()[0].getValue();
-        SVCERR << "Align::tuningDifferenceCompletionChanged: Reported tuning frequency = " << tuningFrequency << endl;
-    } else {
-        SVCERR << "Align::tuningDifferenceCompletionChanged: No tuning frequency reported" << endl;
-    }    
-    
-    ModelById::release(tuningDiffOutputModel);
-    
-    alignmentModel->setPathFrom({}); // replace preparatoryModel
-    ModelById::release(rec.preparatory);
-    rec.preparatory = {};
-    
-    m_pendingTuningDiffs.erase(tuningDiffOutputModelId);
-
-    SVDEBUG << "Align::tuningDifferenceCompletionChanged: Erasing model "
-            << tuningDiffOutputModelId << " from pending tuning diffs and "
-            << "launching the alignment phase for alignment model "
-            << rec.alignment << " with tuning frequency "
-            << tuningFrequency << endl;
-    
-    beginTransformDrivenAlignment
-        (rec.input, rec.alignment, tuningFrequency);
-}
-
-bool
-Align::beginTransformDrivenAlignment(ModelId aggregateModelId,
-                                     ModelId alignmentModelId,
-                                     float tuningFrequency)
-{
-    TransformId id = getAlignmentTransformName();
-    
-    TransformFactory *tf = TransformFactory::getInstance();
-
-    auto aggregateModel =
-        ModelById::getAs<AggregateWaveModel>(aggregateModelId);
-    auto alignmentModel =
-        ModelById::getAs<AlignmentModel>(alignmentModelId);
-
-    if (!aggregateModel || !alignmentModel) {
-        SVCERR << "Align::alignModel: ERROR: One or other of the aggregate & alignment models has disappeared" << endl;
-        return false;
-    }
-    
-    Transform transform = tf->getDefaultTransformFor
-        (id, aggregateModel->getSampleRate());
-
-    transform.setStepSize(transform.getBlockSize()/2);
-    transform.setParameter("serialise", 1);
-    transform.setParameter("smooth", 0);
-    transform.setParameter("zonewidth", 40);
-    transform.setParameter("noise", true);
-    transform.setParameter("minfreq", 500);
-
-    int cents = 0;
-    
-    if (tuningFrequency != 0.f) {
-        transform.setParameter("freq2", tuningFrequency);
-
-        double centsOffset = 0.f;
-        int pitch = Pitch::getPitchForFrequency(tuningFrequency, &centsOffset);
-        cents = int(round((pitch - 69) * 100 + centsOffset));
-        SVCERR << "frequency " << tuningFrequency << " yields cents offset " << centsOffset << " and pitch " << pitch << " -> cents " << cents << endl;
-    }
-
-    alignmentModel->setRelativePitch(cents);
-    
-    SVDEBUG << "Align::alignModel: Alignment transform step size " << transform.getStepSize() << ", block size " << transform.getBlockSize() << endl;
-
-    ModelTransformerFactory *mtf = ModelTransformerFactory::getInstance();
-
-    QString message;
-    ModelId pathOutputModelId = mtf->transform
-        (transform, aggregateModelId, message);
-
-    if (pathOutputModelId.isNone()) {
-        transform.setStepSize(0);
-        pathOutputModelId = mtf->transform
-            (transform, aggregateModelId, message);
-    }
-
-    auto pathOutputModel =
-        ModelById::getAs<SparseTimeValueModel>(pathOutputModelId);
-
-    //!!! callers will need to be updated to get error from
-    //!!! alignment model after initial call
-        
-    if (!pathOutputModel) {
-        SVCERR << "Align::alignModel: ERROR: Failed to create alignment path (no MATCH plugin?)" << endl;
-        alignmentModel->setError(message);
-        return false;
-    }
-
-    pathOutputModel->setCompletion(0);
-    alignmentModel->setPathFrom(pathOutputModelId);
-
-    m_pendingAlignments[alignmentModelId] = pathOutputModelId;
-
-    connect(alignmentModel.get(), SIGNAL(completionChanged(ModelId)),
-            this, SLOT(alignmentCompletionChanged(ModelId)));
-
-    return true;
-}
-
-void
-Align::alignmentCompletionChanged(ModelId alignmentModelId)
-{
-    QMutexLocker locker (&m_mutex);
-
-    auto alignmentModel = ModelById::getAs<AlignmentModel>(alignmentModelId);
-
-    if (alignmentModel && alignmentModel->isReady()) {
-
-        if (m_pendingAlignments.find(alignmentModelId) !=
-            m_pendingAlignments.end()) {
-            ModelId pathOutputModelId = m_pendingAlignments[alignmentModelId];
-            ModelById::release(pathOutputModelId);
-            m_pendingAlignments.erase(alignmentModelId);
-        }
-        
-        disconnect(alignmentModel.get(),
-                   SIGNAL(completionChanged(ModelId)),
-                   this, SLOT(alignmentCompletionChanged(ModelId)));
-        emit alignmentComplete(alignmentModelId);
-    }
-}
-
-bool
-Align::alignModelViaProgram(Document *doc,
-                            ModelId referenceId,
-                            ModelId otherId,
-                            QString program,
-                            QString &error)
-{
-    // Run an external program, passing to it paths to the main
-    // model's audio file and the new model's audio file. It returns
-    // the path in CSV form through stdout.
-
-    auto reference = ModelById::getAs<ReadOnlyWaveFileModel>(referenceId);
-    auto other = ModelById::getAs<ReadOnlyWaveFileModel>(otherId);
-    if (!reference || !other) {
-        SVCERR << "ERROR: Align::alignModelViaProgram: Can't align non-read-only models via program (no local filename available)" << endl;
-        return false;
-    }
-
-    while (!reference->isReady(nullptr) || !other->isReady(nullptr)) {
-        qApp->processEvents();
-    }
-    
-    QString refPath = reference->getLocalFilename();
-    if (refPath == "") {
-        refPath = FileSource(reference->getLocation()).getLocalFilename();
-    }
-    
-    QString otherPath = other->getLocalFilename();
-    if (otherPath == "") {
-        otherPath = FileSource(other->getLocation()).getLocalFilename();
-    }
-
-    if (refPath == "" || otherPath == "") {
-        error = "Failed to find local filepath for wave-file model";
-        return false;
-    }
-
-    QProcess *process = nullptr;
-    ModelId alignmentModelId = {};
-    
-    {
-        QMutexLocker locker (&m_mutex);
-
-        auto alignmentModel =
-            std::make_shared<AlignmentModel>(referenceId, otherId, ModelId());
-
-        alignmentModelId = ModelById::add(alignmentModel);
-        other->setAlignment(alignmentModelId);
-
-        process = new QProcess;
-        process->setProcessChannelMode(QProcess::ForwardedErrorChannel);
-
-        connect(process,
-                SIGNAL(finished(int, QProcess::ExitStatus)),
-                this,
-                SLOT(alignmentProgramFinished(int, QProcess::ExitStatus)));
-
-        m_pendingProcesses[process] = alignmentModelId;
-    }
-
-    QStringList args;
-    args << refPath << otherPath;
-
-    SVCERR << "Align::alignModelViaProgram: Starting program \""
-           << program << "\" with args: ";
-    for (auto a: args) {
-        SVCERR << "\"" << a << "\" ";
-    }
-    SVCERR << endl;
-
-    process->start(program, args);
-
-    bool success = process->waitForStarted();
-
-    {
-        QMutexLocker locker(&m_mutex);
-        
-        if (!success) {
-        
-            SVCERR << "ERROR: Align::alignModelViaProgram: "
-                   << "Program did not start" << endl;
-            error = "Alignment program \"" + program + "\" did not start";
-        
-            m_pendingProcesses.erase(process);
-            other->setAlignment({});
-            ModelById::release(alignmentModelId);
-            delete process;
-        
-        } else {
-            doc->addNonDerivedModel(alignmentModelId);
-        }
-    }
-
-    return success;
-}
-
-void
-Align::alignmentProgramFinished(int exitCode, QProcess::ExitStatus status)
-{
-    QMutexLocker locker (&m_mutex);
-    
-    SVCERR << "Align::alignmentProgramFinished" << endl;
-    
-    QProcess *process = qobject_cast<QProcess *>(sender());
-
-    if (m_pendingProcesses.find(process) == m_pendingProcesses.end()) {
-        SVCERR << "ERROR: Align::alignmentProgramFinished: Process " << process
-               << " not found in process model map!" << endl;
-        return;
-    }
-
-    ModelId alignmentModelId = m_pendingProcesses[process];
-    auto alignmentModel = ModelById::getAs<AlignmentModel>(alignmentModelId);
-    if (!alignmentModel) return;
-    
-    if (exitCode == 0 && status == 0) {
-
-        CSVFormat format;
-        format.setModelType(CSVFormat::TwoDimensionalModel);
-        format.setTimingType(CSVFormat::ExplicitTiming);
-        format.setTimeUnits(CSVFormat::TimeSeconds);
-        format.setColumnCount(2);
-        // The output format has time in the reference file first, and
-        // time in the "other" file in the second column. This is a
-        // more natural approach for a command-line alignment tool,
-        // but it's the opposite of what we expect for native
-        // alignment paths, which map from "other" file to
-        // reference. These column purpose settings reflect that.
-        format.setColumnPurpose(1, CSVFormat::ColumnStartTime);
-        format.setColumnPurpose(0, CSVFormat::ColumnValue);
-        format.setAllowQuoting(false);
-        format.setSeparator(',');
-
-        CSVFileReader reader(process, format, alignmentModel->getSampleRate());
-        if (!reader.isOK()) {
-            SVCERR << "ERROR: Align::alignmentProgramFinished: Failed to parse output"
-                   << endl;
-            alignmentModel->setError
-                (QString("Failed to parse output of program: %1")
-                 .arg(reader.getError()));
-            goto done;
-        }
-
-        //!!! to use ById?
-        
-        Model *csvOutput = reader.load();
-
-        SparseTimeValueModel *path =
-            qobject_cast<SparseTimeValueModel *>(csvOutput);
-        if (!path) {
-            SVCERR << "ERROR: Align::alignmentProgramFinished: Output did not convert to sparse time-value model"
-                   << endl;
-            alignmentModel->setError
-                ("Output of program did not produce sparse time-value model");
-            delete csvOutput;
-            goto done;
-        }
-                       
-        if (path->isEmpty()) {
-            SVCERR << "ERROR: Align::alignmentProgramFinished: Output contained no mappings"
-                   << endl;
-            alignmentModel->setError
-                ("Output of alignment program contained no mappings");
-            delete path;
-            goto done;
-        }
-
-        SVCERR << "Align::alignmentProgramFinished: Setting alignment path ("
-             << path->getEventCount() << " point(s))" << endl;
-
-        auto pathId =
-            ModelById::add(std::shared_ptr<SparseTimeValueModel>(path));
-        alignmentModel->setPathFrom(pathId);
-
-        emit alignmentComplete(alignmentModelId);
-
-        ModelById::release(pathId);
-        
-    } else {
-        SVCERR << "ERROR: Align::alignmentProgramFinished: Aligner program "
-               << "failed: exit code " << exitCode << ", status " << status
-               << endl;
-        alignmentModel->setError
-            ("Aligner process returned non-zero exit status");
-    }
-
-done:
-    m_pendingProcesses.erase(process);
-    delete process;
-}
-
diff -r 83ae68de4401 -r 4c91c95e146a framework/Align.h
--- a/framework/Align.h	Mon May 11 17:29:17 2020 +0100
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,131 +0,0 @@
-/* -*- 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.
-    Centre for Digital Music, Queen Mary, University of London.
-    
-    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 ALIGN_H
-#define ALIGN_H
-
-#include <QString>
-#include <QObject>
-#include <QProcess>
-#include <QMutex>
-#include <set>
-
-#include "data/model/Model.h"
-
-class AlignmentModel;
-class SparseTimeValueModel;
-class AggregateWaveModel;
-class Document;
-
-class Align : public QObject
-{
-    Q_OBJECT
-    
-public:
-    Align() { }
-
-    /**
-     * Align the "other" model to the reference, attaching an
-     * AlignmentModel to it. Alignment is carried out by the method
-     * configured in the user preferences (either a plugin transform
-     * or an external process) and is done asynchronously. 
-     *
-     * The return value indicates whether the alignment procedure
-     * started successfully. If it is true, then an AlignmentModel has
-     * been constructed and attached to the toAlign model, and you can
-     * query that model to discover the alignment progress, eventual
-     * outcome, and any error message generated during alignment. (The
-     * AlignmentModel is subsequently owned by the toAlign model.)
-     * Conversely if alignModel returns false, no AlignmentModel has
-     * been created, and the error return argument will contain an
-     * error report about whatever problem prevented this from
-     * happening.
-     *
-     * A single Align object may carry out many simultanous alignment
-     * calls -- you do not need to create a new Align object each
-     * time, nor to wait for an alignment to be complete before
-     * starting a new one.
-     * 
-     * The Align object must survive after this call, for at least as
-     * long as the alignment takes. The usual expectation is that the
-     * Align object will simply share the process or document
-     * lifespan.
-     */
-    bool alignModel(Document *doc,
-                    ModelId reference,
-                    ModelId toAlign,
-                    QString &error);
-    
-    bool alignModelViaTransform(Document *doc,
-                                ModelId reference,
-                                ModelId toAlign,
-                                QString &error);
-
-    bool alignModelViaProgram(Document *doc,
-                              ModelId reference,
-                              ModelId toAlign,
-                              QString program,
-                              QString &error);
-
-    /**
-     * Return true if the alignment facility is available (relevant
-     * plugin installed, etc).
-     */
-    static bool canAlign();
-
-signals:
-    /**
-     * Emitted when an alignment is successfully completed. The
-     * reference and other models can be queried from the alignment
-     * model.
-     */
-    void alignmentComplete(ModelId alignmentModel); // an AlignmentModel
-
-private slots:
-    void alignmentCompletionChanged(ModelId);
-    void tuningDifferenceCompletionChanged(ModelId);
-    void alignmentProgramFinished(int, QProcess::ExitStatus);
-    
-private:
-    static QString getAlignmentTransformName();
-    static QString getTuningDifferenceTransformName();
-
-    bool beginTransformDrivenAlignment(ModelId, // an AggregateWaveModel
-                                       ModelId, // an AlignmentModel
-                                       float tuningFrequency = 0.f);
-
-    void abandonOngoingAlignment(ModelId otherId);
-
-    QMutex m_mutex;
-
-    struct TuningDiffRec {
-        ModelId input; // an AggregateWaveModel
-        ModelId alignment; // an AlignmentModel
-        ModelId preparatory; // a SparseTimeValueModel
-    };
-    
-    // tuning-difference output model (a SparseTimeValueModel) -> data
-    // needed for subsequent alignment
-    std::map<ModelId, TuningDiffRec> m_pendingTuningDiffs;
-
-    // alignment model id -> path output model id
-    std::map<ModelId, ModelId> m_pendingAlignments;
-    
-    // external alignment subprocess -> model into which to stuff the
-    // results (an AlignmentModel)
-    std::map<QProcess *, ModelId> m_pendingProcesses;
-};
-
-#endif
-
diff -r 83ae68de4401 -r 4c91c95e146a framework/Document.cpp
--- a/framework/Document.cpp	Mon May 11 17:29:17 2020 +0100
+++ b/framework/Document.cpp	Wed May 13 14:10:58 2020 +0100
@@ -15,8 +15,6 @@
 
 #include "Document.h"
 
-#include "Align.h"
-
 #include "data/model/WaveFileModel.h"
 #include "data/model/WritableWaveFileModel.h"
 #include "data/model/DenseThreeDimensionalModel.h"
@@ -39,7 +37,7 @@
 #include <typeinfo>
 
 #include "data/model/AlignmentModel.h"
-#include "Align.h"
+#include "align/Align.h"
 
 using std::vector;
 
@@ -59,6 +57,9 @@
 
     connect(m_align, SIGNAL(alignmentComplete(ModelId)),
             this, SIGNAL(alignmentComplete(ModelId)));
+
+    connect(m_align, SIGNAL(alignmentFailed(ModelId, QString)),
+            this, SIGNAL(alignmentFailed(ModelId, QString)));
 }
 
 Document::~Document()
@@ -557,7 +558,7 @@
     }
 
     if (m_autoAlignment) {
-        SVDEBUG << "Document::setMainModel: auto-alignment is on, aligning model if possible" << endl;
+        SVDEBUG << "Document::setMainModel: auto-alignment is on, aligning main model if applicable" << endl;
         alignModel(m_mainModel);
     } else {
         SVDEBUG << "Document::setMainModel: auto-alignment is off" << endl;
@@ -1147,11 +1148,7 @@
                 << endl;
     }
 
-    QString err;
-    if (!m_align->alignModel(this, m_mainModel, modelId, err)) {
-        SVCERR << "Alignment failed: " << err << endl;
-        emit alignmentFailed(err);
-    }
+    m_align->scheduleAlignment(this, m_mainModel, modelId);
 }
 
 void
diff -r 83ae68de4401 -r 4c91c95e146a framework/Document.h
--- a/framework/Document.h	Mon May 11 17:29:17 2020 +0100
+++ b/framework/Document.h	Wed May 13 14:10:58 2020 +0100
@@ -331,7 +331,7 @@
                                   QString message);
 
     void alignmentComplete(ModelId); // an AlignmentModel
-    void alignmentFailed(QString message);
+    void alignmentFailed(ModelId, QString message); // an AlignmentModel
 
     void activity(QString);
 
diff -r 83ae68de4401 -r 4c91c95e146a framework/MainWindowBase.cpp
--- a/framework/MainWindowBase.cpp	Mon May 11 17:29:17 2020 +0100
+++ b/framework/MainWindowBase.cpp	Wed May 13 14:10:58 2020 +0100
@@ -2740,8 +2740,8 @@
             this, SLOT(modelRegenerationWarning(QString, QString, QString)));
     connect(m_document, SIGNAL(alignmentComplete(ModelId)),
             this, SLOT(alignmentComplete(ModelId)));
-    connect(m_document, SIGNAL(alignmentFailed(QString)),
-            this, SLOT(alignmentFailed(QString)));
+    connect(m_document, SIGNAL(alignmentFailed(ModelId, QString)),
+            this, SLOT(alignmentFailed(ModelId, QString)));
 
     m_document->setAutoAlignment(m_viewManager->getAlignMode());
 
diff -r 83ae68de4401 -r 4c91c95e146a framework/MainWindowBase.h
--- a/framework/MainWindowBase.h	Mon May 11 17:29:17 2020 +0100
+++ b/framework/MainWindowBase.h	Wed May 13 14:10:58 2020 +0100
@@ -361,7 +361,7 @@
     virtual void modelRegenerationWarning(QString, QString, QString) = 0;
 
     virtual void alignmentComplete(ModelId);
-    virtual void alignmentFailed(QString) = 0;
+    virtual void alignmentFailed(ModelId, QString) = 0;
 
     virtual void paneRightButtonMenuRequested(Pane *, QPoint point) = 0;
     virtual void panePropertiesRightButtonMenuRequested(Pane *, QPoint point) = 0;