sync: masked waveform correlation, stretch sync, manual start time

- Waveform sync no longer treats uncached waveform regions as silence:
  the envelope extraction now reports a per-window validity mask and the
  correlation skips invalid windows on either side, improving accuracy
  for partially cached clips
- Add stretch/speed sync: AudioWaveformSync::EstimateStretchAndOffset
  searches a playback-rate range plus offset, and a new timeline
  context action 'Synchronize by Waveform (Adjust Speed)' applies the
  estimated rate as a clip speed change (with undo) when plain offset
  alignment is inconclusive
- Footage properties dialog gains a Source Start Time field so the
  value used by source-time sync can be viewed and edited manually
  instead of relying solely on auto-detected metadata; applied via an
  undo command, with Footage::ClearSourceStartTime() for removal
- Regression tests for masked correlation, stretch estimation, the
  envelope validity mask, and source-start-time set/clear

app/dialog/footageproperties/footageproperties.cpp

@@ -22,6 +22,7 @@
 #include "footageproperties.h"
 
 #include <QGridLayout>
+#include <QHBoxLayout>
 #include <QLabel>
 #include <QComboBox>
 #include <QLineEdit>
@@ -58,6 +59,48 @@ FootagePropertiesDialog::FootagePropertiesDialog(QWidget *parent,
 	layout->addWidget(footage_name_field_, row, 1);
 	row++;
 
+	// Manual source start time: audio/timecode sync relies on this value,
+	// which is otherwise only auto-detected from file metadata
+	layout->addWidget(new QLabel(tr("Source Start Time:")), row, 0);
+
+	{
+		QHBoxLayout *start_time_layout = new QHBoxLayout();
+
+		source_start_time_enable_ = new QCheckBox(tr("Set"));
+		source_start_time_enable_->setChecked(footage_->HasSourceStartTime());
+		start_time_layout->addWidget(source_start_time_enable_);
+
+		source_start_time_spin_ = new QDoubleSpinBox();
+		source_start_time_spin_->setRange(-86400.0, 86400.0);
+		source_start_time_spin_->setDecimals(3);
+		source_start_time_spin_->setSuffix(QStringLiteral(" s"));
+		source_start_time_spin_->setValue(
+			footage_->HasSourceStartTime() ?
+				footage_->source_start_time().toDouble() :
+				0.0);
+		source_start_time_spin_->setEnabled(
+			source_start_time_enable_->isChecked());
+		start_time_layout->addWidget(source_start_time_spin_, 1);
+
+		QString detection_note;
+		if (footage_->HasSourceStartTime()) {
+			const QString &source = footage_->source_start_time_source();
+			detection_note =
+				(source == QStringLiteral("manual")) ?
+					tr("(set manually)") :
+					tr("(auto-detected: %1)").arg(source);
+		} else {
+			detection_note = tr("(not detected)");
+		}
+		start_time_layout->addWidget(new QLabel(detection_note));
+
+		connect(source_start_time_enable_, &QCheckBox::toggled,
+				source_start_time_spin_, &QDoubleSpinBox::setEnabled);
+
+		layout->addLayout(start_time_layout, row, 1);
+	}
+	row++;
+
 	layout->addWidget(new QLabel(tr("Tracks:")), row, 0, 1, 2);
 	row++;
 
@@ -165,6 +208,18 @@ void FootagePropertiesDialog::accept()
 		command->add_child(nrc);
 	}
 
+	// Apply source start time changes
+	{
+		const bool new_enabled = source_start_time_enable_->isChecked();
+		const rational new_time =
+			rational::fromDouble(source_start_time_spin_->value());
+		if (new_enabled != footage_->HasSourceStartTime() ||
+			(new_enabled && new_time != footage_->source_start_time())) {
+			command->add_child(new FootageSetSourceStartTimeCommand(
+				footage_, new_enabled, new_time, QStringLiteral("manual")));
+		}
+	}
+
 	for (int i = 0; i < footage_->GetTotalStreamCount(); i++) {
 		Track::Reference reference = footage_->GetReferenceFromRealIndex(i);
 		bool new_stream_enabled =
@@ -279,4 +334,44 @@ void FootagePropertiesDialog::StreamEnableChangeCommand::undo()
 	}
 }
 
+FootagePropertiesDialog::FootageSetSourceStartTimeCommand::
+	FootageSetSourceStartTimeCommand(Footage *footage, bool enabled,
+									 const rational &time,
+									 const QString &source)
+	: footage_(footage)
+	, new_enabled_(enabled)
+	, new_time_(time)
+	, new_source_(source)
+{
+}
+
+Project *
+FootagePropertiesDialog::FootageSetSourceStartTimeCommand::GetRelevantProject()
+	const
+{
+	return footage_->project();
+}
+
+void FootagePropertiesDialog::FootageSetSourceStartTimeCommand::redo()
+{
+	old_enabled_ = footage_->HasSourceStartTime();
+	old_time_ = footage_->source_start_time();
+	old_source_ = footage_->source_start_time_source();
+
+	if (new_enabled_) {
+		footage_->SetSourceStartTime(new_time_, new_source_);
+	} else {
+		footage_->ClearSourceStartTime();
+	}
+}
+
+void FootagePropertiesDialog::FootageSetSourceStartTimeCommand::undo()
+{
+	if (old_enabled_) {
+		footage_->SetSourceStartTime(old_time_, old_source_);
+	} else {
+		footage_->ClearSourceStartTime();
+	}
+}
+
 }

app/dialog/footageproperties/footageproperties.h

@@ -79,6 +79,30 @@ private:
 		bool new_enabled_;
 	};
 
+	class FootageSetSourceStartTimeCommand : public UndoCommand {
+	public:
+		FootageSetSourceStartTimeCommand(Footage *footage, bool enabled,
+										 const rational &time,
+										 const QString &source);
+
+		virtual Project *GetRelevantProject() const override;
+
+	protected:
+		virtual void redo() override;
+		virtual void undo() override;
+
+	private:
+		Footage *footage_;
+
+		bool new_enabled_;
+		rational new_time_;
+		QString new_source_;
+
+		bool old_enabled_;
+		rational old_time_;
+		QString old_source_;
+	};
+
 	/**
    * @brief Stack of widgets that changes based on whether the stream is a video or audio stream
    */
@@ -89,6 +113,16 @@ private:
    */
 	QLineEdit *footage_name_field_;
 
+	/**
+   * @brief Whether a manual source start time should be used
+   */
+	QCheckBox *source_start_time_enable_;
+
+	/**
+   * @brief Source start time in seconds
+   */
+	QDoubleSpinBox *source_start_time_spin_;
+
 	/**
    * @brief Internal pointer to Media object (set in constructor)
    */