Added further source availablity checks to ld-diffdod

tools/ld-diffdod/diffdod.cpp

@@ -62,6 +62,11 @@ bool Diffdod::process(QVector<QString> inputFilenames, bool reverse,
         length = tbcSources.getMaximumVbiFrameNumber() - vbiStartFrame + 1;
     if (length == -1) length = tbcSources.getMaximumVbiFrameNumber() - tbcSources.getMinimumVbiFrameNumber() + 1;
 
+    // Verify frame source availablity
+    qInfo() << "";
+    qInfo() << "Verifying VBI frame multi-source availablity:";
+    tbcSources.verifySources(vbiStartFrame, length);
+
     qInfo() << "Processing" << length << "frames starting from VBI frame" << vbiStartFrame;
     if (!tbcSources.saveSources(vbiStartFrame, length, dodThreshold, noLumaClip)) {
         qCritical() << "Saving source failed!";

tools/ld-diffdod/tbcsources.cpp

@@ -196,6 +196,32 @@ qint32 TbcSources::getMaximumVbiFrameNumber()
     return maximumFrameNumber;
 }
 
+// Verify that at least 3 sources are available for every VBI frame
+void TbcSources::verifySources(qint32 vbiStartFrame, qint32 length)
+{
+    qint32 uncorrectableFrameCount = 0;
+
+    // Process the sources frame by frame
+    for (qint32 vbiFrame = vbiStartFrame; vbiFrame < vbiStartFrame + length; vbiFrame++) {
+        // Check how many source frames are available for the current frame
+        QVector<qint32> availableSourcesForFrame = getAvailableSourcesForFrame(vbiFrame);
+
+        // DiffDOD requires at least three source frames.  If 3 sources are not available leave any existing DO records in place
+        // and output a warning to the user
+        if (availableSourcesForFrame.size() < 3) {
+            // Differential DOD requires at least 3 valid source frames
+            qInfo().nospace() << "Frame #" << vbiFrame << " has only " << availableSourcesForFrame.size() << " source frames available - cannot correct";
+            uncorrectableFrameCount++;
+        }
+    }
+
+    if (uncorrectableFrameCount != 0) {
+        qInfo() << "Warning:" << uncorrectableFrameCount << "frame(s) cannot be corrected!";
+    } else {
+        qInfo() << "All frames have at least 3 sources available";
+    }
+}
+
 // Private methods ----------------------------------------------------------------------------------------------------
 
 // Perform differential dropout detection to determine (for each source) which frame pixels are valid

tools/ld-diffdod/tbcsources.h

@@ -49,6 +49,7 @@ class TbcSources : public QObject
     qint32 getNumberOfAvailableSources();
     qint32 getMinimumVbiFrameNumber();
     qint32 getMaximumVbiFrameNumber();
+    void verifySources(qint32 vbiStartFrame, qint32 length);
 
 private:
     // Source definition