Clear LdDecodeMetaData contents before reading a file

tools/library/tbc/lddecodemetadata.cpp

@@ -355,22 +355,34 @@ void LdDecodeMetaData::Field::write(JsonWriter &writer) const
 
 LdDecodeMetaData::LdDecodeMetaData()
 {
-    // Set defaults
-    isFirstFieldFirst = false;
+    clear();
 }
 
-// Read all metadata from a JSON file
-bool LdDecodeMetaData::read(QString fileName)
+// Reset the metadata to the defaults
+void LdDecodeMetaData::clear()
 {
     // Default to the standard still-frame field order (of first field first)
     isFirstFieldFirst = true;
 
+    // Reset the parameters to their defaults
+    videoParameters = VideoParameters();
+    lineParameters = LineParameters();
+    pcmAudioParameters = PcmAudioParameters();
+
+    fields.clear();
+}
+
+// Read all metadata from a JSON file
+bool LdDecodeMetaData::read(QString fileName)
+{
     std::ifstream jsonFile(fileName.toStdString());
     if (jsonFile.fail()) {
         qCritical("Opening JSON input file failed: JSON file cannot be opened/does not exist");
         return false;
     }
 
+    clear();
+
     JsonReader reader(jsonFile);
 
     try {

tools/library/tbc/lddecodemetadata.h

@@ -194,6 +194,7 @@ class LdDecodeMetaData
     LdDecodeMetaData(const LdDecodeMetaData &) = delete;
     LdDecodeMetaData& operator=(const LdDecodeMetaData &) = delete;
 
+    void clear();
     bool read(QString fileName);
     bool write(QString fileName) const;
     void readFields(JsonReader &reader);