NO-OP: add comment for cross-reference

libs/ardour/audiofile_tagger.cc

@@ -42,6 +42,8 @@ namespace ARDOUR
 bool
 AudiofileTagger::tag_file (std::string const & filename, SessionMetadata const & metadata)
 {
+	/* see also SessionMetadata::av_export_tag () for ffmpeg/liblame */
+
 	TagLib::FileRef file (filename.c_str());
 	if (file.isNull()) {
 		std::cerr << "TagLib::FileRef is null for file" << filename  << std::endl;

libs/ardour/session_metadata.cc

@@ -651,6 +651,12 @@ SessionMetadata::set_country (const string & v)
 void
 SessionMetadata::av_export_tag (MetaDataMap& meta) const
 {
+	/* this is used for ffmpeg/liblame -metadata key=value
+	 * (video and mp3 export).
+	 * for flac/ogg's vorbis-comment see:
+	 * AudiofileTagger::tag_generic()
+	 * AudiofileTagger::tag_vorbis_comment()
+	 */
 	if (year() > 0) {
 		std::ostringstream osstream; osstream << year();
 		meta["year"] = osstream.str();