Improve handling of image subtitle IDs in XML (DoM bug #1965)

When reading/writing the XML for image subtitles, we assumed that
the content of the <Image> tag is just the ID of the PNG in the MXF,
without any prefix.

DoM bug #1965 mentions a DCP where this is not the case, and SMPTE
429-5-2009 has an example where there is urn:uuid: in the XML.

This change makes DoM write this urn:uuid: prefix, and accept it if
it's present (but not complain if it's not).

If the urn:uuid: _is_ required in the field, it's a bit surprising
that nobody has complained up to this point.  Maybe nobody noticed,
or nobody reported it.

1 files changed, 22 insertions, 1 deletions

diff --git a/src/subtitle_asset.cc b/src/subtitle_asset.cc
index bb752441..bf4b1c63 100644
--- a/src/subtitle_asset.cc
+++ b/src/subtitle_asset.cc
@@ -404,11 +404,31 @@ SubtitleAsset::maybe_add_subtitle (string text, vector<ParseState> const & parse
 			);
 		break;
 	case ParseState::Type::IMAGE:
+	{
+		switch (standard) {
+		case Standard::INTEROP:
+			if (text.size() >= 4) {
+				/* Remove file extension */
+				text = text.substr(0, text.size() - 4);
+			}
+			break;
+		case Standard::SMPTE:
+			/* It looks like this urn:uuid: is required, but DoM wasn't expecting it (and not writing it)
+			 * until around 2.15.140 so I guess either:
+			 *   a) it is not (always) used in the field, or
+			 *   b) nobody noticed / complained.
+			 */
+			if (text.substr(0, 9) == "urn:uuid:") {
+				text = text.substr(9);
+			}
+			break;
+		}
+
 		/* Add a subtitle with no image data and we'll fill that in later */
 		_subtitles.push_back (
 			make_shared<SubtitleImage>(
 				ArrayData(),
-				standard == Standard::INTEROP ? text.substr(0, text.size() - 4) : text,
+				text,
 				ps.in.get(),
 				ps.out.get(),
 				ps.h_position.get_value_or(0),
@@ -421,6 +441,7 @@ SubtitleAsset::maybe_add_subtitle (string text, vector<ParseState> const & parse
 			);
 		break;
 	}
+	}
 }