Fix line numbers in binary STL files.

Here we make sure that line numbers end up not larger than the
MNR (maximum number of rows) to try to avoid subtitles going
off the screen.

1 files changed, 13 insertions, 3 deletions

diff --git a/src/stl_binary_reader.cc b/src/stl_binary_reader.cc
index f441aec..35091f0 100644
--- a/src/stl_binary_reader.cc
+++ b/src/stl_binary_reader.cc
@@ -187,6 +187,7 @@ void STLBinaryReader::read (shared_ptr<InputReader> reader)
 	editor_name = reader->get_string(309, 32);
 	editor_contact_details = reader->get_string(341, 32);
 
+	int highest_line = 0;
 	for (int i = 0; i < tti_blocks; ++i) {
 
 		reader->read (128, "TTI");
@@ -211,10 +212,11 @@ void STLBinaryReader::read (shared_ptr<InputReader> reader)
 			RawSubtitle sub;
 			sub.from = reader->get_timecode(5, frame_rate);
 			sub.to = reader->get_timecode(9, frame_rate);
-                        /* XXX: only the vertical position of the first TTI block should be used (says the spec),
-                           so using reader->get_int(13, 1) here is wrong if i > 0
-                         */
+			/* XXX: vertical position of TTI extension blocks should be ignored (spec page 10) so this
+			 * is wrong if the EBN of this TTI block is not 255 (I think).
+			 */
 			sub.vertical_position.line = reader->get_int(13, 1) + j;
+			highest_line = std::max(highest_line, *sub.vertical_position.line);
 			sub.vertical_position.lines = maximum_rows;
 			sub.vertical_position.reference = TOP_OF_SCREEN;
 			sub.italic = italic;
@@ -283,6 +285,14 @@ void STLBinaryReader::read (shared_ptr<InputReader> reader)
 			/* XXX: justification */
 		}
 	}
+
+	/* Fix line numbers so they don't go off the bottom of the screen */
+	if (highest_line > maximum_rows) {
+		int correction = highest_line - maximum_rows;
+		for (auto& i: _subs) {
+			*i.vertical_position.line -= correction;
+		}
+	}
 }
 
 map<string, string>