From 639407f580918393d438cf715e2ffbd5fe7e0288 Mon Sep 17 00:00:00 2001
From: Moritz Bunkus <moritz@bunkus.org>
Date: Sun, 19 Mar 2017 18:57:17 +0100
Subject: [PATCH] HEVC parser: detect and ignore invalid default display window
 VUI parameters

Certain files seem to lack the "default display window" data (well,
the flag that signals its presence/absence). Therefore a
standards-compliant parser would try to read that flag, but the data
read would belong to another flag (the "vui_timing_info_present_flag").

ffmpeg has a heuristic in place for detecting such invalid default
display window parameters. This commit implements the same heuristic
in mkvmerge.

Fixes #1907.
---
 NEWS.md                                                     | 3 +++
 src/common/hevc.cpp                                         | 6 +++++-
 tests/results.txt                                           | 1 +
 ...est-586h265_invalid_default_display_window_in_sps_vui.rb | 5 +++++
 4 files changed, 14 insertions(+), 1 deletion(-)
 create mode 100755 tests/test-586h265_invalid_default_display_window_in_sps_vui.rb

diff --git a/NEWS.md b/NEWS.md
index 25e1e0c61..ffea27b7d 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -6,6 +6,9 @@
   first key frame as they cannot be decoded properly anyway. See #1908.
 * mkvmerge: HEVC/h.265 parser: mkvmerge will now drop all frames before the
   first key frame as they cannot be decoded properly anyway. See #1908.
+* mkvmerge: HEVC/h.265 parser: added a workaround for invalid values for the
+  "default display window" in the VUI parameters of sequence parameter
+  sets. Fixes #1907.
 
 ## Bug fixes
 
diff --git a/src/common/hevc.cpp b/src/common/hevc.cpp
index c821b2b0a..bafe76cab 100644
--- a/src/common/hevc.cpp
+++ b/src/common/hevc.cpp
@@ -857,7 +857,11 @@ vui_parameters_copy(bit_reader_c &r,
     w.copy_unsigned_golomb(r);               // chroma_sample_loc_type_bottom_field
   }
   w.copy_bits(3, r);            // neutral_chroma_indication_flag, field_seq_flag, frame_field_info_present_flag
-  if (w.copy_bits(1, r) == 1) { // default_display_window_flag
+
+  if (   (r.get_remaining_bits() >= 68)
+      && (r.peek_bits(21) == 0x100000))
+    w.put_bit(0);                    // invalid default display window, signal no default_display_window_flag
+  else if (w.copy_bits(1, r) == 1) { // default_display_window_flag
     w.copy_unsigned_golomb(r);               // def_disp_win_left_offset
     w.copy_unsigned_golomb(r);               // def_disp_win_right_offset
     w.copy_unsigned_golomb(r);               // def_disp_win_top_offset
diff --git a/tests/results.txt b/tests/results.txt
index 25f4ece0a..661473224 100644
--- a/tests/results.txt
+++ b/tests/results.txt
@@ -431,3 +431,4 @@ T_582reading_mp4_with_and_without_track_order:3d668751b7ae3247e866a6cad96db6f2-3
 T_583dvbsub_four_bytes_codecprivate:4e16c6cb196dc6d60b799de8283498ba-4b457add4290c9cb39b792e2313e4043:passed:20170217-183748:0.078521662
 T_584ac_3_misdetected_as_mp3:true-5fa0a9abd94a7f555f519b013a55b980:passed:20170218-123152:0.369584022
 T_585h264_wrong_mapping_of_timestamps_to_frames:87acc96e91f17b007ab38b23da8cca1d:passed:20170318-172210:0.580192044
+T_586h265_invalid_default_display_window_in_sps_vui:f49d79d17235b95a154b5d951e48344f:passed:20170319-185708:0.186032079
diff --git a/tests/test-586h265_invalid_default_display_window_in_sps_vui.rb b/tests/test-586h265_invalid_default_display_window_in_sps_vui.rb
new file mode 100755
index 000000000..ca3847427
--- /dev/null
+++ b/tests/test-586h265_invalid_default_display_window_in_sps_vui.rb
@@ -0,0 +1,5 @@
+#!/usr/bin/ruby -w
+
+# T_586h265_invalid_default_display_window_in_sps_vui
+describe "mkvmerge / h.265 with an invalid default display window in the VUI parameters of the sequence parameter sets"
+test_merge "data/h265/invalid_default_display_window_in_sps_vui.h265"