[vlc-commits] packetizer: hevc: workaround sps vui broken bitstream

[Francois Cartegnie]

vlc | branch: master | Francois Cartegnie <fcvlcdev at free.fr> | Fri May 18 13:50:57 2018 +0200| [d8686ad223752f4b8abcf3ace5a2c77af7bb14ea] | committer: Francois Cartegnie

packetizer: hevc: workaround sps vui broken bitstream

more wtf in the wild

> http://git.videolan.org/gitweb.cgi/vlc.git/?a=commit;h=d8686ad223752f4b8abcf3ace5a2c77af7bb14ea
---

 modules/packetizer/hevc_nal.c | 26 +++++++++++++++++++++-----
 1 file changed, 21 insertions(+), 5 deletions(-)

diff --git a/modules/packetizer/hevc_nal.c b/modules/packetizer/hevc_nal.c
index 8e649b93ee..970aed526e 100644
--- a/modules/packetizer/hevc_nal.c
+++ b/modules/packetizer/hevc_nal.c
@@ -437,7 +437,8 @@ static bool hevc_parse_scaling_list_rbsp( bs_t *p_bs )
     return true;
 }
 
-static bool hevc_parse_vui_parameters_rbsp( bs_t *p_bs, hevc_vui_parameters_t *p_vui )
+static bool hevc_parse_vui_parameters_rbsp( bs_t *p_bs, hevc_vui_parameters_t *p_vui,
+                                            bool b_broken )
 {
     if( bs_remain( p_bs ) < 10 )
         return false;
@@ -488,7 +489,7 @@ static bool hevc_parse_vui_parameters_rbsp( bs_t *p_bs, hevc_vui_parameters_t *p
     p_vui->field_seq_flag = bs_read1( p_bs );
     p_vui->frame_field_info_present_flag = bs_read1( p_bs );
 
-    p_vui->default_display_window_flag = bs_read1( p_bs );
+    p_vui->default_display_window_flag = !b_broken && bs_read1( p_bs );
     if( p_vui->default_display_window_flag )
     {
         p_vui->def_disp.win_left_offset = bs_read_ue( p_bs );
@@ -897,9 +898,24 @@ static bool hevc_parse_sequence_parameter_set_rbsp( bs_t *p_bs,
         return false;
 
     p_sps->vui_parameters_present_flag = bs_read1( p_bs );
-    if( p_sps->vui_parameters_present_flag &&
-        !hevc_parse_vui_parameters_rbsp( p_bs, &p_sps->vui ) )
-        return false;
+    if( p_sps->vui_parameters_present_flag )
+    {
+        bs_t rollbackpoint = *p_bs;
+        if( !hevc_parse_vui_parameters_rbsp( p_bs, &p_sps->vui, false ) &&
+            p_sps->vui.default_display_window_flag &&
+            bs_remain( p_bs ) < 66 )
+        {
+            /* Broken MKV SPS vui bitstreams with missing display_window bits.
+             * Forced to accept it since some decided to accept it...
+             * see https://trac.ffmpeg.org/ticket/6644
+             * Might break decoders since cropping & clock rate have totally
+             * funky values when decoded properly */
+            *p_bs = rollbackpoint;
+            memset( &p_sps->vui, 0, sizeof(p_sps->vui) );
+            if( !hevc_parse_vui_parameters_rbsp( p_bs, &p_sps->vui, true ) )
+                return false;
+        }
+    }
 
     /* incomplete */