[vlc-devel] [PATCH 2/4] demux: mkv: truncate length on preskip, don't set negative pts

[Francois Cartegnie]

Same as other demuxers do with preskip

refs #25129
---
 modules/demux/mkv/mkv.cpp | 20 ++++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)

diff --git a/modules/demux/mkv/mkv.cpp b/modules/demux/mkv/mkv.cpp
index 82f464a74a..2af7d5c87b 100644
--- a/modules/demux/mkv/mkv.cpp
+++ b/modules/demux/mkv/mkv.cpp
@@ -547,8 +547,6 @@ void BlockDecode( demux_t *p_demux, KaxBlock *block, KaxSimpleBlock *simpleblock
         return;
     }
 
-    i_pts -= track.i_codec_delay;
-
     if ( track.fmt.i_cat != DATA_ES )
     {
         bool b;
@@ -695,6 +693,24 @@ void BlockDecode( demux_t *p_demux, KaxBlock *block, KaxSimpleBlock *simpleblock
         }
         else
         {
+            if( track.i_codec_delay ) /* Handle pre-skip */
+            {
+                if( i_pts > track.i_codec_delay )
+                {
+                    p_block->i_length -= track.i_codec_delay;
+                }
+                else
+                {
+                    vlc_tick_t skipped = i_pts - track.i_codec_delay;
+                    if( p_block->i_length <= skipped )
+                    {
+                        p_block->i_length = 0;
+                        p_block->i_flags |= BLOCK_FLAG_PREROLL;
+                    }
+                    else p_block->i_length -= skipped;
+                }
+            }
+
             // correct timestamping when B frames are used
             if( track.b_dts_only )
             {
-- 
2.25.4