1 files changed, 6 insertions, 4 deletions
diff --git a/libhb/muxmkv.c b/libhb/muxmkv.c
index 227159579..b1927ff80 100644
--- a/libhb/muxmkv.c
+++ b/libhb/muxmkv.c
@@ -473,17 +473,19 @@ static int MKVMux( hb_mux_object_t * m, hb_mux_data_t * mux_data,
             return 0;
         }
     }
-    else if ( mux_data->subtitle )
+    else if (mux_data->subtitle)
     {
-        uint64_t   duration;
-        timecode = buf->s.start * TIMECODE_SCALE;
         if( mk_startFrame(m->file, mux_data->track) < 0)
         {
             hb_error( "Failed to write frame to output file, Disk Full?" );
             *job->die = 1;
         }
-
+        uint64_t duration;
+        timecode = buf->s.start * TIMECODE_SCALE;
         duration = buf->s.stop * TIMECODE_SCALE - timecode;
+        // PGS subtitles have negative durations (buf->s.start - 0)
+        if (duration < 0)
+            duration = 0;
         mk_addFrameData(m->file, mux_data->track, buf->data, buf->size);
         mk_setFrameFlags(m->file, mux_data->track, timecode, 1, duration);
         mk_flushFrame(m->file, mux_data->track);