Fix seek in mka

Fix #6078
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>
(cherry picked from commit 7098f402)
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

modules/demux/mkv/matroska_segment.cpp

@@ -690,6 +690,7 @@ void matroska_segment_c::Seek( mtime_t i_date, mtime_t i_time_offset, int64_t i_
     mtime_t     i_pts = 0;
     spoint *p_first = NULL;
     spoint *p_last = NULL;
+    int i_cat;
 
     if( i_global_position >= 0 )
     {
@@ -772,9 +773,12 @@ void matroska_segment_c::Seek( mtime_t i_date, mtime_t i_time_offset, int64_t i_
     es_out_Control( sys.demuxer.out, ES_OUT_SET_NEXT_DISPLAY_TIME, i_date );
 
     /* now parse until key frame */
+    const int es[3] = { VIDEO_ES, AUDIO_ES, SPU_ES };
+    for( int i = 0, i_cat = es[0]; i < 2; i_cat = es[++i] )
+    {
         for( i_track = 0; i_track < tracks.size(); i_track++ )
         {
-        if( tracks[i_track]->fmt.i_cat == VIDEO_ES )
+            if( tracks[i_track]->fmt.i_cat == i_cat )
             {
                 spoint * seekpoint = new spoint(i_track, i_seek_time, i_seek_position, i_seek_position);
                 if( unlikely( !seekpoint ) )
@@ -799,6 +803,12 @@ void matroska_segment_c::Seek( mtime_t i_date, mtime_t i_time_offset, int64_t i_
                 }
             }
         }
+        if( likely( p_first ) )
+            break;
+    }
+    /*Neither video nor audio track... no seek further*/
+    if( unlikely( !p_first ) )
+        return; 
 
     while( i_pts < i_date )
     {
@@ -825,7 +835,7 @@ void matroska_segment_c::Seek( mtime_t i_date, mtime_t i_time_offset, int64_t i_
             i_pts = sys.i_chapter_time + block->GlobalTimecode() / (mtime_t) 1000;
         if( i_track < tracks.size() )
         {
-            if( tracks[i_track]->fmt.i_cat == VIDEO_ES && b_key_picture )
+            if( tracks[i_track]->fmt.i_cat == i_cat && b_key_picture )
             {
                 /* get the seekpoint */
                 spoint * sp;