@@ -3316,15 +3316,13 @@ static int mov_write_header(AVFormatContext *s)

     enable_tracks(s);

-    if (mov->mode == MODE_ISM) {

+    if (mov->flags & FF_MOV_FLAG_FRAGMENT) {

         /* If no fragmentation options have been set, set a default. */

         if (!(mov->flags & (FF_MOV_FLAG_FRAG_KEYFRAME |

                             FF_MOV_FLAG_FRAG_CUSTOM)) &&

             !mov->max_fragment_duration && !mov->max_fragment_size)

             mov->flags |= FF_MOV_FLAG_FRAG_KEYFRAME;

-    }

-

-    if (!(mov->flags & FF_MOV_FLAG_FRAGMENT)) {

+    } else {

         if (mov->flags & FF_MOV_FLAG_FASTSTART)

             mov->reserved_moov_pos = avio_tell(pb);

         mov_write_mdat_tag(pb, mov);