the just one place it is used:
```
    if (!bd->title && bd->title_type == title_bdj) {
        /* BD-J title running but no playlist playing */
        _queue_event(bd, BD_EVENT_IDLE, 0);
        return 0;
    }
```
in ```static int _read_ext(BLURAY *bd, unsigned char *buf, int len, BD_EVENT *event)``` in bluray.c