Problem with advanced title formatting
 

Hi

Currently I am using the following format to view files on my playlist:
$lower(%artist%) - $lower(%album%) - $lower($num(%tracknumber%,2)) - $lower(%title%)
so the format is artist - album - tracknumber - title

The problem is that i have _many_ mp3's which don't have tracknumber in their id3 tag. When the tracknumber info is missing, those files are shown in format:
artist - album-2003-ripper - tracknumber - title-ripper

My files are sorted by standard naming:
directory, for example artist-album_name-2003-ripper contains files 01-artist-song_name-ripper.mp3, 02-artist-song_name-ripper.mp3.

So WA takes all information from directory/filename, not only the tracknumber. Is it possible to only take the tracknumber from filename and load other info from id3 tag.

I have tried adding some [ .. ]'s to format, but they don't help anything - if tracknumber is missing from id3, all info is loaded from dir/filename.