Tvheadend

Is there any way to get the "sub-title" field from the xmltv data exported to the file name? It shows up in the EPG data without problems, but it isn't written out to the filename.

If it helps, here is an xmltv snippet showing how the sub-title field contains the actual episode title:

<programme start="20130215163000 -0800" stop="20130215170000 -0800" channel="I5.164164967.microsoft.com">
        <title lang="en">American Dad</title>
        <sub-title lang="en">The Unbrave One</sub-title>
        <desc lang="en">Steve takes on a superhero persona to prove he is a macho man; Francine receives shocking news.</desc>

(Even if I could get pointed in the right direction here, I'd be glad to play around with the source code to try to get this to work).