I use Firefly (previously called mt-daapd) as a media server for my Roku Soundbridge. It has a feature called ‘Smart Playlists’ that dynamically create playlists based on certain criteria, but they aren’t that powerful - they don’t support sorting or other more advanced query features.

Fortunately, underlying Firefly is a sqlite database, which can be queried using standard SQL syntax. This enables a technique of creating static playlists that are automatically re-generated periodically instead.

The prerequisites for the following technique are:

• Perl, with the File::Spec module (to convert from absolute paths to relative ones, which is what Firefly expects).
• The sqlite3 command-line interface.

The three commands that follow will create a standard .m3u playlist with the top 100 most-played songs from Firefly’s database, and another playlist with all the non-Podcasts added in the last month, ordered by the time they were added. Neither of these are possible using Firefly’s query language.

sqlite3 /var/cache/mt-daapd/songs3.db 'select path from songs order by play_count desc limit 100' | perl -nle 'require File::Spec; $_ = File::Spec->abs2rel($_, "$PLAYLIST_DIR"); print;' > "$PLAYLIST_DIR/Most-played songs.m3u"
 
MONTHAGO=$(perl -e 'use Date::Calc::Object qw(:all); $date = Date::Calc>now(); $date += [0,-1,0,0,0,0]; print $date->mktime();')
 
sqlite3 var/cache/mt-daapd/songs3.db "select path from songs where genre!='Podcast' and time_added > $MONTHAGO order by time_added desc" | perl -nle 'require File::Spec; $_ = File::Spec->abs2rel($_, "$PLAYLIST_DIR"); print;' > "$PLAYLIST_DIR/Music added in last month by most recent.m3u"

(obviously, if you use these, you’ll need to alter paths to suit, make sure the correct Perl modules are installed, remove line breaks to make it easier to read, etc.)

Firefly will read these .m3us if configured correctly during its next rescan, and use them as it would any other playlists. You can force a rescan with the following wget command:

wget --delete-after -q --http-user noone --http-password yourpasswd "http://localhost:3689/config-update.html?action=rescan"

Although not fully dynamic (they are not generated on request from the Soundbridge), if these commands are called from cron or similar, the playlist can be kept up-to-date ‘enough’.