Comment 45 for bug 334082

I just wrote a python skript which removes all defect entries (which have no duration tag) from rhythmbox's database. Store the script to your home directory, close rhythmbox and open a terminal. Run the following commands:
chmod u+x repairRhythmDb.py
./repairRhythmDb.py
mv .local/share/rhythmbox/rhytmdb.xml ./backupRhythmDb.xml
mv repaired_rhythmdb.xml .local/share/rhythmbox/rhythmdb.xml

Restard rhythmbox. It will add all files which have been removed because of their missing duration. Hopefully all of them will appear with a correct length afterwards. If not just run the last three commands again (while rhythmbox is closed).
With the help of the script my database of about 10,000 audio files was fixed after two runs.

Interesting fact: while coding the script I deleted the rhythmdb.xml-file an started rhythmbox to regenerate it. Suddenly only about 1% had a missing length. Yesterday I ended up with 30% of the files with missing duration. I can't remember any software change between yesterday and today.