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To use this, install it through your Scripts manager in amaroK, then select it from the list and click Run. If everything is OK, you’ll see a yellow status message in the playlist window saying Smart DJ is analyzing your collection. Be very, very patient, because analyzing each song takes a minimum of 20 seconds.

Whenever you play a song while watching the Current tab in the Context Browser, Smart DJ will add its list of suggestions (Similar Tracks) right above the Favorite Tracks box. If a song has not been analyzed yet, do not worry: Smart DJ will quietly bump it to the top of its to-do list, and in a few seconds, you’ll see the Similar Tracks box appear in the Current tab.

The following functionality requires you to have certain GUI components installed on your computer. See below, in the requirements section, for more information on the subject.

You can, as well, directly right-click on a song in your playlist and select Smart DJ->Find songs similar to selection… to get a list of songs sorted by similarity against the one you selected.

Auto DJing with Smart DJ’s Auto DJ

To use Auto DJ, select the plug-in in the Scripts manager and click Configure. The Auto DJ options are self-explanatory: all you need to do is enable it, set the options you want (the defaults are very good starters), and start playing a song of your choice. Auto DJ will analyze the song you’re playing (or the last song in the playlist, depending on your chosen settings) and start locating similar files to add to the playlist. Auto DJ will not add songs already on your playlist, or songs that Auto DJ added to the playlist but you removed. You can let Auto DJ choose songs from your entire collection, or from among any of your saved smart playlists. You can also let Auto DJ make a big playlist even before starting to play: all you have to do is let Auto DJ you want to use the last song in your playlist as your reference, and set a large number of songs to be added.

About the analysis

If you want to know how far along the analysis is, you can select the plug-in in the Scripts manager and click Configure, a small window with a progress bar will appear.

Viewing the song tempo in the playlist

Although you can’t normally see the tempo of songs in the standard version of amaroK, a special patch is distributed with this plug-in. If you know how to patch amaroK’s source code and recompile it from scratch, you can apply the patch, which will add a new column named “Tempo” in the playlist.

Frequently asked questions

How does this wonderful wonder work?

Smart DJ does this by performing magic… ehhrmm… running a series of analysis on the songs in your collection, collecting tempo and frequency distribution from each song and storing the information in the collection database. This process is assisted by songanalysis, another program. Songanalysis computes both tempo and relative intensity across 30 frequency bands. This is later compared against the entire collection (pretty quickly, I must say, thanks to your favorite SQL engine), and a compatibility score is computed for each song.

How do I turn on this “extended attributes” thing?

That’s rather easy.

Each file system needs to be mounted with an extra option called user_xattr. To see if this is supported on your system, issue the following command on a command prompt, as root:

mount / -o remount,user_xattr

If you do not get any error message, then you’re all set: you have extended attribute support. Do the command for all other file systems where you store your songs (use the mount command alone to find out about the rest of your file systems).

To make this change permanent (across system restarts), edit the /etc/fstab file and change the mount options field (for each file system where you have your songs), adding user_xattr where appropriate, or replacing the defaults keyword by user_xattr.

By the way, this will be notoriously impossible to do if you’re using a Windows (VFAT) file system to store your music files. VFAT file systems have no support for extended attributes at all. Do yourself a favor and reformat your disk to use either ReiserFS, ext3 or another true UNIX file system.

Remember, extended attributes are optional.

Why are extended attributes used?

Analyzing a song takes quite a while (about 30 seconds for each song).

If you moved your song files to a new directory, and the analysis results were stored only in the collection database, this plug-in would need to analyze each song again, because since the path to the file changed, there would be no way to correlate the already stored information to the new file location.

So, to alleviate this problem, Smart DJ stores the analysis results on extended attributes, so when a file is about to be analyzed we can check whether the analysis was already performed on that file and then simply collect the analysis results, saving you time and electricity.

This is not infallible, of course. If you had file /a/b/c.mp3 and you delete it, replacing it with another file at exactly the same /a/b/c.mp3 location but a different content (and, of course, different attributes) this plug-in won’t detect the special case. There is a solution, but I’m quite lazy to start working on it just about right now.

And, by the way, if you actually rename a file on disk, or move it somewhere else (in your collection folders, of course) even though amaroK would still show that file on your collection browser, you would lose your statistics for that song (play counter, last play date and rating). This is a bug in amaroK.

I’m working on a long-term solution to this problem.