Matching Tracks

As described in the Player Status Summary discussion, the most convenient way to match a track is using metadata obtained from the players, so Beat Link Trigger asks the player hosting the track for details like its title, artist, and so on. You can use this information to automatically write out a playlist during a performance, as described below.

In earlier releases of Beat Link Trigger, automatically matching tracks was not nearly so easy or reliable, and required more tricky and elaborate efforts. This section describes them, for historical reference, and in case you want to understand more about what BLT is doing for you automatically.

If, for some reason, you don’t want to use the Show interface, and you are unable to get metadata (although as of version 0.5.0 we can’t think of any situations where this might apply), you can prepare ahead of time by hard-coding the rekordbox ID numbers in your triggers, or you can set up a Metadata Cache.

The simplest approach is to configure your triggers to Watch Any Player, and use a custom Enabled Filter expression to activate them when any player has loaded the track that the trigger cares about. For example, in the following screen shot we have two triggers watching for two specific tracks:

The Enabled Filter expression for the first trigger is as follows:

This activates the trigger whenever a player has loaded a track with the specified exact title and artist. The values available for matching are listed in the expression documentation you can scroll through in the bottom half of the expression editor window, and other metadata-based values include track-comment, track-genre, track-key, and track-length. The entire TrackMetadata object is available as track-metadata, if you want to use Clojure Java Interop to work with it.

In addition to using = to match entire strings, you can use re-matches with regular expressions for more flexible, loose matching. In addition to the basic Clojure documentation, the Java Pattern documentation provides details of how you can construct your regular expressions. For example, to match any track whose title begins with "Ember" you would use an expression like this:

Of course, you might also want the trigger to activate only when playback reaches a particular beat. You can combine as many different kinds of rules and logic as you need in your Enabled expression to achieve your goals:

To have the trigger active within a specific range of beats, you can express that in a single expression like so:

Including that within the trigger will enable it when a player that has loaded that specific track, and playback is positioned anywhere from beat 65 to 192, inclusive.

Another way to take advantage of metadata support is to write out a file that logs all the tracks that were played during a DJ set. Here is a simple example of how to do that, although you can certainly get fancier in terms of how you format the timestamps and what information you log.

Set up a Trigger that is configured to watch the Master Player, and install the following Tracked Update Expression:

Whenever this trigger is enabled, as soon as a new track is being played by whatever player is currently the tempo master, a new entry will be written to the playlist log. The file content will look like this:

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Distributed under the Eclipse Public License 1.0, the same as Clojure. By using this software in any fashion, you are agreeing to be bound by the terms of this license. You must not remove this notice, or any other, from this software. A copy of the license can be found in LICENSE within this project.