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Sample clients for Harvester (a.k.a. "Traktor Metadata Listener")

These are some sample clients in various languages You can use with Disco-Nova's Harvester v0.0.5 (considered "perpetually Beta"; it's a hobby project).

Some users thought the point of the v0.0.5 upgrade of the Harvester was the silly browser-based visualization built into the server ... nothing could be further from the truth. The actual point instead was to create a simple API for other developers to toy with and create their own implementations around it.

So... here are some samples for Y'all. Enjoy, expand, go wild. Peace out!

But... first things first

  • You need to download Harvester
  • There is no installation; the zip file contains:
    • 32- and 64- bit versions for OSX
    • An executable file for Windows
  • You should start the appropriate version from the command line
    • On Mac (OSX) that means you need to fire up Terminal
    • On Windows that means you need to fire up cmd.exe (I think, I'm very bad with Windows stuff:)
  • And... If You got lost on the previous step ... I don't want to sound too condescending, but since all of this is supposed to be targeted for tinkerers ... most of these samples probably will not make too much sense.
  • Configure Your Traktor to broadcast whatever You're playing to Harvester (by default, the broadcast server address should be and port 8080 ... Your mileage may vary).

And then...

At this point, You've either moved onto something more productive ... or are still here, and interested in what you can actually do with the API.

So... in case You're are still here, You're exactly the kind of tinkerer who might get something out of this repository.


  • Shell scripting on *nix family (Linux, Mac OSX, etc.)
  • Python ... on *nix family (Linux, Mac OSX, etc.) ... and Windows (assuming You've got functional WSL, "Windows Subsystem for Linux") with Python3.

Common gotchas

There are a few things that often cause problems for beginners;

Harvester issues


  • Harvester-server executables are command-line applications. While they can be executed by double-clicking on the executable on supported platforms (Win32 / OSX both 32bit/64bit) ... the recommended way to start them is to:
    • manually start a Terminal client;
      • on Windows: shortcut Windows-key + R and execute CMD.exe or
      • on OS X: shortcut CMD-key + SPACE and execute
    • within the Terminal client, navigate to the Harvester-server folder and
    • start the server executable for the platform (regardless of system architecture)
      • metadata-win32.exe on Windows
      • metadata-osx-universal on OS X

Traktor connectivity

  • You need to have Traktor's Preferences under the "Broadcasting"-view set up for the Harvester-server:
    • The minimum settings necessary are the "Address" and "Port" (defaults "" and "8080", assuming the Harvester-server is running on the local machine with default settings). The current versions of Harvester expect "Mount Path" and "Password" to be empty (these might be implemented in future versions for multi-user Harvester setup, but for the time being, both of these are unnecessary).
    • For "Format", You can choose any of the available options; at the moment Harvester is not using the audio data at all. Note however that the various options do cause a slight overhead on CPU usage ... usually, though - no matter which format You choose, should be negligible.
  • You connect to the Harvester-server using Traktor's "Audio Recorder". Once the settings above have been set up and the server is running, connecting to Harvester-server should only require You to click on the "Broadcast"-button.
    • If/when the connection is successful, the button lights up solid cyan.
    • If the connection fails, the button will be blinking cyan/gray.
    • If the connection fails while the Harvester-server is running, the Terminal window running the server may have some more information regarding the connectivity problem. Also, the logfile metadata.log may contain extra information. More often than not, the connection failure is due to an invalid address and/or port setting in Traktor preferences.

Metadata issues

  • Traktor only sends the metadata (i.e. artist-/track-names) into the broadcast stream when the track has been "playing" for ~10 seconds. The track is considered "playing" if/when the track's volume is "not zero" ... both the track volume fader and, when applicable, crossfader need to be in proper ... however, unlike some users have been reporting, the track does not need to be assigned "tempo master". This can sometimes lead to situations where the track metadata gets sent before the DJ intends. Also...
  • Traktor will only send the metadata into the broadcast stream once. This means that when:
    1. You play Track A for more than 10s, Traktor will send metadata for Track A to Harvester
    2. You overlay Track B's vocals (for example) on top of Track A for more than 10s, Traktor will send metadata for Track B to Harvester
    3. You get back to playing Track A only and eventually mix over to Track B ... you won't get Track A or Track B metadata sent "again" during this mix.
  • The most common issue with metadata is that Traktor doesn't seem to be sending it into the broadcast stream always - or seems to be sending nonsensical metadata that does not get picked up by the Harvester. This is usually caused by not having proper metadata in the track; the metadata Traktor does send is the same you can see and edit within Traktor by selecting the track, right-clicking, and choosing "Edit";
    • e.g.
      • for MP3s, this is generally either the ID3v2.x.x tag physically stored at the beginning of the track (or, if one is not present, the ID3v1 tag physically stored at the end of the track). Most tracks published since the mid-1990s already come with ID3v2.x.x tags and Traktor converts ID3v1 tags to ID3v2.x.x whenever the data is modified
      • for MP4s, the metadata is stored in MPEG4-container metadata atoms following the iTunes metadata-style
      • for FLACs, WAVs, and OGGs the metadata is stored in the container formats' own metadata format's private fields
    • Traktor does not seem to support mid-stream metadata within the container (which most above-mentioned formats support) for a single file; only a single set of metadata.


Example clients you could use with Disco-Nova's Harvester for Traktor metadata







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