Rekordbox OSC

Ableton Link & OSC support for Rekordbox, to connect to visualisers and music software

What does it do?

When run on the same computer as an instance of Rekordbox, it will read the current timing information and send this over your protocol of choice. By default it outputs a 4-beat aligned signal using Ableton Link, but it can also transmit equivalent data over OSC, although with less accurate timing.

The program does not interact with the audio stream in any way, but reads the onscreen text values through memory. Thus your beatgrid must be correct for it to work as expected.

Why?

Rekordbox's Ableton Link integration only allows for receiving a signal, not extracting it.

Usage

rkbx_osc.exe [flags] where

 -h  Print help and available versions
 -u  Fetch latest offset list from GitHub and exit
 -v  Rekordbox version to target, eg. 6.7.3

-- OSC --
 -o  Enable OSC
 -s  Source address, eg. 127.0.0.1:1337
 -t  Target address, eg. 192.168.1.56:6667

If no arguments are given, it defaults to the latest supported rekordbox version and Ableton Link. If OSC is enabled, it will send to 127.0.0.1:6669. As messages are sent with UDP, source address should not need to be set.

OSC Addresses

/beat: the current beat fraction, as a float counting from 0 to 1
/bpm: the master deck tempo in BPM

Supported versions

~~Any version not listed will 99% not work, but you can always try using an adjacent version.~~ As of 7.0.1 the offsets do not seem to change. I hope it continues this way.

Rekordbox Version
7.0.1, 7.0.0
6.8.5, 6.8.4, 6.8.3, 6.8.2, 6.7.7, 6.7.4, 6.7.3

How it works

The timing information is extracted through reading Rekordbox's memory. The program reads the current beat and measure from the text display on top of the large waveform, and detects when these change. When a change occurs, the beat fraction is set to 0 and then counts linearly upwards at a pace dictated by the master track BPM.

Limitations

Only supports two decks.
Might register an extra beat when switching master deck.
Assumes 4/4 time signature - Rekordbox does not support anything else without manually editing the database
Windows only

Technical Details

Offsets file format

The offsets file contain the hex memory addresses (without the leading 0x) for the values we need to fetch. The file supports basic comments (# at start of line). Versions are separated by two newlines.

Example entry with explanations:

7.0.0                   Rerkordbox Version
052EA410 28 0 48 2468   Deck 1 Bar
052EA410 28 0 48 246C   Deck 1 Beat
052EA410 28 0 50 2468   Deck 2 Bar
052EA410 28 0 50 246C   Deck 2 Beat
0544A460 28 180 0 140   Masterdeck BPM
052413A8 20 278 124     Masterdeck index

Updating

Previously, every Rekordbox update the memory offsets changed. From 7.0.0 -> 7.0.1 the old offsets continued working. When the pointers change, I use Cheat Engine, using pointerscans and trying to find the shortest pointer paths.

Easiest method seems to be to find each value, pointerscan, save that, then reopen rekordbox and filter the pointerscans by value. If you can't find any values, try increasing the maximum offset value to something like 32768, offsets = 16. To save performance you can set max level to 5 or 6, paths should not be longer than that.

Updates are welcome, put them in the offsets file.

`master_bpm`

The BPM value of the current master track. Find by loading a track on deck 1 & 2, then search for a float containing the BPM of the deck currently set as Master. Find a value that matches exactly and make sure it doesn't oscillate when you play on that deck.

`masterdeck_index`

The index of the deck currently set as Master. 0 for deck 1, 1 for deck 2. Not sure if the value I've found is the index of the selected deck, or a boolean dictating if Deck 2 is master. Search for a byte.

This one is usually the trickiest. There are a couple of other values wich correlate but actually change on hover etc., so be careful. The path should not be longer than 4 addresses, so find a bunch of candidates (should be able to reduce to <30) and then pointer scan for each until you get a short one - that should be it.

`deck1, deck2, bar, beat`

On the waveform view, these are the values "xx.x" showing the current bar and beat. The second to last value in the offset chain is the same per deck, and the last is the same per beat/bar. Thus, if you find Deck1 Bar and Deck2 Beat, you can calculate Deck1 Beat and Deck2 Bar.

Notes on timing

Windows, by default, only has sleeps in increments of ~16ms. As such, the the sending frequency is a bit uneven. The rate is set to 120Hz in the code, but that results in about 60Hz update rate. I'm not sure if the method measuring the delta time is accurate enough, or

grufkork / rkbx_osc