midiclock.py cannot detect 'master' state from CDJ-2000 because it doesn't exist

[mrobinson513]

TL;DR - got it to work by changing the script to use client.play_state instead of client.state. Use with caution.

Good day,

Maybe this isn't really an "issue", but maybe someone will have an idea how to make it work.

I was attempt to use midiclock.py to sync a hardware device connected via USB. The script works as intended, but I noticed that there was no BPM change when I adjusted the slider on either of my playing CDJ-2K decks.

Looking at the code, I noticed that the update_master() callback function does nothing unless one of the decks returns "master" from client.state. Since the original 2000s don't have beat sync, there is no value in state.

The only logical workaround I could think of was to modify so that it checked if client.play_state == "playing". Now, this is fine when only one deck is playing, but if it's more than one, the resulting MIDI clock signal flips back and forth between the BPMs of each deck. If they're the same tempo, or at least reasonably close (within ~0.1 BPM) this is a non issue. And for many of us in the EDM/Dance scene, we usually beatmatch anyway. But while prepping the next track, one deck's BPM can change more dramatically; I haven't even tried to see how it responds to a backspin yet.

I don't know if there's a way to get the midiclock script to check the play state of both decks, since it's reacting to incoming packets regardless of where they come from.

If any reading this has any ideas, please do share. I'll obviously update if I figure something out on my own, and push up a PR accordingly.

[brunchboy]

For situations like this in Beat Link Trigger, I let you configure a variety of ways to determine which player is considered relevant for a trigger that is driving MIDI clock (I call it the Enabled filter): Master works well for nexus and later players as long as the DJ is using sync. If the mixer and players support the Channels On-Air feature, then you can use that as your Enabled filter; the CDJ you are using to prep a track is generally not on the air. But that may not work for pre-nexus players either; the first gear I bought were CDJ-2000 nexus and a DJM-2000 nexus. However, a player that is not playing is never considered enabled.

In your case you might have to add custom code or explicitly choose which player to watch, even in Beat Link Trigger. I am not sure how many such facilities exist in python-prodj-link.

[flesniak]

Good catch, I have not tested the midiclock with any pre-nexus devices. To be fair, the code is in quite a rough shape and I haven't used it for a long time. Beat Link Trigger is definitely much more mature, especially when looking at the midi stuff.

If you have a nexus mixer, players get their player.on_air property updated. Otherwise it's tough and you probably need some custom code, as @brunchboy said, no matter which software you use.