MIDI handshake for Pioneer DJ DJM-250MK2 to enable recording LINE/PHONO channels

[František Kučera]

Dne 25. 08. 20 v 17:36 František Kučera napsal(a):
> 1) The direct (before fader) PHONO/LINE recording channels are silent until some (yet unknown) special command is send to the mixer. There is quite a lot communication over USB in both directions and I have to dig through the dumps. This would be a separate commit and I do not know, how long it could take.

As mentioned earlier, the Pioneer DJM devices are somehow broken and by default they produce only silence on LINE/PHONO recording channels.

It was really challenging but it is no more hopeless – in the meantime, someone described, how it works inside, and I wrote a standalone program called djm-fix that fixes the device and enables the LINE/PHONO channels (so the mixer is usable e.g. for DVS). Details are described here: <https://blog.frantovo.cz/c/387/>. The djm-fix tool is still a bit raw, but it works for me and at least one more DJM-250MK2 owner confirmed, that it works.

Is it possible to move this fix to the kernel level? Or should it stay rather as a standalone tool? I think that it would be nice to have Pioneer DJM devices fully working out of the box without additional tools.

The fix consists of a MIDI handshake – we need to send and receive some messages, compute some hash and then periodically send a keep-alive message (when we stop, the LINE/PHONO channels become silent again).

Franta