Hi all,

I am having a weird issue, not sure whether it is actually due to Pd or not: in order to turn on and off the LEDs of my Midi controller, I need to send it a noteon message with a velocity of 1 (turn on), 2 (blink) or 0 (off). This works very well on one of my machines with Debian 10, Pd vanilla version 0.49.0-3 or Pd-L20rk 2.15.2, by sending [64 1( or [64 2( or [64 0( to [noteout 1], however on another machine with also Debian 10, Pd vanilla 0.49.0-3, only the velocities of 1 or 2 make the LED turn on or blink, but impossible to turn it off with a velocity of 0!
I first thought that it may be due to Pd interpreting NoteOn with velocity of 0 as NoteOff, but it works fine on one of the computers.

Jack is started on both machines with -dalsa -Xseq and I run a2j -e to access the Midi devices through Alsa. If I stop a2j I can successfully turn the LEDs on and off with amidi -phw,2 -S "90 40 01" or 00". So I am ruling out the hardware/driver issue.

What else could it be, any idea anyone? I shall check the version of a2j later today, but they are both up-to-date using Debian buster repos so I doubt I'll find any difference there...

Sorry if this turns out to actually not be related to Pd, but I hope someone may be able to help anyway
Thanks!

So, continuing my investigations, I have had no more success with [cyclone/xnoteout] and raw hex midi messages sent to [midiout]. And not better either if I start jack with -Xraw, and both laptops use the same version of a2jmidid.

Two more details:

• laptop where it works: Jack 1.9.14, 64 bits
• laptop where it doesn't work: Jack 1.9.12, 32 bits. I could try to upgrade jack to 1.9.14 but it may have to use different repositories or potentially mess up dependencies.

Try taking a look at the midi steam with amidi, watch the port and see what pd actually sends when you send velocity 0 and 1. Will help narrow things down.

Thank you @oid , I should have thought about that right away!
Turns out that aseqdump doesn't show any difference (NoteOn with velocity 0 is interestingly displayed as NoteOff, but it works anyway on the 64bits machine to turn off the LED).

I found one cause by chance however: If I connect Pd with the MIDI device via ALSA-MIDI, it works fine, but if I connect them via JACK-MIDI, I can't turn off the LEDs!

So when I connect PD with the controller with aconnect 130:1 24:0 it does work fine on both laptops. Not sure whether that might be caused by a2jmidid in the end, but I guess it is solved (and indeed not related to Pd!).