Support NRPN?

[yaxu]

NRPN is a way to send high resolution data over MIDI CC messages https://www.elektronauts.com/t/nrpn-tutorial-how-to/46669

For example to change the x parameter on this alesis micron You send first send a two-byte controller identifier for it using CCs 99 and 98 99:0 98:44 (these being cc number, cc value pairs). You then send a two-byte value over CCs 44 (msb) and 38 (lsb), e.g. `44:6 38:4 = 128 * 6 + 4 = a value of 772.

The id and value is always sent over those four cc numbers. You might send the id once followed by a series of values in quick succession.

Here's an example of someone sending a value using supercollider: https://sccode.org/1-57O

I tried this in tidal: once $ cc "[99:0,98:44,6:0,38:9]" # s "midi"

Unfortunately the list comes through in a random order, so the sequence isn't set properly. This works: once $ cc "[99:0 98:44 6:7 38:0] ~@10000" # s "midi"

But it would be great if it could be sent as a name:value pair with supercollider doing the work to break it into bytes for sending as CC:s. e.g.:

once $ nrpn "44*16" # val sine # s "midi"`

[yaxu]

I've had a go, but just can't fathom supercollider out at all. Despite a lot of moving things around, I just get lots of ERROR: Message 'asInteger' not understood.

[telephon]

Maybe some of the variables are nil? The MIDIOut tries to interpret the nils as integers, and fails (probably the thrower is posted further below in the error message).

[telephon]

Are you sure your midicmd is really nil? The whole initialisation of the variabls happens only if this is the case (line 44).

[yaxu]

Yes midicmd is nil. I think maybe the ~ variables are global and so aren't held in the function closure?

[yaxu]

Yes that was it. Will test next time I'm with the synth

[yaxu]

I redid my changes, seems to work well now.

[yaxu]

This isn't working with negative values.

[yaxu]

Any ideas what this should be, to support sending negative numbers?

                    var nrpnMSB, nrpnLSB, valMSB, valLSB;
                    ~val = ~val ? 0;
                    nrpnLSB = ~nrpn % 128;
                    nrpnMSB = (~nrpn - nrpnLSB) / 128;
                    valLSB  = ~val % 128;
                    valMSB  = (~val - valLSB) / 128;
                    schedmidi.value({
                        midiout.control(chan, 99, nrpnMSB);
                        midiout.control(chan, 98, nrpnLSB);
                        midiout.control(chan, 6,  valMSB);
                        midiout.control(chan, 38, valLSB)
                    });

[yaxu]

The standard doesn't seem to permit negative numbers. http://www.somascape.org/midi/tech/spec.html#rpns

My synth demands them though. Hmm!

[bgold-cosmos]

I think it's up to the MIDI device to interpret the 14 bits, usually they use 2's complement. So I think something along these lines will work for both positive and negative values:

var x = -129;
var lsb = (x % 128);
var msb = ((x-lsb) /128) % 128;

i.e. you don't need to change your LSB, and just take % 128 of the MSB

[yaxu]

That worked, thanks a lot @bgold-cosmos !

[johanwk]

Seems Tidal won't send value 0 for CC 38. The midi monitor shows that the following resends the last occurrence of CC 6 instead of CC 38 with value 0.

once $ ccn 38 # ccv 0 # s "midi"

This means that NRPN codes that require CC 38 = 0 won't work. I came across this trying to control the Elektron A4.

For example, this goes wrong, with nrpnv value 4096: once $ nrpnn 128 # nrpnv 4096 # s "midi" # midichan 8, returning

Channel Value
9   99  1
9   98  0
9   6   32
9   6   32

while values that don't imply value 0 for CC 38 are fine; once $ nrpnn 128 # nrpnv 4097 # s "midi" # midichan 8 returns

Channel Value
9   99  1
9   98  0
9   6   32
9   6   32
9   38  1

(but note that CC 6 is sent twice).