Simple example to just send note on and note off

[brandflake11]

Hello,

Thank you very much for making this library. I would like to know if there is a simple example of sending a simple note-on and note-off. What are the bare essentials for doing that? I've checked out the example 4 file, and I'm having a really hard time following it.

Thank you very much for your help!

[osch]

ljack provides a binding for the jackaudio which is a rather technical low level api.

You might also want to have a look at lrtmidi, example lrtmidi/example03.lua.

I tried to make a similar example for ljack:

local nocurses = require("nocurses") -- https://github.com/osch/lua-nocurses
local carray   = require("carray")   -- https://github.com/osch/lua-carray
local mtmsg    = require("mtmsg")    -- https://github.com/osch/lua-mtmsg
local auproc   = require("auproc")   -- https://github.com/osch/lua-auproc
local ljack    = require("ljack")

----------------------------------------------------------------------------------------------------

local MIDI_CHANNEL = 1

local format = string.format

local function printHelp()
    print(format("Press keys c,d,e,f,g,a,b,C for playing MIDI notes on channel %s, q for Quit", MIDI_CHANNEL))
end

----------------------------------------------------------------------------------------------------

local client     = ljack.client_open("example041.lua")
local myMidiPort = client:port_register("midi_out", "MIDI", "OUT")

local midiOutQueue = mtmsg.newbuffer()
local midiSender   = auproc.new_midi_sender(myMidiPort, midiOutQueue)

client:activate()
midiSender:activate()

----------------------------------------------------------------------------------------------------

-- For midi protocol details see for example: 
--   - https://ccrma.stanford.edu/~craig/articles/linuxmidi/misc/essenmidi.html
--   - https://learn.sparkfun.com/tutorials/midi-tutorial/all


local NOTE_OFF = 0x80
local NOTE_ON  = 0x90

local noteBytes = { -- maps note name to midi byte
    c = 60,
    d = 62,
    e = 64,
    f = 65,
    g = 67,
    a = 69,
    b = 71,
    C = 72
}

local function sendMidiBytes(byte1, byte2, byte3)
    local midiBytes = carray.new("uint8"):append(byte1, byte2, byte3)
    midiOutQueue:addmsg(midiBytes)
end

local function playNote(n)
    local noteByte = noteBytes[n]
    if noteByte then
        sendMidiBytes((NOTE_ON  + (MIDI_CHANNEL - 1)), noteByte, 127)
        sendMidiBytes((NOTE_OFF + (MIDI_CHANNEL - 1)), noteByte,   0)
        return true
    end
end

----------------------------------------------------------------------------------------------------

printHelp()

while true do
    local c = nocurses.getch()
    if c then
        c = string.char(c)
        if c == "Q" or c == "q" then
            print("Quit.")
            break
        else
            if playNote(c) then
                print(format("playing note %s", c))
            else
                printHelp()
            end
        end
    end
end