README.md

PortMidi.jl

A Julia wrapper for the C library PortMidi. See the C documentation for a list of functions.

This wrapper is work in progress.

Example

See the examples folder for a test case.

using PortMidi 

Pm_Initialize()

# 0. Get info about devices
for i in 0:Pm_CountDevices()-1
    info = unsafe_load(Pm_GetDeviceInfo(i))
    println(i, ": ", info.output > 0 ? "[Output ] " : "[Input] ", unsafe_string(info.name), " (", unsafe_string(info.interf), ")")
end

# 1. Select device
id = 0  # change this number if needed
print("Use: ", unsafe_string(unsafe_load(Pm_GetDeviceInfo(id)).name))

# 2. Open device 
stream = Ref{Ptr{PortMidi.PortMidiStream}}(C_NULL)
Pm_OpenOutput(stream, id, C_NULL, 0, C_NULL, C_NULL, 0)
# don't forget to call later: Pm_Close(stream[])

# 3. Send MIDI messages 
Note_ON = 0x90
Note_OFF = 0x80
C4 = 60

function play_note(stream, note, velocity, duration)
    Pm_WriteShort(stream[], 0, Pm_Message(Note_ON, note, velocity))
    sleep(duration)
    Pm_WriteShort(stream[], 0, Pm_Message(Note_OFF, note, velocity))
end

# make a random tune...
for i in 1:12
    @async play_note(stream, C4 + rand([-5,-2,0,2,5]), rand(80:120), 0.4 + 0.05*rand())
    sleep(0.5 + 0.05*rand())
end

# 4. Close device
Pm_Close(stream[])

On Windows, one could use the program loopMIDI to create a virtual MIDI device and in combination with some virtual instruments (e.g. DAWs, VCV Rack, ...) one can also then listen to the notes in realtime. But this is only one out of many possible ways to use the PortMidi library.