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https://github.com/rakyll/portmidi

Go bindings for libportmidi
https://github.com/rakyll/portmidi

Last synced: 3 months ago
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Go bindings for libportmidi

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# portmidi

Want to output to an MIDI device or listen your MIDI device as an input? This

package contains Go bindings for PortMidi. `libportmidi` (v. 217) is required as a dependency, it's available via apt-get and brew.



~~~ sh

apt-get install libportmidi-dev

# or

brew install portmidi

~~~



Or, alternatively you can download the source and build it by yourself. See

the instructions on [PortMidi homepage](http://portmedia.sourceforge.net/portmidi/).



In order to start, go get this repository:

~~~ sh

go get github.com/rakyll/portmidi

~~~



## Usage



### Initialize

~~~ go

portmidi.Initialize()

~~~



### About MIDI Devices



~~~ go

portmidi.CountDevices() // returns the number of MIDI devices

portmidi.Info(deviceID) // returns info about a MIDI device

portmidi.DefaultInputDeviceID() // returns the ID of the system default input

portmidi.DefaultOutputDeviceID() // returns the ID of the system default output

~~~



### Write to a MIDI Device



~~~ go

out, err := portmidi.NewOutputStream(deviceID, 1024, 0)

if err != nil {

    log.Fatal(err)

}



// note on events to play C major chord

out.WriteShort(0x90, 60, 100)

out.WriteShort(0x90, 64, 100)

out.WriteShort(0x90, 67, 100)



// notes will be sustained for 2 seconds

time.Sleep(2 * time.Second)



// note off events

out.WriteShort(0x80, 60, 100)

out.WriteShort(0x80, 64, 100)

out.WriteShort(0x80, 67, 100)



out.Close()

~~~



### Read from a MIDI Device

~~~ go

in, err := portmidi.NewInputStream(deviceID, 1024)

if err != nil {

    log.Fatal(err)

}

defer in.Close()



events, err := in.Read(1024)

if err != nil {

    log.Fatal(err)

}



// alternatively you can filter the input to listen

// only a particular set of channels

in.SetChannelMask(portmidi.Channel(1) | portmidi.Channel.(2))

in.Read(1024) // will retrieve events from channel 1 and 2



// or alternatively listen events

ch := in.Listen()

event := <-ch

~~~



### Cleanup

Cleanup your input and output streams once you're done. Likely to be called on graceful termination.

~~~ go

portmidi.Terminate()

~~~