MIDI sound only in one channel (left or right)

I have an WPF application which need to play MIDI sound but only in one channel - on left or right headset channel.

I have a piece of a code that plays a MIDI note (in both channels), however I don't know how to modify it to play the MIDI sound ONLY on the RIGHT or ONLY on the LEFT channel.

This is my code:

public static class MidiNote
{
    public static MidiOut MidiOut = new MidiOut(0);
    public static void PlayNote(int key, int duration)
    {
        MidiOut.Volume = 65535;
        MidiOut.Send(MidiMessage.StartNote(key, 127, 1).RawData);
        Thread.Sleep(duration);
        MidiOut.Send(MidiMessage.StopNote(key, 0, 1).RawData);
    }
}

I found some partial answers but I do not know how can I use them. I read these two articles:

Play sound on specific channel with NAudio

How to play sound only on the left channel of the headphone and only on the right channel of the headphone in c#?

Solution

When you are using MIDI you have to send an appropriate MIDI message (a Control- Change or CC message) to the MIDI OUT device to tell it what PAN setting you want to use.

The PAN setting value should be in the range of 0-127 where:

0 = PAN HARD LEFT
127 = PAN HARD RIGHT
64 = PAN CENTER

I used your code as starting point and added a few methods to allow adjusting the PAN setting of the MIDI OUT device.

My example calls to demonstrate the PANNING are written as if it were a CONSOLE app but the new methods should work fine in your existing class / WPF application.

public static class MidiNote
{
    public static MidiOut MidiOut = new MidiOut(0);

    public static void PlayNote(int key, int duration)
    {
        MidiOut.Volume = 65535;
        MidiOut.Send(MidiMessage.StartNote(key, 127, 1).RawData);
        Thread.Sleep(duration);
        MidiOut.Send(MidiMessage.StopNote(key, 0, 1).RawData);
    }

    public static void SetPanHardLeft()
    {
        var panSettingHardLeft = 0;
        var cce = new ControlChangeEvent(0L, 1, MidiController.Pan, panSettingHardLeft);
        MidiOut.Send( cce.GetAsShortMessage() );
    }

    public static void SetPanHardRight()
    {
        var panSettingHardRight = 127;
        var cce = new ControlChangeEvent(0L, 1, MidiController.Pan, panSettingHardRight);
        MidiOut.Send(cce.GetAsShortMessage());
    }

    public static void SetPanCenter()
    {
        var panSettingCenter = 64;
        var cce = new ControlChangeEvent(0L, 1, MidiController.Pan, panSettingCenter);
        MidiOut.Send(cce.GetAsShortMessage());
    }

    public static void PlayNoteRightChannel(int key, int duration)
    {
        var panSettingHardRight = 127;
        var cce = new ControlChangeEvent(0L, 1, MidiController.Pan, panSettingHardRight);
        MidiOut.Send(cce.GetAsShortMessage());

        PlayNote(key, duration);
    }

    static void Main(string[] args)
    {
        // Plays using current setting (probably CENTER)
        Console.WriteLine( "Pan setting unchanged (should be CENTER)");
        PlayNote( 50, 2000 );

        // Set the PAN for the MIDI device to HARD LEFT...
        Console.WriteLine("Pan setting HARD LEFT");
        SetPanHardLeft();
        // ...and play the note again
        PlayNote( 50, 2000);

        // Set the PAN for the MIDI device to HARD RIGHT...
        Console.WriteLine("Pan setting HARD RIGHT");
        SetPanHardRight();
        // ...and play the note again
        PlayNote(50, 2000);

        // Set the PAN for the MIDI device back to CENTER...
        Console.WriteLine("Pan setting CENTER");
        SetPanCenter();
        // ...and play the note one last time
        PlayNote(50, 2000);
    }

}