Dec
24
2015

Open & Play MIDI Files with winmm.dll in Unity

An article by mgear

load_play_midi_file_in_unity3d

Yay – Playing Midi files in unity!

Notes:
– Works on PC only
– If you make a build, midi files wont be included automatically (unless they are in StreamingAssets folder, havent tested it though..)

References:
– Midi code from http://www.codeguru.com/columns/dotnet/making-music-with-midi-and-c.html
– MidiOutCaps c# struct from http://svn.tapr.org/repos_sdr_windows/PowerSDR/trunk/Source/Console/midi.cs
– Get midi files from internets, like: http://www.vgmusic.com/music/computer/commodore/commodore/

Source: (attach to gameobject in scene, set proper midi path inside PlayMidi())

	// Midi Player – unitycoder.com
	// MidiOutCaps struct from http://svn.tapr.org/repos_sdr_windows/PowerSDR/trunk/Source/Console/midi.cs
	// Midi code from http://www.codeguru.com/columns/dotnet/making-music-with-midi-and-c.html

	// USAGE: set proper path+filename inside PlayMidi(), attach this scrip to gameobject in scene and hit play!
	// Get midi files from internets, like: http://www.vgmusic.com/music/computer/commodore/commodore/

	using UnityEngine;
	using System.Runtime.InteropServices;
	using System.Text;

	public class MidiPlayer : MonoBehaviour
	{
	static string res;
	public const int MAXPNAMELEN = 32;
	public struct MidiOutCaps
	{
	public short wMid;
	public short wPid;
	public int vDriverVersion;
	[MarshalAs(UnmanagedType.ByValTStr, SizeConst = MAXPNAMELEN)]
	public string szPname;
	public short wTechnology;
	public short wVoices;
	public short wNotes;
	public short wChannelMask;
	public int dwSupport;
	}

	// MCI INterface
	[DllImport("winmm.dll")]
	private static extern long mciSendString(string command, StringBuilder returnValue, int returnLength, System.IntPtr winHandle);

	// Midi API
	[DllImport("winmm.dll")]
	private static extern int midiOutGetNumDevs();


	[DllImport("winmm.dll")]
	private static extern int midiOutGetDevCaps(System.Int32 uDeviceID, ref MidiOutCaps lpMidiOutCaps, System.UInt32 cbMidiOutCaps);


	[DllImport("winmm.dll")]
	private static extern int midiOutOpen(ref int handle, int deviceID, MidiCallBack proc, int instance, int flags);

	[DllImport("winmm.dll")]
	private static extern int midiOutShortMsg(int handle, int message);

	[DllImport("winmm.dll")]
	private static extern int midiOutClose(int handle);

	private delegate void MidiCallBack(int handle, int msg, int instance, int param1, int param2);

	static string Mci(string command)
	{
	StringBuilder reply = new StringBuilder(256);
	mciSendString(command, reply, 256, System.IntPtr.Zero);
	return reply.ToString();
	}

	void Start()
	{
	var numDevs = midiOutGetNumDevs();
	MidiOutCaps myCaps = new MidiOutCaps();
	var res = midiOutGetDevCaps(0, ref myCaps, (System.UInt32)Marshal.SizeOf(myCaps));

	PlayMidi();
	}

	static void PlayMidi()
	{
	res = System.String.Empty;

	// set path to midi file here
	string filename = Application.dataPath + "/Mids/" + "commando.mid";
	Debug.Log("Loading midi:" + filename);

	res = Mci("open \"" + filename + "\" alias music");
	res = Mci("play music");
	}

	void OnDestroy()
	{
	res = Mci("close music");
	}

	void OnDisable()
	{
	res = Mci("close music");
	}

	}