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C# MIDI Toolkit

, 18 Apr 2007
A toolkit for creating MIDI applications with C#.
csharpmiditoolkitv4_demo.zip
CSharpMidiToolkitV4_demo
LSCollections.dll
MidiToolkitDemo
Properties
Settings.settings
MidiWatcher
Properties
Settings.settings
Multimedia.dll
Multimedia.Midi
Clocks
Device Classes
InputDevice Class
OutputDevice Classes
Messages
Message Builders
Multimedia.Midi.csproj.user
Processing
Sequencing
Midi File Player
Track Classes
UI
StateMachineToolkit.dll
csharpmiditoolkitv5_demo.zip
CSharpMidiToolkitV5_demo
MidiWatcher
Properties
Settings.settings
Sanford.Collections.dll
Sanford.Multimedia.dll
Sanford.Multimedia.Midi
Clocks
Device Classes
InputDevice Class
OutputDevice Classes
Messages
EventArgs
Message Builders
Processing
Sanford.Multimedia.Midi.csproj.user
Sequencing
Track Classes
UI
Sanford.Multimedia.Timers.dll
Sanford.Threading.dll
SequencerDemo
Properties
Settings.settings
miditoolkit_demo.zip
CSharpMidiToolkit
MidiToolkitDemo
App.ico
MidiToolkitDemo.csproj.user
Multimedia
Multimedia.csproj.user
Multimedia.Midi
Devices
Messages
Message Adaptors
MIDI File
Multimedia.MIDI.csproj.user
Sequencing
Synchronization
UI
miditoolkit_src.zip
MidiToolkit_src
Devices
Messages
MIDI File
Sequencing
TickGenerators
UI
/*
 * Created by: Leslie Sanford
 * 
 * Contact: jabberdabber@hotmail.com
 * 
 * Last modified: 05/08/2004
 */

using System;

namespace Multimedia.Midi
{
    /// <summary>
    /// Represents the various types.
    /// </summary>
    public enum MetaType
    {
        /// <summary>
        /// Represents sequencer number type.
        /// </summary>
        SequenceNumber,

        /// <summary>
        /// Represents the text type.
        /// </summary>
        Text,

        /// <summary>
        /// Represents the copyright type.
        /// </summary>
        Copyright,

        /// <summary>
        /// Represents the track name type.
        /// </summary>
        TrackName,

        /// <summary>
        /// Represents the instrument name type.
        /// </summary>
        InstrumentName,

        /// <summary>
        /// Represents the lyric type.
        /// </summary>
        Lyric,

        /// <summary>
        /// Represents the marker type.
        /// </summary>
        Marker,

        /// <summary>
        /// Represents the cue point type.
        /// </summary>
        CuePoint,

        /// <summary>
        /// Represents the program name type.
        /// </summary>
        ProgramName,

        /// <summary>
        /// Represents the device name type.
        /// </summary>
        DeviceName,

        /// <summary>
        /// Represents then end of track type.
        /// </summary>
        EndOfTrack = 0x2F,

        /// <summary>
        /// Represents the tempo type.
        /// </summary>
        Tempo = 0x51,

        /// <summary>
        /// Represents the Smpte offset type.
        /// </summary>
        SmpteOffset = 0x54,

        /// <summary>
        /// Represents the time signature type.
        /// </summary>
        TimeSignature = 0x58,

        /// <summary>
        /// Represents the key signature type.
        /// </summary>
        KeySignature,

        /// <summary>
        /// Represents the proprietary event type.
        /// </summary>
        ProprietaryEvent = 0x7F
    }

	/// <summary>
	/// Represents Midi meta messages.
	/// </summary>
	/// <remarks>
	/// Meta messages are Midi messages that are stored in Midi files. These
	/// messages are not sent or received via Midi but are read and 
	/// interpretted from Midi files. They provide information that describes 
	/// a Midi file's properties. For example, tempo changes are implemented
	/// using meta messages.
	/// </remarks>
	public class MetaMessage : IMidiMessage
	{
        #region MetaMessage Members

        #region Constants

        /// <summary>
        /// Maximum value allowed for any data value.
        /// </summary> 
        private const int DataValueMax = 127;

        /// <summary>
        /// The amount to shift data bytes when packing and unpacking them.
        /// </summary>
        private const int Shift = 8;

        #endregion

        #region Fields

        // The meta message type.
        private MetaType type;

        // The meta message data.
        private byte[] data;

        #endregion

        #region Construction

        /// <summary>
        /// Initializes a new instance of the MetaMessage class with the
        /// specified type and length.
        /// </summary>
        /// <param name="type">
        /// The type of meta message.
        /// </param>
        /// <param name="length">
        /// The length of the meta message data.
        /// </param>
        /// <exception cref="ArgumentOutOfRangeException">
        /// The length of the meta message is not valid for the type of meta
        /// message.
        /// </exception>
        /// <remarks>
        /// Each meta message has type and length properties. For certain 
        /// types, the length of the message data must be a specific value. For
        /// example, tempo messages must have a data length of exactly three. 
        /// Some meta message types can have any data length. Text messages are
        /// an example of a meta message that can have a variable data length.
        /// When a meta message is created, the length of the data is checked
        /// to make sure that it is valid for the specified type. If it is not,
        /// an exception is thrown. 
        /// </remarks>
        public MetaMessage(MetaType type, int length)
        {
            // Enforce preconditions.
            if(!ValidateDataLength(type, length))
                throw new ArgumentOutOfRangeException("length", length,
                    "Length out of range for meta message.");

            this.type = type;

            // Create storage for meta message data.
            this.data = new byte[length];
        }

        /// <summary>
        /// Initializes a new instance of the MetaMessage class.
        /// </summary>
        /// <param name="type">
        /// The type of meta message.
        /// </param>
        /// <param name="data">
        /// The meta message data.
        /// </param>
        /// <exception cref="ArgumentOutOfRangeException">
        /// The length of the meta message is not valid for the type of meta
        /// message.
        /// </exception>
        /// <remarks>
        /// Each meta message has type and length properties. For certain 
        /// types, the length of the message data must be a specific value. For
        /// example, tempo messages must have a data length of exactly three. 
        /// Some meta message types can have any data length. Text messages are
        /// an example of a meta message that can have a variable data length.
        /// When a meta message is created, the length of the data is checked
        /// to make sure that it is valid for the specified type. If it is not,
        /// an exception is thrown. 
        /// </remarks>
		public MetaMessage(MetaType type, byte[] data)
		{
            // Enforce preconditions.
            if(!ValidateDataLength(type, data.Length))
                throw new ArgumentOutOfRangeException("data", data.Length,
                    "Length of data out of range for meta message.");
            
            this.type = type;
            
            // Create storage for meta message data.
            this.data = new byte[data.Length];

            // Copy data into storage.
            data.CopyTo(this.data, 0);
        }

        /// <summary>
        /// Initializes a new instance of the MetaMessage class with 
        /// another instance of the MetaMessage class.
        /// </summary>
        /// <param name="message">
        /// The MetaMessage instance to use for initialization.
        /// </param>
        public MetaMessage(MetaMessage message)
        {
            type = message.type;
            data = new byte[message.data.Length];
            message.data.CopyTo(data, 0);
        }

        #endregion

        #region Methods

        /// <summary>
        /// Tests to see if a status value belongs to a meta message.
        /// </summary>
        /// <param name="status">
        /// The status value to test.
        /// </param>
        /// <returns>
        /// <b>true</b> if the status value belongs to a meta message; 
        /// otherwise, <b>false</b>.
        /// </returns>
        public static bool IsMetaMessage(int status)
        {
            bool result = false;

            if(status == 0xFF)
            {
                result = true;
            }

            return result;
        }

        /// <summary>
        /// Packs the data from a tempo meta message into an integer.
        /// </summary>
        /// <param name="message">
        /// The tempo meta message.
        /// </param>
        /// <returns>
        /// Returns the tempo packed into an integer.
        /// </returns>
        /// <exception cref="ArgumentException">
        /// Thrown if the message is not a tempo meta message.
        /// </exception>
        public static int PackTempo(MetaMessage message)
        {
            // Enforce preconditions.
            if(message.Type != MetaType.Tempo)
                throw new ArgumentException(
                    "Message is not a tempo meta message", "message");

            int tempo = 0;

            if(BitConverter.IsLittleEndian)
            {
                int d = message.data.Length - 1;

                for(int i = 0; i < message.data.Length; i++)
                {
                    tempo |= message.data[d] << (Shift * i);
                    d--;
                }
            }
            else
            {                    
                for(int i = 0; i < message.data.Length; i++)
                {
                    tempo |= message.data[i] << (Shift * i);
                }                    
            }

            return tempo;
        }

        /// <summary>
        /// Validates data length.
        /// </summary>
        /// <param name="type">
        /// The type of meta message.
        /// </param>
        /// <param name="length">
        /// The length of the meta message data.
        /// </param>
        /// <returns>
        /// <b>true</b> if the data length is valid for this type of meta
        /// message; otherwise, <b>false</b>.
        /// </returns>
        private bool ValidateDataLength(MetaType type, int length)
        {
            const int TempoLength = 3;
            const int SmpteOffsetLength = 5;
            const int TimeSigLength = 4;
            const int KeySigLength = 2;

            bool valid = true;

            // Determine which type of meta message this is and check to make
            // sure that the data length value is valid.
            switch(type)
            {
                case MetaType.SequenceNumber:
                    if(length != 0 || length != 2)
                    {
                        valid = false;
                    }
                    break;

                case MetaType.EndOfTrack:
                    if(length != 0)
                    {
                        valid = false;
                    }
                    break;

                case MetaType.Tempo:
                    if(length != TempoLength)
                    {
                        valid = false;
                    }
                    break;

                case MetaType.SmpteOffset:
                    if(length != SmpteOffsetLength)
                    {
                        valid = false;
                    }
                    break;

                case MetaType.TimeSignature:
                    if(length != TimeSigLength)
                    {
                        valid = false;
                    }
                    break;

                case MetaType.KeySignature:
                    if(length != KeySigLength)
                    {
                        valid = false;
                    }
                    break;

                default:
                    // Assumes one of the variable length meta message.
                    break;
            }

            return valid;            
        }

        #endregion

        #region Properties

        /// <summary>
        /// Gets or sets the element at the specified index.
        /// </summary>
        public byte this[int index]
        {
            get
            {
                // Enforce preconditions.
                if(index < 0 || index >= Length)
                    throw new ArgumentOutOfRangeException("index", index,
                        "Index into meta message out of range.");                

                return data[index];
            }
            set
            {
                // Enforce preconditions.
                if(index < 0 || index >= Length)
                    throw new ArgumentOutOfRangeException("index", index,
                        "Index into meta message out of range.");
                else if(value > DataValueMax)
                    throw new ArgumentOutOfRangeException("value", value,
                        "Data value for meta message out of range."); 

                // Assign value at the specified index.
                data[index] = value;
            }                
        }

        /// <summary>
        /// Gets the length of the meta message.
        /// </summary>
        public int Length
        {
            get
            { 
                return data.Length;
            }
        }
        
        /// <summary>
        /// Gets the type of meta message.
        /// </summary>
        public MetaType Type
        {
            get
            {
                return type;
            }
        }

        #endregion

        #endregion

        #region ICloneable Members

        /// <summary>
        /// Creates a clone of this instance of the MetaMessage class.
        /// </summary>
        /// <returns>
        /// A clone of this instance of the MetaMessage class.
        /// </returns>
        public object Clone()
        {
            return new MetaMessage(this);
        }

        #endregion

        #region IMidiMessage Members

        /// <summary>
        /// Accepts an IMidiMessageVisitor.
        /// </summary>
        /// <param name="visitor">
        /// The IMidiMessageVisitor to accept.
        /// </param>
        public void Accept(IMidiMessageVisitor visitor)
        {
            visitor.Visit(this);
        }

        /// <summary>
        /// Gets the status value.
        /// </summary>
        public int Status
        {
            get
            {
                // All meta messages have the same status byte (0xFF).
                return 0xFF;
            }
        }

        #endregion
    }
}

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This article, along with any associated source code and files, is licensed under The MIT License

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About the Author

Leslie Sanford

United States United States
Aside from dabbling in BASIC on his old Atari 1040ST years ago, Leslie's programming experience didn't really begin until he discovered the Internet in the late 90s. There he found a treasure trove of information about two of his favorite interests: MIDI and sound synthesis.
 
After spending a good deal of time calculating formulas he found on the Internet for creating new sounds by hand, he decided that an easier way would be to program the computer to do the work for him. This led him to learn C. He discovered that beyond using programming as a tool for synthesizing sound, he loved programming in and of itself.
 
Eventually he taught himself C++ and C#, and along the way he immersed himself in the ideas of object oriented programming. Like many of us, he gotten bitten by the design patterns bug and a copy of GOF is never far from his hands.
 
Now his primary interest is in creating a complete MIDI toolkit using the C# language. He hopes to create something that will become an indispensable tool for those wanting to write MIDI applications for the .NET framework.
 
Besides programming, his other interests are photography and playing his Les Paul guitars.

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