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C# MIDI Toolkit

, 18 Apr 2007 MIT
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: 10/29/2004
 */

using System;
using System.Collections;

namespace Multimedia.Midi
{
	/// <summary>
	/// Handles playback of a single Track.
	/// </summary>
	internal class TrackPlayer : MidiMessageVisitor, IDisposable
	{
        #region TrackPlayer Members

        #region Constants

        // Minimum value for turning on the hold pedal.
        private const int HoldPedalOnValue = 64;

        #endregion

        #region Fields

        // Indicates whether or not the track is muted.
        private bool mute = false;

        // Indicates whether or not the track is soloed.
        private bool solo = false;

        // Indicates whether or not the solo mode is enabled.
        private bool soloModeEnabled = false;

        // The MIDI sender for sending MIDI messages.
        private IMidiSender midiSender;

        // The tick generator used for generating ticks.
        private TickGenerator tickGen;

        // The track to playback.
        private Track trk;

        // The enumerator for iterating through the track's MIDI events.
        private IEnumerator enumerator;

        // Indicates whether or not the end of the track has been reached.
        private bool endReached;

        // The current MIDI event to play.
        private MidiEvent currentEvent;

        // The table to keep track of all currently playing notes.
        private ChannelMessage[] noteOnTable =
            new ChannelMessage[ShortMessage.DataValueMax + 1];

        // The hold pedal message. Should be null if the pedal is not currently
        // on.
        private ChannelMessage holdPedalMessage = null;

        #endregion

        #region Events

        /// <summary>
        /// Occurs when the end of the track has been reached.
        /// </summary>
        public event EventHandler EndOfTrackReached;

        #endregion

        #region Construction

        /// <summary>
        /// Initializes a new instance of the TrackPlayer class with the 
        /// specified MIDI sender, tick generator, and track.
        /// </summary>
        /// <param name="midiSender">
        /// The MIDI sender to use for sending MIDI messages.
        /// </param>
        /// <param name="tickGen">
        /// The tick generator used for timing the playback of MIDI messages.
        /// </param>
        /// <param name="trk">
        /// The track to play back.
        /// </param>
		public TrackPlayer(IMidiSender midiSender, TickGenerator tickGen, 
            Track trk)
		{
            this.midiSender = midiSender;
            this.tickGen = tickGen;
            this.trk = trk;

            tickGen.Tick += new EventHandler(TickHandler);

            // Set playback position at the beginning of the track.
            Seek(0);
		}

        #endregion

        #region Methods

        /// <summary>
        /// Turns all currently sounding notes off.
        /// </summary>
        /// <remarks>
        /// When a track is muted, all of the currently sounding notes need to
        /// be turned off. Also, a sequencer can call this method if one of the
        /// other tracks are soloed.
        /// </remarks>
        public void AllSoundsOff()
        {
            ChannelMessage message;

            // If the hold pedal is currently on, turn it off.
            if(holdPedalMessage != null)                
            {
                message =
                    new ChannelMessage(ChannelCommand.Controller, 
                    holdPedalMessage.MidiChannel, holdPedalMessage.Data1, 0);

                midiSender.Send(message);
            }

            // Created channel message for turning notes off.
            message = new ChannelMessage(ChannelCommand.NoteOff, 0, 0, 0);

            // Iterate through the note-on table turning off any currently
            // turned on notes.
            for(int i = 0; i < ShortMessage.DataValueMax; i++)
            {
                // If the note has been turned on, turn it off.
                if(noteOnTable[i] != null)
                {
                    message.MidiChannel = noteOnTable[i].MidiChannel;
                    message.Data1 = noteOnTable[i].Data1;
                    midiSender.Send(message);
                }
            }

            holdPedalMessage = null;
            ResetNoteOnTable();
        }

        /// <summary>
        /// Seeks the specified position in the track.
        /// </summary>
        /// <param name="position">
        /// The position in ticks to seek.
        /// </param>
        public void Seek(int position)
        {
            // Enforce preconditions.
            if(position < 0)
                throw new ArgumentOutOfRangeException("position", position,
                    "Position out of range.");

            enumerator = trk.GetEnumerator();
            enumerator.MoveNext();
            currentEvent = (MidiEvent)enumerator.Current;

            endReached = false;

            // Tick accumulator.
            int ticks = currentEvent.Ticks;

            // Create MIDI chaser to chase MIDI messages so that the sequence 
            // is updated correctly at the specified position.
            MidiChaser chaser = new MidiChaser(midiSender, tickGen);

            if(ticks <= position)
            {
                // Add first message.
                chaser.Add(currentEvent.Message);
            }

            // While the position being sought has not been reached.
            while(ticks < position)
            {
                // Move to the next event in the track.
                endReached = !enumerator.MoveNext();

                // If the position being sought lies beyond the end of the 
                // track, trigger event to notify listeners and return.
                if(endReached)
                {
                    if(EndOfTrackReached != null)
                        EndOfTrackReached(this, EventArgs.Empty);

                    // Chase MIDI messages so that the sequence sounds correctly from 
                    // the specified position.
                    chaser.Chase();
                    
                    return;
                }
                    // Else the position has not yet been reached.
                else
                {
                    // Get the current MIDI event.
                    currentEvent = (MidiEvent)enumerator.Current;

                    // Accumulate ticks.
                    ticks += currentEvent.Ticks;

                    // If we haven't gone beyond the specified position.
                    if(ticks <= position)
                    {
                        // Add message to chaser.
                        chaser.Add(currentEvent.Message);
                    }
                }
            }

            // Initialize the current MIDI event ticks to the number of ticks 
            // remaining until the specified position is reached.
            currentEvent.Ticks = ticks - position;

            // Chase MIDI messages so that the sequence sounds correctly from 
            // the specified position.
            chaser.Chase();
        }

        /// <summary>
        /// Resets the table for keeping track of note-on messages.
        /// </summary>
        private void ResetNoteOnTable()
        {
            for(int i = 0; i < noteOnTable.Length; i++)
                noteOnTable[i] = null;
        }

        /// <summary>
        /// Visit channel messages.
        /// </summary>
        /// <param name="message">
        /// The channel message to visit.
        /// </param>
        public override void Visit(ChannelMessage message)
        {
            // If this is a note-on message.
            if(message.Command == ChannelCommand.NoteOn)
            {
                // If the velocity is greater than zero, keep track of message.
                // This message turns a note on.
                if(message.Data2 > 0)
                {
                    noteOnTable[message.Data1] = message;
                }
                // Else the velocity is zero, treat this note-on message as a
                // note off message.
                else
                {
                    // Indicate that this note is not currently playing.
                    noteOnTable[message.Data1] = null;
                }

                // Send with filtering.
                Send(message);
            }
            // Else if this is a note-off message.
            else if(message.Command == ChannelCommand.NoteOff)
            {
                // Indicate that this note is note currently playing.
                noteOnTable[message.Data1] = null;

                // Send with filtering.
                Send(message);
            }
            // Else if this is a controller message.
            else if(message.Command == ChannelCommand.Controller)
            {                 
                // If this is a hold pedal message.
                if(message.Data1 == (int)ControllerType.HoldPedal)
                {
                    // If the hold pedal is on, indicate that the hold pedal
                    // is on.
                    if(message.Data2 >= HoldPedalOnValue)
                        holdPedalMessage = message;
                    // Else the hold pedal is off, indicate that it is off.
                    else
                        holdPedalMessage = null;
                }

                // Send message without filtering.
                midiSender.Send(message);
            }
            // Else this is another type of MIDI message.
            else
            {
                // Send message without filtering.
                midiSender.Send(message);
            }
        }

        /// <summary>
        /// Visit meta messages.
        /// </summary>
        /// <param name="message">
        /// The message to visit.
        /// </param>
        public override void Visit(MetaMessage message)
        {
            // If this is a tempo change message, change the tempo of the tick
            // generator.
            if(message.Type == MetaType.Tempo)
            {
                TempoChange change = new TempoChange(message);
                tickGen.Tempo = change.Tempo;
            }
        }

        /// <summary>
        /// Visit system exclusive messages.
        /// </summary>
        /// <param name="message">
        /// The message to visit.
        /// </param>
        public override void Visit(SysExMessage message)
        {
            // Send message.
            midiSender.Send(message);            
        }

        /// <summary>
        /// Sends a channel message.
        /// </summary>
        /// <param name="message">
        /// The message to send.
        /// </param>
        /// <remarks>
        /// This method filters messages based on the state of the track.
        /// </remarks>
        private void Send(ChannelMessage message)
        { 
            if(mute)
                return;
            else if(soloModeEnabled && !solo)
                return;
            else
                midiSender.Send(message);
        }

        /// <summary>
        /// Handles tick events generated by the tick generator.
        /// </summary>
        /// <param name="sender">
        /// The tick generator responsible for the tick event.
        /// </param>
        /// <param name="e">
        /// Information about the event.
        /// </param>
        private void TickHandler(object sender, EventArgs e)
        {
            // Guard.
            if(endReached)
                return;

            // While it is time to play the current MIDI event.
            while(currentEvent.Ticks == 0)
            {
                // Visit the MIDI message.
                currentEvent.Message.Accept(this);

                // Move to the next MIDI event in the track.
                endReached = !enumerator.MoveNext();

                // If the end of the track has been reached, raise event.
                if(endReached)
                {
                    if(EndOfTrackReached != null)
                        EndOfTrackReached(this, EventArgs.Empty);

                    return;
                }
                // Else the end of the track has not been reached, get next 
                // MIDI event.
                else
                {
                    currentEvent = (MidiEvent)enumerator.Current;
                }
            }

            // Move the current event forward in time by one tick.
            currentEvent.Ticks--;
        }

        #endregion

        #region Properties

        /// <summary>
        /// Gets or sets a value indicating whether or not the track is muted.
        /// </summary>
        public bool Mute
        {
            get
            {
                return mute;
            }
            set
            {
                // Guard.
                if(mute == value)
                    return;

                mute = value;

                // If the track is muted, turn off all currently sounding 
                // notes.
                if(mute)
                    AllSoundsOff();
            }
        }

        /// <summary>
        /// Gets or sets a value indicating whether or not the track is soloed.
        /// </summary>
        public bool Solo
        {
            get
            {
                return solo;
            }
            set
            {
                solo = value;
            }
        }

        /// <summary>
        /// Gets or sets the value indicating whether or not the solo mode is
        /// enabled.
        /// </summary>
        /// <remarks>
        /// When a sequence is being played back and any one of the tracks is
        /// soloed, only the soloed tracks should sound; all other tracks 
        /// should be quieted. The sequencer can enable the solo mode of its 
        /// track players whenever any of its tracks are soloed. This lets the 
        /// track players know to filter its track based on whether or not it 
        /// is soloed.
        /// </remarks>
        public bool SoloModeEnabled
        {
            get
            {
                return soloModeEnabled;
            }
            set
            {
                soloModeEnabled = value;
            }
        }

        /// <summary>
        /// Gets the track being played back.
        /// </summary>
        public Track Track
        {
            get
            {
                return trk;
            }
        }

        #endregion

        #endregion

        #region IDisposable Members

        /// <summary>
        /// Disposes of the track player.
        /// </summary>
        public void Dispose()
        {
            tickGen.Tick -= new EventHandler(TickHandler);
        }

        #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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