Recording Sheet Music Using C# and .NET

Listing 3 - Stop Button Event Handler to stop the recording and save the music

The SaveRecording method of the Recorder simply saves the Recording string containing the notes and places the string in a file. It also adds the necessary file header information needed by the Sheet Music Editor:

Listing 4 - Save the Recording to a File

Playing the music is a bit more complicated. In order to play the music, we placed our sound creation inside of a thread. This way, while the note is playing, the form isn't frozen. Below is the simple UML sequence diagram that shows what happens when you click the Play button in the Virtual Piano:

Figure 5 - Sequence diagram for playing music drawn using WithClass

Note that the call to PlayNotesFromFile is Asynchronous. This means that when we go tell the Player to play, we don't have to wait for it to finish playing, we just return and do what we normally do in a form. Below is the code in the PlayNotesFromFile that activates the threaded method called PlayNotesThread in the Player class:

The code for playing the notes in the file is just a big long parser that actually calls back to the PianoForm in order to play the sound of the note. To see how to play a note in DirectX, please refer to my previous article, the Virtual Piano. This update actually improves note playing slightly by not recreating the Secondary Buffer every time we want to play a note. Below is the PlayNotes method in the Player class that parses through the notes file and plays each note according to the format described in the MusicMaker article.

public void PlayNotes()
{
// Open the stream that contains the notes
FileStream fs = new FileStream(Filename, FileMode.Open, FileAccess.Read);
StreamReader sr = new StreamReader(fs);
// Loop through each line of the file, parse them and play each note
string strLine = sr.ReadLine();
while (strLine != null)
{
// skip title information and signature information.
int keyIndex = strLine.IndexOf(":");
if (keyIndex != -1) // contains non-note information
{
string strKey = strLine.Substring(0, keyIndex);
strKey = strKey.ToLower();
switch (strKey)
{
case "title":
break;
case "signature1":
break;
case "signature2":
break;
default:
break;
}
}
else // read in the notes
{
strLine = strLine.Trim();
string[] theMeasures = strLine.Split(new char[]{'/'});
// Parse the notes out of the measure
for (int i = 0; i < theMeasures.Length; i++)
{
if (theMeasures[i].Length > 0)
{
// read each note in the measure
if (theMeasures[i][theMeasures[i].Length -1] == '/') // chop it off
{
theMeasures[i] = theMeasures[i].Substring(0, theMeasures[i].Length -1);
theMeasures[i] = theMeasures[i].Trim();
}
// parse the notes out of the measure
string[] notes = theMeasures[i].Split(new char[]{' '});
// Go through each note and play it using the PianoForm object
for (int j = 0; j < notes.Length; j++)
{
// Look up the frequency from the note string
int freq = GetFrequency(notes[j]);
// Look up the duration from the timing symbol
int duration = GetDuration(notes[j]);
// Play the note
ThePiano.PlayNote(freq, duration);
// Wait for the thread to finish before playing the next note
while (PianoForm.PlayNoteThread.IsAlive){}
}
}
}
}
// read the next line of music
strLine = sr.ReadLine();
}
// Close the stream
sr.Close();
fs.Close();
}

Listing 6 - Playing all the notes in the music file

Conclusion

This program is a fun little project that can help you create simple sheet music by playing the piano. To improve the program, I really need to add rests, chords, song words and other music capabilities but this is a good framework to begin. I noticed that the music player seems to play the music a bit choppy so I suspect it can use a lot of improvement. One thing that would probably make the player better is if all of the notes were placed in the Secondary Buffer at once and then played. We'll look into doing this in the next version. Enjoy composing your own songs. If anyone creates any cool classic riffs, e-mail them to me, and I'll add them to the upload.