Making a Metronome by Seth Willits 12-31-03 Printer Version

Metronomes
For those non-musicians out there, Dictionary.com defines a metronome as "a device used to mark time by means of regularly recurring ticks or flashes at adjustable intervals." For my friends who don't know how a metronome works, yes, they still make them by putting little gnomes that hit things in a box. Being a musician myself, I can't emphasize enough how important being able to play in sync. with a metronome (not the band) is. As the members of my drumline know, it's not about how well you play, it's about how well you play in time together.

With that in mind, we're going to create a very small application to create a metronome on your computer. For years I heard nothing but "go buy a metronome!" but I never did. I wrote one in REALbasic instead.

Design
The design for a metronome is really simple. Simple create a new window with an EditField named EFBPM and a button named BtnPlay. We'll use an instance of the NotePlayer class to make the noise for the metronome (since an alert beep would be pretty annoying), so drag one of them to the window and set its Instrument property to 128 in the properites window.

The Few Lines to Make It
All that our application must do to work is turn the Beats Per Minute value in the field into a minutes per beat value by using a very simple calculation. We'll be using Microseconds to do our timing so we know that 1,000,000 microseconds multiplied by 60 gives us 60 million microseconds for one minute, and then dividing that value by the beats per minutes will give us minutes per beat.

The time keeping aspect of the program is a simple do-loop which contains an if-statement that constantly checks to see if the right amount of time has passed since the last beat. If enough time has passed then we use the NotePlayer to play a sound and record the current time. To stop the metronome the do-loop will exit if the user presses Command-Period or the Escape key.