Customizing QuickTime MIDI—Working with custom instruments in the QuickTime synthesizer

Customizing QuickTime MIDI
Working with custom instruments in the QuickTime synthesizer.
By Peter Drescher

In 1991, after finishing my last tour with bluesman Joe Louis Walker and the BossTalkers, I sent résumés to every music-software developer I could find, hoping to get into a new line of work. Steve Hales had the foresight and generosity to offer this burned-out road dog and blues-piano player a job as studio director of his new company, Halestorm.

While at Halestorm, I provided content for SoundMusicSys, a software sample-playback synthesizer developed by Hales and his partner Jim Nitchals. They formed Halestorm to license the SoundMusicSys technology to game developers and other creators of multimedia products, and business was brisk. In fact, seed money to get the company growing came from the first big licensee, Apple Computer.

FIG. 1: This sequence combines General MIDI data in the first four tracks with notes for triggering QTMA samples.

FIG. 2: System 7 sounds get dropped onto the Music Track dialog box to create custom Instruments.

FIG. 3: You can take advantage of an extensive range of sounds in the Roland GS instrument library.

The idea behind SoundMusicSys was simple: use MIDI data to fire off instrument samples at the correct times and pitches. The files could be small, the code would be efficient, and the resulting music would sound as intended on any computer. Apple wanted to incorporate the technology into its QuickTime system extension to render Standard MIDI Files, and it licensed a GM sample library from Roland Corporation to provide the instrument sounds. Apple released its version of the software synthesizer, QuickTime Music Architecture (QTMA), in 1995. (To find out more about the SoundMusicSys family tree, see the sidebar “A Rose by Any Other Name.”)

QTMA has continued to evolve. With a bigger, better sample library and a host of new features and audio-compression algorithms, PCs and Macs can playback Standard MIDI Files with an audio quality rivaling that of hardware sound cards. Of course, QuickTime also has the added advantage of providing soundtracks that are locked to picture. That is a common requirement in the film and TV worlds, but it is often difficult to manage in the chaotic multimedia environment.

Hidden Treasure
The greatest strength of QTMA’s software synthesizer is that it can create custom instruments. General MIDI (GM) is, by definition, a finite palette of sounds, and multimedia musicians typically prefer to be limited only by their imaginations and engineering skills. With QTMA, however, you can include your own samples and trigger them at the appropriate times and pitches, which lets you write for instruments outside the GM specification. Vocals, guitar solos, drum loops, horn-section riffs, explosions, bird calls—whatever kind of audio you want—can be bundled with the MIDI data and transmitted over the Internet.

This feature has been hidden in QTMA for a long time, but the latest version of QuickTime Player Pro (4.1.2 as of this writing) provides access to the Instrument parameters. I put together a QuickTime movie that consisted of a Standard MIDI File enhanced with custom samples. Putting all the pieces together was a little tricky; it required careful planning and a lot of trial and error.

Puzzle Pieces
I began with a Pro Tools session (mainly drum loops and horn riffs) created by house-music producers Agent K and Division 6. Next I cut up the digital-audio tracks into short sections starting on the beat. I converted the audio into 16-bit, 22 kHz System 7 format sounds with SoundApp, a versatile audio-conversion utility. That produced a series of small SFIL Mac files with the audio data stored in an SND resource. The Mac OS can play this native format when you simply double-click on the audio file’s icon, so it’s easily recognized and imported by QuickTime.

I then created a Standard MIDI File containing one track for each sample, with a middle-C trigger note at each place I wanted the sample to play. For example, the “beat1” sample is one bar long starting on the first beat, so I placed a C3 whole note in each bar, starting at bar 10, to keep the beat in sync (see Fig. 1). Other tracks played the additional beats or fired off the vocal and horn riffs at the correct times. I also included the GM piano, organ, and percussion tracks from the original Pro Tools session.

I imported the MIDI file into QuickTime Player Pro and saved it as a movie (MOV) file. (You can purchase QuickTime Player Pro for $29.99 at www.apple.com/quicktime.) When I selected the Get Info command from the Movie menu, a dialog box appeared, offering access to the Music Track section and its associated Instruments list. The tracks I laid out in my sequencer were displayed in the same order, so I knew which tracks went with which samples. I then dragged and dropped the appropriate System 7 files onto the correct tracks and hit Play (see Fig. 2). Voilà! (You can download the results at www.twittering.com/K6.)

Lock, Stock, and Barrel
The Instruments list also provides access to the full range of Roland’s GS sound set. This GM specification extension contains lots of great sounds, including nine drum kits, myriad synths, sound effects, and ethnic percussion, as well as some nice variations on the more standard instruments. I chose the patch for the MIDI bass line by double-clicking on the track and selecting Synth101 from the GS Piano and Chromatic Percussion category (see Fig. 3). You can also audition instrument sounds on the little piano keyboard at the bottom of the dialog box.

Reprinted with permission from

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