EQ Magazine - September 2007 - (Page 54)

KEY ISSUES GETTING THE MOST OUT OF MIDI by Craig Anderton Created back in 1983 amid choruses of “it’s just a passing fad, MIDI (Musical ” Instrument Digital Interface, a protocol that translates performance gestures like playing notes and bending pitch to data messages), looked like it was on the wane in the ’90s. Audio recording was on the ascendancy, and it seemed to make more sense just to record an instrument’s audio out rather than record a performance, feed it into an external keyboard, then send that keyboard’s audio output into a mixer during mixdown time. But with the advent of plug-in virtual instruments, MIDI has gained new life as the protocol that triggers software synthesizers. So now, we’re in the unusual position of having MIDI be something new and different to people who weren’t even alive when it was born. Let’s investigate some of the most important highlights of this protocol, and how to apply it in today’s recording world. VIRTUAL VS. OUTBOARD MIDI INSTRUMENTS You may have heard complaints about MIDI being slow, and horror stories of MIDI delay. But this is true only when the computer is driving outboard MIDI gear, because MIDI is a serial protocol where a new piece of data gets sent out every millisecond or so. When a computer sends MIDI to an external sound module, the data has to exit through a port (interface), be scanned by the keyboard, interpreted, and turned into a sound. Virtual instruments bypass all those issues because the MIDI data is flying around inside the computer, so timing is extremely tight. ABOUT MIDI RESOLUTION However, computers have limits, too. Running lots of virtual instruments will test those limits, with one potential result being “loose” timing. MIDI timing resolution is specified in PPQ (pulses per quarter note). Early hardware MIDI devices had as little as 24 PPQ resolution, with computer-based sequencers opting for resolutions of 96, 192, or 240 PPQ. The lower the resolution, the less the computer has to work. To see if there are places where notes are playing back unintentionally at the same time. Figure 2 gives an example of a pad part. Notice how the red notes from held chords “hang on” past the onset of the next held chord. Even though each chord plays only four notes, during that transition eight notes are playing. Trimming the ends of the notes, as shown with the blue notes, prevents this situation from happening, unless you’ve programmed a lengthy release time so that the note sounds even after you’ve let your fingers off the keys. In this case, consider using reverb or delay to extend the decay, so you can shorten the release time. Fig. 1: Digital Performer records MIDI internally at an extremely high resolution, so you don’t have to work with huge numbers while editing, and lets you display the resolution in whatever PPQ value you find most comfortable. Here, 960 PPQ is being selected. CPU SALVATION THROUGH FREEZING We’re not talking cryogenic cooling of your processor, but rather, a sequencer or DAW’s “freeze” function. Freezing takes advantage of the fact that, thanks to high-speed/density hard drives, modern hard disk recording programs can run dozens, or even Fig. 2:Trimming the ends of notes to prevent overlap can conhundreds, of audio tracks without serve polyphony, and place less load on your computer’s CPU. breaking a sweat (unlike soft synth tracks, where you’ll be lucky if your computer can handle more than a dozen or accommodate older computers, some proso in a complex project). So, the freeze grams let you specify lower timing resolufunction implements a two-step process: tions. As computers evolved, resolutions of Convert the soft synth’s output to a hard 960 and above became common. disk audio track, then “disconnect” the soft Modern computers are powerful enough synth from the CPU. that many programs simply record at a high Different programs handle this differlevel of resolution; for example, Digital ently. For example, some programs can’t Performer records at 10,000 PPQ. However, really do anything with the frozen track, editing notes at this level of resolution can while others let you move it, or perhaps let become unwieldy, so DP allows you to change you change signal processing being applied the way resolution is displayed. If you’re used to to the track, even though it’s “frozen. ” 480 PPQ resolution, for example, you can see Those with older hosts that can’t freeze, or note timings displayed that way; if you’re have newer programs without a freeze option switching to DP from another program and are used to a different resolution (e.g., 960 PPQ), per se (Figure 3), can nonetheless enjoy the you could choose that display instead (Figure 1). benefits of unloading soft instruments from the CPU — and still be able to edit them LIMIT POLYPHONY later if needed. Here’s the procedure. Nothing sucks CPU power faster than playing back lots of voices from a soft synth. As 1. If audio effects plug-ins process the soft a result, look at the MIDI data stream and synth and you want to freeze these too, 54 EQ SEPTEMBER 2007 www.eqmag.com http://www.eqmag.com

Table of Contents Feed for the Digital Edition of EQ Magazine - September 2007

Contents Talk Box Sounding Board Get Cape. Wear Cape. Fly Ben and Vesper Kaiser Chiefs Toolbox Ozma Porcupine Tree Rush The Software Power User Guide Guitar Trax Bass Management Key Issues Drumheads Vocal Cords Mix Bus Cheat Sheet Chameleon Labs TS1 and TS2 Primera Bravo Se Disc Publisher Roland MC-808 Magix Samplitude Professional 9.1 Massey Tape-Head Big Fish Audio Revolucion Reggaeton Sonivox World Beats Sony Pocket Diva Adobe Audition 2.0 Cakewalk Sonar 6 Room with a VU: J Street Recorders, Sacramento, CA

EQ Magazine - September 2007

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