Producing Interactive Audio

Tools of the Trade
 
Producing Interactive Audio
Introduction

The Rules of Interactive Sound Design

Creating an Adaptive Audio Engine

Case Study: The GEX Project

Only the Beginning

Tools of the Trade

Getting More Info about the IASIG

Workstations and Sequencers

Digidesign ProTools
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Digidesign's Pro Tools III 4.0

I try to use off-the-shelf tools whenever I can. When I evaluate commercial tools, I look for unique functionality, efficiency, reliability, and cost-effectiveness. Our main control room at Crystal Dynamics is based around a Macintosh Power PC running Digidesign's Pro Tools III 4.0, Digital Audio workstation hardware and software, and Opcode's Studio Vision Pro 3.5 MIDI plus digital audio sequencer. Pro Tools was an easy choice for me because of the TDM (time domain multiplexing) real-time plug-in architecture. This allows me to use Pro Tools as a general purpose DSP platform. In addition, version 4.0 is native PowerPC software and is much faster than the previous version . The upgrade includes extensive real-time automation, rivaling or surpassing that of most high-end mixing consoles. The value of Pro Tools as a platform really shines when you get into the plug-ins from K.S. Waves. With L1 digital limiter and C1 digital compressor, Pro Tools turns into a rack of super high-quality dynamics gear that can be used to control unwieldy audio volume levels and minimize noise. These two plug-ins are excellent for maximizing dynamic range and are essential for anyone who needs to work in low bit rates or just needs to be loud. Wave's Q10 is the most flexible and best sounding equalizer that I have used, and their Truverb reverb is warm, clear, and very programmable.


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StudioVision Pro 3.5

In addition to handling all of our the MIDI composition chores, the recently upgraded StudioVision Pro 3.5 has some essential digital audio features. Like Pro Tools, the recent update "went native" and is therefore much faster. Still, the most unique feature of StudioVision Pro is the ability to convert digital audio to MIDI and then back again. The best way to describe this is to give an example of how we use it. As you know, there is nothing like a live guitar track to "humanize" a MIDI composition. Unfortunately, it's seldom possible for us to record such a track and have any way to play it back as a digital audio stream. MIDI guitar tracks, which are recorded with a keyboard and played with a guitar sample, are more realistic, but tend to lack all of the subtle pitch gestures and tonal variations that make the track sound "real." Our solution is to record a live guitar track into StudioVision Pro. We convert that track to MIDI, which yields a stream of notes and pitch bend data that matches the performance. Next, we move all of the pitch bend data to another track and reconvert the MIDI data back into the digital audio track. This gives us a less interesting, but more easily looped set of guitar samples.

The StudioVision Audio to MIDI converter window

Choosing the individual notes (samples) that have the most tumbrel variation, we build a compact, but varied guitar instrument . Finally, we play this instrument with the full MIDI plus pitch bend track and use program changes or velocity to switch between the different guitar samples, thus recreating (approximately) the original performance.

Audio Batch Conversion Tools


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K.S. Wave's WaveConvert Pro

Wave's WaveConvert Pro is the latest update to WaveConvert, a batch converter that I often refer to as "the third member of my staff." The new version of the product is as easy to use and as solid as the old version, but it adds some much desired features. For one thing, it now allows you to use all of Wave's high-end plug-ins. You can also save job lists in order to keep track of and reload your files and settings from previous jobs. The job list is exported as a text file, which is great because you can get in and edit it by hand if you want to make a small change to a big job. If all of that this isn't enough, they even include their own Waves IMA ADPCM (Adaptive Pulse Code Modulation) compressor, which simply kicks ass.


Synthesizers & Digital Audio Processing Software

I rely on four main units: Digidesign's SampleCell II, Kurzweil's K2500, my Oberheim Matrix 1000s, and the new Yamaha VL-70m. SampleCell is great because, as a NuBus board, it is integrated into the Mac's file system. There is no need to transfer files over SCSI or (God forbid) MIDI. I like to make my own samples, but I recently got a some great disks from ILIO's Heart of Africa and Supreme Beats series, which I'm using extensively on ENTER THE GECKO.

Since it's not easy for me in my limited space to record live players, I've been looking for a physical modeling synthesizer to add some human feel to my Red Book tracks. I found one that I like in Yamaha's VL-70m. Physical modeling is a technique for creating sounds that is very different from sampling. In a physical model, rather than recording a single performance and looping it, you model the physical characteristics (length and diameter of a pipe; length and thickness of a string; size, shape and reflectivity of a body of a real or imagined instrument) in DSP. You can then tweak these parameters to get the nuances of the of the real thing. Although I've just begun to experiment with it, I've already made some outrageous saxophone patches.

TurboSynth
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Digidesign Turbosynth

On the software side, I spend a lot of time in Digidesign's Turbosynth and Antares Infinity. Turbosynth, though aging without much support, is a great sound effects program. It works like a modular digital synthesizer, allowing you to set up custom patches in the old patch cord paradigm. What I like about it is that you have flexibility in how you route things and that you can have very precise control over filter, amplitude, and pitch envelopes. You can even extract the amplitude envelope off of a sample and then use it as you wish.


Digital Looping Tools


Infinity
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Antares Infinity digital audio processing software digital

Infinity is the definitive set of digital audio looping tools. The term "looping a sample" refers to defining a section of the sound data to repeat as many times as necessary to last a specified duration, as opposed to writing all of those repeats out longhand. When you have 512K of sound RAM to work with, compressing your instrument and sound effects data with looping technology may be your best and only option. Looping is a very tricky business, however, and there's nothing even close to Infinity's set of advanced tools.

Infinity's Rotated Sums Looper is especially well-suited to the PlayStation. The PlayStation has built-in ADPCM compression with a 28-sample block size. While this is essential, as it gives you, effectively, more space to store sound in, it also puts a limitation on your ability to loop sounds. Loop points must occur on sample numbers that are divisible by 28. Anyone who has looped small sounds before knows that it is hard enough just to get something that sounds decent, let alone to do so with such a draconian restriction. Fortunately, Infinity's Rotated Sums Looper allows you to get a rough loop with the loop points on the mathematically correct samples and then process the data in between the loop points until it is smooth and even without screwing up the math. How exactly this is done is more than I have room for, but trust me, it works wonders, especially for ambience and other long, looping sound effects.

 

Manufacturer Links
Antares http://www.antares-systems.com
Digidesign http://www.digidesign.com
Ilio http://www.ilio.com
K.S. Waves http://www.waves.com
Kurzweil http://www.youngchang.com/kurzweil
Oberheim http://www.gibson.com/products/oberheim
Opcode http://www.opcode.com
Yamaha http://www.yamaha.com