Interviewee: Simon N Goodwin (Principal Programmer, Central Technology, Codemasters Software Ltd.)

Developer: Codemasters
Publisher: Codemasters
Game Title: DiRT

My games have always had sound, even in the early 80s when that meant one-bit clicks under control of a TRS-80, Apple ][ or Sinclair 8 bit CPU, but it wasn't till the remake of my Spectrum hit Gold Mine for the MGT SAM that I got sound effects I was happy with, for things like rock falls and underground streams, using the Philips SA1099 chip for stereo effects.

But almost 20 years ago I was writing and publishing useful audio effects for home micros. The Crash magazine Tech Tape included sample editing tools and ZX-FX, a real-time DSP application; the peak metering, costly but vital in 8 bit sampling, blinked the border colour, which worked surprisingly well!

Five people worked directly on the audio: besides me, Adam Sawkins and Giannis Ioannou worked on game code and Stafford Bawler and Andy Grier did the sound design. We outsourced the localized speech and music.

There was also a strong legacy of system code from Jon Mitchell, Colin McRae Rally 2005 game audio programmer. None of the old game code was used, but before he left Jon wrote much of the audio system framework which we've used on new platforms and the OpenAL implementations. That greatly benefited from his experience working on the old version even though we chose to do it differently this time. And four OpenAL programmers at Creative should be considered honorary members of our team: Pete Goodwin, Ian Minett, Dan Peacock and Carlo Vogelsang, for their contributions to the Xbox 360 and PC.

We used to have just a couple of minutes of samples in RAM; now we have over an hour we can trigger at any time. So there's vastly more variety, and digital effects like EAX^® increase this. For instance CMR05 had to have separate in-car and external kick-up sounds, but now we have one bank, which is much bigger, and let the DSP make the difference. The game now uses a sophisticated sound group system and multiple listeners which greatly improve the balance between camera views and the dynamics during play.

The most obvious things are the reverb and real-time reflections, and the in-car filtering. But more subtle things like the vastly superior sample-rate conversion in the hardware contribute a lot, bringing the quality of the sound closer to that of our source recordings, especially with so many uncompressed 16 bit PCM assets in the game - the PC version has room for those (only the speech is compressed) which the consoles do not, and quality assets only shine through if the rest of the signal chain keeps up. Current software mixers can't compete with dedicated hardware, though when they get a core to themselves - as on the new consoles - they might yet.

The hardware reverbs are true surround ones, and that's great if you've got a good 7.1 set-up. Many of these things are subtle - like a lot of stuff rarely done right, you take it for granted when it's there and only really notice when it's taken away.

For us the crucial thing was it meant a lot of work could be shared between PC and Xbox 360 versions, and Vista was automatically bundled into the PC implementation without us having to worry about it. The convenience of writing for one low-level API, rather than three, cannot be understated. It also helped us get surround working quickly on PlayStation 3, as the positional audio API is the same.

The real-time reflections work well on many stages, especially in Japan, Italy and the final sections of the hill climbs where there are many narrow gullies. There are many great-sounding cars in the game, but the Toyota Celica GT4, the Fiat 131 Abarth and Subaru Impreza are amongst our favourites. All the multi-car races work the audio system very hard - especially on lower-spec PCs. Hardware acceleration is a significant benefit here. There was no multi-car racing and no virtual voice system in the previous three versions of CMR; from an audio point of view, the latter made the former possible.

 

That's more a question for the sound designers, but I enjoyed the truck recording. The 8-channel Zaxcom DEVA recorder arrived late in the development but allows our new captures to keep up with the high sample-rate and bit-resolution on X-Fi. We do a lot of recording at MIRA, under expertly controlled conditions, but when Adam and Stafford went out for a serious drive with Colin McRae in his rally car they returned informed and inspired. Collisions, scrapes and mechanical sounds are as important as the engines in DiRT; when one designer's car died in the Codemasters carpark we had fun throwing stones at it, in the interests of great game audio, and I know Stafford found the sledgehammer session in the scrapheap very cathartic.

More cars, more variety, more effects, and more feedback from the game world to the audio system, so the audio experience never need be the same twice. And we'd really like to get game audio truly into 3D and are working with Creative and other companies to make that practical.

Designers: learn about the real-time effects and mix topology available in games, experiment with them so you know how things will sound, not just the names on the knobs. Programmers: learn C++ and remember that in games, only the worst case matters. Both: learn about transfer functions and psychoacoustics, and use those to map information from the game into the audio system, so that your games are as interesting an hour, a day and a week on as they sound in the first minute.

(Simon Goodwin) Not me - my strong points are strictly crashing and fixing crashes! Stafford's your man for that.

(Stafford Bawler, sound designer at Codemasters)
In-car camera, with standard car setup:

(DEMO) Windy Point B, Mitsubishi Lancer Evo 9, 2:30.85
(FULL GAME) Numata, Toyota Celica GT4, 2:57.57