Dolby packs five-channel sound for DVD games
eetimes.com
(see diagram in article)
By Junko Yoshida
EE Times
(03/12/99, 2:30 p.m. EDT)
SAN JOSE, Calif. — Dolby Laboratories will unveil its latest effort to
promote multichannel PC game development at next week's Game
Developers' Conference. FilterGraph is a piece of software code that lets
game developers mix, in real-time, 5.1-channel music with game sound
effects for DVD-ROM-based videogame play.
"Our goal is to bring home-theater experiences to PC titles," said John Loose,
multimedia audio specialist at Dolby Laboratories. The implementation lets
consumers enjoy four-channel, home-theater-like sound effects through a
pair of front-positioned speakers and dual rear speakers with separate left
and right channels, eliminating the need for a hookup to a separate
home-theater system.
Lander, a videogame title due for launch this month by Sony-owned
entertainment-software publisher Psygnosis, is the first DVD-ROM-based
PC videogame title to feature Dolby Digital streams mixed with interactive
game sound effects. Dolby is betting its effort will encourage more PC-game
developers to take advantage of DVD's multichannel capabilities.
Dolby is not charging licensing fees for FilterGraph-enabled content
development or for participation in certification programs. Though the formal
rollout is set for next week, Loose said half-a-dozen game developers are
already implementing the software.
To date, game developers have limited use of multichannel Dolby Digital to
such elements as transitional vignettes or the "minimovies" that precede
gameplay. That's largely because of the awkward setup required by today's
PC-game platform.
"Dolby Digital music and videogame sound effects don't come from the same
spigots," explained Dennis Staats, manager of technology marketing at Dolby.
Realization of 5.1-channel Dolby Digital audio streams in a six-speaker
environment for DVD-ROM gameplay requires hookup of an external
home-theater system to the PC. The game's PCM sound effects, by contrast,
are channeled through the PC speakers.
Development of PC games with six separate but truly interactive digital audio
channels awaits the common implementation of a high-speed, "fat" data pipe,
such as IEEE 1394 in both PCs and home-theater systems. Until then,
FilterGraph provides "a good transitional solution," Dolby's Loose said.
FilterGraph translation code acts as a set of drivers within the game title.
When the PC's host CPU decodes the 5.1-channel Dolby Digital audio,
FilterGraph intercepts it before it is transformed into two-channel Dolby
Digital sound. It then translates the audio into Microsoft Corp.'s Direct
Sound/Direct Show calls, enabling Dolby Digital sound streams to be mixed
with the PC game's sound effects in real-time and reproducing the sound as
four-channel audio.
The implementation responds to the push for four-channel audio among such
sound-card vendors as Creative Labs and Diamond Multimedia, said Staats.
FilterGraph does not require changes in the sound card to enable
four-channel Dolby Digital PC games. Consumers simply add two rear
speakers to the current setup.
"We provide authors of videogame titles with new tools and techniques to do
multichannel PC games," said Dolby's Loose. "The key is that the only way
to get true multichannel effects out of your game is through Dolby."
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