The
Benefits of Dedicated Hardware Acceleration for Audio A Diamond Multimedia
White Paper For years, computers have benefited from boosts in
performance provided by graphics accelerator cards. It
would almost seem unheard of to have a system that didn't
have one inside. To some extent this is true with audio.
However, most FM/Wavetable sound cards are built to play
back one monophonic or stereo digital channel and
don't have a dedicated processor to deal with digital
mixing and other CPU-intensive tasks. Due to the demands
placed on today's gaming, applications and the Internet,
changes need to be made in the way audio is handled. Even
though there may be a sound card in your current system
(or on the motherboard), there may be reason to upgrade
the audio quality of your machine, especially if you are
a game player. Read on, and you will see there are many
benefits in having a sound card quite different from the
one you own today. For the purpose of this article, dedicated hardware
acceleration can be defined as a device having an
on-board processor that provides additional computational
power for sound-related processing, thus freeing the CPU
to concentrate on tasks other than those intended by the
additional processor. Some of the benefits from having a dedicated
accelerator include: Reducing CPU drain to increase overall performance Although computers are increasing in speed, it has
been shown that even with the speed of today's machines
there is always a need for more power, especially with
newer games and applications. Example: Many applications use multiple streams
of audio. A 90Mhz Pentium takes a hit of around 1 percent
per stream to digitally mix individual audio streams.
Adding tasks such as pitch transposition, bit-rate
conversion and positional 3D imaging raises the CPU usage
exponentially. If enough streams are mixed and modified
there is little horsepower left for graphics, video and
the engine needed to run the application. Although the
standard computer model has moved away from P-90's to
faster machines, the horsepower demands continue to drive
on. Higher quality audio through complex algorithms In 1995, Microsoft introduced DirectX™
technology (software algorithms to accelerate graphics,
3D, sound, etc) along with the release of Windows 95®.
Even though DirectX was designed to make use of the CPU
for these computations, the quality and speed of the
designated tasks are raised significantly if a
DirectX-certified accelerator is present. Example: If DirectSound™ is called by an application and a sound accelerator is installed, DirectSound will offload the computations to the card for processing of the audio function. If not present, the workload will revert back to the CPU. The point of this is to note that DirectX is a scaleable architecture. Dedicated processors allow DirectX to work best. That means smoother mixing, higher quality audio and more believable 3D sound in the game you are playing right now! 3D positional audio The advent of 3D graphics technology has created the
need to hear in 3D to complete the total
experience. It would be confusing to visualize a three
dimensional world, and only hear sounds in stereo. How
would it be possible to hear the roar of a lion behind
you or a torpedo blast overhead? Without 3D sound in 3D
graphics applications, you only receive part of the
overall experience. Although 3D sound comes in different flavors, there is
a drastic difference between "true" 3D audio
and extended stereo enhancement. An extended stereo field
is wider and presents sound in a half circle on a
horizontal plane. This gives the listener the perception
of sound coming from farther positions to the left and
right. It does not position sounds above, below or behind
the ears. Widening a stereo field achieves only part of
the full 3D experience. True 3D positional sound produces
imaging that appears to come from behind, above, below
and the sides, and can be heard in headphones and
speakers alike (either 2 or 4 speakers). It also accounts
for the reflections of surfaces and boundaries in the
present sound field. Because 3D algorithms take quite a bit of horsepower,
a dedicated accelerator can be of great help. Having a
dedicated accelerator for 3D audio makes games much more
realistic and exciting to play. Using the CPU to do the
math can make a game slow to a crawl just from a few
bullets being sent 3D calls. On the other hand, the game
doesn't flinch when an accelerator is present. Increased throughput of data via the PCI bus The PCI bus moves data at rates many times faster than
the ISA bus. It is by this means that multiple streams of
digital audio can run across the bus with relative ease.
Using the PCI bus for audio also keeps the system from
being bogged down due to the lack of processor cycles
needed to bridge the ISA and PCI bus together. Using a
higher bandwidth bus makes for much more efficient audio.
Once again, that means higher powered, more interactive
and more exciting game play. Freeing up system memory for applications All Windows® operating systems are made to multitask.
In order to multitask, there must be sufficient memory to
run all relevant applications. Every time an application
runs out of system memory, it moves to the hard drive to
temporarily store it's work. With many applications
running, the hard drive spins constantly. Offloading
unnecessary math and computations to the dedicated
hardware processor allows much of the precious system
memory to be freed up and used for applications. This
allows you to enjoy the freedom of playing a game without
unnecessary waiting. With the release of DirectX architecture and the
enthusiasm of the development community, dedicated
hardware accelerators for audio are the natural next step
for the game player. New games are already making use of
3D audio as well as other DirectX technologies. These
games and technologies bring entertainment to a level of
realism and excitement never before experienced on the
PC. Freedom 5600 Diamond Multimedia Systems, Inc. has announced that it
has developed its first multimedia audio processor, Freedom
5600, for Microsoft DirectSound and DirectSound 3D
applications running on the Windows 95 operating system.
Designed to provide an immersive 3D audio experience, Freedom
5600 will be an integral component of next-generation
audio solutions from Diamond Multimedia planned for the
first quarter of 1997. Diamond's Freedom 5600 will allow computer game
and entertainment developers to fully utilize Microsoft's
DirectSound and DirectSound 3D APIs for multi-stream
audio processing. Current sound technology is limited to
ISA-based, single-stream audio. Freedom 5600 can
support up to 24 independent audio streams without
incurring any significant CPU overhead. The design of Freedom
5600 facilitates the integration of DSP and CODEC
technologies to provide interactive 3D positional sound
for headphone, dual- and quad-speaker output. Diamond's Freedom 5600 is expected to be one of
the first Windows 95, Plug and Play, PCI-bus enabled
solutions on the market. Diamond Multimedia plans to
incorporate Freedom 5600 into a family of products
along with Analog Devices' DSP and audio CODEC components
in the first quarter of 1997. |
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