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Introduction
With the launch of Windows Vista just around the corner, both gamers and game developers are asking questions
about audio compatibility with OpenAL. This document is intended to address the issues.
The OpenAL API will provide a direct path to any native OpenAL driver for delivering premium quality interactive
3D audio for gaming on Windows Vista. Since Windows Vista does not inherit the
hardware abstraction layer for audio
that was present under previous versions of Windows, including Windows XP, there will be no more hardware
acceleration of DirectSound 3D. For this reason, OpenAL becomes very important as a solution for
game developers
wanting to take advantage of audio hardware. Overall, this will be a positive development for both OpenAL and for
the PC gaming industry. It allows developers to choose an open audio API to write to, and lets hardware companies
like Creative Labs® have a direct path to its hardware, with the ability to add in new features at will.
OpenAL was launched at the Game Developers Conference in 1999. Initially it was a joint collaboration between
Creative Labs and Loki Entertainment. Right away, OpenAL was able to grab the attention of developers
and it began
to be incorporated into games. Later on, Creative Labs and former employees of Loki assumed responsibility for
OpenAL (when Loki Entertainment dissolved) and committed to maintaining and improving the API. Since that time
OpenAL has continued to build support among the developer community, becoming the standard PC audio rendering solution
for premier game engines such as Unreal, Torque and the Doom3 engine. OpenAL has also received support from hardware
vendors, including Apple® and NVIDIA®. Under previous versions of Windows, OSX
and Linux, the OpenAL community has
built itself a very strong base, and will continue to build momentum under Windows Vista as the
dominant game audio API.
On the Windows platform, Creative Labs provides three different OpenAL playback devices. Firstly,
there is a native
device that ships with soundcards such as the Sound Blaster Audigy® and Sound Blaster
X-Fi series of cards. The native
device communicates directly with the drivers of the soundcard and offers the best performance, quality and feature
set of all the OpenAL devices. Secondly, there is a device known as Generic Hardware which uses
DirectSound 3D
hardware buffers to enable hardware acceleration of OpenAL on soundcards that don't have their own native devices.
Finally, there is a Generic Software device that uses a built-in software mixer to output a single audio stream to
a DirectSound Buffer.
OpenAL on Windows Vista
As already stated above, Microsoft® will be removing DirectSound 3D Hardware support from Direct X
with the launch of
Windows Vista. DirectSound and DirectSound3D will still function; however, they will no longer
use hardware
acceleration.
The native OpenAL devices on Sound Blaster Audigy and Sound Blaster X-Fi soundcards do not use
DirectSound or
DirectSound 3D and so they will be completely unaffected. For games that use these devices, nothing will change.
The game will continue to enjoy hardware based 3D audio and effects.
The Generic Hardware device will no longer be available, as it requires the use of hardware DirectSound 3D Buffers.
Instead, this device will gracefully, and automatically, fallback to using the Generic Software device, which
will continue to work as before.
DirectSound3D on Windows Vista
With Microsoft's decision to remove the audio hardware layer in Windows Vista, legacy
DirectSound 3D games will no
longer use hardware 3D algorithms for audio spatialization. Instead they will have to rely upon the new Microsoft
software mixer that is built into Windows Vista. This new software mixer will give the users
basic audio support
for their old Direct Sound games but since it has no hardware layer, all EAX® effects will be lost,
and no individual
per-voice processing can be performed using dedicated hardware processing.
EAX has become the de facto standard for real-time effects processing. It has been incorporated
in hundreds of games
and has become the method of choice for game developers wanting to add interactive environment effects to their titles.
Some of the best selling games of all time use the EAX extensions to DirectSound 5.0 and beyond,
including Warcraft3,
Diablo2, World of Warcraft, Half Life, Ghost Recon, F.E.A.R. and many others. Under Windows Vista, these games will
be losing the hardware support that came as standard under the previous Windows Operating Systems, and will no longer
provide real-time interactive effects, making them sound empty and lifeless by comparison to the way they sound on
Windows XP.
In some cases, where a game specifically looks for a hardware audio path, it may even fall back to plain stereo output.
This will be a very different landscape for 3D audio than the one that both Creative Labs and Aureal
Technologies® pioneered
8 years ago. Both companies dedicated hardware power to rendering increasing numbers of 3D voices, with each voice
taking full advantage of HRTF (Head Related Transfer Function) technology, wave tracing and other advanced processing.
With the native Windows Vista audio APIs, all this advanced, hardware-based 3D audio processing will be inaccessible.
Instead, basic mapping to a generic speaker placement scheme will be employed, and all interactive processing and
rendering will be dependent on the host CPU. While it is true that CPUs continue to get faster, the Vista audio
architecture intentionally simplifies things, such that the potential processing load for multiple 3D voices is limited.
Inevitably there is a tradeoff. This will be especially true for gamers that have come to depend on the kind of high-end
3D audio experience available from products like the SoundBlaster X-Fi, with its advanced headphone 3D audio processing
and dedicated hardware DSP effects. For gamers this would be the most noticeable loss in Windows Vista, and it would
be a definite step backwards for PC gaming audio if developers only had the option of using native Windows Vista audio
APIs. However, they do have a legitimate, proven alternative in OpenAL.
The Future Is OpenAL
The good news for owners of advanced audio cards like SoundBlaster X-Fi is that the developer community has been preparing
for this for over 3 years. Hardware audio will not be disappearing with the launch of Windows Vista. Games that support
OpenAL today will continue to provide full hardware-enhanced 3D audio under Windows Vista. This includes games such as
Battlefield 2, Doom3, Unreal Tournament2k4, Dungeon and Dragons Online, Prey, Quake 4, and many others (a full list can
be found at http://www.openal.org/titles.html). These games have complete hardware-based HRTF support for multiple speaker
and headphone setups as well as full support for all the different versions of EAX. Also, these games will be able to
take advantage of the hardware-accelerated path on supporting hardware for performance and quality increases.
OpenAL support will also be incorporated into the Unreal 3 engine from Epic Games®, the new Doom 3 engine
from Id Software®
and the new Torque Gaming Engine from Garage Games®. These engines represent literally hundreds
of upcoming titles for PC
and will provide the majority of upcoming major PC title releases. All of these titles will have OpenAL support at the
core and will sound as good as they look in Windows Vista. Other top tier developers including
D.I.C.E.®, Turbine®, Bioware®
and others are working to ensure their home-grown audio engines fully support OpenAL hardware. For game developers that
are serious about the PC platform, OpenAL is presently the only viable option for delivering the 3D audio experience that
gamers have come to expect.
OpenAL has an extremely strong future. The OpenAL community has been able to expand its API with new features, and these
were delivered in the recent release of OpenAL version 1.1. With the flexible extension mechanism in OpenAL, more and
more extensions are being created to handle tasks such as effects processing, multi-channel buffer playback, and support
for features like X-RAM.
Also, OpenAL is working across more platforms than just Windows -- support exists for multiple varieties of
Unix®,
OS X (from Apple), and Xbox® / Xbox360 (from Creative Labs).
Windows Vista will be ushering in a new age for PC gaming, with great new graphics, physics and CPU support. When combined
with OpenAL and the widespread developer support it is receiving, gamers will also be hearing some of the best audio ever
on Windows Vista.
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