OpenAL® and Windows Vista™

http://www.openal.org/openal_vista.html

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.