Audio Hardware - 3D Audio Processing

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A second important issue for game players is how the sound cards produce 3D audio. As with 3D video, there are two major methods:

• Host-based processing (which uses the CPU to process 3D, which can slow down overall system operation)

• Processing on the audio adapter (referred to as 3D acceleration)

Some 3D audio cards perform some or all of the processing necessary for 3D using the host's CPU, whereas others use a powerful DSP that performs the processing on the audio adapter itself. Cards that use host-based processing for 3D audio as well as systems that use AC'97 audio codecs for integrated 3D audio can cause major drops in frame rate (frames per second of animation displayed onscreen by a 3D game) when 3D sound is enabled on systems with processors running at speeds under 1GHz. However, cards with their own 3D audio processors onboard have little change in frame rate whether 3D sound is enabled or disabled. Many of the latest chips from major audio adapter and chipset vendors support 3D acceleration, but the number of 3D audio streams supported varies greatly by chip—and it can sometimes be limited by problems with software drivers.

A good rule of thumb for realistic gaming is to have an overall average frame rate of at least 30fps (frames per second). With CPUs running at 1GHz or above, this is easy to achieve with any recent 3D audio card or recent onboard integrated audio solutions. However, gamers using older CPUs, such as those running slower than 1GHz, will find that cards using the host CPU for some of the 3D processing will have frame rates that fall below the desired average of 30fps, making for clumsy gameplay. To see the effect of enabling 3D sound on the speed of popular games, you can use the built-in frame-rate tracking feature found in many games or check online game-oriented hardware review sources, such as http://www.anandtech.com. Frame rates are closely related to CPU utilization; the more CPU attention your 3D audio card or integrated audio solution requires, the slower the frame rate will be.

As with 3D video, the main users of 3D sound are game developers, but business uses for ultra-realistic sound will no doubt follow.

DirectX Support Issues

The latest version of DirectX, DirectX 9.0b, is designed to give all sound cards with 3D support a major boost in performance compared to DirectX 8.x and earlier versions. Previous versions of DirectX supported 3D with DirectSound3D, but the performance of DirectSound3D was limited. Game programmers needed to test the audio adapter to see whether it supported DirectSound3D acceleration and then would either enable or disable 3D sounds based on the host hardware. Starting with DirectX 5.0, DirectSound3D works with third-party 3D acceleration features. Compared to DirectX 8.x, DirectX 9.0b improves 3D audio quality and performance. You can download it from the Microsoft DirectX Web site at http://www.microsoft.com/windows/directx.

Installing the Sound Card

Before you can install a sound card, you must open your computer. In almost all cases today, you will install a PCI audio adapter that supports Plug and Play configuration. Compared to the previous generation of ISA audio adapters, PCI audio adapters use fewer hardware resources, feature a lower CPU utilization rate, and provide better support for advanced 3D gaming APIs.

If you need to install an ISA audio adapter, see "Installing the Sound Card (Detailed Procedure)" in Chapter 20 of Upgrading and Repairing PCs, 11th Edition, supplied in electronic form on the disc packaged with this book.

If your computer has integrated audio, in most cases you should disable it. You could have audio conflicts with AC'97 codec-based solutions and resource conflicts with solutions that emulate the Creative Labs Sound Blaster. See Chapter 5, "BIOS," for details.

If you have several empty bus slots from which to choose, install the audio adapter in the slot that is as far away as possible from the other cards in the computer. This reduces any possible electromagnetic interference; that is, it reduces stray radio signals from one card that might affect the sound card. The analog components on audio adapters are highly susceptible to interference, and even though they are shielded, they should be protected as well as is possible. Next, you must remove the screw that holds the metal cover over the empty expansion slot you've chosen. Remove your audio adapter from its protective packaging. When you open the bag, carefully grab the card by its metal bracket and edges. Do not touch any of the components on the card because any static electricity you might transmit can damage the card. Also, do not touch the gold-edge connectors. You might want to invest in a grounding wrist strap, which continually drains you of static build-up as you work on your computer.

Before you make your final decision about which slot to use for your audio adapter, take a careful look at the external cables you must attach to the card. Front and rear speakers, microphone, game controller, line in, S/PDIF, and other cables that attach to your system can interfere with (or be interfered by) existing cables already attached to your system. It's usually best to choose a slot that allows you to route the audio cables away from other cables. If you're installing a sound card that uses an internal 5 1/4'' breakout box, be sure the ribbon cable from the drive bay used for the breakout box can comfortably reach the connector on the sound card. You might have to move a CD-ROM, CD-RW, or DVD drive to a different drive bay to free up a drive bay needed by the breakout box.

Figure 16.10 shows a Creative Labs Audigy sound card after installation in a computer. The four-wire analog and two-wire digital cables to the CD-ROM drive are connected to the card, as is the ribbon cable to the Audigy Drive internal breakout box. However, the cable to the Audigy Drive's SB1394 (IEEE-1394a-compatible) port has not yet been connected to the card.

Figure 16.10 A Creative Labs Audigy sound card installed in a typical PC.

If your system has an internal CD-ROM drive with an analog audio cable, connect the audio cable to the adapter's CD Audio In connector, as shown in Figure 16.10. This connector is a four-pin connector and is keyed so that you can't insert it improperly. Note that no true standard exists for this audio cable, so be sure you get the correct one that matches your drive and adapter. If you need to purchase one, you can find cables with multiple connectors designed for various brands of CD-ROM drives. This will allow you to play music CDs through the sound card's speakers and to use analog ripping if you want to create MP3 files from your CDs.

Many recent CD-ROM and DVD drives also have a digital audio connector that supports a two-wire connector. Attach one end of the digital audio cable to the rear of the drive and the other end to the CD SPDIF or CD Digital Audio connector on the sound card (refer to >Figure 16.10). This enables you to perform digital ripping if you want to create MP3 files from your CDs. Note that some ripping programs can also use digital signals received through the drive's data cable.

Next, insert the adapter's edge connector in the bus slot, but first touch a metal object, such as the inside of the computer's cover, to drain yourself of static electricity. When the card is firmly in place, attach the screw (refer to Figure 16.10) to hold the expansion card and then reassemble your computer.

This chapter is from Upgrading and Repairing PCs, 16th edition,by Scott Mueller. (Que Books, 2004, ISBN: 0789731738).  Check it out at your favorite bookstore today. Buy this book now!

Next: Connecting PC Speakers and Completing the Installation >>
 

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