Sound Card Technobabel
A sound card has many electronic components that encode/decode all of the sounds that are input/output from your computer. Here is a explanation of how those things work together to provide sound pleasure to the end-user.
Current sound cards usually plug into a Peripheral Component Interconnect (PCI) slot, while some older or inexpensive cards may use the Industry Standard Architecture (ISA) bus. Many of the computers available today incorporate the sound card as a chipset right on the motherboard. This leaves another slot open for other peripherals. The SoundBlaster Pro is considered the de facto standard for sound cards. Virtually every sound card on the market today includes SoundBlaster Pro compatibility as a bare minimum.
Often, different brands of sound cards from different manufacturers use the same chipset. The basic chipset comes from a third-party vendor. The sound card manufacturer then adds various other functions and bundled software to help differentiate their product.
What can I connect?
Some higher end sound cards
now include the ability to hook up surround sound
. You can have up 6 speaker
s including a subwoofer
attached to your sound card giving you a live surround sound experience. Most of these same sound cards use Dolby Digital
to provide this surround sound.
It does what with sound?
Most sound cards can do 4 main processes with sound:
handles of these processes that involve sound leaving the computer
. The ADC
handles all of these processes the involove sound
entering the computer.
How does it all work then?
Let's say you speak into your computer's microphone. A sound card creates a sound file in wav format from the data input through the microphone. The process of converting that data into a file to be recorded to the hard disk is:
Step 1: The sound card receives a continuous, analog-waveform input signal from the microphone jack. The analog signals received vary in both amplitude and frequency.
Step 2: Software in the computer selects which input(s) will be used, depending on whether the microphone sound is being mixed with a CD in the CD-ROM drive.
Step 3: The mixed, analog waveform signal is processed in real-time[ by an analog-to-digital converter (ADC) circuit chip, creating a binary (digital) output of 1s and 0s.
Step 4:The digital output from the ADC flows into the DSP. The DSP is programmed by a set of instructions stored on another chip on the sound card. One of the functions of the DSP is to compress the now-digital data in order to save space. The DSP also allows the computer's processor to perform other tasks while this is taking place.
Step 5: The output from the DSP is fed to the computer's data bus by way of connections on the sound card (or traces on the motherboard to and from the sound chipset).
Step 6: The digital data is processed by the computer's processor and routed to the hard-disk controller. It is then sent on to the hard-disk drive as a recorded wav file.
To listen to a prerecorded wav file, the process is simply reversed:
Step 1: The digital data is read from the hard disk and passed on to the central processor.
Step 2: The central processor passes the data to the DSP on the sound card.
Step 3: The DSP uncompresses the digital data.
Step 4: The uncompressed, digital data-stream from the DSP is processed in real-time by a digital-to-analog converter (DAC) circuit chip, creating an analog signal that you hear in the headphones or through the speakers, depending on which is connected to the sound-card's headphone jack.
So can I upgrade if I don't have the features I want?
Sound-card upgrades are an option if the user wants higher performance. A common upgrade path is to move from an ISA sound card to a PCI sound card or from a built-in soundcard to a PCI soundcard. However upgrading from a built-in sound-card can be more difficult then the other options. Generally, your intended application determines whether you need a new sound card. For some audio applications, such as telephony or certain games, full-duplex sound is a must. Full-duplex sound has the ability to accept a sound input while simultaneously providing sound output.