Understanding Multimedia Devices
Multimedia devices such as webcams, digital cameras, MIDI ports, microphones, sound cards, and video capture cards are used by both home and business-oriented PCs. The following sections discuss the characteristics of each of these devices.
A webcam is a simple digital camera capable of taking video or still images for transmission over the Internet. Unlike digital cameras (next section), webcams don't include storage capabilities.
Most webcams plug into a USB port, but a few have used IEEE 1394 or parallel ports.
Webcams are generally used in live chat situations, such as with AOL Instant Messenger or other IM clients. They offer resolutions ranging from sub-VGA to as high as 2 million pixels (2 megapixels). Some offer autofocus and zoom features for better image clarity, and some have built-in microphones.
Digital cameras have largely replaced film cameras for both amateur and professional photography. They use CMOS or CCD image sensors to record images onto internal or card-based flash memory form factors such as Compact Flash, SD, Memory Stick, xD-Picture Card, and Smart Media.
Digital cameras transfer images to computers for emailing, printing, or storage via either flash memory card readers or direct USB port connections.
MIDI Music and MIDI Ports
Musical instrument digital interface (MIDI) music is created from digitized samples of musical instruments that are stored in the ROM or RAM of a MIDI device (such as a sound card) and played under the command of a MIDI sequencer. MIDI sequences can be stored as files for future playback, and can be transferred between sound cards and MIDI-enabled devices such as keyboards via the MIDI port. To learn more about MIDI ports, see the section "MIDI Port," earlier in this chapter.
Sound cards are used to record and play back analog audio, and most can also play back digital audio sources as well. When recording analog audio sources such as CDs, line in or microphone in, sound cards digitize the audio at varying sample rates and store files in either uncompressed forms such as WAV or compressed forms such as WMA or MP3.
Most recent sound cards support 5.1 or 7.1 surround audio, and many sound cards also support digital stereo or surround audio playback standards via SPDIF ports. In recent years, sound cards have become less popular due to the popularity of onboard audio, but sound cards are preferred by users who create audio recordings.
Figure 3-31 illustrates a typical sound card.
Figure 3-31 Typical input and output jacks on a typical sound card (the Creative Labs X-Fi Xtreme Gamer).
Microphones plug into the 1/8-inch mini-jack microphone jack on a sound card or integrated motherboard audio. The most common microphones used on PCs include those built into headsets (see Figure 3-32) or those that use a stand.
Figure 3-32 A typical PC stereo headset with microphone.
Microphone volume is controlled by the Windows Sounds and Audio Devices applet's mixer control. Open the Recording tab to adjust volume, to mute or unmute the microphone, or to adjust microphone boost.
Video Capture Card
As the name suggests, video capture cards are used to capture live video from various sources, including analog camcorders, VCRs, analog output from DV camcorders, broadcast TV, and cable TV. Most recent cards with video capture capabilities are actually multi-purpose cards that include other functions. These include ATI's All-in-Wonder series of video (graphics) cards with onboard TV tuner and video capture functions, video (graphics) cards with VIVO (video-in/video-out) S-video or composite video ports, and TV tuner cards and USB devices. Video can be stored in a variety of formats, including MPEG, AVI, and others for use in video productions.