Audio input devices may digitize sound by means of an audio board or a MIDI board. Video input devices may use frame-grabber or full-motion video cards. Electronic cameras are still-video or digital cameras; the latter use light-sensitive silicon chips to capture photographic images. Sensors collect specific kinds of data directly from the environment. Human-biology input devices include biometric systems, line of sight systems cyber gloves and body suits and brainwave devices.
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The machine never grew impatient never gave up reported journalist Jerry Adler about the miracle piano teaching system, this combination of electronic keyboard and software for an IBM compatible computer promises to teach novices handles water music in only 40 lessons it simply devised new exercises sent me back to practice again issued wildly inflated praise at the slightest signs of improvement until at last I made it through all 15 cars of marry had a little lamb and was rewarded with a heart-felt WHEW! YOUTH BECOMING A MUSICIAN!’’
As this example suggests there are all kinds of input devices beyond those we have mentioned. Here we describe five types
# Audio-input devices
# Video-input devices
# Electronic cameras
#human-biology input devices
Voice-recognition devices are only one kind of audio input which can include music and other sounds. An audio-input device records or plays analog sound translates it for digital storage and processing. As we mentioned in chapter 1 an analog sound signal represents a continuously variable wave within a certain frequency range. Such continuous fluctuations are usually represented with an analog device such as a cassette player. For the computer to process them these variable waves must be converted and 1s the language of computer.
There are two ways in which audio is digitized:
# Audio board: analog sound from say a cassette player goes through a special circuit board called an audio board. An audio board is an add-on circuit board in a computer that converts analog sound to digital sound and stores it for further processing.
#MIDI board: A MIDI pronounced ‘’middle’’) board—MIDI stands for musical instrument digital interface is an add-on board that creates performs for example on a special MIDI keyboard.
The principal use of audio-input devices such as these is to precise digital input for multimedia system is a microcomputer that incorporates text, graphic, sound, video, and animation, in a single digital presentation. Video input is also often used for this purpose as we describe next.
As with sound most film and videotape is in analog form eith the signal a continuously variable wave. Thus to be converted to digital form through a special video card installed in the computer.
Two types of video cards are the frame-grabber video and the full-motion video:
# Frame grabber video card: some video cards called frame grabbers can capture and digitize only a single frame at a time.
# Full-motion video card: other vide cards, called full-motion video cards, can convert analog to digital signals at the r5ate of 30 frames per second giving the effect of a continuously flowing motion picture.
The main limitation in capturing full video is not input but storage it takes a huge amount of storage space to store just 1 second of video.
The electronic camera is a particularly interesting piece of hardware because it foreshadows major change for the entire industry of photography instead of using traditional (chemical) film electronic camera captures images in electronic form for immediate viewing on a television or computer display screen.
Electronic cameras are of two types: still-video and digital.
# Still-video cameras: still-video cameras are like camcorders. However, they capture only a single video image at a time. Because the cameras are meant to display images only on a television screen, the pictures must be concerted by a video capture board before they can be stored in a computer in addition compared to the digital camera picture resolution and color range ate limited. An example of a still-video camera is the RC-570 from canon.
# Digital cameras: more interesting is the digital camera. A digital camera uses a light-sensitive processor chip to capture photographic images in digital form. The bits of digital information can then be copied onto a computer’s hard disk for manipulation and printing out. Examples of digital cameras are apple Computers Quick takes 100 Logitech’s Footman and Dycam’s model.
In February 1994, Eastman Kodak and the associated press (AP) introduces an electronic camera specifically designed for news photograph, the News camera 200. The camera stores 30-50 digitized images in a battery-backed memory. Later a photographer can download transfer these images to his or her microcomputer or transmit them by modem or even via satellite uplink to photo editor at the APs New York office.
A sensor is a type of input device that collects specific kinds of data directly from the environment and transmits it to a computer. Although you are unlikely to see such input devices connected to a PC in an office they exist all around us often in invisible form. Sensors can be used for detecting all.
Kind of things: speed, movement, weight, pressure, temperature, humidity, wind, current, fog, gas, smoke, light, shapes, images, and so on.
Beneath the pavement, for example, are sensors that detect the speed and volume of traffic. These sensors send data to computers that can adjust traffic lights to keep cars and trucks away from gridlocked areas. In aviation sensors are used to detect ice buildup on airplane wings or to alert pilots to sudden changes I wind direction. In California sensors have been planted along major earthquake fault lines in an experiment to see if scientist can predict major earth movements. Sensors are also used by government regulators to monitor whether complying with air pollution standards.
Characteristics and movements of the human body when interpreted by sensors optical scanners voice recognition and other technologies can become forms of input some examples ate as follows:
# Biometric systems: Biometric security devices identify a person through a fingerprint voice intonation or other biological characteristic. For example retinal-identification devices use a ray of light to identify the distinctive network of bold vessels at the back of one’s eyeball. Biometric systems are used, for example, in lieu of typed passwords’ to identify people authorize to use a computer system.
#Line-of-sight systems: Line-of-sight systems enable a person to use is or her eyes to point at the screen a technology that allows physically handicapped users to direct a computer. This is accomplished by a video camera mounted beneath the monitor in front of the viewer. When the user looks at a certain place on the screen, the video camera and computer translate the area being focused on into screen coordinates.
#cyber gloves and body suits: Special gloves and body suits often used in conjunction with virtual reality or the computer-generated simulation of reality-use sensors to detect body movements. The data for these movements is sent to a computer system. Similar technology is being used for human-controlled robot hands which are used in nuclear power plants and hazardous-waste sites.
# Brainwave devices: perhaps the ultimate input device analyzes the electrical signals of the brain and translates them into computer commands. Experiments have been successful in getting users to move a cursor on the screen through sheer power of thought. Other experiments have shown users able to type a letter by slowly spelling out the words in their heads. Although there is a very long way to go before brainwave input technology becomes practicable the consequences could be tremendous not only for handicapped people but for all of us.