Unit 3.1 Multimedia Basics
Hardware Specifications of Multimedia
Multimedia combines text, high-quality sound, two- and three-dimensional graphics, animation, photo images, and full-motion video. In order to work with multimedia, a personal computer typically requires a powerful microprocessor, large memory and storage capabilities, a high-quality monitor and a video accelerator, external loudspeakers or headphones and a sound card (or sound board) for improved sound generation, and a CD-ROM or DVD-ROM drive, as well as special software to utilize many of these devices. A multimedia computer may also use other devices, such as a microphone or keyboard for audio input, a digital camera or scanner for graphics input, and a videocassette recorder or camcorder for video input or output. Today personal computers are becoming more and more powerful and most of those purchased today have built-in multimedia capabilities that allow you to deliver and display multimedia applications. However, if creation of high-end multimedia applications is your goal, you will definitely want to consider certain specifications that have been established specifically for multimedia.
With the right adapters, software, and hardware, camcorders and digital video cameras can be used to capture full-motion images. Although regular camcorders store video on film, digital video cameras store images as digital data. This enables the digital images to be transferred directly into the product being created. Digital video cameras range in price from under a hundred dollars for small desktop cameras to thousands of dollars for higher-end equipment. Digital video cameras offer an inexpensive means of getting images into your computer, however, you should be aware that the resolution is often quite low and the color is sometimes questionable.
Digital cameras allow you to take pictures just as you would with a regular camera, but without film developing and processing. Unlike regular cameras, photographs are not stored on film but are instead stored in a digital format on magnetic disk or internal memory. The photographs can be immediately recognized by the computer and added to any multimedia product.
Scanners digitize already developed images including photographs, drawings, pages of text. By converting these images to a digital format, they can be interpreted and recognized by the microprocessor of the computer. A better way of scanning larger images is to use a page or flatbed scanner. These scanners look like small photocopiers. Page scanners are either gray-scale scanners that work well with black-and-white photographs or color scanners that can record millions of colors.
A graphics tablet is similar to a digitizing tablet, however, it contains additional characters and commands. Like the digitizing tablet, each location on the graphics tablet corresponds to a specific location on the screen.
As is true with most equipment, all microphones are not created equal. If you are planning to use a microphone for input, you will want to purchase a superior, high-quality microphone because your recordings will depend on its quality. Next to the original sound, the microphone is the most important factor in any sound system. The microphone is designed to pick up and amplify incoming acoustic waves or harmonics precisely and correctly and convert them to electrical signals. Depending on its sensitivity, the microphone will pick up the sound of someone's voice, sound from a musical instrument, and any other sound that comes to it. Regardless of the quality of the other audio-system components, the true attributes of the original sound are forever lost if the microphone does not capture them, Macintosh computers come with a built-in microphone, and more and more PCs that include Sound Blaster sound cards also include a microphone. These microphones are generally adequate for medium-quality sound recording of voice-over's and narration. These microphones are not adequate for recording music
MIDI (Musical Instrument Digital Interface) is a standard that was agreed upon by the major manufacturers of musical instruments. The MIDI standard was established so musical instruments could be hooked together and could thereby communicate with one another.
To communicate, MIDI instruments have an "in" port and an "out" port that enables them to be connected to one another. Some MIDI instruments also have a "through" port that allows several MIDI instruments to be daisy chained together. Storage Multimedia products require much greater storage capacity than text-based data. All multimedia authors soon learn that huge drives are essential for the enormous files used in multimedia and audiovisual creation. In addition to a hefty storage capacity, a fast drive is also important. This is because large files, even if they are compressed, take a long time to load and a long time to save and back up. Consequently, if the drive is slow, frustration and lost productivity will undoubtedly follow. When purchasing a storage medium, consider the speed of the device - how fast it can retrieve and save large files as well as the size of its storage capacity.
Optical Disks Optical storage offers much higher storage capacity than magnetic storage. This makes it a much better medium for storing and distributing multimedia products that are full of graphics, audio, and video files. In addition, reading data with lasers is more precise. Therefore, when working with multimedia, optical storage media such as Magneto-Optical Disks (MO), CD-ROM (CD) and Digital Versatile Disk (DVD) are used.
CD-ROM stands for compact disk read only memory. A CD-ROM can hold about 650MB of data. Because CDs provide so much storage capacity, they are ideal for storing large data files, graphics, sound, and video. Entire references such as encyclopedias complete with text and graphics, as well as audio and video to further enhance the information, can be stored on one CD-ROM. In addition, interactive components that enable the user to respond to and control the medium ensure that the user will be even more attentive and likely to retain information. For these reasons, CDs have been the medium of choice for publishing multimedia applications.
Because a CD-ROM is the most common type of optical disk, computers sold today include a CD-ROM drive as standard equipment. In fact, in order to have a multimedia personal computer based on the standards set by the MPC, you must have a CD-ROM drive. Therefore, when considering the purchase of a multimedia computer, the important consideration in regard to the CD-ROM drive is the speed of transfer.
CD-ROM speed is measured in kilobytes (KB) per second. This refers to the speed at which data is transferred from the CD to the computer processor or monitor. Double speed (2x) CD-ROM drives can transfer data at a rate of 300 KB per second, quadruple speed (4x) can transfer data at a rate of 600 KB per second, and so on up to 24x and higher.
DVD, which in some places stands for Digital Versatile Disk, but really doesn't stand for anything, is the newest and most promising multimedia storage and distribution technology. DVD technology offers the greatest potential to multimedia because its storage capacity is extensive. DVD's are the same size as CDs, but they offer much more storage capacity. DVD's are either single or double sided. A double-sided DVD is actually two single DVD's glued together. By using more densely packed data pits together with more closely spaced tracks, DVD's can store tremendous amounts of data. DVD disk types and capacities include the following four:
• DVD-5: one layer, one side-max. capacity about 4.7GB.
• DVD-9: one layer, dual sided-max. capacity about 8.5GB.
• DVD-10: two layers, one side-max. capacity about 9GB.
• DVD-18: two layers, dual sided-max. capacity about 17GB.
A bus is any line that transmits data between memory and input/output devices or between memory and the CPU. Parallel bus structures transmit eight bits of data at one time while a serial bus transmits one bit of data at one time. The following are the common bus structures.
FireWire or IEEE-1394 is a Sony-backed standard that was developed by Apple Computer. It appears on Sony's latest digital video cameras. The goals of FireWire are to reduce network bottlenecks and sluggish file transfers. FireWire can connect up to 63 devices always accessible at full speed. FireWire has already been adopted as the transmission standard for digital video. Therefore, it will probably be used as an audio and video interconnect with multimedia applications, but its future beyond that is uncertain.
Universal Serial Bus (USB) is a low-cost, low-speed interconnect designed to PCs to keyboards, mice, joysticks, telephones, and low-end scanners daisy chain configuration. Due to its low speed, its storage use will be limited to midrange CD-ROM drives.
The image displayed on the computer monitor depends on the quality of the monitor and software, as well as the capability of the video adapter card. For multimedia applications, it is critical that all of these elements work together to create high quality graphic images. However, because all display systems are not the same, you will have very little control over how your images appear on other people's systems. Consequently, it is a good idea to test your projects on different display systems to see how your digital images appear. When purchasing a computer monitor to be used with multimedia applications, you will want to consider purchasing a larger screen. Screen sizes are measured along the diagonal and range in size from eight to more than 50 inches. You will probably want at least a 17-inch monitor. Though this larger monitor will cost you a bit more, it will prove well worth it if you intend to spend any time at all either designing or otherwise working with multimedia applications. The number of colors that the monitor can display is also important. The number colors is dependent on the amount of memory installed on the video board as well as the monitor itself. The number of colors a monitor can ay varies as listed below:
- 4-bit system will display 16 different colors
- 8-bit system will display 256 different colors
- 16-bit system will display 65,636 different colors
- A 24-bit system will display more than 16 million different colors.
Most monitors can display at least 256 colors (8-bit), which is probably adequate for multimedia presentations, particularly if the presentation is delivered via the Web, but it may not be adequate for video. Eight-bit images are the most compatible across multiple platforms and they also take up very little disk space. Computer monitors capable of displaying thousands of colors (16-bit) are quickly becoming the multimedia standard. Images on these displays not only look better, they also display much faster.
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