Chapter 2. Introduction to Multimedia
2.1 What Is Multimedia
Multimedia has been around for several years, but most early developments and applications were for the Macintosh, Amiga, and Commodore machines. The introduction of the Microsoft Windows 3.1 in 1990 served to accelerate the multimedia move to the PC world. Multimedia is a term that encompasses a large and growing technology including hardware and software. There is no strict definition of the term, and it might be used to denote aspects of several different systems and processed. Generally, multimedia refers to a combination of technologies that enables the PC to utilize text, sound, graphics, animation, audio, and video.
Multimedia is transforming the role of personal computers in business and home. Until recently, computers are used widely to process data and designed printed materials-activities that improved productivity. With multimedia, computers are used to inform, entertain, educate, or persuade audiences in various areas. Personal computers now act as a communication medium as well as a productivity tool like E-Mail, Voice-Mail, and VedioConferencing. The emergence of multimedia reflects our need for effective tools to manage the volume of information we encounter daily. Multimedia provides a richer set of options to appeal to audiences overwhelmed by the proliferation of information.
Multimedia projects can vary dramatically in organization, approach, and content, but most share three characteristics that define them as multimedia projects. They
- Integrate two or more media effects (text, graphics, sound, video, and animation) to convey a message or tell a story. As shown in Figure 2-1.
- Are designed to be viewed and interacted with on a computer.
- Let an audience browse through on-line information in any sequence.
Figure 2-1. Five types of multimedia effects
| Media types | Common file formats | Description |
| Text | .TXT
.RTF
.DOC | Text often shapes the content of a multimedia title, delivering key information and helping people navigate among topics. As a rule, keep text brief and select a font that is easy to read on screen. |
| Graphics | .DIB
.BMP
.TIF
.WMF | Graphics shape the design of your title, adding visual appeal and expressing concepts that text alone cannot easily communicate. You can scan graphics or create them on a computer, then save them in the file format you need. |
| Sound | .WAV
.MID | Sound complements titles with music, sound effects, and voice-overs that create a mood, and emphasis, communicate ideas, or signal interactivity. |
| Video | .AVI
.DVI
.MOV | Full-motion video offers a level of authenticity similar to television or movies. With video, you can show tasks and events that words and graphics are inadequate to explain. And video quickly and effectively reaches a busy audience. |
| Animation | .FLC
.FLI
.MMM | Animation enhances a project by activating graphics-charts that grow, mechanical objects that function-to illustrate main point. you can also use animated effects, such as text or logos flying onto the screen. |
2.2 Components of Multimedia
2.2.1 Text
Text is the first element appearing in computer as the publishing material did. Nowadays, printed materials are often prepared electronically using a word processor or desktop publishing program. You can convert the electronic text into the title, such an ASCII or RTF (rich-text format) file. Getting text file by typing directly into the authoring program from keyboard is slower and costs more. Alternatively, you can adopt an optical character recognition (OCR) system, which includes a scanner, a computer, and OCR system, you scan each printed page into a bitmap file. The OCR software then evaluates the bitmap to identify type and converts them into ASCII letters, which you can process and reformat it. OCR systems have some drawbacks that they typically recognize only a few type faces, and tend to spelling errors. However, they offer a fast and relatively cost-effective way to transform large volumes of printed text into computer-ready text.
Four famous OCR products in Market:
| Products | Company | Address |
| OmniPage | Caere Corp. | 100 Cooper Court
Los Gatos, CA 95030
(800) 535-7226 |
| Recongita | Recognita Corp. of America | 1156 Aster Ave.
Sunnyvale, CA 94086
(800) 255-4627 |
| TextBridge | Xerox Imaging systems | 9 Centennial Dr.
Peabody, MA 01960
(800) 248-6550 |
| WordScan | Calera Recognition Systems | 475 Potrero Ave.
Sunnyvale, CA 94086
(800) 422-5372 |
Hypertext is the other ultimate utilization of text, that is used to refer to text-based information connected with hyperlink, like WWW(World-Wild Web, a network of server that uses hypertext links to find and access files which include movie, sound, and picture multimedia) as shown in Figure 2-2, in the Internet and Windows Help, as shown in Figure 2-3.
Figure 2-2. The WWW browser of Netscape program for Internet
Figure 2-3 The Screen of Windows Help
2.2.2 Graphics
Computer graphics are a staple of today's media-from desktop publishing to on-screen presentations, slides, and broadcast video graphics. Graphics serve a various purposes in Multimedia, from illustrating the content to providing a main focus for the actions. You can get the graphics from many sources-drawing them on screen by drawing programs or picture publish programs, scanning pictures from scanner, taking pictures from camera, even capturing a image from video camera. Generally , the graphics can fall into two categories:
- Draw-type: The program maps the shapes of every objects you draw and stores them as a set of instructions, which describe the size. position and shape of object including other information, such as line width and fill colors. The program looks them as OLE (Object Linked and Embedded). Drawing-type graphics have several benefits because they give more freedom to corporate with each object. Also they are easy to reuse by exporting into other screens. Furthermore, those kinds of graphics offer smaller file sizes then bitmaps, because they don't store file for each pixels. The drawbacks for the drawing-type graphics are that if the screen consists of a lot of objects, it will take more time to display. On the other hand, Drawing-type graphics can't give dedicated photo effect. So for simple illustrations, drawing-type graphics are the ideal choice, but for the fantasy picture the bitmaps are the best one. As shown in Figure 2-4.
Six famous Drawing-Graphic products in Market:
| Products | Company | Address |
| Publisher | Microsoft Company | 15220 Greenbrier Parkway
Beaverton,
OR 97006
(800) 626-2778 |
| VISIO | Shapeware Corporation | 2422, South Trenton way
Denver,CO 80231
(800) 446-3335 |
| CorelDraw | Corel Corporation | 1600, Carling Ave.
Ottawa, Ontario CANADA |
| IntelliDraw
FreeHand
PageMaker | Aldus Corporation | 5120, Shoreham Place
San Diego, CA 92122
(619) 558-6000 |
Figure 2-4. The Draw-type Program
- Bitmaps: Bitmaps are the graphics that compose of dots, or called pixels arranged in rows and columns. The more bits that represent each pixel, the more shades of color you can see. There are various kinds of size to represent each pixel: 4-bit image, 8-bit image, and 24-bit image.
a. 4-bit image: It is the basic one that offers the smaller file size then others, provides blur visual effect than others, but quickly display on screen. It can represent 16 colors or gray levels. For example: a image 320 pixels * 240 pixels occupies (320 * 240 * 4 / 8 ) = 38400 bytes.
b. 8-bit image: It offers more discrete visual image, but display slower on screen. It can represent 256 colors. For example: a image 320 pixels * 240 pixels occupies (320 x * 240 * 8 / 8 ) = 76800 bytes.
c. 24-bit image: It offers the most valuable visual effect, but display slower on screen. It can represent 16 million colors. For example: a image 320 pixels * 240 pixels occupies (320 * 240 * 24 / 8) = 230400 bytes.
You can create bitmaps by
a. drawing them in a paint program.
b. scanning existing photographs and art on a scanner.
c. capturing a still-image with a video camera and video capture card.
Now the new fashion is the 3 D graphics using the concepts of perspective and shading. A computer display cannot actually present anything in three dimension; height and width can be shown, but depth must be simulated. This is done through perspective and shading. In prospective, parallel lines dealing away from the viewer eventually intersect at the horizon, so the portion of an object that is farther away from the viewer appears to be narrower than the portion that is closer. The basic rule of shading is that colors get darker as the distance from the light source grows. The angle at which light falls on a surface determines how quickly the brightness fades, and the type of surface further changes the effect of reflected light. As shown in Figure 2-5.
Bitmaps have several drawbacks:
a. Bitmaps contain the information for each pixel, so they have large file size.
b. Bitmaps are difficult to edit or resize without distorting them.
Four famous photo design programs:
| Products | Company | Address |
| Picture Publish | Micrografx Company | (800) 733-3726 |
| Photoshop | Adobe Company | 5120, Shoreham Place, San Diego. CA 92122
(619) 558-6000 |
| CorelPhoto | Corel Corporation | 1600, Carling Ave. Ottawa, Ontario CANADA |
| Dabbler | Fractal Design Company | |
Figure 2-5. The Bitmaps type program
2.2.3 Sound
Sound comes into the computer from some external source: a microphone, tape player, CD player, radio or television-any device that emits an electrical audio signal. There are three types of digital sound: wave audio, MIDI audio, and CD-audio. Wave audio files are recorded sounds converted into a digital format to play on a computer. MIDI audio is the musical instrument digital interface for the digital representation and transmission of music that is now adhered to worldwide by virtually all makers of electronic music equipment. CD-audio is digital sound stored on a compact disc. It cannot be used directly, but by link to a particular track on the CD through CD-ROM driver.
An analog waveform has two properties, amplitude and frequency. The distance from the top or bottom of the waveform to its baseline shows the amplitude or volume of the sound. The height of the waveform is roughly proportional to how loud the sound is. A flat line indicated silence. A period is the distance between any point in the wave form and the next time that same point appears. The number of periods per second determines the frequency of the sound, Hertz. Sound frequency is measured in hertz. One period per second equals one hertz(1 Hz). One hertz is so low a frequency that human can't hear. The average range of human hearing is 20 Hz to 20 kHz.
The transformation process of audio to a digital form is called analog-to-digital (A/D) conversion when you record digital audio, and digital-to-analog (D/A) conversion when you play it back. For example, when you listen to music recorded on a compact disc, the CD-Driver converts the digital audio file back into an analog signal. Whey you record sound, the sound card converts analog signal into digital audio. As shown in Figure 2-6.
Figure 2-6. The screen of Creative WaveStudio Program
2.2.4 Video
Video is a truly universal medium; most of us deal with it daily. Now that video can be stored on computer's hard disk, video from a VCR can be played in a window on system's display, and video can be put into the work, presentations, and programs. Computer technology has evolved significantly to support video, but that evolution is not yet complete, and creating high-quality video footage in the first place can often be a challenge. Video capture involves translating analog video frames into a series of bitmaps. During playback, the bitmaps display onscreen at a speed that tricks the eye into seeing motion.
There are several concepts relative to the Video: Capture Card, Video signal, frame, file size, compressor, and Video-Edit program.
a. Capture Card: It is one kind of device that can transfer the analog video into digital video. like Intel Smart Video Recorder. With the proper card and drivers, you can incorporate analog video from a VCR, video, camera, or videodisc player directly into computer.As shown in Figure 2-7.
b. Video signal: Different video source stores on various format. Composite video is the NTSC standard that combines color and brightness into one signal. S-Video (S-VHS) improves NTSC picture quality by separating color and brightness into two signals. RGB separates the composite signal into the three color components that display onscreen: red, green, and blue. Digital provides the signal in a digital form using either an industry-standard or a propriety format.
c. Frame & file size: Frame is the unit of picture for video. When capturing the video, you should decide the number of frames per second to capture, called frame rate, that will affect the ability of playback video, and file size. Many computers and CD-ROM drives do not have the processing power to play video faster than 15 or 16 fps and full motion video, so in order to fit the most requirement, designers should consider the frame rate and frame size. The more frame rate you have, the larger file size you get.
d. Compressor: Compressor is used to reduce the file size by compressing digital data. The methods of compressing fall into two type: hardware compress, and software compress. Hardware compress offers the compressing through the hardware that builds a on-board video processor providing the power to record and compress all the data needed for high-quality playback. It is better way to compress the video data, because that reduces the store memory and time, but need expensive hardware. Software compress uses software program to compress the video data. It will take more time and memory to do the same job, but cost less.
Figure 2-7 The Screen of Asymetrix Digital Video Capture program
e. Video-Edit program: After capturing a video file, you may want to modify the file to be better, so you need video-edit program, like Asymetrix Digital Video Producer Software as shown in Figure 2-8 , 2-9, and 2-10, and Adobe Premiere. Most of Video-Edit programs offer the following functions:
- cut digital video and paste other digital video into project.
- provide several transition function to make two or more digital video or image together in order.
- import wave or MIDI file into video.
- overlay the text, graphic, and video together. You can select various type of overlaying, relative to color, transparency, and path.
- compress the output file. When finishing the project, you can compress the file to small file size in order to reduce the memory required.
Figure 2-8. The Screen of Asymetrix Digital Video Producer
Figure 2-9. The Screen of Transition functions
Figure 2-10. The Screen of Overlay Function
2.2.5 Animation
Motion brings graphics one step closer to being alive, and motion attracts our attention because it seems alive. Most animation involves tweeting, in which each step of a graphical object's movement is represented by a redrawing of the object itself. Animation can fall into two types:
- 2-D Animation: It is the process of moving "flat" images, graphics created with 2-D paint or illustration programs, across the screen and possibly changing their shapes as they go.
- 3-D Animation: 3-D animation brings to the world of simulated 3-D. Most 2-D animation software creates animation that you play back on your computer's display. 3-D animation packages can do the same thing, but the best results are derived from recording 3-D animation directly to video tape.
Animation software uses either a cell-based or a frame-based approach to animation. Cell-based animation likes using old-fashioned paint on transparent celluloid. Better cell animation software can take over most of the redrawing for you. The name comes from a technique of using celluloid layers to overlay the active elements in an animation frame on a static background. Cell-based animation on a computer works even more efficiency because of the tasks that a computer automates. Frame-based animation works as flipbooks that the foreground is static, but background changes.
Four famous animation programs
| Products | Company | Address |
| Director
Authorware | Macromedia Inc. | 600 Townsend Street, San Francisco, CA 94103
(800) 449-3329 |
Multimedia
Tool Book | Asymatrix Company | 110-110th Avenue N.E. Suite 700 Bellevue, WA 98004
(800) 844-7097 |
| CorelMovie | Corel Corporation | 1600, Carling Ave. Ottawa, Ontario CANDAD |
Last update: May 13, 1995; Version 1.0.0
This page was made by
Alex Tsai
.
You may email any suggestions to:
ksiwww@ksi.edu