UNIT II – MULTIMEDIA TOOLS
HARDWARE
COMPONENTS OF MULTIMEDIA SYSTEM
THE PLAYBACK SYSTEM
Playback is a term used to describe media files that are
accessed by a user after their initial creation. An example of playback is an
audio or video file that is stored on the computer and can be opened at any
time. The type of Playback System is
related to the installed market, that is, the computers in use. When multimedia
was developing in the 1980s, there were millions of desktop computers in
businesses, homes and school.
The following are essential hardware components of
playback system.
•
PROCESSOR :
The type of processor determines,
among other things, how quickly data is processed and transferred. This becomes
critical as the multimedia title becomes more graphic intensive. The minimum
specification of MPC at Level 2 standard is a 486SX 25 MHz processor. This
configuration will provide optimal quality video, sound and graphics and
smoother animation.
•
MEMORY :
The two basic types of memory in
a computer are temporary and permanent. The temporary memory, called RAM, is
used to store instructions and data that are used while an application is
running. When you turn off the computer when you are finished, the instructions
are erased from the temporary memory.
The computer’s hard drive is used
to permanently store program instructions that are needed each time the program
is run. This is called ROM. This memory stores the data permanently for the
future use and can be accessed when it is necessary. CDs are available as ROM
but you can erase programs from hard drives.
•
MONITOR AND VIDEO CARD
:
The monitor or display is
critical in the playback system, because it provides the primary feedback to
the user. Standards have been established for the screen resolution and the
number of colors.
Screen resolution is measured in
the number of dots displayed on the monitor. These dots are called pixels and
are the smallest units a monitor can display. A standard resolution is 800
pixels across and 600 pixels down the screen. The number of pixels is
determined by the video graphics adapter card and its memory capacity. For
Windows based systems, the VGA (Video Graphics Array) cards support a
resolution of 800X600, whereas the SVGA (Super VGA) cards can support much higher
screen resolutions (1024X768 pixels).
The video card also determines
the number of colors that can displayed on the screen and, the color quality.
The more colors, the higher the image quality, each pixel can
display
from one color to millions of colors. The number of colors is determined by
information associated with the pixel. The information is coded in bits(binary
digits). Let’s say that you want to use 16 different colors in your graphics.
Each pixel would need to be able to display each of the 16 different colors.
Each color could be assigned a number from 0 to 15 (16 total colors). The
following table shows the display resolution with number of colors.
|
Screen Size |
Color
Depth |
Number |
Video Graphics |
|
in Pixels |
in Bits |
of Colors |
Adapter |
|
|
|
|
|
|
640 X 480 |
4 |
16 |
VGA or SVGA |
|
|
|
|
|
|
640 X 480 |
8 |
256 |
SVGA |
|
|
|
|
|
|
800 X 600 |
8 |
256 |
SVGA |
|
|
|
|
|
|
1024 X 768 |
16 |
65,536 |
SVGA |
|
|
|
|
|
|
1280 X 960 |
24 |
16.7 million |
SVGA |
|
|
|
|
|
•
AUDIO CARD :
In order
to incorporate sound, the computer needs an audio card, such as Sound Blaster,
and speakers. Just as a video card is used to display digital images, an audio
card used to play digital sounds. The number of bits used to represent a sound
determines the quality of the sound. The standard is now 16 bit sound. In order
to be played through a computer, sounds need to be digitized. The process,
called sampling, changes an analog signal into a digital signal.
•
CD ROM DRIVE :
CD-ROM
stands for compact disc-read-only memory. A CD-ROM drive reads the data on the
CD and transfers it to the computer. If the transfer time is too long, the user
may get impatient. The CD-ROM drive determines the type of CD that can be
played, the speed at which data is located on the CD, and the speed at which
data is transferred from the disc to the computers. The data transfer rate is
measured in kilobytes per second (Kbps). Now there are quad 4x, as well as 6x,
8x and even 12x speed drives with a transfer rate of 1800 Kbps. The seek time
required to find a specific piece of data on the CD is measured in milliseconds
(ms), that is, thousandths of a second. The Level 3 standard is 200ms.
THE DEVELOPMENT SYSTEM
Development
system needs to be the fastest & most powerful and need to have largest
storage capacity. By using the better tools in the development system, we can
work quickly. In addition to the computer system, several related hardware
components are needed in the process of development. In this system the
software always allows a developer to choose platform for creating a multimedia
title. It can lower the production costs by reducing the time of programmers,
graphic artists and animators.
Page No. 10
The
following are essential hardware components of playback system.
•
PROCESSOR :
The minimum specification a model
would be 486D X 66 MHz unit for the development. A microprocessor is a
particular implementation of processor which happens to fit in a single
electronic component (chip).
A Macintosh System with a 68040
processor running at 33 MHz would be a minimum configuration with a Power Mac
with more the 100 MHz being desirable.
•
MEMORY :
Multimedia titles are extremely
memory intensive. Therefore, 16 MB of RAM would be a minimum, with 32 or 64
recommended. Hard drive disk space is determined by the number of programs that
need to store on the drive. It is common to use several programs to create a
multimedia title, including drawing, authoring and image, sound and video
edition. Minimum hard disk space would be 1 gigabyte (1 GB).
•
VIDEO CAPTURE CARD :
If video is going to be used, it
needs to be digitized using a video card. The card fits internally within the
computer, and a video source (camera, VCR, TV, Videodisc) is plugged into the
card. As the video signal is sent from the source, it is captured, digitized,
and stored. Later it could be edited by deleting frames, adding text, adding
sound, and so forth.
•
MONITOR :
The developers need larger (20
inch) models of monitor. This allows them to enlargean image for detailed
editing and to use the monitor as you would a desktop, with several items
displayed and available. Ideally, the developer would have two monitors, one
that is used to work on the title, and another for displaying the title as it
is being created.
•
PERIPHERALS :
In addition to the basic computer
system, other hardware called peripheral devices or peripheral may be needed
when developing a multimedia title.
1.
SCANNER :
A scanner is used to create
digitized images so they can be incorporated into multimedia titles. Scanners
are an excellent way to generate graphics from photographs, books, and artwork –
essentially any printed material as well as any object that can be placed in a
scanner. It vary in terms of configuration (flatbed, handheld, slide), quality
(number of colors), editing features (such as adjusting color, contrast and
brightness), and price.
Additional storage space to
relieve the pressure on a computer’s hard drive is provided by external storage
devices. They can be used to back up data from the hard drive, which prevents
accidental loss of work. They give needed portability when files must be
transferred from one system another.
3.
CD RECORDER :
As the price of CD recorders has
dropped from $10,000 to less than $ 500, multimedia developers are using them
in multiple ways. CD records can be used to create single CDs of products from
testing, to generate finished CDs when only a few are required, to provide a
way to deliver the files to a manufacturer for mass production, and to back up
and archive data.
4.
DIGITAL CAMERA :
A digital camera is used to
capture still images just like a regular camera. After taking a picture, we can
transfer it directly from the cameral to the computer as a graphic image.
Software that comes with the camera allows you to edit the image and save it as
a graphic file.
5.
MICROPHONE :
A microphone could be used to add
narration, voice-overs, or sound effects to the title.
6.
OTHER :
Depending on the elements to be
incorporated into the multimedia title, other hardware components might include
a video camera, a VCR, or a videodisc player.
MULTIMEDIA
ELEMENTS
WORKING WITH TEXT :
Most computer users have had
experience with word processing and are familiar with entering and editing text
and working with fonts and point sizes. The following are some considerations
and guidelines to keep in mind when working with text.
•
CONCISE :
Reading volumes of text on a
computer screen is difficult and tiring. It may not be the best way to
communicate an idea, concept or even a fact. The saying “A picture is worth a
thousand words” is as true in multimedia as on the printed page. There are
certainly titles where text predominates, such as reference works like
encyclopedias, combining other elements with text can often reduce the amount
of text needed to convey a concept. From a design standpoint, text should fill
less than half the screen.
Huge, gray blocks of text can be
boring to read. We can choose to enliven text by selecting typefaces, called
fonts, and type sizes appropriate to the audience. Fonts are useful in focusing
attention on certain text on the screen, enhancing readability, setting a tone
and projecting an image.
Fonts can be characterized as
Serif, Sans Serif and Decorative. A serif is a line or curve extending from the
ends of a stroke of a character. The French word sans means without, so a sans
serif typeface is one without serifs.
When choosing a font, always
consider the objectives and the intended audience. If the objectives have to do
with creating reference title such as the “Selected Works of Shakespeare” and
the audience is college students, the title would be text intensive and part of
the text, such as headings, might utilize a decorative font appropriate to
Shakespeare’s time.
•
MAKE IT READABLE:
The overriding concern with text
is readability. Although a decorative font may be attractive, it may also be
hard to read. Sans serif text is clean, simple and projects rationality and
objectivity. Serifs create the illusion of a line along the base of a line of
text and guide the eye across the screen, facilitating readability. Research
has shown that comprehension of text blocks with serifs is 75 to 80 percent,
whereas comprehension of text blocks set in sans serif typefaces is 20 to 30
percent. Serif text is described as old-fashioned, friendly, and easy to read.
Sans serif text is described as clean, sleek, modern and not so easy to read. A
sans serif font may be used for multimedia titles in which there is not much
text, such as a game.
Font are measured in point sizes.
There are 72 points per inch. Ten and 12 point are common sizes for type
displayed on the screen. The size often depends on the
application. Suggested guidelines are as follows.
Headings 14 to 18 point
Subheadings Half the heading size
Text blocks 10 to 12 point
•
CONSIDER TYPE STYLES
AND COLORS :
Three common type styles are
bold, italic and underline. These styles are often used for emphasis in print
materials. In multimedia applications, however, they are more often used to
indicate hypertext or hotwords. Click on hypertext will display additional
text, or cause some action, or jump to another part of the application.
•
USE RESTRAINT AND BE
CONSISTENT :
Although it may be tempting and
certainly easy to use various typefaces, size, and styles, it is important to
exercise restraint. Be careful to avoid the “ransom note”
Effect; a
busy and difficult to read design resulting from too many fonts and type styles
on one screen. In addition, you should try to maintain consistency in the use
of text. For example, if several screens have a similar heading, you should use
the same typeface, size and style for all such headings.
ACCOMMODATING TEXT-INTENSIVE TITLES
There are times when a title must
include a great deal of text. Reference titles such as encyclopedias are good
examples. There are two ways to accommodate large amounts of text without
overwhelming and perhaps turning off – the user. First, when possible, use
other ways to communicate the message. For example, show an animation or use
narration rather than write about the idea. Second, consider using a small
amount of text and then allowing the user to obtain more information as
desired, using one of the following techniques.
•
HYPER LINKING :
Allow the user to select a hotword
or a graphic or button to jump to another part of the title that displays more
text.
•
POPUP MESSAGES, SCROLL
BARS AND DROP DOWN BOXES :
Popup message that is displayed
when the user clicks on a hotword. A scroll box that displays more information
as the user clicks on the down arrow or drags the button on the scroll bar. A
drop-down box that can display information when the user clicks on the down
arrow. A drop-down box is often used to display a menu of choices from which
the user can select.
SOFTWARE FOR CREATING AND EDITING TEXT
Word processing programs, such as
Microsoft Word and Word Perfect, are useful in creating text for titles that
are text intensive. Once text is created in a word processing system, it can
easily be copied to a multimedia title. If the title is not text intensive, it
may be more efficient to use graphics programs (Software used to draw and paint
images, such as Corel DRAW and Adobe Illustrator) and authoring programs
(software used to create multimedia titles) to generate the text.
These programs have text tools
that allow you to enter and edit text and select fonts, point sizes and type
styles and colors. They also allow you to create special effects, such as
distorting or animating the text. Font packages can be purchased that provide a
variety of specialized fonts, and programs are available that allow you to
create your own fonts. Other sources of text include text that is already in
electronic form and text that can be scanned. If a particular printed document
was not available in electronic form, or you needed only small parts of it, you
could use a scanner and an optical character recognition (OCR) program to
capture
desired text. As the document is scanned, the OCR program translates the text
into a format that can be used by a word processing program.
WORKING WITH GRAPHICS
Graphics such as drawings and
photographs are integral to multimedia titles. Visualization is an important
part of the communications process, and graphical images can be used to add
emphasis, direct attention, illustrate concepts, and provide a background for
the content.
There are two categories of graphics: draw-type and
bitmaps.
(1)
Draw-type graphics, also called vector graphics,
represent an image as a geometric shape made up of straight lines, ovals and
arcs. When a line is drawn, a set of instructions is written to describe its
size, position and shape. If more than one line is drawn, it has a precise
relationship to the other parts, for example a pie chart made up of a circle
and lines. The instructions that create the circle and lines establish the
relationship between them. If a change is made, say, in the size of the circle,
the relationship between the circle and the lines stays the same. If the
graphic reduced in size and rotated. The reduced graphic keeps the same
relationship as the original graphic. The ability to resize and rotate a
graphic without distortion is a major advantage of draw-type graphics. Another
advantage is their smaller file size. One of the drawbacks of draw-type
graphics is that the more complex they are, the larger the file size and the
longer they take to appear on the screen. Another disadvantage is that they
cannot display photorealistic quality.
(2)
A bitmap represents the image as an array of dots, called
pixels. The screen is made up of grid, and each part of the grid is a picture
element (pixel), color information, called color depth, is recorded for each
pixel. Depending on the number of colors used, a bitmap file can be relatively
small.
GRAPHIC IMAGE QUALITY
The quality of the image can be measured in terms
of image size, color depth and file
size.
IMAGE SIZE, COLOR DEPTH AND FILE SIZE
Screen resolution is measured in
horizontal and vertical pixels, with 640 X 480 being standard. The more pixels
per inch on the screen, the finer the detail and hence the better the image
quality. A screen resolution of 1024 X 768 displays a much better quality image
than 640 X 480 on the same size monitor. Various numbers of colors can
associated with each pixel, depending on the number of bits specified (8 bit,
256 colors; 16 bit, 65,536 colors; 24
bit 16.7
million colors). The range of colors available for pixels is called the color
depth. The file size of a bitmap graphic is related to its image size and color
depth. It can be estimated using the following formula.
Image size in pixels X color
depth in bits ÷ 8
You
divide by 8 because file size is measured in bytes and there are 8 bits per
byte. For Example,
|
Image Size |
Screen |
Color Depth |
Number of |
File Size in |
|
in pixels |
Size |
in Bits |
Available |
Bytes |
|
|
|
|
Colors |
(Approximate) |
|
|
|
|
|
|
|
640 X 480 |
Full Screen |
8 |
256 |
3,00,000 |
|
|
|
|
|
|
|
320 X 240 |
Quarter
Screen |
8 |
256 |
77,000 |
|
|
|
|
|
|
|
1024 X 768 |
Full Screen |
24 |
16.7 million |
24,00,000 |
|
|
|
|
|
|
SOFTWARE FOR CREATUBG AND EDITING GRAPHICS
Graphics
programs are the tools that allow an artist to create and edit designs used in
multimedia titles. There are dozens of graphics programs; some come with
operating systems, such as Microsoft Paint which come with Windows 95, and
others are included in authoring programs used to create multimedia titles.
These are relatively unsophisticated programs, however, lacking many features
found in high-end applications. Generally, graphics programs can be categorized
as drawing, paint and image-editing programs.
Drawing Programs – those
creating draw-type graphics-provide for freehand as well as geometric shapes
and are useful in creating designs where precise dimensions and relationships
are important. For example, Adobe Illustrator.
Paint Programs – Those
creating bitmaps are useful in creating original art, because they provide the
tools (brushes, pens, spray paint) used by artists. For example, Paint Shop
Pro.
Image-editing programs – are
useful for making changes to existing images, such as manipulating the
brightness or contrast, or applying textures or patterns. For example,
Photoshop.
FEATURES OF GRAPHICS PROGRAMS
Following is a list of features
that are available on high-end graphics programs.
•
Type of graphic program : The program is primarily a
drawing, a paint(bitmap), or an image-editing program. Many programs allow you
to create both draw and paint type graphics.
•
Cross-platform compatibility : The program comes in both a
Windows and a Macintosh version, and/or is able to create graphics that can be
used on both the Macintosh and Windows Platforms.
•
Graphics file support : The program allows saving
and/or converting graphic images using several of the more popular file
formats, such as TIFF (Tagged Image File Format), BMP (bitmaps), PCX (Windows
Paint), PICT (Macintosh picture format), and so forth. With the enormous
interest in the world wide web, JPEG (Joint Photographic Expert Group) files
are becoming more important, because they are the standard file formats for the
world wide web.
•
Layers : The program supports object layering, which
allows you to include more than one bitmaps in an image and edit each bitmap
independently of the others.
•
Image enhancement with painting tool : The
program has pencil, brush, airbrush, text, and line tools; user-defined brushes
and the ability to preview the brush size and an option to paint with textures
and patterns and to retouch using smudge, sharpen and blur features.
•
Selection tools : The program allows selection of any part of an
image using a freehand tool, including selection of all the pixels of a certain
color. It also allows the use of masks to isolate parts of an image and apply a
special effect such as a drop shadow.
•
Color Adjustments : The program allows you to
adjust image color and choose from a range of colors simultaneously. You can
selectively change hue (the shade or color itself), saturation (the relative
brilliance or vibrancy of a color), and brightness.
•
Image manipulation : The program can stretch, skew
and rotate an image.
•
Filters : The programs has filters for
sharpening, softening, and stylizing the image.
•
Antialiasing : The program supports Antialiasing. Because
bitmaps made up of rectangular pixels, the outside edge of the image can appear
jagged. Antialiasing smoothes the edges by blending the colors on the edge of
the image with the adjacent colors.
•
Text support : The program allows manipulation of PostScript
and TrueType fonts (standard font types for the Macintosh and Windows operating
Systems).
•
Graphics tablets : The program supports
pressure-sensitive graphics tablets.
•
Open architecture : The program is compatible with
third-party software such as programs that provide special effects.
Draw and paint-type programs are
used to develop graphic images from scratch. Following are other ways to
generate graphics that can be incorporated into a multimedia title.
•
Clip art, Stock photographs, and fine art : Some
graphics programs come with clip art and stock photographs, but these are often
limited or of poor quality. Several companies specialize in providing images
for multimedia titles. For example, Photodisc, a leader in digital stock image,
provides more than 50,000 photographs that can purchased on CD or accessed from
its website. Corel Gallery 2 has 15,000 clip-art images, and Corel Stock Photo
Library has 20,000 photographs.
These large CD libraries have a
function that allows you to search for an image using descriptive words. For
example, it you wanted to view photos of sunsets, you might search using the
word sun or sunset, and a list of photos would appear. The companies that sell
clip art and stock photographs often allow you to use the graphics in a
multimedia title and to distribute the title without paying a royalty. The
Corbis Corporation provides images from a wide variety of sources, including
leading professional photographers, museums, cultural institutions, public and
private archives, an private collections. Corbis has more than 17 million
images, including the Ansel Adams collection.
•
Video Images : Pictures from video sources such as VCRs,
videodiscs, and video cameras can be transferred to a computer, and individual
frames can become graphic image.
•
Still Images : Digital cameras specifically designed to capture
images in a digital form are useful in generating graphics. You like a picture
as you would with any still camera. Then the camera is connected to a computer,
and the images are transferred from the camera to the computer. The programs
that come with the camera allow you name, sort, resize, rotate and save the
images. Photographs that are taken with a regular camera can be made into
graphic image by scanning directly into a computer or writing to a Photo CD.
Photo CDs can hold approximately 100 images, and many film-processing outlets
can create a Photo CD from an ordinary roll of film.
• Scanned images : One of
the most useful pieces of equipment for generating graphics is a scanner.
Depending on the type of scanner and the sophistication of the program, you can
zoom in and crop specific parts of image before capturing it. You can edit the
image by adjusting colors, contrast and brightness. All sorts of images can be
scanned, including photographs, illustrations from books, drawings, slides –
even objects, although they will display in two-dimensional form. Using a
scanner to capture images from objects such as leaves, bricks, fabric or
aluminum foil provides away to generate creative graphics
that can be used for backgrounds in a multimedia title.
•
Screen Capture Program : Both Macintosh and
Windows-based computers allow you to capture as a graphic whatever is on the
computer screen. When you hold down the Command and Shift keys and press 3 on
the Macintosh, whatever is on the screen is captured as a graphic file. When
you press the Print Screen key on a Windows-based computer, whatever is on the
screen is placed on the Clipboard and can be pasted into a graphics program and
then saved as a graphic file. In addition, there are programs such as Hijack
Pro and Collage Plus that are specifically designed to capture a screen or part
of a screen and save it as graphic file of a type you specify. Capturing a
screen can be useful if you are working with text that you want to display as a
graphic. You could type the text using a word processing program and then
capture it on-screen as a graphic.
SOUND
In the early days of using
desktop computers, usually the only sound that you heard was a beep often
accompanied by an error message. Now a whole range of sounds can be played
'through a computer, including music, narration, sound effects, and original
recordings of such events as a presidential address or a rock concert. Sounds
are critical to multimedia. Often sound provides the only effective way to
convey an idea, elicit an emotion, or dramatize a point. How would you describe
in words or show in an animation the sound a whale makes? Think about how
chilling it is to hear the footsteps on the stairway of the haunted house.
Consider how useful it is to hear the pronunciation of "Buenos dies"
as you are studying Spanish.
To study the use of sound in
computers, you need a basic understanding of sound. When we speak, vibrations,
called sound waves, are created. These sound waves have a recurring pattern
that is called an analog wave pattern.
The wave pattern has two attributes that affect how you work with sound on a
computer: volume and
frequency. The
height of each peak in the sound wave relates to its volume the higher the
peak, the louder the sound. The distance between the peaks is the frequency the
greater the distance, the lower the pitch. Frequency is measured in hertz (Hz).
A pattern that recurs every second is equal to 1 Hz. If the pattern recurs
1,000 times in 1 second, it would be 1,000, or 1 kHz (kilohertz).
In order
for a computer to Work with sound waves, they must be converted from analog to
digital form. This is done through a process called sampling, in which every
fraction of a second a sample of the sound is recorded in digital bits. There
are two factors that affect the quality of the digitized sound: the number of
times the sample is taken, called the sample rate; and the amount of
information stored about the sample, called the sample size.
The three
most common sample rates are 11.025 kHz, 22.05 kHz, and 44.1 kHz. The higher
the sample rate, the more samples that are taken and, thus, the better the
quality of the digitized sound. The two most common sample sizes are 8 bit and
16 bit. An 8-bit sample allows 256 values that are used to describe the sound,
whereas a 16-bit sample provides 65,536 values. Again, the greater the sample
size, the better the quality of the sound.
|
Sample Rate |
Bit Value |
Size of
File |
|
|
|
|
|
44.1 kHz |
16 |
1.75 MB |
|
|
|
|
|
44.1 kHz |
8 |
882 KB |
|
|
|
|
|
22.05 kHz |
16 |
882 KB |
|
|
|
|
|
22.05 kHz |
8 |
440 KB |
|
|
|
|
|
11.025 kHz |
8 |
220 KB |
|
|
|
|
The above
table shows the file size (in bytes) for 10 seconds of digital audio given
various sample rates and bit values. The following formula is used to determine
the byte size of a 1-second recording:
sample
rate X bit value 8
Thus a
1-second recording at a sample rate of 44.1 kHz and 16 bits would be 88,200
bytes (44,100 x 16 8). You would double this number for a stereo recording. The
44.1 kHz 16-bit sample is CD quality; whereas the 11.025 kHz 8-bit sample would
be marginal quality.
A sound
card, is used to digitize sound. A sound from some external source is sent to
the card. The external source could be a cassette tape, videotape player, CD,
or someone speaking into a microphone. The sound card samples the sound based
on the sample rate and bit value and produces the digital approximation of the
analog signal.
Once a
sound has been digitized, it can easily be manipulated using a. sound- editing
program. Figure 4.5 shows a sound-editing program and some of its features.
Using the mouse pointer, you can select part of the recording and • cut it out
of the pattern or replace it with another sound. Or you can choose to add sound
effects such as an echo or fade-in and fade-out.
Another way to incorporate sound
into multimedia titles is with MIDI files. MIDI, which stands for Musical
instrument Digital interface, is a standard format that enables computers and
electronic musical instruments to communicate sound information. Digitized
audio begins with a sound, samples it, and creates a digital representation
which is stored in a file. MIDI begins with an event, such as pressing a key on
an electronic musical instrument such as a MIDI keyboard, and codes the event
(including which key and how hard and long it was pressed) as a series of
commands. These are stored in a file and can be sent from the computer to
another instrument, such as a synthesizer, for playback.
MIDI has been compared to a
musical score, because it represents the notes that are played, along with such
information as volume and frequency, rather than the sound itself. This level
of detail allows more-precise editing than with digitized sound. Also, because
MIDI files contain code instead of the actual digitized sounds, they can be
hundreds of times smaller than audio files. On the other hand, working with
MIDI requires specialized software and may require additional equipment for recording
and playback, or a MIDI- compatible audio card.
ANIMATION
We often think of animation as
full-length Disney movies and Saturday- morning cartoons in which illustrated
heroes and villains and especially animal characters come to life. Television
programs, movies, and videos are part of our daily lives. Animation plays a
huge role in entertainment (providing action and realism) and education
(providing visualization and demonstration). Entertainment multimedia titles in
general, and children's titles specifically, rely heavily on animation. But
animation can also be extremely effective in other titles, such as training
applications. For example, say a mechanic needs to be trained on a hydraulic
system for the landing gear of a jet plane. The training includes information
on the flow of hydraulic fluid through the system. It might be impossible to
videotape the actual flow of the fluid inside the landing gear, but an
animation could provide a simulation arid even dramatize how pressure is
created during the process.
The perception of motion in an
animation is an illusion. The movement that we see is, like a movie, made up of
many still images, each in its own frame. Movies on video run at about 30
frames per second (fps), but computer animations can be effective at 12 to 15
fps. Anything less results in a jerky motion, as the eye detects the changes
from one frame to the next.
There are two types of 2-D
animation, cel and path. Cel animation is based on the changes that occur from
one frame to another to give the illusion of movement. Cel comes from the word
celluloid (a transparent sheet material) which was first used to draw the
images and place them on a stationary background. Notice that the background
remains fixed as the object changes from frame to frame. You could have more
than one object move against a fixed background.
Computer-based cel animation is usually done with
animation programs, although some multimedia authoring programs can create cel
animations.
Path animation moves an object along a predetermined path on the
screen. The path could be a straight line or it could include any number of
curves. Often the object does not change, although it might be resized or
reshaped. This can be a relatively easy process, because you need only one
object (the ball), rather than several objects. Path animations can often be
created using a multimedia authoring program by simply dragging the mouse
pointer around the screen, or by pointing to different locations on the screen
and clicking the mouse button. Some authoring programs even allow you to set
the object's beginning position on one frame and its ending position on another
frame; then the program uses a technique called Tweening to automatically fill in the intervening frames.
3D ANIMATION
Although 2-D animation can be
effective in enhancing a multimedia title, 3-D animation takes the entire
experience of multimedia to another level. Three-dimensional animation is the
foundation upon which many multimedia CD games and adventure titles are
constructed. Top-selling products such as Myst and 7th Guest use 3-D animation
to bring the user into the setting and make him or her seem a part of the
action. Whether opening doors, climbing stairs, or exploring mysterious rooms,
the user is a participant, not a spectator. Creating 3-D animation is
considerably more complex than 2-D animation and involves three steps:
modeling, animation, and rendering.
Modeling is the process of creating 3-D objects and scenes.
One technique involves drawing various views of an object (top, side,
cross-section) by setting points on a grid. These views are used to define the
object's shape. The animation step involves defining the object's motion and
how the lighting and views change during the animation. Rendering is the final
step in creating 3-D animation and involves giving objects attributes such as
colors, surface textures, and degrees of transparency. Rendering can take
considerable time (days), depending on the complexity of the animation. There
are different rendering processes, varying in time needed and quality of the
completed animation. Animators therefore often render the animation using a
quicker, lower-resolution process as a test. Then they use a
slower, higher-quality process for the finished animation. Strata Pro 3D,
Swivel 3D, and 3D Studio are examples of programs.
ANIMATION SPECIAL EFFECTS
A common special effect for
animations is morphing. Morphing is
the process of transforming one image into another via a series of frames. An
example would be a photo kiosk in which two people would have their pictures
taken and a photo would be generated by the computer that combines their
images. The morphing process involves selecting sets of corresponding points on
each of the images. Thus, in morphing the two faces, the sets of points might
include eyes, lips, ears, and outline of the head. Based on these sets of
points, the morphing program rearranges the pixels to transition the original
image into the second via a series of intervening images. Morphing is useful
not only in showing how two images blend together, but also in showing how an
image might change over time. Warping is a related special effect that allows
you to manipulate a single image. For example, you could stretch a facial
feature to change a frown into a smile.
VIRTUAL REALITY
Virtual reality (VR) attempts to
create an environment that surrounds the user so that he or she becomes part of
the experience. The term virtual reality has been used to describe various
types of applications some that are more experiential than others, as the
following examples illustrate.
•
Boeing uses flight simulators that are cockpits of
actual airplanes, mounted on hydraulically controlled legs that can simulate
every motion of an aircraft. Flight crews training in these simulators can be
presented with any number of environments (airports, weather conditions,
landing approaches) on displays viewed through the cockpit windows. These
simulators are so realistic that the Federal Aviation Administration (FAA) will
approve current pilots for certification on a specific model using the
simulator alone.
•
In some compact disc based adventure games, the
surroundings change as the user points the mouse cursor and walks through doors,
up stairs, turns left or right, or otherwise moves through the various scenes.
The goal of the multimedia developer is to make it seem as though the user is
actually standing in the middle of a room, or in an arcade, or in a haunted
house, and so on. Related applications are those that allow a walk-through of a
building. A popular title is a walk-through of the White House, which allows
the user to view different rooms and to zoom in on objects such as paintings
and sculptures.
•
There are arcade-type games and educational
applications that require headgear with goggles that allow the user to
"step into" a virtual world. As the user turns his head, a different
view of the world appears Gloves and handheld equipment can be used to allow
the user to interact with the environment.
Although most virtual reality
applications are animations, Apple Computer has developed a QuickTime VR
system. This system starts with photographs taken in a panoramic format. This
is accomplished by mounting a digital camera on a tripod that allows the user
to take a series of still pictures. The camera is rotated a few degrees after
each picture, until a complete 360-degree panorama is obtained. These
photographs are electronically "stitched" together to provide a seamless
360-degree view. The files created with this system can be brought into a
multimedia title that allows the user to point the mouse cursor to navigate
around the setting and to zoom in on any, object.
Because virtual reality is so 3-D
graphic intensive, it is not as applicable to home and school CD titles that
are played on typical multimedia computers.
VIDEO
The ability to incorporate
digitized video into a multimedia title marked an important achievement in the
evolution of the multimedia industry Consider the following: You are developing
a report on the civil rights movement in the United States to be presented to
your fellow students. The purpose is to inform them of various significant
events. You want to include excerpts from Martin Luther King Jr.'s "I Have
a Dream" speech. You could:
•
Type part
of the speech and hand it out (text)
•
Show a
photo of Martin Luther King Jr. (graphics)
•
Play an
audio except of the speech (sound)
•
Play a
video except of the speech (video)
Those
viewing the video would recognize the impact of seeing the actual event rather
than simply reading about it or listening to it. Video brings a sense of
realism to multimedia titles and is useful in engaging the user and evoking
emotion.
DIGITIZING THE VIDEO SIGNAL
Video, like sound, is usually
recorded and played as an analog signal. It must therefore be digitized in
order to be incorporated into a multimedia title. Figure 4.12 shows the process
for digitizing an analog video signal. A video source, such as a video camera,
VCR, TV, or videodisc, is connected to a video capture card in a computer. As
the video source is played, the analog signal is sent to the video card and
converted into a digital file that is stored on the hard drive. At the same
time, the sound from the video source is also digitized.
One of the advantages of digitized video is that it
can be easily edited. Analog video, such as a videotape, is linear; there is a
beginning, middle, and end. If you want to edit it, you need to continually
rewind, pause, and fast-forward the tape to display the desired frames.
Digitized video, on the other hand, allows random access to any part of the
video, and editing can be as easy as the cut-and-paste process in a word processing
program. In addition, adding special effects such as fly-in titles and
transitions is relatively simple.
FILE SIZE CONSIDERATIONS
Although digitized video has many
advantages, there is an important consideration: file size. Digitized video
files can be extremely large. A single second of high-quality color video that
takes up only one-quarter of a computer screen can be as large as 1 MB. Several
elements determine the file size; in addition to the length of the video, these
include frame rate, image size, and color depth.
Frame rate : Earlier
you learned that animation is an illusion caused by the rapid display of still
images (frames). Television and movies play at 30 fps, but acceptable playback
can be achieved with 15 fps.
Image size : A standard
full-screen resolution is 640 x 480 pixels, but often video is more
appropriately displayed in a window that is one-fourth (320 x 240) the size of
the full screen.
Color Depth :
Color depth Digitized video is
really made up of a series of still graphic bitmaps. Hence the quality of video
is dependent on the color quality (related to the number of colors) for each
bitmap. As you learned earlier, an 8-bit color depth provides 256 colors,
16-bit provides more than 64,000 colors, and 24-bit provides over 16 million
colors.
Using the following formula, you
can estimate the file size of 1 second of digitized
video:
fps x image size x color depth ÷ 8 = file size
Thus 1 second of video at a frame
rate of 15 fps, with an image size of 320 x 240 and a color depth of 24 bits,
would equal a file size of 3.5 MB. This means that a CD could hold only three
minutes of digitized video with the stated frame rate, image size, and color
depth.
Although it might be desirable to
run several minutes of photorealistic full- screen video at 30 fps, it may not
be feasible. The file size would be prohibitive, and the current playback
multimedia systems would not support the processing power required. Thus the
use of video becomes a trade-off between quality and file size. What
constitutes acceptable quality depends on the purpose of the title and the
intended audience. Reducing the color depth below 256 colors yields a markedly
poorer-quality image. Also, reducing the frame rate to below 15 fps causes a
noticeable and distracting jerkiness that is usually unacceptable. Changing the
image size arid compressing the file therefore become primary ways of reducing
file size.
You usually do not need to show
full-screen video in a multimedia title, because it is only one of several
elements that appear on-screen. Other elements might include text and
navigational buttons. The video can therefore be played in a window as small as
one-quarter or even one-sixteenth of the screen. One technique is to use video
for the parts of an object that are changing. For example, assume you want to
show a dinner table with a lit candle. The flame of the candle is the only
moving, part of the screen. Instead of creating a video of the entire table
with the candle, you could use the table as a background still image and
videotape only the flame. Then you could play the flame in a window at the tip
of the candle, giving the impression that the entire screen is one video. The
video could be played continuously to create the motion of a flickering candle.
In most cases, a quarter-screen image size (320 x 240), an 8-bit color depth
(256 colors), and a frame rate of 15 fps is acceptable for a multimedia title.
And even this minimum result in a very large file size
VIDEO COMPRESSION
Because of the large sizes
associated with video files, video compression/ decompression programs, known
as codecs, have been developed. These programs can substantially reduce the
size of video files, which means that more video can fit on a single CD and
that the speed of transferring video from a CD to the computer can be
increased. There are two types of compression: lossless and lossy. Lossless
compression preserves the exact image throughout the compression and
decompression process. An example of when this is important is in the use of
text images. Text needs to appear exactly the same before and after file
compression. One technique for text compression is to
identify
repeating words and assign them a code. For example, if the word multimedia
appears several times in a text file, it would be assigned a code that takes up
less space than the actual word. During decompression, the code would be
changed back to the word multimedia. Lossy compression actually eliminates some
of the data in the image and therefore provides greater compression ratios than
lossless compression. The greater the compression ratio, however, the poorer
the decompressed image. Thus, the trade-off is file size versus image quality.
Lossy compression is applied to video because some drop in the quality is not
noticeable in moving images.
Certain standards have been
established for compression programs, including JPEG (Joint
Photographic Experts Groups) and
MPEG (Motion Picture Experts Group).
Both of these programs reduce the file size of graphic images by eliminating
redundant information. Often areas of an image (especially backgrounds) contain
similar information. JPEG compression identifies these areas and stores them as
blocks of pixels instead of pixel by pixel, thus reducing the amount of
information needed to store the image. Compression rations of 20:1 can be
achieved without substantially affecting image quality. A 20:1 compression
ratio would reduce a 1 MB file to only 50 KB.
MPEG adds another process to the
still-image compression when working with video. MPEG looks for the changes in
the image from frame to frame. Key frames are identified every few frames, and
the changes that occur from key frame to key frame are recorded.
MPEG can provide greater
compression ratios than JPEG, but it requires hardware (a card inserted in the
computer) that is not needed for JPEG compression. This limits the use of MPEG
compression for multimedia titles, because MPEG cards are not standard on the
typical multimedia playback system.
Two widely used video compression
software programs are Apple's QuickTirne (and QuickTime for Windows) and
Microsoft's Video for Windows. QuickTime is popular because it runs on both
Apple and Windows-based computers. It uses lossy compression coding and can
achieve ratios of 5:1 to 25:1. Video for Windows uses a format called Audio
Video Interleave (AVI) which, like QuickTime, synchronizes the sound and motion
of a video file.
SOFTWARE FOR CAPTURING AND EDITING VIDEO
Several steps are needed to prepare
video to be incorporated into a multimedia title. These include capturing and
digitizing the video from some video source, such as a video camera, VCR, TV,
or videodisc; editing the digitized video; and compressing the video. Some
software programs specialize in one or the other of these steps, and other
programs, such as Adobe Premiere,
can perform all of them. Although capturing and compressing
are necessary, it is editing that receives the most attention. Editing
digitized video is similar to editing analog video, except that it is easier.
For one thing, it is much quicker to access frames in digital form than in
analog. For example, with analog video, a lot of time is spent fast-forwarding
and rewinding the videotape to locate the desired frames; whereas with digital
editing you can quickly jump from the first frame to the last—or anywhere in
between. Removing frames or moving them to another location is as easy as the
cut-and-paste process in a word processing program. The following are some
other features that may be included in editing software programs:
Incorporating
transitions such as dissolves, wipes, and spins Superimposing titles and
animating them, such as a fly-in logo
Applying
special effects to various images, such as twisting, zooming, rotating, and
distorting
Synchronizing sound with the
video-
Applying filters that control
color balance, brightness and contrast, blurring, distortions, and morphing.
AUTHORING PROGRAMS
Authoring Programs are used to
create multimedia titles. They help the developer do all of the following
tasks:
Produce
content with paint, text and animation tools Design screen layout using
templates
Create interactivity
Incorporate
text, sound, video, animation and graphics Create hyperlinks
Multimedia authoring programs
vary significantly in the features they provide and in their cost and
ease-of-use. There are dozens of authoring programs to choose from, and various
ways to compare them. These include the following criteria:
Platform
(Mac and/or PC) used for development and playback Way the developer works with
them and ease of use
Feature(paint
tool, animation tool, programming language) Price
Learning curve
Ability to develop multimedia
applications that can be delivered via the internet.
Two ways in which multimedia is
used are in presentations and as standalone titles. It is helpful to
distinguish between these uses, because the type of application affects the
design of the title, the cost, development time and often the authoring program
used.
Multimedia presentations involve a presenter and an
audience of one or more persons.
Examples include the following:
A college professor lecturing on
the art collection of the Hermitage Museum in St.Petersburg and using a
computer to display various paintings as well as biographic of the artists.
A sales presentation in which a
representative uses a computer to display the company’s new product line,
including animations of how the products work.
A corporate CEO making a
presentation at the annual stockholders’ meeting and using a computer to
display highlights of the past year, pictures of corporate officers, and
financial data.
In these cases, the presenter has
control over the multimedia title, and it is primarily a one-way, linear
communication process. If the multimedia title allows the presenter to quickly
navigate through the contents of the title, a great deal of interactivity can
be built into the presentation. For example, a sales representative may be
making a pitch to a prospective client that starts with a relatively linear
presentation about her company’s history and product line. Then she may ask a
few questions and, based on the responses, jump to information about pricing or
product availability or to video clips of testimonials from current customers.
These types of presentations are useful when the presenter wants to utilize the
power of multimedia while maintaining control of the presentation. Many of
these presentations are similar to a slide show and can be developed easily,
quickly, and inexpensively.
STAND-ALONE APPLICATIONS :
Stand alone titles are those that
are intended for use by individuals in a one-on-one situation. Examples include
the following:
A computer based simulation of
biology lab procedure in which students learn how to dissect a frog.
An informational kiosk located in
a shopping mall, with which customers can locate various stores and product
lines.
An interactive CD-based
encyclopedia located in a library.
A CD based sales catalog
distributed through the mail to potential customers.
A
corporate training CD used to teach employees how to deal with angry customers.
A solve-the mystery adventure game distributed on CD.
The primary differences between
presentation and stand-alone titles are who has control and the amount of
interactivity that is involved. A major advantage of stand-alone title is that
the user has control and can determine what to view and review based on his or
her
needs. It is possible, however, for developers to build into these titles
conditions that the user must satisfy before proceeding along a certain path.
For example, in an adventure game the user might be required to solve a puzzle
before being allowed through a certain door, or in an educational title the
user might be required to take a pretest that determines which tutorial can be
accessed.
All stand-alone authoring
programs have one thing in common; the ability to create hyperlinks.
Hyperlinking is the process of establishing a relationship (link) between two
elements or objects within a title. An example would be a word or phrase,
called a hotword or hypertext, that, when clicked, causes the program to jump
to another screen. Because control is turned over to the user, several design,
navigation, and “what-if” issues must be addressed. This makes these titles
generally more difficult, expensive, and time consuming to develop than
presentation-type titles.
HOW AUTHORING SYSTEM WORK
Multimedia authoring systems can
be categorized by the way in which they work i.e., metaphor used. These include
the electronic slide show, the card stack or book, icon-based programs and time
based programs using a movie metaphor.
1. ELECTRONIC SLIDE SHOWS :
Giving an electronic slide show
presentation is similar to using overhead transparencies or traditional
photographic slides. Programs such as Microsoft PowerPoint, Adobe Persuasion,
Asymetrix Compel used a slide show metaphor.
These types of programs have
several advantages. They are relatively inexpensive, easy to learn, and easy to
use. These programs provide templates with different background colors and
graphics and allow you to incorporate all of the multimedia elements, including
video, animation and sound. Some program has Hyperlinking capabilities that
allow the user to navigate to any part of the application.
2. THE CARD STACK AND BOOK METAPHORS :
One of the first multimedia
authoring programs was HyperCard. HyperCard uses a card stack metaphor. Cards
are developed that have different elements associated with them and are put to
stacks. You can link the cards by allowing the user to click on buttons or
other elements and jump to a different card in the stack.
A similar type of program uses a
book metaphor, in which each page represents a different screen, and the pages
combine to make up a book. ToolBook by Asymetrix is an example of this type of
program. These are two levels in this program : author and reader. The author
level allows you to create the title, whereas the reader level allows you to
interact with it as a user.
The
advantages of using the card and book type authoring programs include the ease
in understanding the metaphor, and the straightforward relationship between
what is displayed on any particular screen and what is created on a card or
page. These programs also provide templates that reduce development time.
3. ICON BASED AUTHORING PROGRAMS :
With icon based programs, you use
symbols in a flowchart scheme. Each icon represents a particular event. For
example, the wait icon stops the process until the user clicks the mouse button
or presses a key, or a specific amount of time passes.
An advantage of icon based
programs is that you can easily see how a title is structured that is, the flow
of a program and especially the branching. This makes it easy to edit and
update the program by merely adding or deleting icons representing content or
events.
4. TIME BASED AUTHORING
PROGRAMS :
Time based programs use a movie
metaphor. That is, like a movie on videotape, you start the multimedia title
and it plays until some action causes it to pause or stop. Director movies are
made of a series of individual frames. Each frame consists of up to 48 objects
such as graphics buttons, and text placed on a stage. As the movie is played,
frames are displayed, revealing their elements. They are good for creating
animations.
5. WEB BASED AUTHORING PROGRAMS :
As the World Wide Web has become
more viable as a distribution alternative for multimedia, companies are
adapting their authoring tools to accommodate the web. Asymetrix and Quest
provide versions of their authoring programs specifically designed for
developing multimedia title to be delivered over the Internet. Macromedia
provides a utility program called Shockwave, that allows an Internet user to
play Director Movies; and Microsoft provides its ActiveX controls that allow
movies, animations and sound to be delivered over the Internet.
DELIVERING MULTIMEDIA
The following are different methods of delivering
multimedia.
1. COMPACT DISC
The growth of multimedia is often
expressed in terms of the growth of Compact Disc(CD) titles. CDs are popular
medium because they can hold substantial amounts of data, including sound and
video. They are relatively inexpensive, easy to mass produce, distribute and
transport and they take up little retail shelf space.
A kiosk is a stand alone or
networked computer system that allows the user to access information performs
transactions, and even plays games. Examples are college information kiosks
that students use to learn about academic programs, print out schedules and
transcripts, and access a campus map, retain store kiosk that allow customers
to locate merchandise, print out coupons, and purchase products and museum
kiosks that allow the user to locate specific works of art, view parts of a
collection that are not on display, and obtain detailed information about the
artists.
3. ONLINE
One of the fastest growing areas
for multimedia delivery is online, which includes telecommunications and the
Internet. Telecommunications involving phone lines, satellite, and cable
transmission is being used by educational institutions to deliver multimedia
courseware to rural areas, and by companies for teleconferencing and training.
The use of the Internet is growing exponentially, companies are developing home
pages for the World Wide Web that allow customers to purchase products, access
product, information including video demonstrations, and even subscribe to real
time multimedia events such as rock concerts.
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