Transcript Understanding Multimedia Elements – Sound, Animation, Video

Understanding
Multimedia Elements –
Sound, Animation, Video
Unit C
Objectives
Understand sound
Sound on the Web
2-D animation
3-D animation
Animation on the
Web
2
Objectives
Video
Video
compression &
video editing
Video on the
Web
3
Understanding Sound: Analog
Sound waves
Analog wave pattern
– Volume = height of each peak
• Higher the peak, louder the sound
– Frequency(pitch) = distance between
peaks measured in hertz(Hz)
• Greater the distance, lower the sound
4
Understanding Sound: Digital
Converted to bits via sampling
Quality depends on:
– Sample rate: number of times sample is
taken (11.025 kHz, 22.05 kHz & 44.1 kHz)
– Sample size: amount of information stored
(8 bit and 16 bit)
5
Digitizing Process
Cassette tape player,
videotape player, CD or
microphone is captured
by sound card
Software/user controls
sample rate and size
Sound-editing program
used for manipulation
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Sound File Formats
WAV
– Windows or Macintosh
– Used on the Web
AIFF (Audio Interchange File Format)
– AIFFC (AIFF Compressed)
– Windows or Macintosh
RealAudio (.ra)
– Allows streaming of sound over Web
MP3 (MPEG Layer 3)
– Compresses entire songs for Web
– Near stereo quality
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MIDI Sound Files
Musical Instrument
Digital Interface
Electronic musical
instruments create
sound; then stored
on computer
Contain
code/commands, not
digitized sounds
Very small files
8
Sound on the Web
File size is an issue
File compression used for
certain file formats
(RealAudio and MP3)
Sounds stored on Web
server
Media player installed on
user computer
– RealPlayer, Windows Media
Player, MP3, QuickTime
9
Streaming Media
Audio and video can
be played in real time
File starts playing
immediately – doesn’t
wait for full download
Connection to web
server is continuous
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Tips for Using Sound on Web
Is the sound appropriate? Is there a
benefit?
Is it a good sound quality?
Can you afford the cost of recording
the sound?
Should you just use sound with still
images instead of video?
Can you stream the files?
Can you give the user control?
11
2-D Animation Can Provide
Simulation of actual events
Action and realism in entertainment
Visualization and demonstration in education
12
2-D Animation Issues
Movement is made up of many
still images
Each still image has its own
frame
Speed of moving these frames:
– Movies on film: 24 fps
– Television: 30 fps
– Computer animation: 12-15 fps
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2-D Animation Types:
Cel Animation
Based on changes that
occur from one frame to
another
Background image is
stationary
Celluloid images placed on
background
Celluloid images change
from frame to frame
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2-D Animation Types
Cel
Animation
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2-D Animation Types:
Path Animation
Object moved along predetermined
path on screen
Object can stay the same, be resized
or rotated
Tweening in an authoring program
– Define beginning position in one frame
– Define ending position in another frame
– Software fills in intervening frames
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2-D Animation Types
Path
Animation
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2-D Animation Software Allows
Frame rate changes
Transitions
User playback control
Looping
Object drawing and animating
Sound clips
Cheap shareware to expensive authoring packages
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3-D Animation
Games and adventure
titles
Users are participants, not
spectators
Much more complex than
2-D
Involves:
– Modeling
– Animation
– Rendering
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3-D Modeling and Animation
Draw views by setting points on a grid
Create contours and structure
Define object’s motion,
lighting & perspective views
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3-D Rendering
Give objects attributes
– Colors
– Surface textures
– Transparency amounts
Programs
–
–
–
–
–
Strata 3D
LightWave 3D
3D Studio Max
Maya
Houdini
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3-D Morphing
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Warping
Distort a single image
Change a frown into a smile
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Virtual Reality (VR)
Creates an environment that surrounds
the user so the user becomes part of the
experience
Examples:
– Boeing Corporation flight simulators
– CD-based adventure games: Myst and 7th Guest
– Virtual tour sites
Some require special equipment like
goggles & gloves
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Animation on the Web
Animated text
Animated GIF
Macromedia Director applications
3-D environments
You must have the plug-ins to play these animations!
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Animated Text on the Web
Rotating, zooming, scrolling,
distorting, blinking
Use authoring software
Use HTML
– <blink>Hello</blink>
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Animated GIFs on the Web
Each .gif
image file is
a little
different
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Macromedia Applications
on the Web
Director or Flash to author
Shockwave to deliver on Web
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VRML
Virtual Reality Modeling Language
Creates interactive 3-D on the Web
User is moved through the
environment (instead of object
moving)
Environment is dynamic and
always changing
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Understanding Video
Video can be
– Very expensive
– Time-consuming to create
– Very large files
Video can be found in stock film
companies
Video must be digitized from an
analog signal
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Digitizing an
Analog Video Signal
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Editing Video
Digitized video is not
linear like analog video
Can access any part of
video randomly
Can cut and paste
Can use special effects
and transitions
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Digital Video File Size
Considerations
1 second of high-quality
color video on ¼ of the
computer screen = 1 MB
file size
Determining file size
– Frame rate: lower the better
(15 fps minimum)
– Image size: use smaller
playback window
– Color depth: 8-bit vs. 16-bit
vs. 24-bit color
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Video
Compression/Decompression
Codecs
Lossless: gives larger file by
preserving exact image
Lossy: eliminates some image
data; smaller file, but poorer
quality
34
MPEG Compression Format
Motion Pictures Experts Group
Reduce file size by eliminating
redundant information (backgrounds)
Also looks for changes from frame to
frame
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Video Compression Software
Apple’s QuickTime and QuickTime for
Windows
– Dual platform
– Lossy compression
Microsoft Windows Media Player
– AVI format
Both synchronize sound and motion
– Synchronized Multimedia Integration Language
(SMIL)
– Markup language like HTML
36
Video Editing Software
Adobe Premiere
Transitions: dissolves, wipes, spins
Animations: fly-in logo
Special effects: twisting, zooming,
rotating
Filters: color balance,
brightness/contrast, blurring,
distortions, morphing
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Video on the Web
Only practical for 56K
or higher connections
Planning
– Is animation or still images
with sound better?
– Are stock videos better?
– Quality-versus-cost and
relevance of video to
application
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Video Transfer Types: HTTP
HyperText Transfer
Protocol
Downloads entire video
to hard drive of user
User can play it over
and over quickly
Better for small video
clips
39
Video Transfer Types: RTSP
Real-Time Streaming Protocol
Continuous playing/streaming
Not saved on hard drive
User can randomly access any video
part
Better for large videos and live
broadcasts
40
Streaming Video
HorizonLive: live video presentations
41
Video and Virtual Reality
Apple QuickTime VR system
iPEX system
Starts with panoramic photographs
Camera rotated after each picture for
360 degrees
Photographs electronically “stitched”
together
User can navigate and zoom (White
House site)
42
Issue: The Napster Controversy
Intellectual Property
Rights and Emerging
Web Technologies
Sharing MP3 files
through the web
Recording Industry
Association of
America filed suit
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Understanding
Multimedia Elements –
Sound, Animation, Video
End