Transcript Slide 1

Chapter 8
Digital Media
8 Chapter Contents
 Section A: Digital Sound
 Section B: Bitmap Graphics
 Section C: Vector and 3-D Graphics
 Section D: Digital Video
 Section E: Digital Rights Management
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8
SECTION
A
Digital Sound
 Digital Audio Basics
 Portable Audio Players
 MIDI Music
 Speech Recognition and Synthesis
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8 Digital Audio Basics
 Sampling a sound wave
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8 Digital Audio Basics
 Sampling rate refers to number of times per second that a
sound is measured
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8 Digital Audio Basics
 Sound cards are responsible for transforming bits stored in
an audio file into music, sound effects, and narrations
– Digital signal processor
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8 Digital Audio Basics
 The most popular digital audio formats include AAC, AIFF,
MP3, RealAudio, Wave, and WMA
 Audio or media player software allows you to record and
play digital audio files
 Audacity
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8 Portable Audio Players
 Pocket-sized, battery-powered device that stores digital
music
– Zune
 Digital music is available from
a wide variety of sources
– Formats include AAC, MP3, WAV,
and AIFF
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8 MIDI Music
 MIDI (Musical Instrument Digital Interface) specifies a
standard way to store music data for synthesizers, electronic
MIDI instruments, and computers
 MIDI-capable sound cards contain a wavetable
– Set of prerecorded musical instrument sounds
 Does not produce high-quality vocals
 Does not have full resonance of “real” sound
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8 MIDI Music
MIDI music tends
not to have the full
resonance of digital
audio.
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8 MIDI Music
Music composition
software
provides tools for
entering notes,
specifying instruments,
printing sheet music,
and saving
compositions in
formats
such as MIDI.
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8 Speech Recognition
and Synthesis
 Speech synthesis is the process by which machines produce
sound resembling spoken words
– Text-to-speech software
 Speech recognition refers to the ability of a machine to
understand spoken words
– Speech recognition software
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8 Speech Recognition
and Synthesis
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8
SECTION
B
Bitmap Graphics
 Bitmap Basics
 Scanners and Cameras
 Image Resolution
 Color Depth and Palettes
 Image Compression
 Bitmap Graphics Formats
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8 Bitmap Graphics
 Composed of a grid of dots
– Color of each dot is stored as a binary number
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8 Scanners and Cameras
To scan an image, turn on the
scanner and start your scanner
software. Place the image face
down on the scanner glass, and
use the scanner software to
initiate the scan. The scanned
image is saved in RAM and can
then be saved on your
computer’s hard disk.
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8 Scanners and Cameras
The controls for a digital
camera are very similar
to those for an analog,
or film, camera. To take
a photo, simply point
and shoot.
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8 Scanners and Cameras
 Digital cameras use storage medium
– Solid state storage
 Transfer images using:
– Card readers
– Direct cable transfer
– Infrared port
– Media transfer
– Docking station
– E-mail
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8 Scanners and Cameras
 Graphics software is used to modify or edit bitmap graphics
– Modify individual pixels to
• Retouch photographs
• Wipe out red eye
• Erase rabbit ears
 Require a bit of storage
space
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8 Image Resolution
 Expressed as the number of horizontal and vertical pixels
– Higher resolutions contain more data (larger file size) and
are higher quality
 Bitmaps do not have a fixed physical size
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8 Image Resolution
 File size of bitmaps can be reduced by cropping
 Bitmaps are resolution dependent
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8 Image Resolution
 When you increase the resolution of a bitmap, pixel
interpolation may occur
– Some images may appear pixilated
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8 Color Depth and Palettes
 Color depth is the number of colors available for use in an
image
– Monochrome bitmap
 Increasing color depth increases file size
– True Color bitmap (24-bit bitmap)
– 32-bit bitmap
 Color palettes are used to control color depth
– Grayscale palette
– System palette
– Web palette
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8 Color Depth and Palettes
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8 Image Compression
 Any technique that recodes data in an image file so it
contains fewer bits
– Lossless compression
– Lossy compression
 Run-length encoding
 File compression utility
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8 Image Compression
File compression
utilities, such as
open source 7Zip, zip one or
more files into a
new compressed
file with a .zip
extension.
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8 Bitmap Graphic Formats
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8
SECTION
C
Vector and 3-D Graphics
 Vector Graphics Basics
 Vector-to-Bitmap Conversion
 Vector Graphics on the Web
 3-D Graphics
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8 Vector Graphic Basics
 Contain instructions for re-creating a picture
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8 Vector Graphic Basics
 Vector graphics resize better than bitmaps
 Vector graphics usually require less storage space than
bitmaps
 Vector graphics are not usually as realistic as bitmap images
 It is easier to edit an object in a vector graphic than an object
in a bitmap graphic
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8 Vector Graphic Basics
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8 Vector-to-Bitmap Conversion
 Rasterization superimposes
a grid over a vector image
and determines the color
for each pixel
 Tracing software locates
the edges of objects in a
bitmap image and converts
the resulting shapes into
vector graphic objects
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8 Vector Graphics on the Web
 SVG (Scalable Vector Graphics) and Flash are vector
graphic formats for the Web
 Flash
 Animated GIF
 Advantages of using
vector graphics
– Consistent quality
– Searchable
– Compact file size
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8 3-D Graphics
 Stored as a set of instructions
– Contain locations and lengths of lines forming a
wireframe
 Rendering covers a wireframe with surface color and texture
 Ray tracing adds light and shadows to a 3-D image
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8 3-D Graphics
3-D graphics are
based on a
wireframe, which
can be rendered
into a bitmap image
that looks threedimensional.
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8
SECTION
D
Digital Video
 Digital Video Basics
 Producing Video Footage
 Video Transfer
 Video Editing
 Video Output
 Desktop, PDA, and Web Video
 DVD-Video
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8 Digital Video Basics
 Uses bits to store color and brightness data for each video
frame
 Different kinds of digital videos:
– Desktop video
– Web-based video
– DVD-video
– PDA video
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8 Digital Video Basics
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8 Producing Video Footage
 Use digital or analog video camera to shoot video footage
– Digital video cameras store
footage as a series of bits
– Analog video cameras store
video signals as a continuous
track of magnetic patterns
– Videoconferencing cameras
(Web cam) attach directly to
a computer
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8 Producing Video Footage
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8 Video Transfer
 Transfer video footage by connecting a cable between a
video source and computer
 Video capture converts analog video signals into digital
format
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8 Video Transfer
 Video capture software controls the transfer process
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8 Video Transfer
 Raw, uncompressed formats are ideal for editing
 Video capture software can:
– Decrease video display size
– Reduce the frame rate
– Compress data
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8 Video Editing
 Linear editing
– Requires at least two
VCRs
 Nonlinear editing
– Requires a computer
hard disk and video
editing software
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8 Video Output
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8 Video Output
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8 Desktop, PDA, and Web Video
 Desktop videos are usually displayed on a computer screen
 Some PDAs and smartphones can be configured to play
digital video
 Web-based videos
– Streaming video
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8 Desktop, PDA, and Web Video
 You can add external or internet videos to a Web page
 Internet connection speed affects Web videos
 Web video formats include Flash Video, MPEG4, QuickTime
Movie, Windows Movie, and RealMedia
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8 DVD-Video
 Incorporate digital videos onto DVDs with interactive menus
– DVD authoring software
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8 DVD-Video
 With advance planning, menus are easy to create
 Output video in DVD-video format
 A DVD image is a prototype of your DVD
– Stored on your computer’s hard disk
 Thoroughly test DVD on your computer before you burn it
 Recordable vs. rewritable DVDs
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SECTION
E
Digital Rights Management
 DRM Basics
 Signal Scrambling and Digital Watermarks
 CD Copy Protection
 DVD and Blu-ray DRM
 DRM for Digital Downloads
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8 DRM Basics
 Digital rights management (DRM) is a collection of
techniques used by copyright holders to limit access and use
of digital content
– Time shifting
– Place shifting
– Format shifting
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8 Signal Scrambling
and Digital Watermarks
 Signal scrambling is a term commonly used for obscuring
cable or satellite television images until they are
unscrambled by a set-top box or other authorized
mechanism
 A digital watermark is a pattern of bits inserted at various
places in an image or a content stream that can be used to
track, identify, verify, and control content use
– Broadcast flag
– HDCP
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8 CD Copy Protection
 Copy protection refers to technologies designed to prohibit
consumers from copying content
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8 DVD AND Blu-ray DRM
 Copy generation management is a digital watermark that
specifies the number of times a content stream can be
duplicated
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8 DVD AND Blu-ray DRM
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8 DVD AND Blu-ray DRM
 A DVD region code
specifies geographical area
of legitimate use for DVD
disks and players
 AACS (Advanced Access
Content System) is a DRM
technology designed to
encrypt and protect content
on optical discs
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8 DRM for Digital Downloads
 DRM
individualization
allows content
providers to
determine the
source of a file
 Windows Media
DRM is used in
music stores,
including Zune
Marketplace
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Chapter 8 Complete
Digital Media