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Computer Networking
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Data Link Layer
Session No. 7
Multimedia
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Agenda
▪ What is Multimedia ?▪ Multimedia representation
▪ Multimedia processing
▪ Multimedia compression
▪ Multimedia communications
▪ Multimedia applications
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Multimedia – different viewpoints
▪ A PC vendor: a PC that has sound capability, a DVD-ROM drive, and perhaps the superiority of multimedia-enabled microprocessors that understand additional multimedia instructions
▪ A consumer entertainment vendor: interactive cable TV with hundreds of digital channels available, or a cable TV-like service delivered over a high-speed Internet connection
▪ A Computer Science student: applications that use multiple modalities, including text, images, graphics, animation, video, sound including speech, and interactivity
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History of Multimedia
r 1. Newspaper: perhaps the first mass communication medium using text, graphics, and images
r 2. Motion pictures: conceived of in 1830's in order to observe motion too rapid for perception by the human eye
r 3. Wireless radio transmission: Guglielmo Marconi, at Pontecchio, Italy, in 1895
r 4. Television: the new medium for the 20th century, established video as a commonly available medium and has since changed the world of mass communications
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History of Multimedia
r The connection between computers and ideas about multimedia covers what is actually only a short period:m 1945 - Vannevar Bush wrote a landmark article describing what
amounts to a hypermedia system called Memexm 1960 - Ted Nelson coined the term hypertextm 1967 - Nicholas Negroponte formed the Architecture Machine
Group m 1968 - Douglas Engelbart demonstrated the On-Line System
(NLS) another very early hypertext programm 1969- Nelson and van Dam at Brown University created an
early hypertext editor called FRESS
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History of Multimedia
1976 - The MIT Architecture Machine Group proposed a project entitled
1977 Multiple Media | resulted in the Aspen Movie Map, the first
1978 hypermedia videodisk, in 1978r 1985 - Negroponte and Wiesner co-founded the MIT Media
Labr 1989 - Tim Berners-Lee proposed the World Wide Webr 1990 - Kristina Hooper Woolsey headed the Apple
Multimedia Labr 1991 - MPEG-1 was approved as an international standard
for digitalr videor 1991 - The introduction of PDAs in 1991 began a new period
in the use r of computers in multimedia
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History of Multimedia
r 1992 - JPEG was accepted as the international standard for digital image
r compression ; led to the new JPEG2000 standardr 1992 - The first MBone audio multicast on the Net was mader 1993 - The University of Illinois National Center for
Supercomputingr Applications produced NCSA Mosaic, the first full-
edged browserr 1994 - Jim Clark and Marc Andreessen created the Netscape
programr 1995 - The JAVA language was created for platform-independentr application development
1996 - DVD video was introduced; high quality full-length movies were1997 distributed on a single disk
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History of Multimedia
r 1998 - XML 1.0 was announced as a W3C Recommendation1998 - Hand-held MP3 devices first made inroads into
consumerist tastes1999 in the fall of 1998, with the introduction of devices
holding 32MBr of flash memoryr 2000 - WWW size was estimated at over 1 billion pages
………….and multimedia continues to evolve
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Hypermedia and Multimedia
r A hypertext system: meant to be read nonlinearly, by
r following links that point to other parts of the document, or
r to other documents
r HyperMedia: not constrained to be text-based, can include
r other media, e.g., graphics, images, and especially the
r continuous media , sound and video(e.g. the WWW)
r Multimedia means that computer information can be
r represented through audio, graphics, images, video, and
r animation in addition to traditional media
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Hypermedia and Multimedia
Hypertext is non-linear
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Multimedia Representation
r Multimedia content –r text, images, audio, video represented as digital
data
r Data acquisition – using analog-to-digital devices
r • Audio – microphone + audio cardr • Images – picture + scanner, digital cameras,
graphics, imager editorr • Videos - analog camera + video capture card,
digital videor cameras, video editing software,
computer graphicsr rendering
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Multimedia Representation
r Data playback - digital-to-analog devicesr • Audio – speakerphone + audio card, CD player,
MP3 playerr • Images – Computer monitor, printerr • Videos – Computer monitor or TV with Stream
Video,r VCD/DVD, Direct TV
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Multimedia Representation
r Text -r Each character (letters and symbols) is
represented by a fixedr number of bits. In ASCII code ‘A’ is 01000001
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Multimedia Representation
r Image -r • Represented as 2-dimensional signal
r • Arranged in units called pixels
r • The value of each pixel represents the radiance intensity of
r the scene. For color image, there are usually three components,
r e.g. red, green, and blue. Each range from 0 to 255
r • Image compression method can dramatically reduce the size
r of the image data. Some standards include JPEG,JPEG2000
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Multimedia Representation
r Audio –
r • Represented as 1-dimensional
r signal
r • Continuous acoustic wave is
r digitized into a sequence of
r bytes
r • Audio compression method
r is used to reduce the amount
r of data (MP3 e.g. 10:1 ratio)
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Multimedia Representation
r Video -r • Video is represented
asr sequence of images
calledr frames
r • NTSC video has roughly 30
r frames per second
r • Video compression standard
r such as MPEG2(DVD) and
r MPEG4 can significantly
r reduce the size of video
r files
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Multimedia Processing
r Audio - Video -r • Equalization • Change frame rater • Denoise • Blendingr • Voice removal (for karaoke) • stabilization
r Image -r • Negationr • Histogram equalizationr • Denoiser • Deblur/Sharpen/Edge enhancement … and many
morer
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Multimedia Compression
r How does compression work ?r Assume that we have 4 letters in a language viz. “A” “B”
“S” “Z”
r To uniquely encode each letter, let us assign two bits each :
r A-00, B-01, S-10, Z – 11. Message “AAABSAAAAZ” is encoded with 20 bits
r Now let us assign:A- 0, B-100, S-101, Z – 111. The same message can be encoded using 16 bits
r The basic idea behind data compression – assign shorter codeword to more frequently used symbols
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Multimedia Compression Standards
▪ In order to enable communication between different media source
▪ compression standards are established
▪ Audio – Differential pulse code modulation (DPCM), adaptive predictive coding (APC), linear predictive coding (LPC), MPEG audio coders (e.g MP3)
▪ Image – Graphics interchange format (GIF), Joint- Photographic Experts Group (JPEG 10:1 to 20:1), JPEG-2000
▪ Video – Moving JPEG (MJPEG), ITU-T H.261, H.263, Motion Picture Expert Group (MPEG-1, MPEG-2, MPEG-4)
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Multimedia Communications
r Interpersonal applications -r Circuit-mode networks – physical connection, constant bit
rate per channelr Packet-switched networks – virtual connection, packets
are transmitted in a shared networkr Interaction over the Internet -r Information browsing (Web servers and browsers)r Electronic commence (information travel in both
directions)r Entertainment -r Movie/Video-on-demandr Interactive television
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Multimedia Applications
▪ Digital video editing and production systems▪ Electronic newspapers/magazines▪ World Wide Web▪ On-line reference works: e.g. encyclopedias, games,
etc▪ Home shopping▪ Interactive TV▪ Multimedia courseware▪ Video conferencing▪ Video-on-demand▪ Interactive movies▪ Live camera – surveillance, traffic monitoring
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Overview of Multimedia Software Toolsr The categories of software tools briefly examined
here are:
r 1. Music Sequencing and Notationr 2. Digital Audior 3. Graphics and Image Editingr 4. Video Editingr 5. Animationr 6. Multimedia Authoring
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Music Sequencing and Notation
r Cakewalk: now called Pro Audior Allows to insert WAV files and Windows MCI
commandsr (for animation and video) into music tracks
r Cubase: Capabilities similar to those of Cakewalk. It includes
r some digital audio editing tools
r Macromedia SoundEdit: Program for creating audio for
r multimedia projects and the web; integrates with other
r Macromedia products such as Flash and Director
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Digital Audio
r Cool Edit: emulates a professional audio studio - multi-track
r productions and sound file editing including digital signal
r processing effects
r Sound Forge: a sophisticated PC-based program for editing
r audio WAV files
r Pro Tools: a high-end integrated audio production and editing
r environment - MIDI creation and manipulation; powerful audio
r mixing, recording, and editing software
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Graphics and Image Editing
r Adobe Illustrator: a powerful publishing tool that uses vector
r graphics; graphics can be exported to Webr Adobe Photoshop: a graphics and image processing
tool r Macromedia Fireworks: software for making graphics
for the webr Macromedia Freehand: a text and web graphics
editing toolr that supports many bitmap formats such as GIF, PNG
and JPEG
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Video Editing
r Adobe Premiere: a simple video editing tool for puttingr video clips into any orderr Adobe After Effects: a video editing tool that enables
users to add and change existing movies.r Can add many effects:r lighting, shadows, motion blurring; layers
r Final Cut Pro: a video editing tool by Apple; Macintosh only
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Rendering Tools
r 3D Studio Max: includes a number of very high-end professional
r tools for animation, game development, and visual effectsr Softimage XSI: a powerful modeling, animation, and
renderingr package used for animation and special effects in films
and gamesr Maya: competing product to Softimage; as well, it is a
completer modeling packager RenderMan: rendering package created by Pixar
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Authoring Tools
r Macromedia Flash: allows users to create interactive movies
r using the score metaphor, i.e., a timeline arranged in parallel
r event sequences
r Macromedia Director: uses a movie metaphor to create
r interactive presentations - very powerful and includes a built-
r in scripting language, Lingo
r Authorware: a mature, well-supported authoring product
r based on the Iconic/Flow-control metaphor
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Multimedia API’s
r Java3D: API used by Java to construct and render 3D graphics,
r similar to the way in which the Java Media Framework is used
r for handling media files
r DirectX : Windows API that supports video, images, audio and
r 3-D animation
r OpenGL: the highly portable, most popular 3-D API
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Thanks for your attention !!!
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