Basics of Multimedia Technology.ppt

Basics of Multimedia Technology: Lecture 3Multimedia Devices, CD Technology

Ram Chatterjee : Asst. Prof.(CSE)

Multimedia SystemsCan be categorized based on functionality as below:

Multimedia Presentation Systems (for user)

Multimedia Development Systems (for developer)


Multimedia Presentation SystemsPC with high resolution screenCD-ROM drivespeakers and microphone


Multimedia Development SystemsIncludes the following:software toolkit for development worksoftware library for support functionslibraries of clip art, music and videoRelated hardware Development systems has more resources and utilities.

Presentation systems must be checked to have the required components and resources.


Six Categories of Multimedia DevicesAnalog Media DevicesDigital Media DevicesGeneral Purpose DevicesSynchronization DevicesInteraction DevicesMultimedia Platforms


1. Analog Media Devices

These devices deal with analog media, but may be under computer control

Divided into 3 sub categories :

SourcesFiltersSinks


Sources (Analog Input)

MicrophoneVideo CameraPhotographic Camera


Filters (Analog Processing)

Analog Video Effects DeviceAnalog Audio Effects DeviceAudio Mixer


Sinks (Analog Output/Storing)

SpeakerVideo DisplayVideo Tape RecorderAudio Tape Recorder


2. Digital Media Devices

These devices deal with digital signal.

Can be divided into 3 sub categories :

Capturing devicesProcessing devicesPresentation devices


Capturing Devices (Input)

KeyboardImage ScannerOCR device


Processing Devices

Video Encoder/DecoderAudio Encoder/DecoderDigital Video Effects DeviceDigital Audio Effect Device


Presentation Devices (Output)

PrinterMonitorProjector


3. General Purpose Devices

Examples: storage devices like CD-ROM, floppy drive, hard drive, network interface, and general purpose processorsMost devices are digital


4. Interaction Devices

Multimedia application means ability to interact within the application itselfInteraction devices enable user direct control over the multimedia application behaviorExamples: keyboard, mouse, joystick, electronic pen


5. Synchronization Devices

Simultaneous presentation using multiple media (text,audio,video etc).

Requires hardware assistance to maintain proper timing.

Example: sync generator in audio and video studios, Macromedia Flash, computer games etc.


A true multimedia platform integrates and combines various multimedia devices and components

Apple MacintoshPopularized the graphical user interfacePopularized computer graphicsNative sound file formats (aiff & mid)Native digital video file format (QuickTime)

IBM Compatible PCOriginal emphasis was on business computing 6. Multimedia Platform


History

1973 Video Long Play (VLP) published1983 Compact Disc Digital Audio (CD-DA) available: the Red Book standard1985 Compact Disc Read Only Memory (CD-ROM):- Yellow Book standard for physical format- ISO 9660 standard for logical file format1986 Compact Disc Interactive (CD-I)announcement: the Green Book standard1987 Digital Video Interactive (DVI): first presentation1988 CD-ROM Extended Architecture(CD-ROM-XA) announcement1990 CD Write Once (CD-WO),CD Magneto-Optical (CD-MO):- the Orange Book standard1996 Digital Video Disk (DVD)


Fundamentals Material CD is a wafer of clear polycarbonate plastic and metal (usually pure aluminum sputtered onto the polycarbonate surface). WorkingAs the disc spins in the CD player, light from tiny IR laser falls on its metallic surface.The light reflected from the CD surface is collected by a light-sensitive receiver diode.The reflected light is then converted into an electric signal and further converted to digital data. StorageAll the information is stored in pitsLength of pit is (1-3) micron (1x10-6 m)Width of pit is 0.5 micronDepth of pit is 1/10 micron


FundamentalsInformation is stored in a spiral-shaped track: Series of pits and lands in substrate layer Transition from pit to land and from land to pit: 1 Between transitions: sequence of 0s 16000 turns/inch (tpi)

Reading: Laser focused onto reflective layer Lands - almost totally reflecting the light Pits scattering the light


Advantages of Optical Storage MediaHigh data density 1.66 data bits/m of track Inter-track density: 16000 tpi; (Magnetic diskette at 96 tpi)Long term storage Insensitive to magnetic/electric interference Insensitive to dust, scratchesLow probability of head crashes Distance between head and substrate surface > 1 mmAdequate error correction allows handling of many defectsPerception quality e.g., each digital music disc is exactly equivalent to an important precursor of the audio CD.


CD ConstructionGlass master is created using photolithographic techniques.The glass disc is coated with photo resistant material (1/10 micron thick).Laser beam is used to write a pattern of pits onto the surface of photo resistant material.All the exposed areas are washed away and finally the disc is silvered.This gives glass master with actual pit structure.


CD ConstructionThe glass mater is then electroplated with nickel.The first plating stage is called father or metal negative.Then, by plating the surface of father, several mothers or positives are obtained doing second plating.The third plating stage is called sons or stampers and are used in injection molding machines.


CD-DA: Compact Disc Digital AudioGoal Storage of audio dataHistory Development of basic technology by Philips Cooperation of Philips N.V. and Sony Corporation 1983: CD-DA players and disks available in the marketPhysical characteristics Diameter: 120 mm Constant linear velocity (CLV), i.e., number of rotations/s depends on the position of the head Track shape: one spiral with approx. 20000 turns


CD-DA: CharacteristicsAudio data rate Sampling frequency: 44,100 Hz Quantization: 16 bits Pulse code modulation (PCM) Audio data rate = 1,411,200 bit/s = (~ 1.4 Mbit/s)Quality Signal to noise ratio (S/N): ~ 6 dB/bit, 16 bit quantization => S/N exactly 98 dBCapacity (without error correction data) Playback time: maximal 74 min Raw capacity =74 min x 1,411,200 bit/s = 6265728000 bit ~ 747 Mbyte


CD-DA: Pits and LandsLength of pits and lands: multiples of 0.3 m

Bit Encoding Transition from pit to land or from land to pit encodes a 1 Between two transitions: a sequence of 0s


CD-ROM: Compact Disc Read Only MemoryCD-DA provides a suitable means for the handling of typical errors caused by damage or dust. The CD-DA specification became the base for a family of optical storage media.

Used for: storing computer data. read through CD-ROM drive.But not conceived for: video (different ECC, EDC scheme required). discrete data (error rate too high). simultaneous play back of various media.


CD-I: Compact Disc InteractiveConsumer electronics format that uses optical disk in combination with computer to provide home entertainment system.Unlike CD-ROM drive, its a standalone system that requires no external computer.Plugs in directly with TV and stereo system & comes with remote control to allow users to interact with s/w programs sold on disks. Note: CD-ROM, CD-ROM/XA and CD-I disks are mastered, as opposed to burned.


CD-ROM/XA:CD-ROM Extended ArchitectureHistory Philips N.V., Sony and Microsoft (announcement in 1988) An extension of the Yellow Book standard

Goal: Simultaneous transfer of various media data Interleaving of blocks of different media within the same track Definition of a new type of track used for:- compressed audio (ADPCM) and video data- images, text, programs Special h/w in an XA drive controller to handle audio playback.


XA: Extended ArchitectureDrawbacks Compatibility to audio and video compression- For some media only reference to standard- MPEG audio not compatible (MPEG does not use ADPCM) Interleaved storage of data of different types in the same track:- Requires special disc layout- Requires effective interleaving with a choice of the suitable audio level- Complex application development


Photo Compact Disc: Example of a CD Bridge DiscPurpose: Storage of photos of high quality History Eastman Kodak and N.V. Philips Company 1990 announcement of the Kodak Photo CD systemCharacteristics Based on CD Write Once (CD-WO) Readable with:- Photo CD players- CD-I players- CD-ROM/XA players Written by:- Special Photo CD writers and CD-WO writersCapabilities New professional and private application areas Simultaneous display of several images Image editing


CD-WO: Compact Disc Write OnceDefined in the Orange Book Standard Part II

A raw CD-WO has: a pre-grooven track an absorption layer between the substrate and the reflective layer

Recording: an irreversible change of the reflectioncharacteristics by heating up the absorption layer(burning)

The CD-WO can be played in CD-DA players.


CD-MO: Features and PrinciplesDefinition in the Orange Book Standard Part I High capacity (double-sided): about 650 MByte Data transfer rate: about 1.2 Mbit/s

Features write data read data erase data rewrite data


CD-MO: Features and PrinciplesPrinciples of the magneto-optical technique Write:- Heat up the blocks- Apply about 10 x earth magnetic field- Polarization of single elements Erase:- Use a constant magnetic field- Simultaneously heat up the block Read:- Polarization of light is influenced by magnetic characteristics


DVD: Digital Video DiskAlso known as: Digital Versatile Disk

Goal: to create a new optical medium to store an entire high-quality digital movie on one disk.

Formats single-sided single-layer single-sided double-layer: laser must switch focus to read the other layer double-sided: disk must be flipped over to read the other side


DVD Technical OverviewCD-like optical storage mediumCapacity considerably higher than CD pits and lands shorter tracks more narrow


CD vs. DVD


DVD: VariantsDVD Read Only Specification (DVD-ROM, Book A): Storage medium with high capacity, successor of the CD- ROMDVD Video Specification (DVD-Video, Book B): Special application of the DVD for the distribution of linear video streamsDVD Audio Specification (DVD-Audio, Book C): Special application of the DVD for the distribution of pure audio data, similar to the CD-DADVD Recordable Specification (DVD-R, Book D): Variant of the DVD that allows to record onceDVD Rewriteable Specification (DVD-RW, Book E): Variant of the DVD that allows to record several times. Also called DVD-RAM (Random Access Memory)


CD StandardsRed Book (CD-DA format)Launched in 1979 by Philips & Sony.Audio CDs can store upto 72 min. of high quality audio.Sample size: 16 bits.Sample rate: 44.1 Khz.Identified by words Digital Audio printed below the logo.CD+G CD+GraphicsAllows producer to add still graphics to a CD-DA disk. Note: All CDs at music stores are based on CD-DA format.


CD StandardsYellow Book (CD-ROM format)Extension of CD-DA.Announced by Philips & Sony in 1985.Provides two modes:Mode 1: for computer data.Mode 2: for compressed Images, audio data and video data.Identified by words Data Storage below the logo.


CD StandardsOrange Book (CD-ROM format)Specifications for recordable CDHas two parts:Part 1: covers CD-MOPart 2: covers CD-WOEx: Photo CD stores image captured by image scanner in accordance with part 2 of orange book.Has multi-session storage.


CD StandardsGreen Book (CD-ROM format)Developed by Philips, Sony & Matsushita in 1987.Published as new standard- Green Book for CD-I.It is self-contained computer system with own processor unit with specific audio, video, control h/w and CD drive. A standard TV display is used for output.


CD StandardsWhite Book (Video CD)Supports text, graphics, CD quality audio & FSFM video.Developed as a joint effort of Philips and Victor company of Japan.Also supported by Panasonic & Sony.Uses- MPEG-I Compression Standards.


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