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G6DPMM - Lecture 8

G6DPMM - Lecture 8. Multimedia Hardware & Storage Technology. Multimedia Development Platforms. Microsoft Windows Multimedia capable since 3.1 (c. 1992) Win32 – Windows API since 1995 DirectX – Game API since 1995

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G6DPMM - Lecture 8

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  1. G6DPMM - Lecture 8 Multimedia Hardware & Storage Technology

  2. Multimedia Development Platforms • Microsoft Windows • Multimedia capable since 3.1 (c. 1992) • Win32 – Windows API since 1995 • DirectX – Game API since 1995 • DirectDraw (bitmap graphics), Direct3D (3D graphics), DirectInput (mouse and other controllers), DirectPlay (network communications), DirectSound (waveform sound), DirectMusic (high level music), DirectShow (streaming audio/video), DirectSetup (installation) • Frequent version updates (9.0) and compatibility issues • WinFX – new API in Longhorn • Apple Macintosh • Always multimedia capable (i.e. since 1984) • OS has changed radically several times – Unix since the release of OSX in 2001 • Quicktime – multimedia framework released in 1991

  3. Multimedia Development Platforms (cont.) • Windows vs Mac for multimedia development • Historically multimedia developers have mostly used Macintosh • Now hardware is comparable • Most tools are available on both • Mac slightly more expensive, but have far more bundled multimedia development hardware and software • Other platforms • Linux • Viable delivery platform, not used widely for development (due to lack of tools) • Other Unix • Silicon graphics • Very high end workstations • Now largely overtaken by Macs and Windows

  4. Requirements for Multimedia • Fast processor • High quality display • High quality sound • All modern computers have these! • Suitable i/o devices • NB mouse not always suitable – eg for public kiosks • High capacity storage

  5. Magnetic Storage Devices • Sliders physically move an electromagnetic head over the surface of a spinning disk. • Ferrous coating is magnetized, storing bits. • Bits are arranged in concentric circles – called tracks.

  6. Magnetic Storage Devices (2) • Floppy disk • 1.4 Mb & very slow (0.06 Mb per second) • Rapidly becoming obsolete – useless for multimedia • Hard disk • Fast, cheap and large • Typically 60Gb – 1Tb • 16-66 Mb per second • Can now be made very small • Zip / Jaz disks (Iomega) • 100Mb – 2 Gb • Up to 20 Mb per second • Used as “giant floppy” • Other similar devices

  7. Flash Storage • Flash RAM is non-volatile RAM • Retains data even when there is no current • May be formatted and used as if it were magnetic media • Flash RAM cartridges • Various proprietary standards • Memory Stick (Sony) • SmartMedia • CompactFlash • SecureDigital (SD) Memory • Typically 8-512Mb • Used in devices such as digital cameras & MP3 players • Portable USB devices • Flash RAM • Hard disk

  8. Optical Storage Devices • Laserdisk (analogue – largely obsolete) • CD-ROM & DVD (digital) • Pits are moulded into a polycarbonate surface, encoding digital data • This surface is coated with a reflective aluminium layer • Data is read by deflecting lasers while the disk is spinning

  9. Compact Disk • CD-DA (Digital Audio) • Developed for the music industry in 1982 by Sony & Philips • Stores 70 minutes stereo digital audio • Encoding • Transition between pit and land represents 1 • No transition represents 0 • Manufacture • Pre-mastering • Glass master • Pressing • Mastering is expensive • Pressing is extremely cheap

  10. CD-ROM • CD-ROM (Read Only Memory) • Developed in 1985 by Sony & Philips • Provides digital data storage for computers • 650-700Mb • Modern CD-ROM is capable of an average data transfer rate of 4.5 Mb/s • Two important international standards • European Computer Manufacturers Association • ECMA-119 – defines CD-ROM physical hardware • International Standards Organisation • ISO-9669 – defines CD-ROM file and directory conventions • Many other standards (and compatibility issues) in the past. These are now largely resolved, and CD-ROM is mostly interoperable

  11. CD-R & CD-RW • CD-R – CD Writeable • Write once, thereafter use as a CD-ROM • Drive has a more powerful laser that can burn a dye layer of an otherwise reflective blank – therefore creating optical “pits” • CD-RW – CD Rewritable • Can be overwritten many times • Pits can be ereased by the laser melting the plastic • CD-R & CD-RW are most useful for backup and pre-mastering • Cannot be mass produced • Blanks are more expensive, and burning takes too long • Supposedly less robust than CD-ROM • CD-writers require lasers that can operate at different power levels • Most CD-writers are compatible with CD-ROM, CD-R & CD-RW

  12. DVD • Digital Video Disk / Digital Versatile Disk • Developed by Sony & Phillips in 1994 • Replacement for VHS and Laserdisk • Same technology as CD-ROM with the following differences • Track width – half (0.74µ vs 1.6 µ) • Pit length – half (0.4µ vs 0.83 µ) • Speed – thrice (3.8m/s vs 1.3 m/s) • Laser wavelength red rather than infra-red (365nm vs 780 nm) • Disk may be 2-sided • Better error correction (by an order of magnitude) • Hence much higher data capacity • 4.7 – 17.08 Gb, depending upon format

  13. DVD (cont.) • DVD backwardly compatible with CD • Manufacture very similar to CD • Designed for video, audio & multimedia • Specification includes: • File system • Video compression standards • Audio compression standards • Copy protection • Region locking

  14. DVD Writing • Technology similar to CD-writers • However, there are several competing standards • DVD-R / DVD-RW • DVD+R / DVD+RW • DVD-RAM • These standards have different physical media • Drives and software may be standard specific or multi-standard • DVD in the future • Technology for HDTV • Currently warring standards!

  15. Standards • Standards are crucial for interoperability of hardware and software • Hardware standards • Data standards • Software standards • Formalised Standards • de facto standards (industry standards)

  16. Formalised Standards • Formal standards are published by recognised standards bodies • Governmental standards bodies • American National Standards Institute (ANSI) • British Standards Institute (BSI) • International Organisation for Standardisation (ISO) • Professional Bodies • Institute for Electrical and Electronic Engineers (IEEE) • International Telecommunications Union (ITU) • Electronic Industries Association (EIA)

  17. Industry Standards • Created by corporations (eg IBM, Microsoft, Intel, Apple etc) • Open vs closed standards • Industry Standards may or may not become de facto standards in common use • Open industry standards, if they are widely adopted (ie de facto standards) are sometimes adopted by standards organisations

  18. De facto standards • Anyone can create a standard! It only matters if it is widely used. • Control of successful standards is an issue • They may become formal standards • They may establish their own organisation • WWW • Invented by Tim Berners-Lee at CERN in 1990 • W3C founded by MIT in 1994 • Now W3C is essentially an independent standards body

  19. Hardware Standards • Many hardware standards are formalised and tightly defined eg • RS-232 (serial) - EIA • IDE - originally Compaq, now ANSI • SCSI - originally Seagate, now ISO • Some standards are more problematic

  20. The VGA “standard” • Video Graphics Array • Industry standard - set by IBM in mid 1980’s • VGA displays either 320 x 200 in 256 colours or 640 x 480 in 16 colours • Super-VGA (SVGA) • This is not a standard - video hardware has proprietary low level API • This causes major compatibility problems for multimedia • Partly solved by MS Windows • More completely solved by DirectX

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