1. COMP135/COMP535 Digital Multimedia, 2nd edition Nigel Chapman & Jenny Chapman Chapter 2 Lecture 3 – Enabling Technologies – Hardware, Software, and Standards 1

2. COMP135/COMP535 Consumption –Capabilities of typical consumer systems determine limits of what is feasible –Mobile devices may impose even tighter limitations Production –Highly demanding on processor power, memory, secondary storage (especially for video) Hardware Requirements 2

3. COMP135/COMP535 High capacity disks connected via high speed buses –Firewire 400, Firewire 800, USB 2.0, –A very fast external bus standard that supports data transfer rates of up to 400Mbps (in 1394a) and 800Mbps (in 1394b). –USB 2.0 –Also referred to as Hi-Speed USB, USB 2.0 is an external bus that supports data rates up to 480Mbps. USB 2.0 is an extension of USB 1.1.busMbpsUSB 1.1 –Universal Serial Bus (USB) is an industry standard developed in the mid-1990s that defines the cables, connectors and communications protocols used in a bus for connection, communication, and power supply between computers and electronic devicesindustry standardcommunications protocolsbuscomputers Peripherals 3

4. COMP135/COMP535 Peripherals –SCSI III –Small Computer System Interface (is a set of standards for physically connecting and transferring data between computers and peripheral devices.peripheral devices –The SCSI standards define commands, protocols and electrical and optical interfaces.commandsinterfaces –SCSI is most commonly used for hard disks and tape drives, but it can connect a wide range of other devices, including scanners and CD drives.CDdrives –RAID arrays –RAID (originally redundant array of inexpensive disks; now commonly redundant array of independent disks) is a data storage virtualization technology that combines multiple disk drive components into a logical unit for the purposes of data redundancy or performance improvement. 4

5. COMP135/COMP535 Peripherals Graphics tablet and pressure-sensitive pen High-resolution monitor Digital camera, scanner, DV camera,… 5

6. COMP135/COMP535 Applications for different media types –Images: image editing, painting and drawing (Photoshop, Illustrator) –Text: editors, layout programs –Video: editing and post-production (Premiere, After Effects, Final Cut Pro) –Animation: drawing, interpolation (Flash) –Animation is the process of creating motion and shape change[Note1] illusion by means of the rapid display of a sequence of static images that minimally differ from each other. –Sound: editing and effects (Audition, Bias Peak) Software Requirements 6

7. COMP135/COMP535 Applications for combining media types 'Authoring systems‘ An authoring system is a program which has pre- programmed elements for the development of interactive multimedia software titles. Authoring systems can be defined as software which allows its user to create multimedia applications for manipulating multimedia objects. –Timeline-based (e.g. Director) –Markup-based for WWW (e.g. Dreamweaver) May require some programming in a scripting language to provide interactivity Software Requirements 7

8. COMP135/COMP535 Local area networks (LANs) connect several computers on one site (Ethernet) LANs connected together by routers, bridges and switches form an internet The Internet is a global network of networks (internet) communicating via TCP/IP protocols –Mostly operated by commercial Internet Service Providers (ISPs) –Domestic users connect via telephone, cable or satellite Networks 8

9. COMP135/COMP535 Dial-up connection uses modem and analogue telephone line –V90 modem, 56kbps maximum –V90 is a standard for 56-Kbps modems approved by the International Telecommunication Union (ITU)KbpsmodemsInternational Telecommunication Union (ITU) Broadband always-on digital connection (may be as little as 512kbps, not true broadband) In telecommunications, broadband is wide bandwidth data transmission with an ability to simultaneously transport multiple signals and traffic types. The medium can be coaxial cable, optical fiber, twisted pair, DSL local telephone networks or wireless broadband.telecommunicationsbandwidthdata transmissioncoaxial cableoptical fibertwisted pairDSL local telephone networkswireless broadband –ADSL Asymmetric digital subscriber line (ADSL) is a type of digital subscriber line (DSL) technology, a data communications technology that enables faster data transmission over copper telephone lines digital subscriber linecoppertelephone lines Internet Acess 9

10. COMP135/COMP535 Internet Acess –Cable –Satellite –Dedicated line (T1, T3) T1 and T3 are two common types of leased lines used in telecommunications. BothT1 lines and T3 lines are reserved circuits that operate over either copper or fiber optic cables.leased linesfiber optic cables T1 and T3 are typically rented by organizations at a monthly or yearly rate to connect geographically separated offices for private voice and/or data networking. The high cost of these lines prevents most individuals from leasing them. 10

11. COMP135/COMP535 kbps (max) 100kB image 4MB movie slow modem28.81.5s28s19mins fast modem561s14s9mins T1 line1544<1s1s21s Typical broadband 6000<1s 5s T3 line44736<1s 1s Download Times 11

12. COMP135/COMP535 Servers listen on a communication channel for requests from clients and send responses –Often servers (the programs) run on dedicated machines, also referred to as servers –Clients run on separate machines (e.g. desktop computer) Interaction is governed by protocols In telecommunications, a communications protocol is a system of digital rules for data exchange within or between computers.telecommunications Clients and Servers 12

13. COMP135/COMP535 HTTP – Hypertext Transfer Protocol Client (Web browser) sends request for a Web page, server returns it (HTML document) Identify server and location of page from a URL A uniform resource locator (URL; also known as a web address, is a specific character string that constitutes a reference to a resource. Most web browsers display the URL of a web page above the page in an address bar. A typical URL might look like:character stringresourceweb browsersaddress bar http://domain name/path –e.g. http://www.digitalmultimedia.org/DMM/index.html Server may create page dynamically –Communicates with other program via CGI etc The World Wide Web 13

14. COMP135/COMP535 The World Wide Web Common Gateway Interface (CGI) is a standard method used to generate dynamic content on Web pages and Web applications.dynamic content on Web pagesWeb applications CGI, when implemented on a Web server, provides an interface between the Web server and programs that generate the Web content.Web serverWeb content These programs are known as CGI scripts or simply CGIs; they are usually written in a scripting language, but can be written in any programming language.scripting languageprogramming language 14

15. COMP135/COMP535 Need to identify the type of media data in a data stream in a platform-independent way MIME (Multipurpose Internet Mail Extension) –Originally designed to allow inclusion of data other than text in email, adopted by HTTP –Content-type: type/subtype –Types include text, image, audio, video, application, subtypes define specific formats –e.g. text/html, image/gif MIME Types 15

16. COMP135/COMP535 "Standards are documented agreements containing technical specifications … to be used consistently … to ensure that materials, products, processes and services are fit for their purpose" (ISO) Ensure things that conform to standards are interchangeable / substitutable Multimedia standards concern file formats, markup languages etc, and especially network protocols Standards 16

17. COMP135/COMP535 ISO (International Organization for Standards) –All technical fields except electrical and electronic engineering IEC (International Electrotechnical Commission) ITU (International Telecommunications Union) –IT dealt with by joint ISO/IEC technical committee Standards Organizations 17

18. COMP135/COMP535 Internet Architecture Board (IAB) –Internet Engineering Task Force (IETF) deals with technical development –Internet Assigned Numbers Authority (IANA) registers MIME types, language codes, etc World Wide Web Consortium (W3C) –No official status, but Recommendations are treated as standards for the WWW Internet Standards 18