1. Business and Computing Deanery Multimedia Week 2 Enabling Technologies

2. Multimedia 2 Today’s Contents Module guide and discuss your presentation Enabling technologies Digital representations Hardware and software requirements Networks Standards Look at Flash

3. Multimedia 3 Module guide Any questions? For information on the BBC computer (or Micro) try http://en.wikipedia.org/http://en.wikipedia.org/

4. Multimedia 4 Presentations List of groups List of subjects

5. Multimedia 5 Analogue or digital? What is the difference between music on a cassette to that of music on a CD?

6. Multimedia 6 Digital representations Digital multimedia depends upon the ability of digital computers to perform operations at high speed Image, text, moving pictures and sound are all reduced to binary digits inside a computer Chapman N and Chapman J (2004).

7. Multimedia 7 Bits and Bytes Devices can only be in one of two states 0 or 1, yes or no, on or off, … Bit: a unit of data that can only have one of two values Byte: an ordered sequence of eight bits Word: a short sequence of bytes, usually four (32 bits) 32–33 Chapman N and Chapman J (2004).

8. Multimedia 8 Interpretation of Bits Numbers to base 2 (binary) 01100001 = 97 decimal Characters – associate bit patterns (numbers) with characters via a character set 01100001 = a in ASCII Brightness of an image at a point, instantaneous amplitude of a sound wave, etc 33 Chapman N and Chapman J (2004).

9. Multimedia 9 Addresses Each byte can be identified by its position in the sequence of all bytes in memory – its address Collections of bytes can be combined into data structures using addresses e.g. store an image as a sequence of brightness values, use address of the first to access the image data store a video sequence as series of images, add address of next and previous to each frame 34 Chapman N and Chapman J (2004).

10. Multimedia 10 Instructions Bit patterns that cause the processor to carry out operations on values stored in memory Hardware is constructed so that the desired effect is achieved Programs stored in memory as a sequence of instructions to be executed in order A computer is a stored program machine It can therefore be used for many different tasks, depending on the programs it runs 34 Chapman N and Chapman J (2004).

11. Multimedia 11 Understanding analogue What is Sound?

12. Multimedia 12 Analogue or digital? What is the difference between music on a cassette to that of music on a CD?

13. Multimedia 13 Analogue and digital Describe two types of clock

14. Multimedia 14 Soundwaves Images used with permission from: Burk et al (data unknown) Music and Computers, Dartmouth College [online] http://eamusic.dartmouth.edu/~book/MATCpages/chap.1/1.1.what_is.html [accessed] July 2003http://eamusic.dartmouth.edu/~book/MATCpages/chap.1/1.1.what_is.html

15. Multimedia 15 Analogue to Digital Winamp is sound software available free from www.winamp.com. Soundwave representation of music. Digital representation of music.

16. Multimedia 16 Converting Analogue is soundwaves. Digital is binary (1s and 0s). Analogue to digital converter (ADC) Digital to analogue converter (DAC)

17. Multimedia 17 Digitization Converting a signal from analogue to digital form Analogue signal can vary continuously, digital is restricted to discrete values Two-stage process Sampling – measure the value at discrete intervals Quantization – restrict the value to a fixed set of quantization levels 35–36 Chapman N and Chapman J (2004).

18. Multimedia 18 Sampling and Quantization Why is the sampling rate important? Why is the quantisation level important? 36 Sampling Quantisation Chapman N and Chapman J (2004).

19. Multimedia 19 Digital Signals Only certain signal values are valid Relatively immune to corruption by noise Do not degrade when copied or transmitted over network Some information lost Undersampling Samples 'too far apart' so cannot accurately reconstruct original signal 36–37 Chapman N and Chapman J (2004).

20. Multimedia 20 Sampling Theorem If the highest frequency component of a signal is at fh the signal can be properly reconstructed if it has been sampled at a frequency > 2fh Nyquist rate Undersamping leads to aliasing Sound distortion, image 'jaggies' or Moiré patterns, jerky or retrograde motion 40–41 Chapman N and Chapman J (2004).

21. Multimedia 21 Too Few Quantization Levels Reducing memory requirements by using fewer bits for each value means fewer quantization levels are available Cannot distinguish between values that fall between levels Images: banding and posterization Sound: coarse hiss, loss of quiet passages, general fuzziness (quantization noise) 41–42 Chapman N and Chapman J (2004).

22. Multimedia 22 Hardware requirements Two distinct uses Requirements for production Requirements for consumption Depends what you are going to do For web use? To display a full feature video Render 3D animation What is a multimedia spec for a PC?

23. Multimedia 23 Hardware Requirements 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) 42–45 Chapman N and Chapman J (2004).

24. Multimedia 24 What do you need? Raw processing power High speed data buses Large main memories Powerful graphics and sound cards Fast high-capacity secondary storage Chapman N and Chapman J (2004).

25. Multimedia 25 Peripherals What peripherals might you need for multimedia? Graphic tablet? Digital camera Digital video camera An extra monitor Microphone Transfer of data to the computer Firewire USB 2

26. Multimedia 26 Peripherals High capacity disks connected via high speed buses Firewire 400, Firewire 800, USB 2.0, SCSI III RAID arrays Graphics tablet and pressure-sensitive pen High-resolution monitor Digital camera, scanner, DV camera,… 46–47 Chapman N and Chapman J (2004).

27. Multimedia 27 Software Making multimedia requires a whole host of software and skills Multimedia production often involves a whole team of people What type of software do you think you might need for your portfolio work? Name examples

28. Multimedia 28 Software Requirements 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) Sound: editing and effects (Audition, Bias Peak) 48 Chapman N and Chapman J (2004).

29. Multimedia 29 Software Requirements Applications for combining media types 'Authoring systems' Timeline-based May require some programming in a scripting language to provide interactivity 48 Chapman N and Chapman J (2004).

30. Multimedia 30 Software we will be using Multimedia authoring Flash Image editing Fireworks Sound editing Cool edit Video

31. Multimedia 31 Distribution of multimedia Stand alone with a projector with a CD or DVD Or over an Network Give an example of a network? How often do you use the Internet? How important is it to you?

32. Multimedia 32 Networks 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 50 Chapman N and Chapman J (2004).

33. Multimedia 33 Internet Acess Dial-up connection uses modem and analogue telephone line V90 modem, 56kbps maximum Broadband always-on digital connection (may be as little as 512kbps, not true broadband) ADSL asymmetric digital subscriber line Cable Satellite Dedicated line (T1, T3) 51–52 Chapman N and Chapman J (2004).

34. Multimedia 34 kbps (max) 6kB text page 100kB image 4MB movie slow modem 28.81.5s28s19mins fast modem 561s14s9mins T1 line1544<1s1s21s Typical broadband 6000<1s 5s T3 line44736<1s 1s Download Times 53 Chapman N and Chapman J (2004).

35. Multimedia 35 Clients and Servers 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 54 Chapman N and Chapman J (2004).

36. Multimedia 36 Why Flash? “A bandwidth friendly and browser independent vector-graphic animation technology. As long as different browsers are equipped with the necessary plug-ins, Flash animations will look the same.” Webopedia (2005) Designed for the WWW Small file sizes Embed into web pages

37. Multimedia 37 The World Wide Web 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 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 54–56 Chapman N and Chapman J (2004).

38. Multimedia 38 MIME Types 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 56–57 Chapman N and Chapman J (2004).

39. Multimedia 39 Standards "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 Multimedia standards concern file formats, markup languages etc, and especially network protocols 57–58 Chapman N and Chapman J (2004).

40. Multimedia 40 Standards Organizations 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 58–59 Chapman N and Chapman J (2004).

41. Multimedia 41 Internet Standards 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 60 Chapman N and Chapman J (2004).

42. Multimedia 42 Some questions Scenario: You have been asked by Hope to create an Library Induction for use by new students using Flash Why would you use Flash? Why is HTTP important for Flash? Is a standard browser enough? Discuss the merits of including a video Draw up a list of the hardware you would require Draw up a list of the software you would require Discuss the process of digitization of media for the project Why is the Nyquist rate important?

43. Multimedia 43 For Next Week Directed Reading Digital Multimedia, Second Edition Chapters 1 and 2 if you have not read them yet Chapter 13Design principles Chapter 3 Introduction to computer graphics Independent study Finalise your groups Work on your presentation Get to know Flash Help/How Do I Work with layers Create a user interface

44. Multimedia 44 What have we covered today? Enabling technologies Digital representations Hardware and software requirements Networks Standards Any questions?

45. Multimedia 45 References Chapman N and Chapman J (2004). Digital Multimedia, Second Edition. London. Wiley pp 7 ISO - International Organization for Standardization http://www.iso.org/iso/en/ISOOnline.fron tpage, accessed 01/10/2005 http://www.iso.org/iso/en/ISOOnline.fron tpage Webopedia http://www.webopedia.com/TERM/F/Flas h.html, accessed 01/10/2005 http://www.webopedia.com/TERM/F/Flas h.html