Understanding Multimedia Elements – Sound, Animation, Video Unit C

2 Objectives Understand sound Sound on the Web 2-D animation 3-D animation Animation on the Web

3 Objectives Video Video compression & video editing Video on the Web

4 Understanding Sound: Analog Sound waves Analog wave pattern –Volume = height of each peak Higher the peak, louder the soundHigher the peak, louder the sound –Frequency(pitch) = distance between peaks measured in hertz(Hz) Greater the distance, lower the soundGreater the distance, lower the sound

5 Understanding Sound: Digital Converted to bits via sampling Quality depends on: –Sample rate: number of times sample is taken ( kHz, kHz & 44.1 kHz) –Sample size: amount of information stored (8 bit and 16 bit)

6 Digitizing Process Cassette tape player, videotape player, CD or microphone is captured by sound card Software/user controls sample rate and size Sound-editing program used for manipulation

7 Sound File Formats WAV –Windows or Macintosh –Used on the Web AIFF (Audio Interchange File Format) –AIFFC (AIFF Compressed) –Windows or Macintosh RealAudio (.ra) –Allows streaming of sound over Web MP3 (MPEG Layer 3) –Compresses entire songs for Web –Near stereo quality

8 MIDI Sound Files Musical Instrument Digital Interface Electronic musical instruments create sound; then stored on computer Contain code/commands, not digitized sounds Very small files

9 Sound on the Web File size is an issue File compression used for certain file formats (RealAudio and MP3) Sounds stored on Web server Media player installed on user computer –RealPlayer, Windows Media Player, MP3, QuickTime File size is an issue File compression used for certain file formats (RealAudio and MP3) Sounds stored on Web server Media player installed on user computer –RealPlayer, Windows Media Player, MP3, QuickTime

10 Streaming Media Audio and video can be played in real time File starts playing immediately – doesn’t wait for full download Connection to web server is continuous

11 Tips for Using Sound on Web Is the sound appropriate? Is there a benefit? Is it a good sound quality? Can you afford the cost of recording the sound? Should you just use sound with still images instead of video? Can you stream the files? Can you give the user control?

12 2-D Animation Can Provide Action and realism in entertainment Visualization and demonstration in education Simulation of actual events

13 2-D Animation Issues Movement is made up of many still images Each still image has its own frame Speed of moving these frames: –Movies on film: 24 fps –Television: 30 fps –Computer animation: fps

14 2-D Animation Types: Cel Animation Based on changes that occur from one frame to another Background image is stationary Celluloid images placed on background Celluloid images change from frame to frame

15 2-D Animation Types CelAnimationCelAnimation

16 2-D Animation Types: Path Animation Object moved along predetermined path on screen Object can stay the same, be resized or rotated Tweening in an authoring program –Define beginning position in one frame –Define ending position in another frame –Software fills in intervening frames

17 2-D Animation Types PathAnimationPathAnimation

18 2-D Animation Software Allows Frame rate changes Transitions User playback control Looping Object drawing and animating Sound clips Cheap shareware to expensive authoring packages

19 3-D Animation Games and adventure titles Users are participants, not spectators Much more complex than 2-D Involves: –Modeling –Animation –Rendering

20 3-D Modeling and Animation Draw views by setting points on a grid Create contours and structure Define object’s motion, lighting & perspective views

21 3-D Rendering Give objects attributes –Colors –Surface textures –Transparency amounts Programs –Strata 3D –LightWave 3D –3D Studio Max –Maya –Houdini Give objects attributes –Colors –Surface textures –Transparency amounts Programs –Strata 3D –LightWave 3D –3D Studio Max –Maya –Houdini

22 3-D Morphing

23 Warping Distort a single image Change a frown into a smile

24 Virtual Reality (VR) Creates an environment that surrounds the user so the user becomes part of the experience Examples: –Boeing Corporation flight simulators –CD-based adventure games: Myst and 7 th Guest –Virtual tour sites Some require special equipment like goggles & gloves

25 Animation on the Web Animated text Animated GIF Macromedia Director applications 3-D environments You must have the plug-ins to play these animations!

26 Animated Text on the Web Rotating, zooming, scrolling, distorting, blinking Use authoring software Use HTML – Hello – Hello Scrolling Text

27 Animated GIFs on the Web Each.gif image file is a little different

28 Macromedia Applications on the Web Director or Flash to author Shockwave to deliver on Web

29 VRML Virtual Reality Modeling Language Creates interactive 3-D on the Web User is moved through the environment (instead of object moving) Environment is dynamic and always changing

30 Understanding Video Video can be –Very expensive –Time-consuming to create –Very large files Video can be found in stock film companies Video must be digitized from an analog signal

31 Digitizing an Analog Video Signal

32 Editing Video Digitized video is not linear like analog video Can access any part of video randomly Can cut and paste Can use special effects and transitions

33 Digital Video File Size Considerations 1 second of high-quality color video on ¼ of the computer screen = 1 MB file size Determining file size –Frame rate: lower the better (15 fps minimum) –Image size: use smaller playback window –Color depth: 8-bit vs. 16-bit vs. 24-bit color

34 Video Compression/Decompression Codecs Lossless: gives larger file by preserving exact image Lossy: eliminates some image data; smaller file, but poorer quality

35 MPEG Compression Format Motion Pictures Experts Group Reduce file size by eliminating redundant information (backgrounds) Also looks for changes from frame to frame

36 Video Compression Software Apple’s QuickTime and QuickTime for Windows –Dual platform –Lossy compression Microsoft Windows Media Player –AVI format Both synchronize sound and motion –Synchronized Multimedia Integration Language (SMIL) –Markup language like HTML

37 Video Editing Software Transitions: dissolves, wipes, spins Animations: fly-in logo Special effects: twisting, zooming, rotating Filters: color balance, brightness/contrast, blurring, distortions, morphing Adobe Premiere

38 Video on the Web Only practical for 56K or higher connections Planning –Is animation or still images with sound better? –Are stock videos better? –Quality-versus-cost and relevance of video to application

39 Video Transfer Types: HTTP HyperText Transfer Protocol Downloads entire video to hard drive of user User can play it over and over quickly Better for small video clips

40 Video Transfer Types: RTSP Real-Time Streaming Protocol Continuous playing/streaming Not saved on hard drive User can randomly access any video part Better for large videos and live broadcasts

41 Streaming Video HorizonLive: live video presentations

42 Video and Virtual Reality Apple QuickTime VR system iPEX system Starts with panoramic photographs Camera rotated after each picture for 360 degrees Photographs electronically “stitched” together User can navigate and zoom (White House site)

43 Issue: The Napster Controversy Intellectual Property Rights and Emerging Web Technologies Sharing MP3 files through the web Recording Industry Association of America filed suit

Understanding Multimedia Elements – Sound, Animation, Video End