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  1. 1. Information Resources on the Web Part 3 - Multimedia Tutorial 4
  2. 2. Images and Graphics <ul><li>Graphics Interchange Format (GIF) : </li></ul><ul><ul><li>older image format </li></ul></ul><ul><ul><li>good compression for small- or medium-sized files </li></ul></ul><ul><ul><li>.gif filename extension, usually </li></ul></ul><ul><ul><li><= 256 different colors </li></ul></ul><ul><ul><li>widely used on the Internet for images that have only a few distinct colors </li></ul></ul><ul><ul><ul><li>line drawings, cartoons, simple icons, and screen objects </li></ul></ul></ul>
  3. 3. Images and Graphics <ul><li>Animated GIF file : </li></ul><ul><ul><li>combine several images into a single GIF file </li></ul></ul><ul><ul><ul><li>special editor </li></ul></ul></ul><ul><ul><li>browser displays with appearance of cartoon-like animation. </li></ul></ul>
  4. 4. Images and Graphics <ul><li>Joint Photographic Experts Group (JPEG) : </li></ul><ul><ul><li>newer file format </li></ul></ul><ul><ul><li>>= 16 million colors </li></ul></ul><ul><ul><li>good for photographs and continuous-tone art </li></ul></ul><ul><ul><ul><li>images that do not have sharp edges </li></ul></ul></ul><ul><ul><li>.jpg filename extension. usually </li></ul></ul>
  5. 5. Images and Graphics <ul><li>GIF and JPEG formats offer file compression </li></ul><ul><li>Uncompressed graphics files </li></ul><ul><ul><li>-- too large to transmit efficiently. </li></ul></ul><ul><li>JPEG file compression is lossy . </li></ul><ul><li>lossy compression </li></ul><ul><ul><li>-- erases some elements of the graphic. </li></ul></ul><ul><ul><li>The greater the level of compression , the more graphic detail is lost. </li></ul></ul>
  6. 6. Images and Graphics <ul><li>More graphic image file formats: </li></ul><ul><ul><li>Windows bitmap file format (.bmp) </li></ul></ul><ul><ul><li>Tagged Image File Format (TIFF) (.tif) </li></ul></ul><ul><ul><li>PC Paintbrush format (.pcx ) </li></ul></ul><ul><ul><li>Portable Network Graphics (PNG) format (.png) </li></ul></ul><ul><li>Windows bitmap , TIFF , and PC Paintbrush formats </li></ul><ul><ul><li>all uncompressed graphics formats </li></ul></ul><ul><ul><li>avoid them -- too long to download. </li></ul></ul><ul><li>PNG format newer -- not yet approved as a Web standard </li></ul>
  7. 7. Images and Graphics <ul><li>WebMuseum site -- fine arts </li></ul><ul><li>Search engines/Web directories -- improving image classification for databases. </li></ul>
  8. 8. Sounds, Music, and Video <ul><li>Sound or video clips </li></ul><ul><ul><li>enhance information </li></ul></ul><ul><ul><li>often require software extensions to Web browser. </li></ul></ul><ul><li>Software extensions , or plug-ins: </li></ul><ul><ul><li>are usually available as free downloads. </li></ul></ul><ul><li>Firms that offer media players for free </li></ul><ul><ul><li>earn $ by selling encoding software to developers </li></ul></ul><ul><ul><li>earn $ by selling enhanced player software </li></ul></ul>
  9. 9. Sounds, Music, and Video <ul><li>Computer needs sound card and speaker(s) or earphones to play an audio file. </li></ul><ul><li>Wave (WAV) format </li></ul><ul><ul><li>digitizes audio waveform information at a user-specified sampling rate </li></ul></ul><ul><ul><li>can be played on any Windows computer that supports sound. </li></ul></ul><ul><li>size of WAV files limits use on the Web to short, lower-quality audio information. </li></ul>
  10. 10. Sounds, Music, and Video <ul><li>MIDI (Musical Instrument Digital Interface) format </li></ul><ul><ul><li>standard adopted by music industry for to create and read musical information. </li></ul></ul><ul><ul><li>digitally records information about each element of the sound, including pitch, length, and volume. </li></ul></ul><ul><ul><li>Easier to edit music recorded in the MIDI format </li></ul></ul><ul><ul><ul><li>can manipulate individual characteristics of the sound precis ely . </li></ul></ul></ul><ul><ul><li>much smaller than WAV files </li></ul></ul><ul><ul><li>often used on the Web </li></ul></ul><ul><ul><li>.midi or .mid file extension usually </li></ul></ul>
  11. 11. Sounds, Music, and Video <ul><li>UNIX operating system’s audio file format </li></ul><ul><li>known as the AU format because file extension usually .au . </li></ul><ul><li>AU files similar size as WAV files to store same information. </li></ul>
  12. 12. Sounds, Music, and Video <ul><li>Streaming transmission : </li></ul><ul><ul><li>server sends first part of file to browser </li></ul></ul><ul><ul><li>browser begins playing file </li></ul></ul><ul><ul><li>while browser is playing file, server sends next segment of file </li></ul></ul><ul><ul><li>popular for transferring sound and video files </li></ul></ul><ul><ul><li>can access very large audio or video files in much less time than download-then-play procedure requires. </li></ul></ul>
  13. 13. Sounds, Music, and Video <ul><li>RealNetworks, Inc ., developed </li></ul><ul><ul><li>RealAudio format for audio files </li></ul></ul><ul><ul><li>RealVideo format for video files. </li></ul></ul><ul><li>Must download and install one of the real file players </li></ul><ul><li>file extension is .ra or .ram </li></ul><ul><li>RealNetworks formats compressed further – more efficient Internet transfer </li></ul>
  14. 14. Sounds, Music, and Video <ul><li>Older video file formats available on the Web </li></ul><ul><ul><li>AVI (Audio Video Interleaved) format </li></ul></ul><ul><ul><li>QuickTime format </li></ul></ul><ul><li>1 minute of AVI or QT video and sound  file that is about 6 MB </li></ul><ul><ul><li>too large to transmit over slower types of Internet connections. </li></ul></ul><ul><li>International Standards Organization’s (ISO) Moving Picture Experts Group (MPEG)  series of standards for compressed file formats. </li></ul><ul><li>Lossy: technique deletes information file </li></ul><ul><ul><li>result can deteriorate quality </li></ul></ul>
  15. 15. Sounds, Music, and Video <ul><li>MP3 : </li></ul><ul><ul><li>MPEG format’s audio track </li></ul></ul><ul><ul><li>somewhat lower quality than WAV format files </li></ul></ul><ul><ul><li>90 percent smaller than WAV </li></ul></ul><ul><ul><li>popular when disk storage on personal computers dropped in price and CD writers (also called CD burners) became affordable for home use </li></ul></ul><ul><ul><li>CD might hold </li></ul></ul><ul><ul><ul><li>15 songs in WAV format (about 40 MB per song) </li></ul></ul></ul><ul><ul><ul><li>150 popular songs in MP3 format (about 4 MB per song) </li></ul></ul></ul>
  16. 16. Ethical and Legal Concerns: Sharing Audio Files <ul><li>MP3 files smaller  easy to send by Internet </li></ul><ul><li>File sharing software – Napster, Kazaa, ... </li></ul><ul><li>File-sharing activity is unethical </li></ul><ul><ul><li>deprives the creators of their rights to control distribution and to profit from their work. </li></ul></ul><ul><li>File-sharing is also illegal in many countries, including the United States. </li></ul>
  17. 17. Legal MP3 File Distribution <ul><li>Portable digital music players with flash memory technology can store thousands of songs. </li></ul><ul><li>Sites now sell digital music in MP3 and other formats. </li></ul><ul><ul><li>some charge per song </li></ul></ul><ul><ul><li>others charge a flat monthly fee </li></ul></ul><ul><ul><li>restrictions on the number of copies of each song </li></ul></ul><ul><ul><li>may restrict you from converting downloaded song files into other formats </li></ul></ul><ul><ul><li>may restrict types of devices you may play the song on </li></ul></ul>
  18. 18. Future of Electronic Publishing <ul><li>Information can be spread more rapidly than ever, in large quantities, but with low required investment. </li></ul><ul><li>E-zines : </li></ul><ul><ul><li>Web-based magazines </li></ul></ul><ul><ul><li>appearing on the Web in increasing numbers. </li></ul></ul><ul><ul><li>can focus on specialized, narrow interests </li></ul></ul><ul><ul><li>Usually managed by an editor </li></ul></ul><ul><li>Blogs : </li></ul><ul><ul><li>usually written by single person, expressing particular viewpoint </li></ul></ul><ul><ul><li>most focus on issues where people have strong opinions </li></ul></ul>