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