Week Ten Notes

Announcements

• We are doing 'self-service' roll call today. Please mark the appropriate box with an 'X'. Please tell me if your name is missing from the sheet.
• Monday: Go over ideas for Web Search
• Monday: Review for quiz on Wednesday
• Wednesday: Quiz
• Friday: No Class
• Next Monday: Web Search Assignement is due
• We are reading chapter five & six this week.

Chapter Six -- Graphics, Digital Media, and Multimedia

• Tim Berners-Lee invented the WWW: URL scheme, HTML, HTTP, a Browser. He made everything freely available. Others added multimedia capability.
• With the right software users can control the look of each pixel in an image. There is 8- 24- and 32-bit color. This kind of graphics is called bit-mapped graphics.
• Resolution measured in dpi. Images can be stored at high resolution and printed to look very realistic on paper. Painting programs are possible.
• Vector graphics have "infinite" resolution because they are equivalent to formulas for the shapes.
• CAD/CAM
• Presentation Software for making slide presentations
• There are graphics programs that use vector graphics formats to represent animations. Vector graphics representations take up less space than bit mapped graphics and can be much easier to render on differing platforms. (Bit values are determined at the time of rendering.)
  
  Macromedia's Shockwave Flash MX and Director MX are examples of such graphics programs. Vector graphics formats Shockwave Flash Format (SWF) and Sclable Vector Graphics (SVG).
  
  Animators can "create key frames and objects and use software to ... fill in ... ." This process is called Tweening.
• Analog and digital media are two fundamentally different ways of storing information.
  
  The phonograph technology invented by Thomas Edison is "classic" analog technology: Using a mechanical apparatus, a singer's voice causes a needle to vibrate as it plows a groove in a revolving wax cylinder. The vibrations of the needle create tiny "peaks and valleys" in the wax groove. Later when a needle is dragged through the groove, it vibrates as it runs over the peaks and valleys. The vibrations create sounds that duplicate ("play back") the sounds that created the peaks and valleys in the first place.
  
  Digital media is created by sampling. For example a digital voice recorder will measure the voltage output of a microphone thousands of times per second. Each measurement is stored as a binary number representing the value of the voltage. To "play back" digital media, a device scans through the list of digital samples one at a time and, for each one, outputs the voltage corresponding to the numerical value.
• Computers and digital video have made it quite easy to create and edit high-quality video presentations on inexpensive equipment.
• The computer files containing video tend to be very large because a large amount of information is required to represent each frame of video. To save storage space and allow for quicker downloads, video is compressed. Digital video playback also makes difficult demands on computer hardware. Often smaller image sizes are played and fewer of them per second to help the computer keep up with the playback rate.
• Computers can work with digitized sound in much the same way they work with video. Waveform audio involves working with a visual image of the waveform corresponding to sounds. Terms: sampling rate, bits per sample, lossless compression, lossy compression (e.g. MP3, AAC, WMA), rip, burn, Napster, iTunes.
• MIDI: Musical Instrument Digital Interface - to send commands between musical instruments and computers, synthesizers, samplers, sound cards.
• MIDI and digital audio technologies allow the computer to be used to edit and compose music - create, synchronize, and blend tracks.
• Synthesized Virtual Instruments are becoming more common.
• Hypertext has advantages over "linear" text, but there are also disadvantages.
• Multimedia combines media such as text, graphics, animation, video, music, voice, and sound. Computers allow for Interactive Multimedia. Multimedia authoring software includes HyperStudio and MetaCard. Macromedia's Director and Authorware are multi-media authoring software packages for professionals.
• Problem: "... one-way passive communication has become more common than interactive discourse." Will interactive multi-media technology help, or make the problem worse?