Audio

1
Audio Animation Overview

• IT 130
• Web Graphics and Multimedia

2
Audio Overview

• Early days beep only
• Audio basics sound waves have a recurring or
  analog wave pattern
• Volume height of the peak
• Frequency (pitch) distance between peaks

3
Audio Overview

• Measurement
• Pattern recurs every second 1 hertz (Hz)
• Example 1000 per second 1000 Hz or 1 kHz
  (kilohertz)
• Sound converted from analog (sound waves) to
  digital (bits) form

4
Audio Overview

• Conversion process called sampling
• Two factors that affect quality
• Sample rate - of times sample is taken
• Sample size amount of info stored about the
  sample

5
Audio Overview

• Most common sample rates
• 11.025 kHz
• 22.05 kHz
• 44.1 kHz
• Most common sample sizes
• 8 bit (256 values)
• 16 bit (65,536 values)

6
Audio Overview

• Sound card and software are used to digitize
  sound
• User may determine the sample rate and bit value
  used by the sound card

7
Audio Overview

• Audio File Formats
• WAV developed by Microsoft and widely used
• AIFF (Audio Interchange File Format) developed
  by Apple but can be used on Windows-based PCs

8
Audio Overview

• Audio File Formats
• RealAudio (.ra) compression format developed by
  Real Networks
• MP3 (MPEG Layer 3) format that compresses large
  audio files (entire songs) at near stereo quality

9
Audio Overview

• Audio File Formats
• MIDI (Musical Instrument digital Interface)
  enables computers and electronic musical
  instruments to communicate sound info
• Example File sent from computer to synthesizer
  for playback

10
Audio on the Web

• Primary concern is file size
• 10-seconds 2 MB 30 seconds to download (56k
  modem)
• File compression is needed
• Automatically performed when saved using certain
  formats (RealAudio or converting WAV to MP3)

11
Audio on the Web

• Streaming media technology that allows
  audio/video played real time
• Starts playing while downloading
• Media players
• RealPlayer (www.real.com)
• Windows Media Player
• MP3
• QuickTime

12
Animation Overview

• 2-D Animation
• Cartoons movies
• Frames
• Transitions
• Looping

13
Animation Overview

• 3-D Animation
• Modeling creates the structure of 3-D objects
  and scenes
• Animation defines the objects motion
• Rendering giving objects attributes, such as
  colors, textures, and transparency
• Example (www.webreference.com/3d)

14
Animation on the Web

• Increase appeal of a Web site
• Blinking text, scrolling headlines, rotating
  logos, 2-D action figures
• Example www.smashingideas.com

15
Animation on the Web

• Animated text
• Animated GIF
• Hundreds of free GIF animations available
• GIF animation software is also available
• www.download.com

16
Software Examples

• Sound editing software
• Sonic Foundry Sound Forge
• www.sonicfoundry.com