Alice Workshop
Working with Sound
Sound
Working with sound is appealing to
students
Demo: Penguin Sound
Opportunity
Using sound offers an opportunity to
discuss fair use and copyright
guidelines.
For educational purposes, fair use and
copyright guidelines rule of thumb is 30
seconds*.
http://www.utsystem.edu/ogc/INTELLECTUALPROPERTY/ccmcguid.htm
* Or 10%, whichever is less
Questions
Questions students ask:
Can more than 1 clip (from different sound
files) be used? Yes
Can a 30 second clip be played again and
again? Yes
How to get a 30 second sound clip?
Sound editor
Alice is not, nor has, a sound editor.
Obtain sound editor software
Example: Audacity
Freeware from
audacity.sourceforge.net/download/
Soundcards
Audacity works with OS
Capturing sounds to a file
Editing files
Mixing different tracks
OS of the computer uses a soundcard to
Convert analog sound (from a CD) to digital
format when recording, and
Convert digital sound file to analog sound,
when playing audio
Digital Sound
Digital wave form
Each dot in the figure above represents
one audio sample.
Sample Rate
The rate at which the samples are
captured, measured in Hertz (Hz),
or samples per second.
For Alice clips we will use a
sample rate of 22.5 KHz
Higher sampling rates allow a
digital recording of higher quality.
Sample Size
Essentially this is the number of digits in
the digital representation of each sample.
Think of the sample rate as the horizontal
precision of the digital waveform, and the
sample size as the vertical precision.
Higher sample sizes allow for more
dynamic range - louder louds and softer
softs
File Formats
Uncompressed (Pulse Code Modulation)
Each number in the file corresponds to
one sample
Audacity supports WAV, AIFF, and others
Compressed
Logarithmic encodings
Audacity supports MP3 and Ogg Vorbis
Not WMA and MPEG4 (AAU)
Alice supports WAV and MP3
Launch Audacity
Clip from Song
Original Song
Penguin Sound
Has a 3+ minute sound track
Modify to use a 30 second clip repeatedly
Skate Routine
SkateRoutine
Grab a 30 second clip from a song
Import it into an existing world
Add it to the skating routine