skills: set sample size and rate in audacity concepts: analog versus digital data, analog to digital...
Post on 19-Dec-2015
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Skills: Set sample size and rate in AudacityConcepts: analog versus digital data, analog to digital conversion, digital to analog conversion, sample rate, sample size, quality-file size trade off
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Recording and encoding analog data
Where does this topic fit?
• Internet concepts– Applications– Technology– Implications
• Internet skills– Application development– Content creation– User skills
http://som.csudh.edu/fac/lpress/presentations/clocks/clocks.html
Which clock is digital? Analog?
Analog to digital converter
Digital to analog converter
Recording and playing sound
Computer
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Computer
10010110 (150)11001001 (201)11000111 (199)…
Analog to digital converter
Digital to analog converter
Reading and adjusting temperature
Computer
10010110 (150)11001001 (201)11000111 (199)…
Computer
10010110 (150)11001001 (201)11000111 (199)…
Sensors for all sorts of things• Speed• Rate of flow• Pressure• Altitude• Acceleration• Motion• Rotation• Temperature• Light level• Sound• Compass direction• Blood pressure• Heart rate• And more …
The Internet of things
1. Increase the sampling rate
What is the second thing we can increase? Hint: how did we increase the variety of colors in images or symbols in text?
Increase sample rate → quality ↑ file size ↑
Increase sample size → quality ↑ file size ↑
Recording tradeoffs
0 0 A
0 1 B
1 0 C
1 1 D
Text2-bits/character
Image1-bit/pixel
Sound2-bits/sample
Increase code bits → quality ↑ file size ↑
Self-study questions
At a sampling rate of 8,000 16-bit mono samples per second, what would be the file size for a one minute recording?
How much larger would a stereo recording be?
How much larger would the file size be if we were to sample at 48,000 samples per second?
How much larger would the file size be if the samples were 32 bits each?
Resources
Wikipedia analog:http://en.wikipedia.org/wiki/Analog_signal
Wikipedia digital:http://en.wikipedia.org/wiki/Digital
A more detailed tutorial:http://www.planetoftunes.com/digiaudio/how_a_to_d.html