Skills: Set sample size and rate in Audacity Concepts: analog versus digital data, analog to digital conversion, digital to analog conversion, sample rate, sample size, quality-file size trade off This work is licensed under a Creative Commons Attribution- Noncommercial-Share Alike 3.0 License. Recording and encoding analog data
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Skills: Set sample size and rate in Audacity Concepts: analog versus digital data, analog to digital conversion, digital to analog conversion, sample rate,
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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
This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 License.
Recording and encoding analog data
Where does this topic fit?
• Internet concepts– Applications– Technology– Implications
• Internet skills– Application development– Content creation– User skills
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
Sampling an analog signal
How can we improve the fit of the digital curve? (Hint: 2 ways)
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?
2. Increase the sample size (more bits per sample)
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 ↑
Edit > Preferences > Quality
Set default sample rate and size
Set sample rate and size
Analog Digital
What other real world phenomena can we sample and input to a computer?
Summary
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