1. Introduction to Digital Audio

2. Objectives Explain the difference between analog and digital signals
Identify audio sampling standards
Describe audio sampling variables
Determine how variables affect file size and quality

3. Analog vs. Digital Signals
A continuously recorded sine wave signal usually recorded on a magnetic medium

4. Analog vs. Digital Signals
A signal that samples specified portions of a signal resulting in discrete digital information (i.e. bits of data)
“Sampled” discrete
data

5. Audio Sampling Variables
Three main criteria:
How many samples? OR “sampling rate”
How much data per sample? OR “bit depth”
How many channels sampled?

6. How Many Samples? Audio “Sampling Rates”
Digital Video
CD Quality
Stereo
FM Radio
AM Radio
Telephone

7. How Many Samples? Audio “Sampling Rates”
Digital Video
48,000 per sec
32,000 per sec

8. How Many Samples? Audio “Sampling Rates”
CD Quality
44,100 per sec
Left & Right
Channels Combined

9. Other Sample Rates Typical Sample Rates: Sample Rate Less 8000 Quality
Telephone
11000
AM Radio
16000
FM Radio
22050 per
Stereo

10. How Much Data per Sample?
Common Sampling
“Bit Depth”
8 bits of data
per sample
16 bits of data

11. How Many Channels Sampled?
Number of Channels
Stereo (2 channels)
Mono (1 channel)
Multiple tracks

12. Audio Sampling Variables
Quality
File Size
Digital Audio

13. Audio Sampling Variables
Sample Rate
Bit Depth
Number of Channels
Record
Settings
Sound
Quality
File
Size
Balance

14. Audio Record Rate
More
Audio
Samples
Larger
Files

15. Audio File Size File size is determined by a combination of:
Bit Depth
Sample Rate
No of Channels

16. Audio File Size File size is determined by a combination of:
Sample Rate
Bit Depth
No of Channels
Length in Minutes

17. Audio File Size Variables of concern: Various Sample Rates
8 bit or 16 bit
Various Sample Rates
Stereo or Mono
Length in Minutes

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