Introduction to Digital Audio
Objectives <ul><li>Explain the difference between analog and digital signals </li></ul><ul><li>Identify audio sampling sta...
Analog vs. Digital Signals <ul><li>Analog – </li></ul><ul><li>A continuously recorded sine wave signal usually recorded on...
Analog vs. Digital Signals <ul><li>Digital – </li></ul><ul><li>A signal that samples specified portions of a signal result...
Audio Sampling Variables <ul><li>Three main criteria: </li></ul><ul><ul><li>How many samples? OR “sampling rate” </li></ul...
How Many Samples? Audio “Sampling Rates” <ul><li>Digital Video </li></ul><ul><li>CD Quality </li></ul><ul><li>Stereo </li>...
How Many Samples? Audio “Sampling Rates” <ul><li>Digital Video </li></ul><ul><ul><li>48,000 per sec </li></ul></ul><ul><ul...
How Many Samples? Audio “Sampling Rates” <ul><li>CD Quality  </li></ul><ul><ul><li>44,100 per sec </li></ul></ul><ul><ul><...
<ul><li>Other Sample Rates </li></ul>Typical Sample Rates: Sample Rate Less 8000 Quality Telephone 11000 AM Radio 16000 FM...
How Much Data per Sample? <ul><li>Common Sampling </li></ul><ul><li>“ Bit Depth”  </li></ul><ul><ul><li>8 bits of data </l...
How Many Channels Sampled? <ul><li>Number of Channels </li></ul><ul><ul><li>Stereo (2 channels) </li></ul></ul><ul><ul><li...
Audio Sampling Variables File Size Digital Audio Quality
<ul><li>Audio Sampling Variables </li></ul>Balance Sample Rate Bit Depth Number of Channels Record Settings Sound Quality ...
<ul><li>Audio Record Rate </li></ul>More Audio Samples Larger Audio Files
<ul><li>Audio File Size </li></ul>File size is determined by a combination of: Bit Depth Sample Rate No of Channels
<ul><li>Audio File Size </li></ul>File size is determined by a combination of: Length in Minutes Bit Depth Sample Rate No ...
<ul><li>Audio File Size </li></ul>Variables of concern: 8 bit or 16 bit  Various Sample Rates  Stereo or Mono Length in Mi...
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Digaudio

  1. 1. Introduction to Digital Audio
  2. 2. Objectives <ul><li>Explain the difference between analog and digital signals </li></ul><ul><li>Identify audio sampling standards </li></ul><ul><li>Describe audio sampling variables </li></ul><ul><li>Determine how variables affect file size and quality </li></ul>
  3. 3. Analog vs. Digital Signals <ul><li>Analog – </li></ul><ul><li>A continuously recorded sine wave signal usually recorded on a magnetic medium </li></ul>
  4. 4. Analog vs. Digital Signals <ul><li>Digital – </li></ul><ul><li>A signal that samples specified portions of a signal resulting in discrete digital information (i.e. bits of data) </li></ul>“ Sampled” discrete data
  5. 5. Audio Sampling Variables <ul><li>Three main criteria: </li></ul><ul><ul><li>How many samples? OR “sampling rate” </li></ul></ul><ul><ul><li>How much data per sample? OR “bit depth” </li></ul></ul><ul><ul><li>How many channels sampled? </li></ul></ul>
  6. 6. How Many Samples? Audio “Sampling Rates” <ul><li>Digital Video </li></ul><ul><li>CD Quality </li></ul><ul><li>Stereo </li></ul><ul><li>FM Radio </li></ul><ul><li>AM Radio </li></ul><ul><li>Telephone </li></ul>
  7. 7. How Many Samples? Audio “Sampling Rates” <ul><li>Digital Video </li></ul><ul><ul><li>48,000 per sec </li></ul></ul><ul><ul><li>32,000 per sec </li></ul></ul>
  8. 8. How Many Samples? Audio “Sampling Rates” <ul><li>CD Quality </li></ul><ul><ul><li>44,100 per sec </li></ul></ul><ul><ul><li>Left & Right </li></ul></ul><ul><ul><li>Channels Combined </li></ul></ul>
  9. 9. <ul><li>Other Sample Rates </li></ul>Typical Sample Rates: Sample Rate Less 8000 Quality Telephone 11000 AM Radio 16000 FM Radio 22050 per Stereo
  10. 10. How Much Data per Sample? <ul><li>Common Sampling </li></ul><ul><li>“ Bit Depth” </li></ul><ul><ul><li>8 bits of data </li></ul></ul><ul><ul><li>per sample </li></ul></ul><ul><ul><li>16 bits of data </li></ul></ul><ul><ul><li>per sample </li></ul></ul>
  11. 11. How Many Channels Sampled? <ul><li>Number of Channels </li></ul><ul><ul><li>Stereo (2 channels) </li></ul></ul><ul><ul><li>Mono (1 channel) </li></ul></ul><ul><ul><li>Multiple tracks </li></ul></ul>
  12. 12. Audio Sampling Variables File Size Digital Audio Quality
  13. 13. <ul><li>Audio Sampling Variables </li></ul>Balance Sample Rate Bit Depth Number of Channels Record Settings Sound Quality File Size
  14. 14. <ul><li>Audio Record Rate </li></ul>More Audio Samples Larger Audio Files
  15. 15. <ul><li>Audio File Size </li></ul>File size is determined by a combination of: Bit Depth Sample Rate No of Channels
  16. 16. <ul><li>Audio File Size </li></ul>File size is determined by a combination of: Length in Minutes Bit Depth Sample Rate No of Channels
  17. 17. <ul><li>Audio File Size </li></ul>Variables of concern: 8 bit or 16 bit Various Sample Rates Stereo or Mono Length in Minutes

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