Introduction Introduction to to Digital Audio Digital Audio
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Introduction toIntroduction toDigital AudioDigital Audio
ObjectivesObjectivesExplain the difference between analog and digital signals
Identify audio sampling standards
Describe audio sampling variables
Determine how variables affect file size and quality
Analog vs. Digital Analog vs. Digital SignalsSignals
Analog –A continuously recorded sine wave signal usually recorded on a magnetic medium
Analog vs. Digital Analog vs. Digital SignalsSignals
Digital –A signal that samples specified portions of a signal resulting in discrete digital information (i.e. bits of data)
“Sampled” discretedata
Audio Sampling Audio Sampling VariablesVariables
Three main criteria:How many samples? OR “sampling rate”How much data per sample? OR “bit depth”How many channels sampled?
How Many Samples?How Many Samples?Audio “Sampling Rates”Audio “Sampling Rates”
Digital VideoCD QualityStereoFM RadioAM RadioTelephone
How Many Samples?How Many Samples?Audio “Sampling Rates”Audio “Sampling Rates”
Digital Video48,000 per sec
32,000 per sec
How Many Samples?How Many Samples?Audio “Sampling Rates”Audio “Sampling Rates”
CD Quality 44,100 per sec
Left & Right
Channels Combined
Other Sample RatesOther Sample RatesTypical Sample Rates:
Sample Rate
Less 8000
Quality
Telephone
11000 AM Radio
16000 FM Radio
22050 per Stereo
How Much DataHow Much Dataper Sample?per Sample?
Common Sampling “Bit Depth”
8 bits of dataper sample16 bits of dataper sample
How Many Channels How Many Channels Sampled?Sampled?
Number of ChannelsStereo (2 channels)
Mono (1 channel)
Multiple tracks
Audio Sampling Audio Sampling VariablesVariables
File Size
Quality
Audio Sampling VariablesAudio Sampling Variables
RecordSetting
s
SoundQuality
FileSize
Balance
Sample RateBit DepthNumber of Channels
Audio Record RateAudio Record Rate
MoreAudio
Samples
LargerAudioFiles
Audio File SizeAudio File Size
Bit Depth
Sample Rate
No of Channels
File size is determined bya combination of:
Audio File SizeAudio File SizeFile size is determined bya combination of:
Bit Depth
Sample Rate
No of Channels
Length in MinutesLength in Minutes
Audio File SizeAudio File Size
8 bit or 16 bit
Various Sample Rates
Stereo or Mono
Variables of concern:
Length in Minutes