University of Kansas - ECE 101
Waveform Coding
Digitize speech
- Usually digitized at high rate
- Linear usually 128000 bits/second (16 bits per sample)
- Mu-law usually 64000 bits/second (8 bits per sample)
Mu-law
- perform nonlinear transformations on numbers
- 64 kb/s mu-law uses only 8 bits per sample
- "telephone quality speech"
ADPCM
- Adaptive delta pulse code modulation
- Used for speech at 32000 bits/second
- Tries to reduce bit rate by predicted future samples from past values
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