Code-Excited Linear Preduction(CELP)

CELP -- a voice compression technology.
- 4.8kbps or 2kbps
- 2 time-varying linear recursive filter
* long-delay with 3 coeff, determined by minimizing the mean-squared prediction error after pitch prediction over a 5ms
* short delay with 16 coeff, determined using weighted stabilized covariance method of LPC analysis once every 10ms
- Instantaneous quantizer deteriorate at bitrate below 10kbps, cannot carry digital speech over a single analog voice channel
- 8kHz, 5ms duration for each block, each block consis of 40 samples from one of 1024 possible innoviation sequeunces
- coding scheme: code-book, tree and trelis