next up previous contents
Next: Audio demonstration Up: Speech coding Previous: Backwards adaptation

CELP coders

Code Excited Linear Prediction (CELP) coders are state-of-the-art in telephony coding:

The theory says that after all the linear correlations have been removed, the prediction residual is uncorrelated values with a Gaussian distribution. Therefore generate the excitation codebook as a set of random numbers.

Complete system looks like figure 48:

  figure1554
Figure 48: Typical CELP coder

Where all parameters of the system are obtained by minimising the final mean squared error. Sequential parameter estimation is non-optimal.



Speech Vision Robotics group/Tony Robinson