Speech coding: Difference between revisions

Revision as of 21:52, 26 November 2004

Revision as of 04:52, 10 January 2005

Line 13:

The most common speech coding scheme is Code-Excited Linear Predictive (CELP) coding, which is used for example in the [[GSM]] standard. In CELP, the modelling is divided in two stages, a [[linear prediction|linear predictive]] stage that models the spectral envelope and code-book based model of the residual of the linear predictive model.

In addition to the actual speech coding of the signal, it is often necessary to use [[channel coding]] for transmission, to avoid losses due to transmission errors. Usually, speech coding and channel coding methods have to be chosen in pairs, with the more important bits in the speech data stream protected by more robust channel coding, in order to get the best overaloverall coding results.

The [[Speex]] project is an attempt to create a [[free software]] speech coder, unemcumbered by patent restrictions.