Low bit rate coding using an interpolated zinc excitation model

摘要

Prototype excitation vocoding has been of particular interest,nparticularly at bit rates below 4 kbits/sec where conventional analysisnby synthesis (AbS) LPC based coders fail to deliver the speech qualitynrequired in a number of new voice communication applications andnservices. The present authors propose a new time domain, interpolatednzinc function prototype excitation technique (IZFPE) for communicationsnquality speech at about 2.0 kb/s. In this method a prototype pitchnsegment is selected every 20 ms. Each prototype segment is then modellednby a zinc orthogonal function which is derived by employing a closednloop AbS procedure (ZFE-AbS). Successive prototype zinc excitations arenthen interpolated such that the characteristics of the resultingnexcitation signal evolve slowly with time