Backward adaptation for transform trellis coding of speech

Recently, Mazor and Pearlman[1] proved a source coding theorem for transform trellis codes. In this paper we apply their results to code speech using backward adaptation. Two spectral estimation techniques, called the moving average (MA) and autocorrelation (AR) techniques, are presented for estimating the spectrum from past and current blocks of speech for the purpose of constructing the trellis code for the next block of speech. Simulations are performed using both methods. The performance for the MA method is about 11 dB for a code of rate 1 bit/sample. For the AR method, the performance is about 12.5 dB for the same code rate. Tests are also performed on the effect of the trellis parameters on coding performance.