Codec structures for achieving two-stage prediction and two-stage noise
spectral shaping at the same time, resulting in a Two-Stage Noise
Feedback Coding (TSNFC) method. One approach combines two predictors into
a single composite predictor; and derives appropriate filters for use in
a conventional single-stage NFC codec structure. Another approach
duplicates a conventional single-stage NFC codec structure in a nested
manner, thereby decoupling the operations of the long-term prediction and
long-term noise spectral shaping from the operations of the short-term
prediction and short-term noise spectral shaping.