The multimode transform predictive coding paradigm

Abstract

Presented is a new coding paradigm, multimode transform predictive coding (MTPC), which combines speech and audio coding principles in a single coding structure. The paradigm is an adaptive coding paradigm which automatically adjusts how different coding modules are used based on the input signal. This allows MTPC coders to robustly handle a wider range of signals than single configuration (mode) transform predictive coding (TPC) designs. A wideband MTPC coder design targeting two-way communication applications and bitrates from 13 to 40 kbit/s is also presented. Subjective absolute category rating test results on speech, speech in noise and music demonstrate that the performance at 16, 24 and 32 kbit/s meets or exceeds that of ITU-T Rec. G.722 at 48, 56 and 64 kbit/s respectively for many coding conditions. Subjective Reference-ABx (R-ABx) tests are also included to show the potential advantages of the multimode coder over a single mode TPC coder. Finally, possible improvements in the MTPC coder design for applications such as broadcasting, which are less sensitive to delay and encoder complexity, are discussed.