A pitch-synchronous pitch-cycle modification method for designing a hybrid i-MELP/waveform-matching speech coder

In this paper, we introduce a new approach to solve encoding method switching problems in a parametric/waveformmatching hybrid coder. This method only requires modification of the waveform-matching coder’s target signal. For this purpose, we introduce a new pitch-synchronous cycle length modification method using the constant pitch transformation (CPT) and a frequency domain zero-phase equalization filter. An experimental I-MELP/PCM coder is used to explore the largest achievable quality improvement over a MELP coder. Test results show that encoding transitions with waveform-encoding techniques improves the quality over a fully parametric coder.