Limited error based event localizing temporal decomposition and its application to variable-rate speech coding
This paper proposes a novel algorithm for temporal decomposition (TD) of speech, called limited error based event localizing temporal decomposition (LEBEL-TD), and its application to variable-rate speech coding. In previous work with TD, TD analysis was usually performed on each speech segment of about 200300ms or more, making it impractical for online applications. In this present work, the event localization is determined based on a limited error criterion and a local optimization strategy, which results in an average algorithmic delay of 65ms. Simulation results show that an average log spectral distortion of about 1.5dB can be achievable at an event rate of 20events/s. Also, LEBEL-TD uses neither the computationally costly singular value decomposition routine nor the event refinement process, thus reducing significantly the computational cost of TD. Further, a method for variable-rate speech coding an average rate of around 1.8kbps based on STRAIGHT (Speech Transformation and Representation using Adaptive Interpolation of weiGHTed spectrum), which is a high-quality speech analysissynthesis framework, using LEBEL-TD is also realized. Subjective test results indicate that the performance of the proposed speech coding method is comparable to that of the 4.8kbps FS-1016 CELP coder.
temporal decomposition speech coding straight event vector event function line spectral frequency