3rd IEEE Workshop on Signal Processing Advances in Wireless Communications (SPAWC 01), T'ao-yuan, Tayvan, 20 - 23 Mart 2001, ss.372-375
Efficient quantization of linear predictive coding (LPC) filter coefficients play an essential role in very low bit rate speech coding systems. This paper examines a new suboptimal matrix quantization scheme for LPC parameters, called multi stage matrix quantization (MSMQ), which operates at bit rates between 400 and 800 bits/s, With the new matrix quantization method, using a 22,5 ms LPC analysis frame, spectral distortion about 1 dB is achieved at 800 bits/s, In the proposed coder, line spectral frequency (LSF) parameters of multiple consecutive frames are grouped into a superframe and jointly quantized. The new residual LSF vector quantization scheme gives a bit rate reduction in MSMQ without any additional complexity or storage. The new MSMQ leads into several schemes of various computational complexity/storage characteristics.