Title :
New directions in subband coding
Author :
Cox, Richard V. ; Gay, Steven L. ; Shoham, Yair ; Quackenbush, Schuyler R. ; Seshadri, Nambirajan ; Jayant, N.S.
Author_Institution :
AT&T Bell Labs., Murray Hill, NJ, USA
fDate :
2/1/1988 12:00:00 AM
Abstract :
Two very different subband coders are described. The first is a modified dynamic bit-allocation-subband coder (D-SBC) designed for variable rate coding situations and easily adaptable to noisy channel environments. It can operate at rates as low as 12 kb/s and still give good quality speech. The second coder is a 16-kb/s waveform coder, based on a combination of subband coding and vector quantization (VQ-SBC). The key feature of this coder is its short coding delay, which makes it suitable for real-time communication networks. The speech quality of both coders has been enhanced by adaptive postfiltering. The coders have been implemented on a single AT&T DSP32 signal processor
Keywords :
digital filters; encoding; filtering and prediction theory; noise; speech analysis and processing; vocoders; voice equipment; AT&T DSP32 signal processor; adaptive postfiltering; coding delay; modified dynamic bit-allocation-subband coder; noisy channel environments; real-time communication networks; speech quality; subband coding; vector quantization; waveform coder; Bit rate; Communication networks; Communication system control; Delay; Noise generators; Noise shaping; Protection; Speech coding; Vector quantization; Working environment noise;
Journal_Title :
Selected Areas in Communications, IEEE Journal on
