Adaptive differential coding and decoding device

Abstract

Abstract PURPOSE:To apply coding with high quality to a period of leading by expanding rapidly the quantization step width of both the coder and decoder with respect to a sudden change in an input signal such as a voice signal rising from no- sound period. CONSTITUTION:The leading part of voice is detected by monitoring a local decoding signal Yj and a reproduced prediction error signal Eqj in receiving a signal Xj having a part changing suddenly such as a leading of voice from a no-sound period. A coefficient used to revise the quantization step width is switched to a special quantization step width revision coefficient to expand steeply the quantization step DELTAj in the leading of voice to correct adaptively the quantization step width. Thus, the coefficient in the inside of prediction devices 8a, 8b is revised to reduce the time required to optimize the signal after leading thereby improving the S/N at the leading of the output signal Xj from the no-sound period.

Inventors

• 👤 Masahiro Iwadare

Bibliographic Details