| 摘要 |
In a speech coding system with a speech encoder and a speech decoder cooperating with said speech encoder, the speech encoder comprises a pre-processor and an ADPCM (adaptive differential pulse code modulation) encoder with a quantizer and step-size adaptation means, while the speech decoder comprises an ADPCM decoder with similar step-size adaptation means as in the ADPCM encoder and a decoder, and a post-processor. The pre-processor is provided with phase-smearing filtering means to smooth the effect of high and/or rapid energy changes at the input of the quantizer, while the post-processor is provided with filtering means inverse to said phase-smearing filtering means. |
