A 4 kbit/s renewal code excited linear prediction speech coder
نویسندگان
چکیده
This paper proposes a new 4 kbit/s speech coder based on CELP structure with 45 ms total codec delay. The coder is mainly featured by the renewal codebook of the excitation signal and the linked split-vector quantizer of LSPs which enable the coder to get high quality speech at low bit rate. In addition, techniques of the formant enhancement in spectral envelop and the harmonic recovery in transient region are also introduced to reduce buzzy and hoarse sounds, respectively. From the intensive listening test with intermediated response system (IRS) speech, we obtained the comparable subjective quality to 32 kbit/s ADPCM (ITU Recommendation G.726) under nominal speech input level of -26 dB overload.
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