Variable code rate encoder and decoder based on amr-nb speech signal and its encoding and decoding method

Abstract

The invention discloses a variable-bit-rate encoder based on AMR (adaptive multi-rate)-NB (narrow band) voice signals. The variable-bit-rate encoder comprises a preprocessing unit, a voice frame quality judging unit, an encoding mode selecting unit, a bit rate determining unit and a code-excited linear predictive encoding unit, wherein the preprocessing unit is used for numeralization of voice signals to form voice frames; the voice frame quality judging unit is used for judging quality grades of the current voice frames to provide respective encoding modes and target bit rates for the voice frames; the encoding mode selecting unit is used for selecting the voice frame encoding modes according to the quality grades; the bit rate determining unit is used for determining the target bit rates of the voice frames according to the encoding modes; the code-excited linear predictive encoding unit is used for encoding the voice frames according to the target bit rates of the voice frames to form encoded voice frames. The invention further discloses a variable-bit-rate decoder used correspondingly to the encoder, and discloses a variable-bit-rate encoding method and a variable-bit-rate decoding method. The variable-bit-rate encoder is lower in bit rate than AMR, capable of achieving variable bit rates according to voice frame content and capable of selecting required encoding bit rate modes according to voice frame content importance judgment by setting channel voice quality.

Description

technical field [0001] The present invention relates to the field of communications, in particular to a variable code rate encoder based on AMR-NB voice signals in mobile Internet communication voice technology; the present invention also relates to an AMR-NB-based A variable code rate decoder for speech signals, a variable code rate encoding method based on AMR-NB speech signals, and a variable code rate decoding method based on AMR-NB speech signals. Background technique [0002] In various application fields such as voice over the mobile Internet, there is an increasing demand for digital narrowband speech coding techniques with good balance between subjective quality and bit rate and high efficiency. The subjective quality level is usually dictated by the bitrate specified for the encoded speech portion of the input stream. A higher bit rate generally indicates that a greater amount of information about the original speech is encoded and preserved, and thus a more accur...

AI Technical Summary

Problems solved by technology

[0007] Although the standard AMR speech codec method has been put into use, it can only select the encoding bit rate through the transformation of the channel environment, and cannot select the encoding bit rate according to the content of the speech frame itself. In the unchanged channel, Using a unified code rate encoding method will increase redundant bits, and the encoding rate mode 4.75kbit / s is not enough for practical applications

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