Variable-bitrate Speech Coding using Time Scale Modification

We propose a novel procedure for variable rate coding of a speech signal using time scale modification (TSM) technique. Art-of-state TSM method of waveform similarity overlap add (WSOLA) is modified and appended into speech codec, such as AMR and SELP to form a variable-bitrate vocoder. This method outperforms the classic way to design variable bitrate vocoder for its convenience to design and realize which do not need extra cost to redesign quantization codebook and other time-wasting structure and parameters. Testing of implementing TSM algorithm into AMR and SELP show that with TSM as appendant, we could easily get variable bitrate vocoder with perceptually slight distortion