This letter presents two improvements on 2.4 kb/s Mixed-Excitation Linear Prediction (MELP) vocoder. The one is a new parameter Redzc named energy to differential zerocrossing rate which is used in adaptation of V/UV ...This letter presents two improvements on 2.4 kb/s Mixed-Excitation Linear Prediction (MELP) vocoder. The one is a new parameter Redzc named energy to differential zerocrossing rate which is used in adaptation of V/UV decision of transitional segments and low energy level speech segments. The other is a multi-path searching method for Multi-Stage Vector Quantization (MSVQ) of line spectral frequency. Subjective tests show that the intelligiblity and naturallity of improved MELP vocoder are preferable to those of the original one.展开更多
To make speech watermarking achieve both copyright protection and integrity verification, a novel multipurpose speech watermarking algorithm based on the multistage vector quantization （MSVQ） of linear prediction co...To make speech watermarking achieve both copyright protection and integrity verification, a novel multipurpose speech watermarking algorithm based on the multistage vector quantization （MSVQ） of linear prediction coefficients （LPCs） is presented in this article. The property of natural speech that the vector quantization （VQ） indices of the LPCs amongst neighboring frames tend to be very similar is utilized to embed the robust watermark in the indices of the first-stage VQ（VQ1）. Then, the semi-fragile watermark is embedded in the indices of the second-stage VQ（VQ2） with index constrained VQ encoding scheme. Both the robust watermark and the semi-fragile watermark can be extracted without host speech. Simulation results verify the effectiveness of the proposed algorithm in terms of robustness and semi-fragility.展开更多
文摘This letter presents two improvements on 2.4 kb/s Mixed-Excitation Linear Prediction (MELP) vocoder. The one is a new parameter Redzc named energy to differential zerocrossing rate which is used in adaptation of V/UV decision of transitional segments and low energy level speech segments. The other is a multi-path searching method for Multi-Stage Vector Quantization (MSVQ) of line spectral frequency. Subjective tests show that the intelligiblity and naturallity of improved MELP vocoder are preferable to those of the original one.
文摘To make speech watermarking achieve both copyright protection and integrity verification, a novel multipurpose speech watermarking algorithm based on the multistage vector quantization （MSVQ） of linear prediction coefficients （LPCs） is presented in this article. The property of natural speech that the vector quantization （VQ） indices of the LPCs amongst neighboring frames tend to be very similar is utilized to embed the robust watermark in the indices of the first-stage VQ（VQ1）. Then, the semi-fragile watermark is embedded in the indices of the second-stage VQ（VQ2） with index constrained VQ encoding scheme. Both the robust watermark and the semi-fragile watermark can be extracted without host speech. Simulation results verify the effectiveness of the proposed algorithm in terms of robustness and semi-fragility.
