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In harsh channel conditions, the quality of the synthetic speech at low bit rate would be affected severely. In order to improve the robustness of the vocoder and make it more resilient to errors in random channel, unequal error protection (UEP) channel coding is usually adopted. However, when the errors cannot be corrected in some cases, UEP channel coding will not improve the quality of the synthetic...
This paper presents a new embedding strategy to extend the performance bound of spread spectrum (SS) based watermarking by introducing more imperceptible distortions measured in the mean square errors (MSE). The potential of the host is sufficiently exploited and utilized to maximize the watermark robustness. This strategy is then realized in audio watermarking by adaptively inverting the host according...
In order to improve the channel bandwidth utilization of voice communication, a variable bit rate speech coding algorithm based on enhanced mixed excitation linear prediction (MELPe) is proposed in the paper. In voice communication, only about 40% of the time is occupied by talking, whereas the rest is engaged by silence or background noise. In addition, unvoiced frame usually requires less transmission...
This paper presents a speech protection system based on adaptive masking. The system can adaptively adjust the masking noise volume according to the Speech Intelligibility Index (SII) proposed in ANSI S3.5-1997. The volume of the masking noise is minimized by limiting SII to a low level at which the speech to be protected can not be understood. This method can effectively reduce excess masking noise...
With rapid development of information technology and upgrading of intelligent terminals, two-dimensional barcode has been widely used as a carrier to store, transfer and retrieve information. Due to the limited capacity, current two-dimensional barcodes are designed to embed text-only messages. In this paper, a generation method for acoustic two-dimensional barcode is proposed. It is based on speech...
In the underwater communication, satellite communication, secure communication and other channels, the channel bandwidth is narrow and the channel condition is relatively poor. Therefore, higher quality and lower rate speech coding is needed. In order to improve the synthetic speech quality and save channel bandwidth, voice activity detection (VAD) technique is introduced to Mixed Excitation Linear...
Low bit rate speech coding is important to speech communications over band-limited or harsh channels. In this paper, based on the mixed excitation linear prediction (MELP) model, we propose a high-quality 400bps low bit rate speech coding algorithm which introduces multi-frame joint vector quantization, adaptive spectral enhancement and multi-band sinusoidal mixed excitation. Efficient parameter quantization...
With the rapid development of communication technology, there is an urgent need for high quality speech coding algorithm at very low bit rate. In the paper, based on the Mixed Excitation Linear Prediction (MELP) and unequal error channel coding, a low bit rate speech coding algorithm is proposed. According to the different importance for each parameter, the relatively significant code stream information...
Masking the speech signal by using noise is an effective method to protect speech privacy. Speech-like noise has a better masking effect than other natural or artificial noise signals. In this paper, we propose a random probability method to generate speech-like noise. The method generates random text according to a random number and the probability table of Chinese language, and then inputs the text...
To obtain high quality synthetic speech at 2400 bps, this paper presents a vocoder based on the Mixed Excitation Linear Prediction (MELP) model. The differences of the vocoder parameters are analyzed, and an unequal error protection channel coding and a parameter substitution method for error frame are proposed to improve the robustness over random error channel. Several channel coding schemes are...
Code phase shift keying (CPSK) is an efficient M-ary modulation that can be applied to spread spectrum (SS) based watermarking to improve the watermark payload. However, the host media acts as interference that degrades the watermark robustness, especially in high-payload applications. In this paper, an informed embedding method for CPSK-based watermarking is proposed. The host is utilized at the...
This paper presents a robust audio watermarking scheme based on spread spectrum in frequency domain using constant amplitude zero autocorrelation (CAZAC) sequence. First, the watermark bits are modulated by using M-ary phase shift keying (PSK), and then the modulated symbols are spread in phase by using the CAZAC sequence. At the extractor, the embedded information is recovered by despreading the...
This paper presents an informed embedding method for code division multiple access (CDMA) based robust watermarking. First, a generalized model for CDMA-based watermarking with informed embedding is described, taking into account more detailed host information and possible pre-processing operations on the watermark at both the embedder and the extractor. Then, as special cases of this model, several...
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