Showing papers on "Code-excited linear prediction published in 2017"

AMR Steganalysis Based on Second-Order Difference of Pitch Delay

Abstract: This paper presents a novel steganalysis scheme for the detection of adaptive multi-rate (AMR) audio steganography. AMR audio codec is used widely in mobile communication and mobile Internet system. Due to the modifiability of pitch delay, several AMR steganography schemes based on pitch delay modulation have emerged gradually and have high capacity and good imperceptibility. Based on the difference between cover and stego AMR audios on the continuity of adjacent pitch delay, this paper proposes the matrix of the second-order difference of pitch delay (MSDPD) steganalysis features by calculating the Markov transition probability MSDPD, and uses the calibration method to estimate the cover’s features to get the calibrated MSDPD features to improve the accuracy of the scheme. Support vector machine is used as the steganalyzer to test the performance of our proposed scheme. The experimental results show that the correct detection rate of our proposed method is more than 85% when the embedding bit rate is 30% or above, and can reach above 85% for cover audios. The results of contrast experiment show that the performance of our proposed method is better than the existing method, especially on low embedding rate. The method can be extended to other CELP codec, such as G.723.1 and G.729.

Characterization of endoglucanase from Paenibacillus sp. M33, a novel isolate from a freshwater swamp forest.

Abstract: The newly isolated Paenibacillus sp. M33 from freshwater swamp forest soil in Thailand demonstrated its potential as a cellulose degrader. One of its endoglucanase genes from Paenibacillus sp., celP, was cloned to study the molecular characteristics of its gene product. The celP gene was recognized firstly by degenerate primer designed from Paenibacillus endoglucanase gene, and subsequently identified flanking region by inverse PCR technique. The celP gene consists of an open reading frame of 1707 bp encoding for 569 amino acids including 33-amino acids signal sequence. CelP is a member of glycoside hydrolase family 5 appended with a family 46 carbohydrate-binding module. CelP from recombinant Escherichia coli was purified by affinity chromatography. SDS-PAGE analysis of purified CelP showed a protein band at about 60 kDa. The purified enzyme gave a specific CMCase activity of 0.03 μmol min-1 mg-1 . It had higher activities on lichenan (0.19 μmol min-1 mg-1 ) and barley β-glucan (0.14 μmol min-1 mg-1 ). Maximum activity on lichenan was obtained at 50 °C, pH 5.0. CelP was stable over a pH range of 3.0-10.0 and retained 80% activity when incubated at 50 °C for 1 h. The properties of its CelP endoglucanase, especially substrate specificity, will make it useful in various biotechnological applications including biomass hydrolysis.

Implementation of CELP encoder using Vivado HLS

Abstract: Eminent research scholars have confirmed the feasibility of CELP principle and its implementation which overcomes the hurdles of primitive algorithms like RELP, where in the residual signal information can't be reconstructed further, but which is possible in CELP implemented technique which produces good quality speech at low bit rates. This paper's central idea is the design and implementation of CELP encoder. This LPC technique achieves LP analysis of speech by extracting the LP parameters and coefficients and utilizes a scheme to search a codebook and compute the excitation signal. With the help of Vivado HLS we have implemented synthesizable set of codes and shown the report including timing, latency and hardware utilization.

Optimization of code excited linear prediction speech coder with PSVQ-genetic codebook

Abstract: The development of high quality speech coders at low bit rate and low delay is a challenging task in the field of speech communication, due to ever increasing users in wireless communication networks. CELP codec gives good quality at 4.8 kbps. By optimizing the excitation vectors in the codebook many changes in the performance can be observed to achieve toll quality speech. Codebook optimization can be achieved by improving the training process in the generation process and by using fast searching algorithms. Gaussian (X-means clustering), Fixed (PSVQ) and PSVQ-Genetic codebooks were generated to be included in CELP 4.8. Variations in performance were evaluated using objective and subjective quality measures. Experiments show that CELP 4.8 provides toll quality and reduced delay with PSVQ-Genetic codebook.

Securing compressed real-time audio codec based on iLBC and SM4

Abstract: The rapid development of computer network and communication technology facilitates the voice communication based on network. More and more voice data are generated and transmitted in day and day life in the fields like commercial, military, communication, where include sensitive information which should be protected. Our research concentrates on security & privacy and real-time. The research proposes a combination with iLBC soft coding technique and SM4 symmetric encryption algorithm which makes real-time voice secure communication system. The proposed scheme covers two parts, the first one is audio encryption and decryption based on SM4, while the second one is data embedding and extraction based on iLBC. The Internet Low Bit-rate Codec (iLBC) inherently has higher robustness to packet loss than most of the Code Exited Linear Prediction (CELP) codecs. SM4 (SMS4) algorithm is a block cipher used in the Chinese National Standard. The experiment shows combining voice compression algorithm and SM4 encryption algorithm, effectively reduce the data bandwidth needed in the process of transmission and the time needed for encryption. The result shows encrypted voice waveform distributes evenly and the decrypted voice has little distortion, which proves this scheme is suitable for confidentiality of the real-time voice communications.

Flexible and scalable transform-domain codebook for high bit rate CELP coders

Abstract: The Code-Excited Linear Prediction (CELP) model is very efficient in coding speech at low bit rates. However, if the bit rate of the coder is increased, the CELP model does not gain in quality as quickly as other approaches. Moreover, the computational complexity of the CELP model generally increases significantly at higher bit rates. In this paper we focus on a technique that aims to overcome these limitations by means of a special transform-domain codebook within the CELP model. We show by the example of the AMR-WB codec that the CELP model with the new flexible and scalable codebook improves the quality at high bit rates at no additional complexity cost.

Filtering and Denoising Analysis for Decoded Speech Signal of CELP Codec

Abstract: Efforts to eliminate the noise of CELP coding method have been made in order to get better aural effect. The emphasis of eliminating the noise is usually attached on CELP coders. However, this paper pays more attention to encoded speech by using power spectrum estimation and filtering analysis. In the experiments, the aural effect of encoded speech has been improved by the proposed method.

MATLAB based encoder designing of 5.90 kbps narrow-band AMR codec

Abstract: In the speech signal transmission, there is lot of difference between the bit rate requirement and information rate Many codec were designed for speech coding to decrease the bandwidth requirements This paper aims to provide a technical aspect for designing the encoder for 590 kbps Narrow-band AMR codec using MATLAB as simulation tool This paper describes a procedure for designing a speech production model that takes the samples of speech as input and generates the essential parameters from which the decoded speech can be obtained close to the original speech Beyond AMR, additional techniques supporting codec like AMR-WB and Enhanced Voice Service are working for 3G and 4G services respectively

Pre- and Postfiltering

Abstract: At low bitrates, basic CELP codecs have an easily recognisable distortion characteristic often described as noisiness or roughness. To reduce the perceptual distortion, we can try to identify and remove typical artefacts by filtering the decoded signal. In this chapter we present most typical postfiltering techniques such as formant enhancement and bass post filtering.

Speech signal decoding device and method for decoding speech signal

Abstract: A speech signal decoding device includes an adaptive code-book decoder, a fixed code-book decoder, a ratio calculator, a determination unit, and an attenuator. The adaptive code-book decoder generates an adaptive code-book vector using an adaptive code-book code of an encoded signal encoded by a CELP method. The fixed code-book decoder generates a fixed code-book vector using a fixed code-book code of the encoded signal. The ratio calculator calculates an amplitude ratio or an energy ratio between the adaptive code-book vector and the fixed code-book vector. The determination unit determines whether the amplitude ratio or the energy ratio exceeds a predetermined threshold. When the amplitude ratio or the energy ratio is determined to exceed the predetermined threshold, the attenuator attenuates an excitation signal that has been defined by adding the adaptive code-book vector to the fixed code-book vector.

A Wide Band Speech Coding Technique using Low Delay Code Excited Linear Predictive Algorithm (LD-CELP).

Abstract: A fair level of speech quality is desired in speech transmission for mobile voice services. The effective utilization of bandwidth and higher bit rate is must for a best quality speech coder. But at a time the both requirements are not fulfilled in desired format. The research is ongoing in the area of designing speech coder’s. In general the CELP is an algorithm to design a good quality speech coder. From 80’s to present the advancement in this technique is going on. In this paper a wide band speech coding technique is proposed using LD-CELP algorithm. The overall performance of LD-CELP (16Kbps) is summarized and computed on MATLAB version R2016a with parameters MSE and SNR. In conclusion we observe that SNR for LD-CELP is not much better and enhancement in this is necessary.