Showing papers on "Code-excited linear prediction published in 2020"

Speech Information Hiding by Modification of LSF Quantization Index in CELP Codec

Abstract: A prospective method for securing digital speech communication is by hiding the information within the speech. Most of the speech information hiding methods proposed in prior research are lacking in robustness when dealing with the encoding process (e.g. the code-excited linear prediction (CELP) codec). The CELP codecs provide a codebook that represents the encoded signal at a lower bit rate. As essential features in speech coding, line spectral frequencies (LSFs) are generally included in the codebook. Consequently, LSFs are considered as a prospective medium for information hiding that is robust against CELP codecs. In this paper, we propose a speech information hiding method that modifies the least significant bit of the LSF quantization obtained by a CELP codec. We investigated the feasibility of our proposed method by objective evaluation in terms of detection accuracy and inaudibility. The evaluation results confirmed the reliability of our proposed method with some further potential improvement (multiple embedding and varying segmentation lengths). The results also showed that our proposed method is robust against several signal processing operations, such as resampling, adding Gaussian noise, and several CELP codecs (i.e., the Federation Standard-1016 CELP, G.711, and G.726).

Method and device for efficiently distributing a bit-budget in a celp codec

Abstract: A method and device allocates a bit-budget to a plurality of first parts of a CELP core module of (a) an encoder for encoding a sound signal or (b) a decoder for decoding the sound signal. In the method and device, bit-budget allocation tables assign, for each of a plurality of intermediate bit rates, respective bit-budgets to the first CELP core module parts. A CELP core module bit rate is determined and one of the intermediate bit rates is selected based on the determined CELP core module bit rate. The respective bit-budgets assigned by the bit-budget allocation tables for the selected intermediate bit rate are allocated to the first CELP core module parts.

Withdrawal Notice: CELP-IR: Caching Efficiency with Location Prediction based Invalidation and Replacement Policy

Abstract: The article has been withdrawn at the request of the editor of the journal International Journal of Sensors, Wireless Communications and Control Bentham Science apologizes to the readers of the journal for any inconvenience this may have caused. The Bentham Editorial Policy on Article Withdrawal can be found at https://benthamscience.com/editorial-policies-main.php. BENTHAM SCIENCE DISCLAIMER: It is a condition of publication that manuscripts submitted to this journal have not been published and will not be simultaneously submitted or published elsewhere. Furthermore, any data, illustration, structure or table that has been published elsewhere must be reported, and copyright permission for reproduction must be obtained. Plagiarism is strictly forbidden, and by submitting the article for publication the authors agree that the publishers have the legal right to take appropriate action against the authors, if plagiarism or fabricated information is discovered. By submitting a manuscript the authors agree that the copyright of their article is transferred to the publishers if and when the article is accepted for publication.

Quality Enhancement of Low Bit Rate Speech Coder with Nonlinear Prediction

Abstract: Toll quality speech codec design with a low bit rate is really a challenging task in modern communication because of the drastic increase in end-users in social networks. Most of the low bit rate speech codecs are based on linear prediction. The code-excited linear prediction codec (CELP) gives good quality decoded speech at a lower bit rate of 4.8 Kbps. But, it neglects the natural nonlinear effects present in speech production process. So, some adaptive techniques are to be used to make the system nonlinear to perform better than linear prediction speech codecs. An adaptive technique with nonlinear prediction of speech, based on truncated Volterra series, is used to generate the nonlinear prediction coefficients. The generated nonlinear prediction coefficients are implemented in G723.1 CELP codec to introduce code-excited nonlinear prediction (CENLP) codec. Advancements in the performance are evaluated using subjective and objective quality measures and compared with the normal G723.1 CELP codec.

Stage Audio Classifier Using Artificial Neural Network

Abstract: Perceptual quality of audio signals at the receiver and transmission data rate are the major concerns for the speech codec developers. But both these parameters are inversely proportional in general. In the era of 4G, 3GPP launched Enhanced Voice Services (EVS) codec which can operate in multiple data rates with a six-stage speech classifier using threshold-based GMM statistical model. In this work, we propose a seven-stage audio classifier for voiced, unvoiced, transition, multi-speaker, silence, background noise and music signals using neural network by employing Levenberg Marquardt (LM) algorithm. In comparison with conventional statistical approach that requires determination of manual thresholds, the neural network method can simplify the categorization process especially while using a large number of parameters. The categorization is done by using extracted seven features that constitute to a 32-dimensional vector. TIMIT and NOIZEUS databases are used to generate the dataset and a classification accuracy of 94% is obtained. As the network model can perform efficiently using lesser number of neurons, the complexity is also less.

Method and Device for Allocating a Bit-Budget Between Sub-Frames in a CELP CODEC

Abstract: A method and device for allocating a bit-budget to a plurality of first parts and to a second part of a CELP core module of (a) an encoder for encoding a sound signal or (b) a decoder for decoding the sound signal. In a frame of the sound signal comprising sub-frames, respective bit-budgets are allocated to the first CELP core module parts and a bit-budget remaining after allocating to the first CELP core module parts their respective bit-budgets is allocated to the second CELP core module part. According to an alternative, the second CELP core module part bit-budget is distributed between the sub-frames of the frame and a larger bit-budget is allocated to at least one of the sub-frames of the frame. The at least one sub-frame may be the first sub-frame of the frame, at least one sub-frame following the first sub-frame, or the sub-frame using a glottal-impulse-shape codebook.

Low Delay Sparse and Mixed Excitation CELP Coders for Wideband Speech Coding

Abstract: Code Excited Linear Prediction (CELP) algorithms are proposed for compression of speech in 8 kHz band at switched or variable bit rate and algorithmic delay not exceeding 2 msec. Two structures of Low-Delay CELP coders are analyzed: Low-delay sparse excitation and mixed excitation CELP. Sparse excitation is based on MP-MLQ and multilayer models. Mixed excitation CELP algorithm stems from the narrowband G.728 standard. As opposed to G.728 LD-CELP coder, mixed excitation codebook consists of pseudorandom vectors and sequences obtained with Long-Term Prediction (LTP). Variable rate coding consists in maximizing vector dimension while keeping the required speech quality. Good speech quality (MOS=3.9 according to PESQ algorithm) is obtained at average bit rate 33.5 kbit/sec.