In voice coding applications where there is no constraint on the encoding delay, segment coding techniques can be used to achieve a reduction in data rate. For low data rate linear predictive coding schemes, increasing the encoding delay allows one to exploit any long term temporal stationarities on an interframe basis, thus reducing the transmission bandwidth or storage needs of the speech sig...

Speech and audio codecs model the overall shape of the signal spectrum using envelope models. In speech coding the predominant approach is linear predictive coding, which offers high coding efficiency at the cost of computational complexity and a rigid systems design. Audio codecs are usually based on scale factor bands, whose calculation and coding is simple, but whose coding efficiency is low...

Linear predictive coding (LPC) is a widely used technique in audio signal processing, especially in speech signal processing. It has found particular use in voice signal compression, allowing for very high compression rates. As widely adopted as it is, LPC is covered in many textbooks and is taught in most advanced audio signal processing courses. So why another article on LPC? Despite covering...

This paper describes a real-time implementation of a multirate (2.4, 4.8, 8 and 16 Kbit/sec) speech codec designed to fulfil the requirements of the telecommunication sub-system for HERMES spacecraft. Considering these requirements, our choice tumed to the Multi-Pulse Excited Linear Predictive Coding (MPLPC) approach (except for the 2.4 Kbit/sec emergency rate which is based on the standard LPC...

This paper presents a novel method for estimating a vocal-tract spectrum from speech signals, based on a modeling of excitation signals of voiced speech. A formulation of linear prediction coding with impulse train is derived and applied to the phaseequalized speech signals, which are converted from the original speech signals by phase equalization. Preliminary results show that the proposed me...

An improved genetic programming is proposed in this paper to construct the nonlinear models of speech signals, and the speech coding is further accomplished. After the preprocessing of the speech signals, the improved GP is used to construct the corresponding model of each speech frame. Then by analyzing these models, a normalized model that has generalization ability is obtained. And finally t...

Line spectral frequencies (LSF) are widely used in the field of speech coding. Due to its properties, the LSF are qualified for the quantisation and the efficient compression of speech signals. In this paper we introduce the line cepstral quefrencies (LCQ). They are derived from the cepstrum in the same manner as the LSF are derived from linear predictive coding (LPC) features. We show that the...

The human voice is the most difficul t musical instrument to simulate convincingly. Yet a great deal of progress has been made in voice coding, the parameterization and re-synthesis of a source signal according to an assumed voice model. Source-filter models of the human voice, particularly Linear Predictive Coding (LPC), are the basis of most low-bitrate (speech) coding techniques in use today...

The IETF recently standardized the Opus codec as RFC6716. Opus targets a wide range of real-time Internet applications by combining a linear prediction coder with a transform coder. We describe the transform coder, with particular attention to the psychoacoustic knowledge built into the format. The result out-performs existing audio codecs that do not operate under real-time constraints.