Audio signal processing

About: Audio signal processing is a research topic. Over the lifetime, 21463 publications have been published within this topic receiving 319597 citations. The topic is also known as: audio processing & Acoustic signal processing.

Apparatus for processing an audio signal and method thereof

Abstract: An apparatus for processing an audio signal and method thereof are disclosed. The present invention includes receiving a spectral data of lower band and type information indicating a particular band extension scheme for a current frame of the audio signal from among a plurality of band extension schemes including a first band extension scheme and a second band extension scheme, by an audio processing apparatus; when the type information indicates the first band extension scheme for the current frame, generating a spectral data of higher band in the current frame using the spectral data of lower band by performing the first band extension scheme; and when the type information indicates the second band extension scheme for the current frame, generating the spectral data of higher band in the current frame using the spectral data of lower band by performing the second band extension scheme, wherein the first band extension scheme is based on a first data area of the spectral data of lower band, and wherein the second band extension scheme is based on a second data area of the spectral data of lower band.

Recording and reproducing apparatus with limited digital copying

Abstract: A composite digital signal received by a recording and reproducing apparatus includes a digital information signal and a control signal. The control signal represents a number of digital copy generation of the associated information signal. The information signal of the received digital composite signal is recorded into recording medium. The information signal is reproduced from the recording medium. During the reproduction of the information signal, a new control signal is generated which represents a number equal to one plus the number represented by the control signal of the received composite digital signal. The new control signal and the reproduced information signal are combined into a new composite digital signal. The new composite digital signal is outputted. A check is made as to whether or not the number represented by the control signal of the received composite digital signal is equal to a predetermined number. When the number represented by the control signal of the received composite digital signal is equal to the predetermined number, the recording of the information signal of the received composite digital signal is inhibited.

Acoustic Echo Cancellation for Surround Sound using Perceptually Motivated Convergence Enhancement

Abstract: Acoustic echo cancellation (AEC) has become an essential and well-known enabling technology for hands-free communication and human-machine interfaces. AEC for two or more reproduction channels aims at identifying the echo paths between the microphone and each audio reproduction source in order to cancel the associated echo contribution. A number of preprocessing methods have been proposed to decorrelate stereo audio signals in order to enable an unambiguous identification of each echo path and to thus ensure robustness to changing sound source locations. While several of these methods provide enough decorrelation to achieve proper AEC convergence in the stereo case, considerations of subjective sound quality have frequently not been addressed adequately. This paper compares the performance of several methods in terms of both convergence speed and aspects of sound perception, and proposes a novel signal decorrelation approach with attractive properties. The superior performance of the proposed method is demonstrated for 5.1 surround sound reproduction.

Maximum likelihood approach for blind audio source separation using time-frequency Gaussian source models

Abstract: In this paper we propose a simple time-frequency Gaussian model of audio signals that allows for separation of possibly underdetermined and noisy linear instantaneous mixtures. An efficient EM algorithm is proposed to estimate the mixing matrix, the noise covariance and covariances of the source t-f coefficients over a chosen frame/subband tiling of the time-frequency domain. Results are given on 4 /spl times/ 4 and 3 /spl times/ 4 noisy mixtures of audio sources.

Multimedia switching apparatus

Abstract: A multimedia switching apparatus is described for switching multimedia signals comprising audio and video signals received from a public telecommunications network (3) to distribute the multimedia signals automatically. The gateway (12) receives the multimedia signals and generates a separate audio and video signal output. The audio signal is switched by an audio switch (4) to a destination under the control of an automatic call distribution arrangement (6) to automatically control the switching of the audio signal. A separate video switch (13) is provided for switching the video signal to a destination logically associated with the destination of the audio signal. The video switch (13) is controlled by monitoring the events in the audio switch to control the switching of the video signal so that it is switched to the logically associated destination. The switching operations of the audio switch are copied by the video switch (13).