An audio encoder implements multi-channel coding decision, band truncation, multi-channel rematrixing, and header reduction techniques to improve quality and coding efficiency. In the multi-channel coding decision technique, the audio encoder dynamically selects between joint and independent coding of a multi-channel audio signal via an open-loop decision based upon (a) energy separation between the coding channels, and (b) the disparity between excitation patterns of the separate input channels. In the band truncation technique, the audio encoder performs open-loop band truncation at a cut-off frequency based on a target perceptual quality measure. In multi-channel rematrixing technique, the audio encoder suppresses certain coefficients of a difference channel by scaling according to a scale factor, which is based on current average levels of perceptual quality, current rate control buffer fullness, coding mode, and the amount of channel separation in the source. In the header reduction technique, the audio encoder selectively modifies the quantization step size of zeroed quantization bands so as to encode in fewer frame header bits.

Quality improvement techniques in an audio encoder

The invention relates to a method for picking up sound comprising the following steps providing at least two essentially omnidirectional microphones ( 1 a, 1 b, 1 c ) or membranes ( 9 a, 9 b ) which have a mutual distance (d) shorter than a typical wave length of the sound wave; combining these microphones ( 1 a, 1 b, 1 c ) or membranes ( 9 a, 9 b ) to obtain directional signals (F(t), R(t) depending on the direction ( 3 ) of sound; and processing the directional signals (F(t), R(t) to modify the directional pattern of the signals.

Method and apparatus for picking up sound

Methods for streaming web content data via a computer-readable medium. The web content data comprises one or more media samples. The media samples are encoded in a streaming media format as a web component stream. The web component stream is combined with other component streams comprising additional data other than web content data into a presentation stream. The presentation stream is transmitted via a media server to a client. Rendering commands, which are included in one or more rendering samples encoded in the web component stream along with the media samples, coordinate synchronization between the media samples and the additional data when the client renders the presentation stream.

Media streaming of web content data

An audio decoder provides a combination of decoding components including components implementing base band decoding, spectral peak decoding, frequency extension decoding and channel extension decoding techniques. The audio decoder decodes a compressed bitstream structured by a bitstream syntax scheme to permit the various decoding components to extract the appropriate parameters for their respective decoding technique.

Bitstream syntax for multi-process audio decoding

In a multi-speaker audio system for, e.g., a home entertainment system or other entertainment system, each networked-speaker (wired or wireless) is activated or deactivated as appropriate such that audio play follows a user as the user moves around the home.

Networked speaker system with follow me

An electroacoustic channel soundfield is altered. An audio signal is applied by an electromechanical transducer to an acoustic space, causing air pressure changes therein. Another audio signal is obtained by a second electromechanical transducer, responsive to air pressure changes in the acoustic space. A transfer function estimate of the electroacoustic channel is established, responsive to the second audio signal and part of the first audio signal. The transfer function estimate is derived to be adaptive to temporal variations in the electroacoustic channel transfer function. Filters are obtained with transfer functions based on the transfer function estimate. Part of the first audio signal is filtered therewith.

Method for adaptive control and equalization of electroacoustic channels

A method and apparatus for enhancing a desired audio signal for delivery through an electroacoustic channel include obtaining a noise estimate attributable to an external disturbance, applying the noise estimate to a dynamic noise compensation (DNC) process to thereby condition the desired audio signal as a function of the spectral characteristics of the noise estimate, applying the noise estimate to an adaptive equalization (AEQ) process to thereby condition the desired audio signal as a function of the electroacoustic response of the electroacoustic channel, and applying the noise estimate to an active noise cancelation (ANC) process configured to generate anti-noise for delivery into the electroacoustic channel.

Method and apparatus for reducing the effect of environmental noise on listeners

A receiver in an audio coding system receives a signal conveying frequency subband signals representing an audio signal. The subband signals are examined to assess one or more characteristics of the audio signal. Spectral components are synthesized having the assessed characteristics. The synthesized spectral components are integrated with the subband signals and passed through a synthesis filterbank to generate an output signal. In one implementation, the assessed characteristic is temporal shape and noise-like spectral components are synthesized having the temporal shape of the audio signal.

Audio coding system using characteristics of a decoded signal to adapt synthesized spectral components

Embodiments are described for a system of rendering spatial audio content in a listening environment. The system includes a rendering component configured to generate a plurality of audio channels including information specifying a playback location in a listening area, an upmixer component receiving the plurality of audio channels and generating, for each audio channel, at least one reflected sub-channel configured to cause a majority of driver energy to reflect off of one or more surfaces of the listening area, and at least one direct sub-channel configured to cause a majority of driver energy to propagate directly to the playback location.

Reflected and direct rendering of upmixed content to individually addressable drivers

An acoustic crossfeed canceller, intended for implementation in software, such that when run in real time on a personal computer, the canceller has very low mips requirements and uses a small fraction of available CPU cycles. Thus, for example, the program could be included with video games, CD-ROMs, Internet audio and the like, rendering surround sound images outside the space between left and right computer multimedia loudspeakers when the audio from such sources is reproduced.

Matthew Fellers

Papers

Method for adaptive control and equalization of electroacoustic channels

Method and apparatus for reducing the effect of environmental noise on listeners

Audio coding system using characteristics of a decoded signal to adapt synthesized spectral components

Reflected and direct rendering of upmixed content to individually addressable drivers

Multidirectional audio decoding