Realnetworks Gmbh

Intel Corporation

Kenneth Edward Cooke

Wolfgang Alexander Schildbach

A method and apparatus for preserving matrix-surround information in encoded audio/video includes a receiver operative to receive matrix-surround encoded audio signals via a modem, separate the audio signals into a frequency spectrum having discrete audio frequencies, and determine a cutoff threshold used to encode the matrix-surround encoded audio signals. The method and apparatus further includes a decoder operative to decode a first set of the audio frequencies below the determined cutoff threshold using a first matrix-surround preserving audio encoding method and to decode a second set of audio frequencies above the cutoff threshold using a second non matrix-surround preserving audio encoding method.

Preserving matrix surround information in encoded audio/video system and method

A method and apparatus for preserving matrix-surround information in encoded audio/video includes a receiver operative to receive matrix-surround encoded audio signals, separate the audio signals into a frequency spectrum having discrete audio frequencies, and determine a cutoff threshold used to encode the matrix-surround encoded audio signals. The method and apparatus further includes a decoder operative to decode a first set of the audio frequencies below the determined cutoff threshold using a first matrix-surround preserving audio encoding method and to decode a second set of audio frequencies above the cutoff threshold using a second non matrix-surround preserving audio encoding method.

Method and apparatus for preserving matrix surround information in encoded audio/video

A system and method of the present invention cross-fade a first transmitted audio stream to a second transmitted audio stream, wherein both first and second audio streams represent the same original audio signal, but at different quality levels. A client computer receives timestamped packets of compressed encoded audio data from the first audio stream, decodes that data and resamples it to a highest sampling rate supported by playback equipment such as a sound card. A server computer responds to a change in available bandwidth, by transmitting timestamped packets of the second audio stream which correspond to a playback time earlier than that of the final transmitted packet of the first audio stream. The client computer buffers in a first buffer the decoded resampled samples from the final packets of the first audio stream, which represent a playback time period t. The client computer then buffers in a second buffer decoded resampled samples from the initial packets of the second audio stream representing a playback time period t. A cross-fade overlap window is defined by a time period tover which tand toverlap. A cross-fader cross-fades sample pairs drawn from both buffers, each pair corresponding to a playback time in the cross-fade overlap window. A cross-fade table holds a predetermined number of values decreasing from 1 to 0, which values approximate a cross-fade curve. The cross-fader applies a weight value to each sample pair, the weight value calculated by applying linear interpolation across adjacent values in the cross-fade table, by multiplying a sample from the first audio stream by the weight value, and by multiplying a time-corresponding sample from the second audio stream by one minus the weight value. The resulting contributions from both samples are combined and sent to audio reproduction equipment.

System and method for cross-fading between audio streams

A system and method of the present invention conceal errors caused by lost audio in an audio transmission. A frame error detector detects audio data lost in an audio data transmission. An audio decoder generates frequency and time domain data from received audio data. A transient detector detects the presence of a transient audio signal in the received audio data. A frame synthesizer interpolates frequency domain data to generate synthetic audio data to construct audio data in place of the lost audio data.

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Seattle, WA, United States of America

Kenneth Edward Cooke