Abstract: Received audio data may include a first set of frequency coefficients and a second set of frequency coefficients. Spatial parameters for at least part of the second set of frequency coefficients may be estimated, based at least in part on the first set of frequency coefficients. The estimated spatial parameters may be applied to the second set of frequency coefficients to generate a modified second set of frequency coefficients. The first set of frequency coefficients may correspond to a first frequency range (for example, an individual channel frequency range) and the second set of frequency coefficients may correspond to a second frequency range (for example, a coupled channel frequency range). Combined frequency coefficients of a composite coupling channel may be based on frequency coefficients of two or more channels. Cross-correlation coefficients, between frequency coefficients of a first channel and the combined frequency coefficients, may be computed.

Abstract: Multiple channels of audio are combined either to a monophonic composite signal or to multiple channels of audio along with related auxiliary information from which multiple channels of audio are reconstructed, including improved downmixing of multiple audio channels to a monophonic audio signal or to multiple audio channels and improved decorrelation of multiple audio channels derived from a monophonic audio channel or from multiple audio channels. Aspects of the disclosed invention are usable in audio encoders, decoders, encode/decode systems, downmixers, upmixers, and decorrelators.

Abstract: Multiple channels of audio are combined either to a monophonic composite signal or to multiple channels of audio along with related auxiliary information from which multiple channels of audio are reconstructed, including improved downmixing of multiple audio channels to a monophonic audio signal or to multiple audio channels and improved decorrelation of multiple audio channels derived from a monophonic audio channel or from multiple audio channels. Aspects of the disclosed invention are usable in audio encoders, decoders, encode/decode systems, downmixers, upmixers, and decorrelators.

Abstract: A method performed in an audio decoder for decoding M encoded audio channels representing N audio channels is disclosed. The method includes receiving a bitstream containing the M encoded audio channels and a set of spatial parameters, decoding the M encoded audio channels, and extracting the set of spatial parameters from the bitstream. The method also includes analyzing the M audio channels to detect a location of a transient, decorrelating the M audio channels, and deriving N audio channels from the M audio channels and the set of spatial parameters. A first decorrelation technique is applied to a first subset of each audio channel and a second decorrelation technique is applied to a second subset of each audio channel. The first decorrelation technique represents a first mode of operation of a decorrelator, and the second decorrelation technique represents a second mode of operation of the decorrelator.

Abstract: In some embodiments, a method for embedding data (e.g., metadata for use during post-processing) in a stereo audio signal comprising frames. Each of the frames has a saturation value, and data are embedded in the stereo audio signal by modifying the signal to generate a modulated stereo audio signal comprising a sequence of modulated frames having modulated saturation values indicative of the embedded data. Typically, one data bit is embedded in each frame of an input stereo audio signal by modifying the frame to produce a modulated frame whose modulated saturation value matches a target value indicative of the data bit. In other embodiments, a method for extracting data from a stereo audio signal in which the data have been embedded in accordance with an embodiment of the inventive embedding method. Other aspects are systems (e.g., programmed processors) configured to perform any embodiment of the inventive method.

Abstract: Methods for generating a palette of feedback (IIR) filter coefficient sets and using the palette to configure (e.g., adaptively update) a prediction filter which includes a feedback filter, and a system for performing any of the methods. Examples of the system include an encoder, including a prediction filter and configured to encode data indicative of a waveform signal (e.g., samples of an audio signal), and a decoder. In some embodiments, the prediction filter is included in an encoder operable to generate (and assert to a decoder) encoded data including filter coefficient data indicative of the selected IIR coefficient set with which the prediction filter was configured during generation of the encoded data. In some embodiments, the timing with which adaptive updating of prediction filter configuration occurs or is allowed to occur is constrained (e.g., to optimize efficiency of prediction encoding).

Abstract: Multiple channels of audio are combined either to a monophonic composite signal or to multiple channels of audio along with related auxiliary information from which multiple channels of audio are reconstructed, including improved downmixing of multiple audio channels to a monophonic audio signal or to multiple audio channels and improved decorrelation of multiple audio channels derived from a monophonic audio channel or from multiple audio channels. Aspects of the disclosed invention are usable in audio encoders, decoders, encode/decode systems, downmixers, upmixers, and decorrelators.

Abstract: Received audio data may include a first set of frequency coefficients and a second set of frequency coefficients. Spatial parameters for at least part of the second set of frequency coefficients may be estimated, based at least in part on the first set of frequency coefficients. The estimated spatial parameters may be applied to the second set of frequency coefficients to generate a modified second set of frequency coefficients. The first set of frequency coefficients may correspond to a first frequency range (for example, an individual channel frequency range) and the second set of frequency coefficients may correspond to a second frequency range (for example, a coupled channel frequency range). Combined frequency coefficients of a composite coupling channel may be based on frequency coefficients of two or more channels. Cross-correlation coefficients, between frequency coefficients of a first channel and the combined frequency coefficients, may be computed.

Abstract: In some embodiments, a method for automatic detection of polarity of speakers, e.g., speakers installed in cinema environments. In some embodiments, the method determines relative polarities of a set of speakers (e.g., loudspeakers and/or drivers of a multi-driver loudspeaker) using a set of microphones, including by measuring impulse responses, including an impulse response for each speaker-microphone pair; clustering the speakers into a set of groups, each group including at least two of the speakers which are similar to each other in at least one respect; and for each group, determining and analyzing cross-correlations of pairs of impulse responses (e.g., pairs of processed versions of impulse responses) of speakers in the group to determine relative polarities of the speakers. Other aspects include systems configured (e.g., programmed) to perform any embodiment of the inventive method, and computer readable media (e.g., discs) which store code for implementing any embodiment of the inventive method.

Abstract: Ambience signal components are obtained from source audio signals, matrix-decoded signal components are obtained from the source audio signals, and the ambience signal components are controllably combined with the matrix-decoded signal components. Obtaining ambience signal components may include applying at least one decorrelation filter sequence. The same decorrelation filter sequence may be applied to each of the input audio signals or, alternatively, a different decorrelation filter sequence may be applied to each of the input audio signals.

Abstract: Forensic audio upmixer detection is described. Feature sets are extracted from an audio signal that has two or more individual channels. Based on the extracted feature sets, it is determined whether the audio signal was upmixed from audio content that has fewer channels.

Abstract: Methods and apparatus are described by which equalization and/or bass management of speakers in a sound reproduction system may be accomplished.

Abstract: Multiple channels of audio are combined either to a monophonic composite signal or to multiple channels of audio along with related auxiliary information from which multiple channels of audio are reconstructed, including improved downmixing of multiple audio channels to a monophonic audio signal or to multiple audio channels and improved decorrelation of multiple audio channels derived from a monophonic audio channel or from multiple audio channels. Aspects of the disclosed invention are usable in audio encoders, decoders, encode/decode systems, downmixers, upmixers, and decorrelators.

Abstract: In some embodiments, a method for embedding data (e.g., metadata for use during post-processing) in a stereo audio signal comprising frames. Each of the frames has a saturation value, and data are embedded in the stereo audio signal by modifying the signal to generate a modulated stereo audio signal comprising a sequence of modulated frames having modulated saturation values indicative of the embedded data. Typically, one data bit is embedded in each frame of an input stereo audio signal by modifying the frame to produce a modulated frame whose modulated saturation value matches a target value indicative of the data bit. In other embodiments, a method for extracting data from a stereo audio signal in which the data have been embedded in accordance with an embodiment of the inventive embedding method. Other aspects are systems (e.g., programmed processors) configured to perform any embodiment of the inventive method.

Abstract: Methods and apparatus are described by which equalization and/or bass management of speakers in a sound reproduction system may be accomplished.

Abstract: Methods for generating a palette of feedback (IIR) filter coefficient sets and using the palette to configure (e.g., adaptively update) a prediction filter which includes a feedback filter, and a system for performing any of the methods. Examples of the system include an encoder, including a prediction filter and configured to encode data indicative of a waveform signal (e.g., samples of an audio signal), and a decoder. In some embodiments, the prediction filter is included in an encoder operable to generate (and assert to a decoder) encoded data including filter coefficient data indicative of the selected IIR coefficient set with which the prediction filter was configured during generation of the encoded data. In some embodiments, the timing with which adaptive updating of prediction filter configuration occurs or is allowed to occur is constrained (e.g., to optimize efficiency of prediction encoding).

Abstract: M audio input channels, each associated with a spatial direction, are translated to N audio output channels, each associated with a spatial direction, wherein M and N are positive whole integers, M is three or more, and N is three or more, by deriving the N audio output channels from the M audio input channels, wherein one or more of the M audio input channels is associated with a spatial direction other than a spatial direction with which any of the N audio output channels is associated, and at least one of the one or more of the M audio input channels is mapped to a respective set of at least three of the N output channels. At least three output channels of a set may be associated with contiguous spatial directions.

Abstract: Ambience signal components are obtained from source audio signals, matrix-decoded signal components are obtained from the source audio signals, and the ambience signal components are controllably combined with the matrix-decoded signal components. Obtaining ambience signal components may include applying at least one decorrelation filter sequence. The same decorrelation filter sequence may be applied to each of the input audio signals or, alternatively, a different decorrelation filter sequence may be applied to each of the input audio signals.

Abstract: An audio encoder/decoder system suitable for digital motion picture film soundtracks provides for adjusting playback signal gain and dynamic range by modifying the scale factors of scaled spectral information. In one embodiment of a transform coding system, transform coefficients are expressed in floating-point form and adjustments are made by modifying the exponents in the floating-point representation.

Abstract: An adaptive high-fidelity perceptual subband encoder for spatially directional multichannel audio signals, using a mixture of individual-channel subband coding with subband-steered composite-channel signal coding that combines the spectral components of the individual channel subbands selected for steering. The composite channel representation includes a subband steering control signal which either conveys the levels of the spectral components from all the steered channels, or represents the apparent directions (net directional vectors) of the spectral components from all the steered channels.