Patents by Inventor John Robert Stuart

John Robert Stuart has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Publication number: 20210193157
    Abstract: Encoding and decoding systems are described for the provision of high quality digital representations of audio signals with particular attention to the correct perceptual rendering of fast transients at modest sample rates. This is achieved by optimising downsampling and upsampling filters to minimise the length of the impulse response while adequately attenuating alias products that have been found perceptually harmful.
    Type: Application
    Filed: December 14, 2020
    Publication date: June 24, 2021
    Inventors: Peter Graham Craven, John Robert Stuart
  • Publication number: 20200395918
    Abstract: Methods and devices are described for reducing the audible effect of pre-responses in an audio signal. The pre-responses are effectively delayed by employing a digital non-minimum-phase filter, which includes a zero lying outside the unit circle in its z-transform response. This zero is not paired with another zero at a reciprocal position inside the unit circle, as this would linearise the phase modification. The filtering can introduce a greater group delay at the pre-response frequency than at a low frequency, such as 500 Hz or even 0 Hz. The technique can be used to reduce pre-responses in an existing audio signal and also to pre-empt pre-responses that would be introduced to the audio signal by subsequent processing.
    Type: Application
    Filed: August 28, 2020
    Publication date: December 17, 2020
    Inventors: Peter Graham Craven, John Robert Stuart
  • Patent number: 10867614
    Abstract: Encoding and decoding systems are described for the provision of high quality digital representations of audio signals with particular attention to the correct perceptual rendering of fast transients at modest sample rates. This is achieved by optimising downsampling and upsampling filters to minimise the length of the impulse response while adequately attenuating alias products that have been found perceptually harmful.
    Type: Grant
    Filed: October 2, 2018
    Date of Patent: December 15, 2020
    Assignee: MQA Limited
    Inventors: Peter Graham Craven, John Robert Stuart
  • Patent number: 10763828
    Abstract: Methods and devices are described for reducing the audible effect of pre-responses in an audio signal. The pre-responses are effectively delayed by employing a digital non-minimum-phase filter, which includes a zero lying outside the unit circle in its z-transform response. This zero is not paired with another zero at a reciprocal position inside the unit circle, as this would linearise the phase modification. The filtering can introduce a greater group delay at the pre-response frequency than at a low frequency, such as 500 Hz or even 0 Hz. The technique can be used to reduce pre-responses in an existing audio signal and also to pre-empt pre-responses that would be introduced to the audio signal by subsequent processing.
    Type: Grant
    Filed: December 3, 2015
    Date of Patent: September 1, 2020
    Inventors: Peter Graham Craven, John Robert Stuart
  • Patent number: 10224950
    Abstract: Devices and methods for digital to analog conversion (DAC) are provided, in which the analog outputs of an even number of digital to analog converters are combined. The individual converters operate on the same data but there is a relative time delay between the input digital signal received by one or more of the converters and the input digital signal received by other of the converters, wherein the delay is a fraction of the data sample period. Moreover, the data signal fed to half of the converters has an inverse relationship with the data signal fed to the other half of the converters and their analog outputs are subtracted. Dither and filtering techniques may also be employed.
    Type: Grant
    Filed: May 26, 2016
    Date of Patent: March 5, 2019
    Assignee: REINET S.A.R.L.
    Inventor: John Robert Stuart
  • Publication number: 20190057709
    Abstract: Encoding and decoding systems are described for the provision of high quality digital representations of audio signals with particular attention to the correct perceptual rendering of fast transients at modest sample rates. This is achieved by optimising downsampling and upsampling filters to minimise the length of the impulse response while adequately attenuating alias products that have been found perceptually harmful.
    Type: Application
    Filed: October 2, 2018
    Publication date: February 21, 2019
    Inventors: Peter Graham Craven, John Robert Stuart
  • Patent number: 10115410
    Abstract: Encoding and decoding systems are described for the provision of high quality digital representations of audio signals with particular attention to the correct perceptual rendering of fast transients at modest sample rates. This is achieved by optimizing downsampling and upsampling filters to minimize the length of the impulse response while adequately attenuating alias products that have been found perceptually harmful.
    Type: Grant
    Filed: June 10, 2014
    Date of Patent: October 30, 2018
    Inventors: Peter Graham Craven, John Robert Stuart
  • Publication number: 20180167081
    Abstract: Devices and methods for digital to analogue conversion (DAC) are provided, in which the analogue outputs of an even number of digital to analogue converters are combined. The individual converters operate on the same data but there is a relative time delay between the input digital signal received by one or more of the converters and the input digital signal received by other of the converters, wherein the delay is a fraction of the data sample period. Moreover, the data signal fed to half of the converters has an inverse relationship with the data signal fed to the other half of the converters and their analogue outputs are subtracted. Dither and filtering techniques may also be employed.
    Type: Application
    Filed: May 26, 2016
    Publication date: June 14, 2018
    Inventor: John Robert Stuart
  • Publication number: 20170346465
    Abstract: Methods and devices are described for reducing the audible effect of pre-responses in an audio signal. The pre-responses are effectively delayed by employing a digital non-minimum-phase filter, which includes a zero lying outside the unit circle in its z-transform response. This zero is not paired with another zero at a reciprocal position inside the unit circle, as this would linearise the phase modification. The filtering can introduce a greater group delay at the pre-response frequency than at a low frequency, such as 500 Hz or even 0 Hz. The technique can be used to reduce pre-responses in an existing audio signal and also to pre-empt pre-responses that would be introduced to the audio signal by subsequent processing.
    Type: Application
    Filed: December 3, 2015
    Publication date: November 30, 2017
    Inventors: Peter Graham Craven, John Robert Stuart
  • Patent number: 9763007
    Abstract: Methods are provided for equalizing the group delay of a sound reproduction system, in particular a system comprising acoustic transducers with at least one crossover between a lower-frequency and a higher-frequency range. A correction is applied to a signal in the lower-frequency range, including the crossover region, to substantially equalize the group delay for the lower-frequency range, and a signal delay is applied to a signal in the higher-frequency range to bring it into closer alignment with the equalized lower-frequency range signal. The methods may be implemented in the design of an acoustic transducer system and also via a computer program product, which can be implemented as an update or enhancement to an existing digital signal processor loudspeaker system.
    Type: Grant
    Filed: January 7, 2014
    Date of Patent: September 12, 2017
    Assignee: Meridian Audio Limited
    Inventors: Michael D. Capp, John Robert Stuart, Alan S. J. Wood, Richard J. Hollinshead
  • Publication number: 20170110141
    Abstract: Encoding and decoding systems are described for the provision of high quality digital representations of audio signals with particular attention to the correct perceptual rendering of fast transients at modest sample rates. This is achieved by optimising downsampling and upsampling filters to minimise the length of the impulse response while adequately attenuating alias products that have been found perceptually harmful.
    Type: Application
    Filed: June 10, 2014
    Publication date: April 20, 2017
    Inventors: Peter Graham Craven, John Robert Stuart
  • Patent number: 9548055
    Abstract: An encoder for digital audio signals at a higher sample rate creates a stream for consumer distribution at a lower sampling rate, with compatibility for standard PCM players without a decoder. In conjunction with a suitable decoder, two enhanced playback options are supported, the first option allowing full lossless reconstruction of a noise-shaped higher sampling rate signal, the second option allowing lossy bandwidth extension even if an intervening transmission chain has truncated the least-significant-bits of the encoder's output signal.
    Type: Grant
    Filed: June 12, 2013
    Date of Patent: January 17, 2017
    Inventors: Peter Graham Craven, Malcolm Law, John Robert Stuart
  • Publication number: 20160005411
    Abstract: Methods and devices are described whereby a representation of an original PCM signal may be reversibly degraded in a controlled manner and information losslessly embedded to produce a streamable PCM signal, which provides a controlled audio quality when played on standard players and conditional access to a lossless presentation of the original PCM signal. Using such techniques allows control over the level of degradation of the signal and also flexibility in the type information of information embedded. Some methods require a song key, which is employed in one or both of the degrading and embedding steps and for creating a token. These methods may further require a user key, which is used to encrypt the song key before creating the token.
    Type: Application
    Filed: February 13, 2014
    Publication date: January 7, 2016
    Inventors: John Robert Stuart, Richard J. Hollinshead, Peter Graham Craven, Malcolm Law
  • Publication number: 20150350786
    Abstract: Methods are provided for equalising the group delay of a sound reproduction system, in particular a system comprising acoustic transducers with at least one crossover between a lower-frequency and a higher-frequency range. A correction is applied to a signal in the lower-frequency range, including the crossover region, to substantially equalise the group delay for the lower-frequency range, and a signal delay is applied to a signal in the higher-frequency range to bring it into closer alignment with the equalised lower-frequency range signal. The methods may be implemented in the design of an acoustic transducer system and also via a computer program product, which can be implemented as an update or enhancement to an existing digital signal processor loudspeaker system.
    Type: Application
    Filed: January 7, 2014
    Publication date: December 3, 2015
    Inventors: Michael D. Capp, John Robert Stuart, Alan S. J. Wood, Richard J. Hollinshead
  • Publication number: 20150154969
    Abstract: An encoder for digital audio signals at a higher sample rate creates a stream for consumer distribution at a lower sampling rate, with compatibility for standard PCM players without a decoder. In conjunction with a suitable decoder, two enhanced playback options are supported, the first option allowing full lossless reconstruction of a noise-shaped higher sampling rate signal, the second option allowing lossy bandwidth extension even if an intervening transmission chain has truncated the least-significant-bits of the encoder's output signal.
    Type: Application
    Filed: June 12, 2013
    Publication date: June 4, 2015
    Inventors: Peter Graham Craven, Malcolm Law, John Robert Stuart
  • Patent number: 7193538
    Abstract: A lossless encoder and decoder are provided for transmitting a multichannel signal on a medium such as DVD-Audio. The encoder accepts additionally a downmix specification and splits the encoded stream into two substreams, such that a two-channel decoder of meagre computational power can implement the downmix specification by decoding one substream, while a multichannel decoder can decode the original multichannel signal losslessly using both substreams. Further features provide for efficient implementation on 24-bit processors, for confirmation of lossless reproduction to the user, and for benign behaviour in the case of downmix specifications that result in overload. The principle is also extended to mixed-rate signals, where for example some input channels are sampled at 48 kHz and some are sampled at 96 kHz.
    Type: Grant
    Filed: August 5, 2004
    Date of Patent: March 20, 2007
    Assignee: Dolby Laboratories Licensing Corporation
    Inventors: Peter Graham Craven, Malcolm James Law, John Robert Stuart
  • Patent number: 6774820
    Abstract: A lossless encoder and decoder are provided for transmitting a multichannel signal on a medium such as DVD-Audio. The encoder accepts additionally a downmix specification and splits the encoded stream into two substreams, such that a two-channel decoder of meagre computational power can implement the downmix specification by decoding one substream, while a multichannel decoder can decode the original multichannel signal losslessly using both substreams. Further features provide for efficient implementation on 24-bit processors, for confirmation of lossless reproduction to the user, and for benign behaviour in the case of downmix specifications that result in overload. The principle is also extended to mixed-rate signals, where for example some input channels are sampled at 48 kHz and some are sampled at 96 kHz.
    Type: Grant
    Filed: August 18, 2003
    Date of Patent: August 10, 2004
    Assignee: Dolby Laboratories Licensing Corporation
    Inventors: Peter Graham Craven, Malcolm James Law, John Robert Stuart
  • Publication number: 20040070523
    Abstract: A lossless encoder and decoder are provided for transmitting a multichannel signal on a medium such as DVD-Audio. The encoder accepts additionally a downmix specification and splits the encoded stream into two substreams, such that a two-channel decoder of meagre computational power can implement the downmix specification by decoding one substream, while a multichannel decoder can decode the original multichannel signal losslessly using both substreams. Further features provide for efficient implementation on 24-bit processors, for confirmation of lossless reproduction to the user, and for benign behaviour in the case of downmix specifications that result in overload.
    Type: Application
    Filed: August 18, 2003
    Publication date: April 15, 2004
    Inventors: Peter Graham Craven, Malcolm James Law, John Robert Stuart
  • Patent number: 6611212
    Abstract: In one aspect of the invention, a stream is divided into two substreams, the first substream providing information relating to a ‘downmix’ signal obtained by matrixing and containing fewer channels than an original multichannel digital signal, and the second substream providing additional information allowing the original multichannel digital signal to be losslessly recovered by a decoder. In a preferred implementation, an encoder furnishes the downmix signal using a cascade of one or more primitive matrix quantizers, each of which implements an n-by-n matrix, followed by selection of the m channels required for the downnix. In a second aspect, a lossless compression system includes a dither seed in the encoded bitstream. The dither seed is used to synchronize a pseudo-random sequence generator in the decoder with a functionally identical generator in an encoder.
    Type: Grant
    Filed: October 5, 2001
    Date of Patent: August 26, 2003
    Assignee: Dolby Laboratories Licensing Corp.
    Inventors: Peter Graham Craven, Malcolm James Law, John Robert Stuart