Patents by Inventor Per Ekstrand
Per Ekstrand 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).
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Publication number: 20160232912Abstract: A method performed in an audio decoder for reconstructing an original audio signal having a lowband portion and a highband portion is disclosed. The method includes receiving an encoded audio signal and extracting reconstruction parameters from the encoded audio signal. The method further includes decoding the encoded audio signal with a core audio decoder to obtain a decoded lowband portion and regenerating the highband portion based at least in part on a cross over frequency and the decoded lowband portion to obtain a regenerated highband portion. The method also includes creating a synthetic sinusoid with a level based at least in part on a spectral envelope value for the particular subband and a noise floor value for the particular subband and adding the synthetic sinusoid to the regenerated highband portion in the particular frequency band specified by the location information.Type: ApplicationFiled: April 20, 2016Publication date: August 11, 2016Applicant: DOLBY INTERNATIONAL ABInventors: Kristofer KJOERLING, Per EKSTRAND, Holger HOERICH
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Patent number: 9407993Abstract: A latency reduction system in a virtual bass processing system performs harmonic transposition on low frequency components of an audio signal to generate transposed data indicative of harmonics of the audio signal. The system uses a base transposition factor greater than two, and generates the harmonics in response to frequency-domain values determined by forward and inverse transform stages that use asymmetric analysis and synthesis windows. The system combines a virtual bass signal with the delayed wide band audio signal through analysis filter banks having filter coefficient truncated Nyquist filters. The virtual bass signal may lag the delayed wide band audio signal when combining with the audio signal to further reduce the latency caused by the harmonic transposition. The virtual bass input signal may be directly routed from a CQMF analysis filter bank of a preceding Hybrid filter bank stage, in order to avoid the delay associated with a Nyquist filter bank.Type: GrantFiled: September 27, 2013Date of Patent: August 2, 2016Assignee: Dolby International ABInventor: Per Ekstrand
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Publication number: 20160217800Abstract: The present disclosure provides methods, devices and computer program products for non-uniform quantization of parameters relating to parametric spatial coding of audio signals. The disclosure further relates to a method and apparatus for reconstructing an audio object in an audio decoding system taking the non-uniformly quantized parameters into account. According to the disclosure, such an approach renders it possible to reduce bit consumption without substantially reducing the quality of the reconstructed audio object.Type: ApplicationFiled: September 8, 2014Publication date: July 28, 2016Applicant: DOLBY INTERNATIONAL ABInventors: Heiko PURNHAGEN, Per EKSTRAND
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Publication number: 20160210970Abstract: The present document relates to audio encoding and decoding. In particular, the present document relates to audio coding schemes which make use of high frequency reconstruction (HFR) methods. A system configured to determine a master scale factor band table of a highband signal (105) of an audio signal is described. The highband signal (105) is to be generated from a lowband signal (101) of the audio signal using a high frequency reconstruction (HFR) scheme. The master scale factor band table is indicative of a frequency resolution of a spectral envelope of the highband signal (105).Type: ApplicationFiled: August 11, 2014Publication date: July 21, 2016Applicant: DOLBY INTERNATIONAL ABInventors: Per EKSTRAND, Kristofer KJOERLING
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Patent number: 9384750Abstract: The present invention relates to coding of audio signals, and in particular to high frequency reconstruction methods including a frequency domain harmonic transposer. A system and method for generating a high frequency component of a signal from a low frequency component of the signal is described.Type: GrantFiled: October 3, 2014Date of Patent: July 5, 2016Assignee: Dolby International ABInventors: Lars Villemoes, Per Ekstrand
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Patent number: 9349382Abstract: The document relates to modulated sub-sampled digital filter banks, as well as to methods and systems for the design of such filter banks. In particular, the present document proposes a method and apparatus for the improvement of low delay modulated digital filter banks. The method employs modulation of an asymmetric low-pass prototype filter and a new method for optimizing the coefficients of this filter. Further, a specific design for a 64 channel filter bank using a prototype filter length of 640 coefficients and a system delay of 319 samples is given. The method substantially reduces artifacts due to aliasing emerging from independent modifications of subband signals, for example when using a filter bank as a spectral equalizer. The method is preferably implemented in software, running on a standard PC or a digital signal processor (DSP), but can also be hardcoded on a custom chip.Type: GrantFiled: July 23, 2015Date of Patent: May 24, 2016Assignee: Dolby International ABInventor: Per Ekstrand
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Patent number: 9318118Abstract: The document relates to modulated sub-sampled digital filter banks, as well as to methods and systems for the design of such filter banks. In particular, the present document proposes a method and apparatus for the improvement of low delay modulated digital filter banks. The method employs modulation of an asymmetric low-pass prototype filter and a new method for optimizing the coefficients of this filter. Further, a specific design for a 64 channel filter bank using a prototype filter length of 640 coefficients and a system delay of 319 samples is given. The method substantially reduces artifacts due to aliasing emerging from independent modifications of subband signals, for example when using a filter bank as a spectral equalizer. The method is preferably implemented in software, running on a standard PC or a digital signal processor (DSP), but can also be hardcoded on a custom chip.Type: GrantFiled: July 23, 2015Date of Patent: April 19, 2016Assignee: Dolby International ABInventor: Per Ekstrand
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Patent number: 9318127Abstract: An apparatus for generating a bandwidth extended audio signal from an input signal, includes a patch generator for generating one or more patch signals from the input signal, wherein the patch generator is configured for performing a time stretching of subband signals from an analysis filterbank, and wherein the patch generator further includes a phase adjuster for adjusting phases of the subband signals using a filterbank-channel dependent phase correction.Type: GrantFiled: September 5, 2012Date of Patent: April 19, 2016Assignees: Fraunhofer-Gesellschaft zur Foerderung der angewandten Forschung e.V., Dolby International ABInventors: Sascha Disch, Frederik Nagel, Stephan Wilde, Lars Villemoes, Per Ekstrand
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Publication number: 20160099005Abstract: The present proposes new methods and an apparatus for enhancement of source coding systems utilising high frequency reconstruction (HFR). It addresses the problem of insufficient noise contents in a reconstructed highband, by Adaptive Noise-floor Addition. It also introduces new methods for enhanced performance by means of limiting unwanted noise, interpolation and smoothing of envelope adjustment amplification factors. The present invention is applicable to both speech coding and natural audio coding systems.Type: ApplicationFiled: December 14, 2015Publication date: April 7, 2016Applicant: Dolby International ABInventors: Lars G. Liljeryd, Kristofer Kjoerling, Per Ekstrand, Fredrik Henn
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Patent number: 9305557Abstract: Apparatus for processing an audio signal to generate a bandwidth extended signal having a high frequency part and a low frequency part using parametric data for the high frequency part, the parametric data relating to frequency bands of the high frequency part includes a patch border calculator for calculating a patch border such that the patch border coincides with a frequency band border of the frequency bands. The apparatus further includes a patcher for generating a patched signal using the audio signal and the patch border.Type: GrantFiled: September 5, 2012Date of Patent: April 5, 2016Assignees: Fraunhofer-Gesellschaft zur Foerderung der angewandten Forschung e.V., Dolby International ABInventors: Frederik Nagel, Sascha Disch, Stephan Wilde, Lars Villemoes, Per Ekstrand
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Publication number: 20160093310Abstract: The present invention relates to a new method and apparatus for improvement of High Frequency Reconstruction (HFR) techniques using frequency translation or folding or a combination thereof. The proposed invention is applicable to audio source coding systems, and offers significantly reduced computational complexity. This is accomplished by means of frequency translation or folding in the subband domain, preferably integrated with spectral envelope adjustment in the same domain. The concept of dissonance guard-band filtering is further presented. The proposed invention offers a low-complexity, intermediate quality HFR method useful in speech and natural audio coding applications.Type: ApplicationFiled: December 10, 2015Publication date: March 31, 2016Applicant: Dolby International ABInventors: Lars G. Liljeryd, Per Ekstrand, Fredrik Henn, Kristofer Kjoerling
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Publication number: 20160035329Abstract: The present document relates to audio coding systems which make use of a harmonic transposition method for high frequency reconstruction (HFR), and to digital effect processors, e.g. so-called exciters, where generation of harmonic distortion adds brightness to the processed signal. In particular, a system configured to generate a high frequency component of a signal from a low frequency component of the signal is described. The system may comprise an analysis filter bank (501) configured to provide a set of analysis subband signals from the low frequency component of the signal; wherein the set of analysis subband signals comprises at least two analysis subband signals; wherein the analysis filter bank (501) has a frequency resolution of ?f.Type: ApplicationFiled: October 14, 2015Publication date: February 4, 2016Applicant: Dolby International ABInventors: Per Ekstrand, Lars Villemoes, Per Hedelin
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Publication number: 20160035361Abstract: The present invention relates to transposing signals in time and/or frequency and in particular to coding of audio signals. More particular, the present invention relates to high frequency reconstruction (HFR) methods including a frequency domain harmonic transposer. A method and system for generating a transposed output signal from an input signal using a transposition factor T is described. The system comprises an analysis window of length La, extracting a frame of the input signal, and an analysis transformation unit of order M transforming the samples into M complex coefficients. M is a function of the transposition factor T. The system further comprises a nonlinear processing unit altering the phase of the complex coefficients by using the transposition factor T, a synthesis transformation unit of order M transforming the altered coefficients into M altered samples, and a synthesis window of length Ls, generating a frame of the output signal.Type: ApplicationFiled: October 13, 2015Publication date: February 4, 2016Applicant: DOLBY INTERNATIONAL ABInventors: Per Ekstrand, Lars Villemoes
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Patent number: 9245534Abstract: The present invention relates to a new method and apparatus for improvement of High Frequency Reconstruction (HFR) techniques using frequency translation or folding or a combination thereof. The proposed invention is applicable to audio source coding systems, and offers significantly reduced computational complexity. This is accomplished by means of frequency translation or folding in the subband domain, preferably integrated with spectral envelope adjustment in the same domain. The concept of dissonance guard-band filtering is further presented. The proposed invention offers a low-complexity, intermediate quality HFR method useful in speech and natural audio coding applications.Type: GrantFiled: August 19, 2013Date of Patent: January 26, 2016Assignee: Dolby International ABInventors: Lars G. Liljeryd, Per Ekstrand, Fredrik Henn, Kristofer Kjoerling
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Patent number: 9245533Abstract: The present proposes new methods and an apparatus for enhancement of source coding systems utilizing high frequency reconstruction (HFR). It addresses the problem of insufficient noise contents in a reconstructed highband, by Adaptive Noise-floor Addition. It also introduces new methods for enhanced performance by means of limiting unwanted noise, interpolation and smoothing of envelope adjustment amplification factors. The present invention is applicable to both speech coding and natural audio coding systems.Type: GrantFiled: December 9, 2014Date of Patent: January 26, 2016Assignee: Dolby International ABInventors: Lars G. Liljeryd, Kristofer Kjoerling, Per Ekstrand, Fredrik Henn
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Patent number: 9236061Abstract: The present invention relates to transposing signals in time and/or frequency and in particular to coding of audio signals. More particular, the present invention relates to high frequency reconstruction (HFR) methods including a frequency domain harmonic transposer. A method and system for generating a transposed output signal from an input signal using a transposition factor T is described. The system comprises an analysis window of length La, extracting a frame of the input signal, and an analysis transformation unit of order M transforming the samples into M complex coefficients. M is a function of the transposition factor T. The system further comprises a nonlinear processing unit altering the phase of the complex coefficients by using the transposition factor T, a synthesis transformation unit of order M transforming the altered coefficients into M altered samples, and a synthesis window of length Ls, generating a frame of the output signal.Type: GrantFiled: September 14, 2010Date of Patent: January 12, 2016Assignee: Dolby International ABInventors: Per Ekstrand, Lars Villemoes
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Publication number: 20150332703Abstract: The document relates to modulated sub-sampled digital filter banks, as well as to methods and systems for the design of such filter banks. In particular, the present document proposes a method and apparatus for the improvement of low delay modulated digital filter banks. The method employs modulation of an asymmetric low-pass prototype filter and a new method for optimizing the coefficients of this filter. Further, a specific design for a 64 channel filter bank using a prototype filter length of 640 coefficients and a system delay of 319 samples is given. The method substantially reduces artifacts due to aliasing emerging from independent modifications of subband signals, for example when using a filter bank as a spectral equalizer. The method is preferably implemented in software, running on a standard PC or a digital signal processor (DSP), but can also be hardcoded on a custom chip.Type: ApplicationFiled: July 23, 2015Publication date: November 19, 2015Applicant: DOLBY INTERNATIONAL ABInventor: Per Ekstrand
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Publication number: 20150333733Abstract: The document relates to modulated sub-sampled digital filter banks, as well as to methods and systems for the design of such filter banks. In particular, the present document proposes a method and apparatus for the improvement of low delay modulated digital filter banks. The method employs modulation of an asymmetric low-pass prototype filter and a new method for optimizing the coefficients of this filter. Further, a specific design for a 64 channel filter bank using a prototype filter length of 640 coefficients and a system delay of 319 samples is given. The method substantially reduces artifacts due to aliasing emerging from independent modifications of subband signals, for example when using a filter bank as a spectral equalizer. The method is preferably implemented in software, running on a standard PC or a digital signal processor (DSP), but can also be hardcoded on a custom chip.Type: ApplicationFiled: July 23, 2015Publication date: November 19, 2015Applicant: Dolby International ABInventor: Per Ekstrand
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Publication number: 20150333734Abstract: The document relates to modulated sub-sampled digital filter banks, as well as to methods and systems for the design of such filter banks. In particular, the present document proposes a method and apparatus for the improvement of low delay modulated digital filter banks. The method employs modulation of an asymmetric low-pass prototype filter and a new method for optimizing the coefficients of this filter. Further, a specific design for a 64 channel filter bank using a prototype filter length of 640 coefficients and a system delay of 319 samples is given. The method substantially reduces artifacts due to aliasing emerging from independent modifications of subband signals, for example when using a filter bank as a spectral equalizer. The method is preferably implemented in software, running on a standard PC or a digital signal processor (DSP), but can also be hardcoded on a custom chip.Type: ApplicationFiled: July 27, 2015Publication date: November 19, 2015Applicant: Dolby International ABInventor: Per Ekstrand
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Patent number: 9190067Abstract: The present document relates to audio coding systems which make use of a harmonic transposition method for high frequency reconstruction (HFR), and to digital effect processors, e.g. so-called exciters, where generation of harmonic distortion adds brightness to the processed signal. In particular, a system configured to generate a high frequency component of a signal from a low frequency component of the signal is described. The system may comprise an analysis filter bank (501) configured to provide a set of analysis subband signals from the low frequency component of the signal; wherein the set of analysis subband signals comprises at least two analysis subband signals; wherein the analysis filter bank (501) has a frequency resolution of ?f.Type: GrantFiled: February 4, 2015Date of Patent: November 17, 2015Assignee: Dolby International ABInventors: Per Ekstrand, Lars Villemoes, Per Hedelin