公开(公告)号：US20230041798A1

公开(公告)日：2023-02-09

申请号：US17963627

申请日：2022-10-11

Applicant: DOLBY INTERNATIONAL AB

Inventor： Lars Villemoes ,  Heiko Purnhagen ,  Per Ekstrand

IPC: G10L19/26 ,  G10L19/008 ,  G10L19/24

Abstract: A method for decoding an encoded audio bitstream is disclosed. The method includes receiving the encoded audio bitstream and decoding the audio data to generate a decoded lowband audio signal. The method further includes extracting high frequency reconstruction metadata and filtering the decoded lowband audio signal with an analysis filterbank to generate a filtered lowband audio signal. The method also includes extracting a flag indicating whether either spectral translation or harmonic transposition is to be performed on the audio data and regenerating a highband portion of the audio signal using the filtered lowband audio signal and the high frequency reconstruction metadata in accordance with the flag.

公开(公告)号：US11367455B2

公开(公告)日：2022-06-21

申请号：US16932479

申请日：2020-07-17

Applicant: DOLBY INTERNATIONAL AB

Inventor： Lars Villemoes ,  Heiko Purnhagen ,  Per Ekstrand

IPC: G10L19/16 ,  G10L19/035 ,  G10L19/24 ,  G10L21/038

Abstract: Embodiments relate to an audio processing unit that includes a buffer, bitstream payload deformatter, and a decoding subsystem. The buffer stores at least one block of an encoded audio bitstream. The block includes a fill element that begins with an identifier followed by fill data. The fill data includes at least one flag identifying whether enhanced spectral band replication (eSBR) processing is to be performed on audio content of the block. A corresponding method for decoding an encoded audio bitstream is also provided.

公开(公告)号：US11100937B2

公开(公告)日：2021-08-24

申请号：US16827541

申请日：2020-03-23

Applicant: Dolby International AB

Inventor： Per Ekstrand ,  Lars Villemoes

IPC: G10L19/22 ,  G10L21/038 ,  G10L21/04 ,  G10L19/24 ,  G10L19/02 ,  G10L19/022

Abstract: 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.

公开(公告)号：US20210142813A1

公开(公告)日：2021-05-13

申请号：US17154495

申请日：2021-01-21

Applicant: DOLBY INTERNATIONAL AB

Inventor： Lars Villemoes ,  Heiko Purnhagen ,  Per Ekstrand

IPC: G10L19/16 ,  G10L19/035 ,  G10L19/24 ,  G10L21/038

Abstract: Embodiments relate to an audio processing unit that includes a bitstream payload deformatter and a decoding subsystem. The decoding subsystem is coupled to the bitstream payload deformatter and configured to decode at least a portion of a block of an encoded audio bitstream. The block includes a fill element with an identifier indicating a start of the fill element and fill data after the identifier. The fill data includes at least one flag identifying whether a base form of spectral band replication or an enhanced form of spectral band replication is to be performed on audio content of the block. The identifier is a three bit unsigned integer transmitted most significant bit first and having a value of 0x6.

公开(公告)号：US10770079B2

公开(公告)日：2020-09-08

申请号：US16016284

申请日：2018-06-22

Applicant: Fraunhofer-Gesellschaft zur Foerderung der angewandten Forschung e.V. ,  Dolby International AB

Inventor： Lars Villemoes ,  Per Ekstrand ,  Sascha Disch ,  Frederik Nagel ,  Stephan Wilde

IPC: G10L19/008 ,  G10L21/038 ,  G10L19/02 ,  G10L21/04

Abstract: An apparatus for processing an input audio signal relies on a cascade of filterbanks, the cascade having a synthesis filterbank for synthesizing an audio intermediate signal from the input audio signal, the input audio signal being represented by a plurality of first subband signals generated by an analysis filterbank, wherein a number of filterbank channels of the synthesis filterbank is smaller than a number of channels of the analysis filterbank. The apparatus furthermore has a further analysis filterbank for generating a plurality of second subband signals from the audio intermediate signal, wherein the further analysis filterbank has a number of channels being different from the number of channels of the synthesis filterbank, so that a sampling rate of a subband signal of the plurality of second subband signals is different from a sampling rate of a first subband signal of the plurality of first subband signals.

公开(公告)号：US20200027471A1

公开(公告)日：2020-01-23

申请号：US16484077

申请日：2018-03-19

Applicant: DOLBY INTERNATIONAL AB

Inventor： Lars Villemoes ,  Heiko Purnhagen ,  Per Ekstrand

IPC: G10L19/26 ,  G10L19/008 ,  G10L19/24

Abstract: A method for decoding an encoded audio bitstream is disclosed. The method includes receiving the encoded audio bit-stream and decoding the audio data to generate a decoded lowband audio signal. The method further includes extracting high frequency reconstruction metadata and filtering the decoded lowband audio signal with an analysis filterbank to generate a filtered lowband audio signal. The method also includes extracting a flag indicating whether either spectral translation or harmonic transposition is to be performed on the audio data and regenerating a highband portion of the audio signal using the filtered lowband audio signal and the high frequency reconstruction metadata in accordance with the flag.

公开(公告)号：US10403295B2

公开(公告)日：2019-09-03

申请号：US15240727

申请日：2016-08-18

Applicant: DOLBY INTERNATIONAL AB

Inventor： Kristofer Kjoerling ,  Per Ekstrand ,  Holger Hoerich

IPC: G10L19/00 ,  G10L19/02 ,  G10L19/07 ,  G10L19/24 ,  G10L21/038 ,  G10L19/028 ,  G10L19/06 ,  G10L19/093 ,  G10L19/26 ,  G10L19/16

Abstract: The present invention proposes a new method and a new apparatus for enhancement of audio source coding systems utilizing high frequency reconstruction (HFR). It utilizes a detection mechanism on the encoder side to assess what parts of the spectrum will not be correctly reproduced by the HFR method in the decoder. Information on this is efficiently coded and sent to the decoder, where it is combined with the output of the HFR unit.

公开(公告)号：US10304431B2

公开(公告)日：2019-05-28

申请号：US15849915

申请日：2017-12-21

Applicant: Dolby International AB

Inventor： Per Ekstrand ,  Lars Villemoes ,  Per Hedelin

IPC: G10L19/00 ,  G10H1/00 ,  G10L21/038 ,  G10L19/26 ,  G10H1/12 ,  G10L21/0388

Abstract: 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 Δf. The system further comprises a nonlinear processing unit (502) configured to determine a set of synthesis subband signals from the set of analysis subband signals using a transposition order P; wherein the set of synthesis subband signals comprises a portion of the set of analysis subband signals phase shifted by an amount derived from the transposition order P; and a synthesis filter bank (504) configured to generate the high frequency component of the signal from the set of synthesis subband signals; wherein the synthesis filter bank (504) has a frequency resolution of FΔf; with F being a resolution factor, with F≥1; wherein the transposition order P is different from the resolution factor F.

公开(公告)号：US20170345432A1

公开(公告)日：2017-11-30

申请号：US15677454

申请日：2017-08-15

Applicant: Dolby International AB

Inventor： Lars G. Liljeryd ,  Per Ekstrand ,  Fredrik Henn ,  Kristofer Kjoerling

IPC: G10L19/02 ,  G10L19/26 ,  G10L19/00 ,  G10L21/038

CPC classification number: G10L19/0208 ,  G10L19/0017 ,  G10L19/0204 ,  G10L19/26 ,  G10L19/265 ,  G10L21/038

Abstract: 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.

公开(公告)号：US09818417B2

公开(公告)日：2017-11-14

申请号：US15133410

申请日：2016-04-20

Applicant: DOLBY INTERNATIONAL AB

Inventor： Kristofer Kjoerling ,  Per Ekstrand ,  Holger Hoerich

IPC: G10L19/00 ,  G10L19/02 ,  G10L19/07 ,  G10L19/24 ,  G10L21/038 ,  G10L19/028 ,  G10L19/06 ,  G10L19/093 ,  G10L19/26 ,  G10L19/16

CPC classification number: G10L19/0208 ,  G10L19/0017 ,  G10L19/0204 ,  G10L19/028 ,  G10L19/06 ,  G10L19/07 ,  G10L19/093 ,  G10L19/167 ,  G10L19/24 ,  G10L19/26 ,  G10L19/265 ,  G10L21/038

Abstract: 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. Finally, the method includes combining the lowband portion and the regenerated highband portion to obtain a full bandwidth audio signal.