公开(公告)号：US20250087226A1

公开(公告)日：2025-03-13

申请号：US18958177

申请日：2024-11-25

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：US12211513B2

公开(公告)日：2025-01-28

申请号：US18508415

申请日：2023-11-14

Applicant: DOLBY INTERNATIONAL AB

Inventor： Kristofer Kjoerling ,  Lars Villemoes ,  Heiko Purnhagen ,  Per Ekstrand

IPC: G10L21/0388 ,  G10L19/008 ,  G10L19/02 ,  H04S3/00

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. The high frequency regeneration is performed as a post-processing operation with a delay of 3010 samples per audio channel.

公开(公告)号：US12101613B2

公开(公告)日：2024-09-24

申请号：US17913156

申请日：2021-03-19

Applicant: Dolby International AB ,  Dolby Laboratories Licensing Corporation

Inventor： Per Ekstrand ,  Yuxing Hao ,  Xuemei Yu

IPC: H04R3/04

CPC classification number: H04R3/04 ,  H04R2430/01 ,  H04R2430/03

Abstract: A method of audio processing includes generating harmonics in a hybrid complex quadrature mirror filter domain. Generating the harmonics may include multiplication, using a feedback delay loop, and dynamic compression. The harmonics may be generated based on one or more hybrid sub-bands of the complex transform domain signal.

公开(公告)号：US20240212695A1

公开(公告)日：2024-06-27

申请号：US18601546

申请日：2024-03-11

Applicant: Dolby International AB

Inventor： Kristofer Kjoerling ,  Lars Villemoes ,  Heiko Purnhagen ,  Per Ekstrand

IPC: G10L19/02 ,  G10L19/16 ,  G10L19/26 ,  H03M7/30

CPC classification number: G10L19/02 ,  G10L19/167 ,  G10L19/26 ,  H03M7/6005 ,  H03M7/6011

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：US11894002B2

公开(公告)日：2024-02-06

申请号：US18048810

申请日：2022-10-21

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 ,  G10L21/04 ,  G10L19/02

CPC classification number: G10L19/008 ,  G10L19/0204 ,  G10L21/038 ,  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：US11823695B2

公开(公告)日：2023-11-21

申请号：US18178412

申请日：2023-03-03

Applicant: Dolby International AB

Inventor： Kristofer Kjoerling ,  Lars Villemoes ,  Heiko Purnhagen ,  Per Ekstrand

IPC: G10L19/18 ,  G10L21/038

CPC classification number: G10L19/18 ,  G10L21/038

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. The high frequency regeneration is performed as a post-processing operation with a delay of 3010 samples per audio channel.

公开(公告)号：US11810592B2

公开(公告)日：2023-11-07

申请号：US18113406

申请日：2023-02-23

Applicant: Dolby International AB

Inventor： Kristofer Kjoerling ,  Lars Villemoes ,  Heiko Purnhagen ,  Per Ekstrand

IPC: G10L21/0388 ,  G10L19/008 ,  H04S3/00 ,  G10L19/02 ,  G10L19/24

CPC classification number: G10L21/0388 ,  G10L19/008 ,  G10L19/02 ,  H04S3/008

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. The high frequency regeneration is performed as a post-processing operation with a delay of 3010 samples per audio channel.

公开(公告)号：US11646040B2

公开(公告)日：2023-05-09

申请号：US17973397

申请日：2022-10-25

Applicant: DOLBY INTERNATIONAL AB

Inventor： Kristofer Kjoerling ,  Lars Villemoes ,  Heiko Purnhagen ,  Per Ekstrand

IPC: G10L19/02 ,  G10L19/16 ,  G10L19/26 ,  H03M7/30

CPC classification number: G10L19/02 ,  G10L19/167 ,  G10L19/26 ,  H03M7/6005 ,  H03M7/6011

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：US11594234B2

公开(公告)日：2023-02-28

申请号：US17954179

申请日：2022-09-27

Applicant: DOLBY INTERNATIONAL AB

Inventor： Per Ekstrand ,  Lars Villemoes

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

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：US11591657B2

公开(公告)日：2023-02-28

申请号：US17201107

申请日：2021-03-15

Applicant: Dolby International AB

Inventor： Lars Villemoes ,  Per Ekstrand

IPC: C12Q1/6883 ,  G10L21/038 ,  G10L19/26 ,  G10L19/02 ,  G10L19/022

Abstract: 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. The system comprises an analysis filter bank (501) comprising an analysis transformation unit (601) having a frequency resolution of Δf; and an analysis window (611) having a duration of DA; the analysis filter bank (501) being configured to provide a set of analysis subband signals from the low frequency component of the signal; a nonlinear processing unit (502, 650) configured to determine a set of synthesis subband signals based on a portion of the set of analysis subband signals, wherein the portion of the set of analysis subband signals is phase shifted by a transposition order T; and a synthesis filter bank (504) comprising a synthesis transformation unit (602) having a frequency resolution of QΔf; and a synthesis window (612) having a duration of DS; the synthesis filter bank (504) being configured to generate the high frequency component of the signal from the set of synthesis subband signals; wherein Q is a frequency resolution factor with Q≥1 and smaller than the transposition order T; and wherein the value of the product of the frequency resolution Δf and the duration DA of the analysis filter bank is selected based on the frequency resolution factor Q.