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    Oversampling in a combined transposer filterbank
    104.
    发明授权
    Oversampling in a combined transposer filterbank 有权
    在组合式转换器滤波器组中进行过采样

    公开(公告)号：US09384750B2

    公开(公告)日：2016-07-05

    申请号：US14505739

    申请日：2014-10-03

    Applicant: Dolby International AB

    Inventor： Lars Villemoes ,  Per Ekstrand

    IPC: H03G5/00 ,  G10L19/26 ,  G10L21/038

    CPC classification number: G10L21/038 ,  G10L19/0204 ,  G10L19/022 ,  G10L19/265

    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.

    Abstract translation: 本发明涉及音频信号的编码，特别涉及包括频域谐波转移器的高频重构方法。 描述了用于从信号的低频分量产生信号的高频分量的系统和方法。 该系统包括分析滤波器组（501），其包括频率分辨率为＆Dgr; f的分析变换单元（601） 和具有DA持续时间的分析窗口（611）; 所述分析滤波器组（501）被配置为从所述信号的低频分量提供一组分析子带信号; 非线性处理单元（502,650），被配置为基于所述一组分析子带信号来确定一组合成子带信号，其中所述一组分析子带信号的所述部分被相移一个换位阶数T; f）具有频率分辨率为Q＆Dgr; f的合成变换单元（602）的合成滤波器组（504） 和具有DS持续时间的合成窗口（612）; 所述合成滤波器组（504）被配置为从所述一组合成子带信号中产生所述信号的高频分量; 其中Q是具有Q≥1且小于置换次数T的频率分辨率因子; 并且其中基于频率分辨率因子Q选择频率分辨率＆Dgr; f的乘积值和分析滤波器组的持续时间DA。

    Low delay modulated filter bank
    105.
    发明授权
    Low delay modulated filter bank 有权

    公开(公告)号：US09318118B2

    公开(公告)日：2016-04-19

    申请号：US14807554

    申请日：2015-07-23

    Applicant: Dolby International AB

    Inventor： Per Ekstrand

    IPC: G10L21/00 ,  G06F17/10 ,  H03H17/02

    CPC classification number: H04R3/04 ,  G06F17/10 ,  G06F17/11 ,  G10L19/008 ,  G10L19/0204 ,  G10L19/0208 ,  G10L19/26 ,  G10L19/265 ,  G10L21/00 ,  H03H17/0201 ,  H03H17/0248 ,  H03H17/0266 ,  H03H17/0275 ,  H03H17/0294 ,  H03H2017/0297 ,  H04S7/307

    Abstract: 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. The method offers improvements for various types of digital equalizers, adaptive filters, multiband companders and spectral envelope adjusting filter banks used in high frequency reconstruction (HFR) or parametric stereo systems.

    Efficient Combined Harmonic Transposition
    107.
    发明申请
    Efficient Combined Harmonic Transposition 有权
    有效的组合谐波转置

    公开(公告)号：US20150149158A1

    公开(公告)日：2015-05-28

    申请号：US14614172

    申请日：2015-02-04

    Applicant: DOLBY INTERNATIONAL AB

    Inventor： Per Ekstrand ,  Lars Villemoes ,  Per Hedelin

    IPC: G10L19/26

    CPC classification number: G10H1/0091 ,  G10H1/125 ,  G10H2210/311 ,  G10L19/265 ,  G10L21/038 ,  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.

    Abstract translation: 本文件涉及利用用于高频重构（HFR）的谐波转置方法的音频编码系统以及数字效果处理器，例如， 所谓的兴奋剂，其中谐波失真的产生增加处理信号的亮度。 特别地，描述了被配置为从信号的低频分量产生信号的高频分量的系统。 该系统可以包括分析滤波器组（501），其被配置为从信号的低频分量提供一组分析子带信号; 其中所述一组分析子带信号包括至少两个分析子带信号; 其中所述分析滤波器组（501）的频率分辨率为＆Dgr; f。 该系统还包括非线性处理单元（502），其被配置为使用转置顺序P从所述一组分析子带信号中确定一组合成子带信号; 其中所述合成子带信号集合包括所述一组分析子带信号的一部分，所述分析子带信号的相位偏移量是从所述置换顺序P导出的量; 以及合成滤波器组（504），被配置为从所述合成子带信号的集合生成所述信号的高频分量; 其中所述合成滤波器组（504）具有F＆Dgr; f的频率分辨率; F为分辨率因子，F≥1; 其中转置次数P与分辨率因子F不同

    Integration of high frequency audio reconstruction techniques
    108.
    发明授权
    Integration of high frequency audio reconstruction techniques 有权

    公开(公告)号：US12300263B2

    公开(公告)日：2025-05-13

    申请号：US18982152

    申请日：2024-12-16

    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.

    Integration of high frequency reconstruction techniques with reduced post-processing delay
    109.
    发明授权
    Integration of high frequency reconstruction techniques with reduced post-processing delay 有权

    公开(公告)号：US12296028B2

    公开(公告)日：2025-05-13

    申请号：US18982254

    申请日：2024-12-16

    Applicant: DOLBY INTERNATIONAL AB

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

    IPC: G10L19/18 ,  A61B5/055 ,  A61K49/10 ,  G01R33/56 ,  G01R33/563 ,  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.

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