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    Complex exponential modulated filter bank for high frequency reconstruction
    62.
    发明授权
    Complex exponential modulated filter bank for high frequency reconstruction 有权
    用于高频重建的复指数调制滤波器组

    公开(公告)号：US09583118B1

    公开(公告)日：2017-02-28

    申请号：US15353860

    申请日：2016-11-17

    Applicant: Dolby International AB

    Inventor： Per Ekstrand

    IPC: G10L19/26 ,  G10L19/02 ,  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: An apparatus and method are disclosed for filtering and performing high frequency reconstruction of an audio signal. The apparatus includes an analysis filter bank, a high frequency reconstructor, and a synthesis filter bank. The analysis filterbank receives real-valued time domain input audio samples and generates complex valued subband samples. The high frequency reconstructor modifies at least some of the complex valued subband samples. The synthesis filter bank receives the modified complex valued subband samples and generates time domain output audio samples. The analysis filter bank comprises analysis filters that are complex exponential modulated versions of a prototype filter with an arbitrary phase shift.

    Abstract translation: 公开了用于滤波和执行音频信号的高频重建的装置和方法。 该装置包括分析滤波器组，高频重建器和合成滤波器组。 分析滤波器组接收实时的时域输入音频样本并生成复值子带样本。 高频重建器修改至少一些复值子带样本。 合成滤波器组接收经修改的复值子带样本并生成时域输出音频样本。 分析滤波器组包括分析滤波器，其是具有任意相移的原型滤波器的复指数调制版本。

    Spectral translation/folding in the subband domain
    63.
    发明授权
    Spectral translation/folding in the subband domain 有权
    频域翻译/折叠在子带域

    公开(公告)号：US09548059B2

    公开(公告)日：2017-01-17

    申请号：US14964836

    申请日：2015-12-10

    Applicant: Dolby International AB

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

    IPC: G06F17/00 ,  G10L19/02 ,  G10L21/038 ,  G10L19/26 ,  G10L19/00

    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.

    Abstract translation: 本发明涉及使用频率转换或折叠或其组合来改进高频重建（HFR）技术的新方法和装置。 所提出的发明适用于音频源编码系统，并提供显着降低的计算复杂度。 这通过在子带域中的频率转换或折叠来实现，优选地与同一域中的频谱包络调整集成。 进一步提出了不一致保卫带滤波的概念。 所提出的发明提供了一种在语音和自然音频编码应用中有用的低复杂度，中等质量的HFR方法。

    Low Delay Modulated Filter Bank
    64.
    发明申请
    Low Delay Modulated Filter Bank 有权
    低延迟调制滤波器组

    公开(公告)号：US20160329062A1

    公开(公告)日：2016-11-10

    申请号：US15214694

    申请日：2016-07-20

    Applicant: Dolby International AB

    Inventor： Per Ekstrand ,  Nicholas Luke Appleton

    IPC: G10L19/26 ,  G10L19/02

    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 digital filter banks, as well as to methods and systems for the design of such filter banks. In particular, the document discloses a method comprising accessing a time-domain audio signal and applying a first filter bank to the time-domain audio signal, thereby producing a first plurality of subbands of frequency-domain audio data representative of at least a part of the audio signal. The filter bank comprises an decimated modulated filter bank obtained from an asymmetric prototype filter. The method further comprises applying a second filter bank to at least a first subband of the first plurality of subbands of frequency-domain audio data, thereby producing a second plurality of subbands of frequency-domain audio data representative of at least a part of the audio signal. The second modulated filter bank comprises an asymmetric modulated filter bank which includes no decimation. The method further comprises outputting at least the second plurality of subbands of frequency domain audio data.

    Abstract translation: 该文件涉及调制数字滤波器组，以及用于设计这种滤波器组的方法和系统。 特别地，本文件公开了一种方法，包括访问时域音频信号并将第一滤波器组应用于时域音频信号，从而产生频域音频数据的第一多个子带，其代表至少部分 音频信号。 滤波器组包括从不对称原型滤波器获得的抽取调制滤波器组。 该方法还包括将第二滤波器组应用于频域音频数据的第一多个子带中的至少第一子带，从而产生表示音频的至少一部分的频域音频数据的第二多个子带 信号。 第二调制滤波器组包括不包括抽取的不对称调制滤波器组。 该方法还包括至少输出频域音频数据的第二多个子带。

    Efficient Combined Harmonic Transposition
    65.
    发明申请
    Efficient Combined Harmonic Transposition 有权

    公开(公告)号：US20160035329A1

    公开(公告)日：2016-02-04

    申请号：US14882559

    申请日：2015-10-14

    Applicant: Dolby International AB

    Inventor： Per Ekstrand ,  Lars Villemoes ,  Per Hedelin

    IPC: G10H1/00 ,  G10L21/038 ,  G10H1/12

    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.

    Low Delay Modulated Filter Bank
    67.
    发明申请
    Low Delay Modulated Filter Bank 有权

    公开(公告)号：US20150333733A1

    公开(公告)日：2015-11-19

    申请号：US14807554

    申请日：2015-07-23

    Applicant: Dolby International AB

    Inventor： Per Ekstrand

    IPC: 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.

    SYSTEM AND METHOD FOR REDUCING LATENCY IN TRANSPOSER-BASED VIRTUAL BASS SYSTEMS
    68.
    发明申请
    SYSTEM AND METHOD FOR REDUCING LATENCY IN TRANSPOSER-BASED VIRTUAL BASS SYSTEMS 有权
    用于减少基于传输器的虚拟低音系统中的延迟的系统和方法

    公开(公告)号：US20150312676A1

    公开(公告)日：2015-10-29

    申请号：US14433983

    申请日：2013-09-27

    Applicant: DOLBY INTERNATIONAL AB

    Inventor： Per Ekstrand

    IPC: H04R3/04 ,  H04R1/22 ,  G10L21/038

    CPC classification number: H04R3/04 ,  G10H1/16 ,  G10H1/20 ,  G10H2210/245 ,  G10H2250/235 ,  G10L21/038 ,  H04R1/22 ,  H04R2430/03

    Abstract: 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.

    Abstract translation: 虚拟低音处理系统中的延迟降低系统在音频信号的低频分量上执行谐波转置，以产生表示音频信号的谐波的转置数据。 系统使用大于2的基本转置因子，并响应于使用不对称分析和综合窗口的正向和反向变换阶段确定的频域值产生谐波。 该系统通过具有滤波器系数截短的奈奎斯特滤波器的分析滤波器组将虚拟低音信号与延迟的宽带音频信号组合。 当与音频信号组合时，虚拟低音信号可能延迟延迟的宽带音频信号，以进一步减少由谐波转置引起的等待时间。 虚拟低音输入信号可以从先前的混合滤波器组级的CQMF分析滤波器组直接路由，以避免与奈奎斯特滤波器组相关联的延迟。

    Enhancing performance of spectral band replication and related high frequency reconstruction coding
    69.
    发明授权
    Enhancing performance of spectral band replication and related high frequency reconstruction coding 有权
    提高频带复制性能和相关高频重构编码

    公开(公告)号：US08738369B2

    公开(公告)日：2014-05-27

    申请号：US13973193

    申请日：2013-08-22

    Applicant: Dolby International AB

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

    IPC: G10L19/00 ,  G10L19/14

    CPC classification number: G10L19/028 ,  G10L19/035 ,  G10L19/06 ,  G10L19/26 ,  G10L19/265 ,  G10L21/038 ,  G10L25/18

    Abstract: 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.

    Abstract translation: 本发明提出了利用高频重建（HFR）来增强源编码系统的新方法和装置。 它通过自适应噪声层加法解决了重构高频带中噪声含量不足的问题。 它还通过限制不需要的噪声，包络调整放大因子的插值和平滑来介绍新的增强性能的方法。 本发明适用于语音编码和自然音频编码系统。

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