公开(公告)号：US5138568A

公开(公告)日：1992-08-11

申请号：US532435

申请日：1990-06-04

Applicant: Lajos Gazsi ,  Dieter Bruckmann

Inventor： Lajos Gazsi ,  Dieter Bruckmann

IPC: H03H17/02

CPC classification number: H03H17/0201

Abstract: An adaptive, recursive digital wave filter includes a transfer filter and a gradient filter each having a respective adaptor with a given coefficient. A method and circuit configuration for avoiding overflows in the filter include multiplying a signal emitted by the transfer filter to the gradient filter by a scaling factor being equal to the difference between 1 and the amount of the given coefficient.

Abstract translation: 自适应递归数字滤波器包括传送滤波器和梯度滤波器，每个具有给定系数的相应适配器。 用于避免滤波器中的溢出的方法和电路配置包括将由传输滤波器发射的信号与梯度滤波器相乘，比例因子等于1与给定系数的量之间的差。

公开(公告)号：US4095276A

公开(公告)日：1978-06-13

申请号：US751548

申请日：1976-12-16

Applicant: Gerard Verkroost ,  Hans-Jurgen Butterweck

Inventor： Gerard Verkroost ,  Hans-Jurgen Butterweck

IPC: H03H17/02 ,  G06F15/34 ,  H03H7/10

CPC classification number: H03H17/0201

Abstract: A digital signal processing arrangement including a wave digital filter having quantizing means for limiting the signal waves present to a predetermined word length by means of controlled rounding. "Controlled rounding" means that a limit-cycle-free output signal is obtained when a constant input signal is present. If the outgoing signal waves from the N-port adaptor are equal to b.sub.o (j,k), and the signal waves applied to the adaptor are equal to a(j,k), b(j,k) is equal the desired and quantized value of b.sub.o (j,k), where j represents the number of the port, then the process of controlled rounding quantizes b.sub.o (j,k) in such a way that ##EQU1## Here the c(i,j) represent constant coefficients, and r the number of independent information signal waves.

公开(公告)号：US11735198B2

公开(公告)日：2023-08-22

申请号：US17461092

申请日：2021-08-30

Applicant: Dolby International AB

Inventor： Per Ekstrand

IPC: G10L19/00 ,  G10L21/00 ,  G06F17/10 ,  H03H17/02 ,  G10L19/02 ,  G10L19/26 ,  H04R3/04 ,  G06F17/11 ,  G10L19/008 ,  H04S7/00

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

Abstract: An apparatus and method are disclosed for processing an audio signal. The apparatus includes an input interface, a digital filterbank having an analysis part and a synthesis part, a first phase shifter, a spectral envelope adjuster, a second phase shifter, and an output interface. The first phase shifter and the second phase shifter reduce a complexity of the digital filterbank, which includes both analysis and synthesis filters that are complex-exponential modulated versions of a prototype filter.

公开(公告)号：US20180166089A1

公开(公告)日：2018-06-14

申请号：US15676891

申请日：2017-08-14

Applicant: Vios Medical Singapore Pte. Ltd.

Inventor： Carlos A. Ricci ,  Vladimir V. Kovtun

IPC: G10L19/26 ,  H03H17/02

CPC classification number: H03H17/0248 ,  A61B5/0432 ,  G01V1/28 ,  G01V2210/43 ,  G10L19/26 ,  H03H17/0201 ,  H03H17/0266

Abstract: A system and method for representing quasi-periodic waveforms, for example, representing a plurality of limited decompositions of the quasi-periodic waveform. Each decomposition includes a first and second amplitude value and at least one time value. In some embodiments, each of the decompositions is phase adjusted such that the arithmetic sum of the plurality of limited decompositions reconstructs the quasi-periodic waveform. Data-structure attributes are created and used to reconstruct the quasi-periodic waveform. Features of the quasi-periodic wave are tracked using pattern-recognition techniques. The fundamental rate of the signal (e.g., heartbeat) can vary widely, for example by a factor of 2-3 or more from the lowest to highest frequency. To get quarter-phase representations of a component (e.g., lowest frequency “rate” component) that varies over time (by a factor of two to three) many overlapping filters use bandpass and overlap parameters that allow tracking the component's frequency version on changing quarter-phase basis.

公开(公告)号：US09918164B2

公开(公告)日：2018-03-13

申请号：US15441652

申请日：2017-02-24

Applicant: Dolby International AB

Inventor： Per Ekstrand

IPC: G10L19/00 ,  H04R3/04 ,  G10L21/00 ,  G06F17/10 ,  H03H17/02 ,  G10L19/02 ,  G10L19/26 ,  G06F17/11 ,  G10L19/008 ,  H04S7/00

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 an audio signal. The apparatus includes an analysis filter bank, a high frequency reconstructor or parametric stereo processor, 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 or parametric stereo processor 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 to reduce a complexity of the filter bank.

公开(公告)号：US09865275B2

公开(公告)日：2018-01-09

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 ,  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 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.

公开(公告)号：US09779748B2

公开(公告)日：2017-10-03

申请号：US14810174

申请日：2015-07-27

Applicant: Dolby International AB

Inventor： Per Ekstrand

IPC: G06F17/10 ,  G10L19/26 ,  G10L21/00 ,  H03H17/02 ,  G10L19/02 ,  H04R3/04 ,  G06F17/11

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.

公开(公告)号：US09760535B1

公开(公告)日：2017-09-12

申请号：US15608175

申请日：2017-05-30

Applicant: Dolby International AB

Inventor： Per Ekstrand

IPC: G06F7/00 ,  G06F17/11 ,  G10L19/02 ,  G10L19/26 ,  H03H17/02 ,  H04R3/04

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 an audio signal. The apparatus includes a high frequency reconstructor or parametric stereo processor, a phase shifter, and a synthesis filter bank. The high frequency reconstructor or parametric stereo processor generates modified complex-valued subband samples. A phase shifter unshifts a phase of the modified complex-valued subband samples by an amount. The synthesis filter bank receives the modified complex valued subband samples and generates time domain output audio samples.

公开(公告)号：US20170238094A1

公开(公告)日：2017-08-17

申请号：US15586480

申请日：2017-05-04

Applicant: Dolby International AB

Inventor： Per Ekstrand

IPC: H04R3/04 ,  H04S7/00 ,  G10L19/26 ,  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 an audio signal are disclosed. The apparatus includes an analysis filter bank, a high frequency reconstructor or a parametric stereo processor, 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 or parametric stereo processor 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.

公开(公告)号：US20170069334A1

公开(公告)日：2017-03-09

申请号：US15353860

申请日：2016-11-17

Applicant: Dolby International AB

Inventor： Per Ekstrand

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: 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。