Audio-peak limiting in slow and fast stages

一种音频信号、可变的技术，应用在限制幅度、放大的控制、数字/编码信号限制幅度等方向，能够解决改变音频频谱特性和感知音色等问题

Active Publication Date: 2009-08-05
DOLBY LAB LICENSING CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Multi-band limiting is often used to achieve a large amount of limiting, but has the potential to significantly alter the spectral characteristics and perceived timbre of the audio

Method used

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  • Audio-peak limiting in slow and fast stages
  • Audio-peak limiting in slow and fast stages
  • Audio-peak limiting in slow and fast stages

Examples

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Embodiment Construction

[0055] Figure 3a A two-stage audio peak limiter 102 according to one embodiment of the invention is shown. The peak limiter 102 includes a slow gain reducer 202 and a fast gain reducer 204 . Slow gain reducer 202 receives threshold signal 201 and audio signal 101 as input and generates intermediate audio signal 203 . Fast gain reducer 204 receives intermediate audio signal 203 and threshold signal 201 as input and generates audio signal 103 as output.

[0056] Peak limiter 102 operates as follows: Slow gain reducer 202 receives one or more audio channels with input signal 101 and with threshold signal 201 receives a signal representing the threshold of the peak limiter. The absolute peak of the audio channel may exceed the peak limiter threshold.

[0057] The fast gain reducer 204 outputs the signal 103 , the possibly peak-limited audio channel of the input audio signal 101 . The peak limiter 102 limits (gain reduces) any absolute peaks in the input audio signal 101 that ...

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Abstract

A method and apparatus for limiting the absolute magnitude of an audio signal. The method may include firstly variable-gain reducing the gain of an audio signal, and then secondly variable-gain reducing the gain of the audio signal faster than the first variable-gain reduction, thereby limiting the absolute magnitude of the audio signal to a threshold. The first variable-gain reduction may include variable-gain reducing the gain of the audio signal in a first stage, and the second variable-gain reduction may include variable-gain reducing the gain of the audio signal in a second stage that reduces the gain faster than the first stage. The second variable-gain reduction may include delaying the audio signal, finding a peak among the delayed audio signal, calculating a fast gain from a found peak, and modifying the delayed audio signal with the calculated fast gain.

Description

technical field [0001] The present invention relates generally to audio digital signal processing and audio peak limiting. More specifically, the invention relates to variable gain reduction of an audio signal to limit the audio signal to a threshold value. Background technique [0002] Audio peak limiting has been a fundamental part of audio production, transmission and reproduction for 50 years. Such as figure 1 As shown, as the most basic form, the audio peak limiter provides an input-to-output signal level characteristic satisfying that the output voltage is equal to the input voltage until the peak limiter threshold. For an input audio signal whose amplitude is greater than the threshold, the output audio signal level is constrained (limited) not to exceed the threshold. As with other audio dynamic gain control systems, the method of modifying the gain has a significant impact on the nature and audibility of artifacts introduced into the output audio signal. [0003...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H03G7/00H03G11/00
CPCH03G7/007H03G11/008
Inventor M·J·斯密斯尔思B·G·克罗克特D·S·迈克格拉斯
Owner DOLBY LAB LICENSING CORP
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