Method for controlling level of digital audio signal

Abstract

The invention discloses a method for controlling the level of a digital audio signal. The method mainly comprises the following steps: searching the maximum sample absolute value and the average sample absolute value of a current-frame audio signal by taking each frame of audio signal as the unit, comparing the maximum sample absolute value of the current-frame audio signal with the maximum sample absolute value of a previous-frame audio signal, judging the signal strength change tendency so as to obtain different first-order recursive smooth filter parameters, adjusting the maximum sample absolute value of the current-frame audio signal, obtaining an expected gain by utilizing an expected sample absolute value, and finally, obtaining a practical gain adjustment value of the current-frame audio signal in combination with a first-order recursive smooth filtering theory. According to the invention, the strength change of a signal source is judged according to the maximum sample absolute value, the sample absolute average value, the expected level and the pre-set parameters of a voice-frame signal; configuration parameters are updated; the gain value is obtained in combination with first-order smooth filtering; therefore, the algorithm complexity is reduced; the self adaptability of an algorithm is improved; and distortion rate and volume requirements of output audio signals can be satisfied.

Description

technical field [0001] The invention relates to a level control method of a digital audio signal. Background technique [0002] ALC technology is mainly used in audio signal processing, which can optimize the signal level and adjust to the best value, maintain a higher magnification factor when the input signal level is low, and maintain a higher magnification factor when the input signal level is high . [0003] Traditional digital audio signal automatic level control is implemented by analog circuits, and the performance is largely limited by the circuit itself, such as response time and dynamic range. The ALC system based on digital signal processing (DSP, Digital Signal Processing) avoids the influence of the control circuit, has flexible design, high precision, and large control range, which effectively improves the performance of automatic level control. [0004] The current ALC algorithms are all based on energy comparison, and the gain value of the current frame is...

AI Technical Summary

Problems solved by technology

[0005] The change of the audio signal source is unpredictable and may include many situations: long-term large signal or small signal, long-term extremely small signal after a large signal, alternating large and small signals but small energy difference, alternating large and small signals with large energy difference, etc. etc., existing methods cannot obtain good performance requirements according to changes in application scenarios; audio signal ALC technology must not only meet the requirements of dynamic changes in signal levels, but also be as fidelity as possible, and existing methods are difficult to balance the two according to scenarios. relation

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