Audio Signal Dynamic Range Compression
AssigneeGuoguang Electric Company Limited
InventorYuli You
Life of this patent
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Abstract
Provided are systems, methods and techniques for compressing the dynamic range of an audio signal. In one implementation: an input audio signal is obtained, and a time-varying gain signal is provided based on it and a desired output range. The time-varying preliminary gain signal is then applied to the input audio signal to provide an output audio signal. Provision of the time-varying gain signal involves lowpass filtering a signal that is based on the input audio signal, using an attack gain-response time and a release gain-response time as filtering parameters, with the attack gain-response time decreased and the release gain-response time increased in response to a determination that a transient is occurring in the input audio signal.
Claims20
A method of compressing the dynamic range of an audio signal, comprising:
- (a) obtaining an input audio signal;
- (b) providing a time-varying gain signal based on the input audio signal and a desired output range;
- and
- (c) applying the time-varying gain signal to the input audio signal to provide an output audio signal,
- wherein said step (b) includes:
- (i) determining and providing an indication of whether a transient is occurring in the input audio signal, (ii) providing an attack gain-response time and a release gain-response time based on the indication of whether a transient is occurring in the input audio signal, and (iii) lowpass filtering a signal that is based on the input audio signal, using the attack gain-response time and the release gain-response time as filtering parameters, and
- wherein the attack gain-response time is decreased and the release gain-response time is increased in response to a determination that a transient is occurring in the input audio signal.
A system for compressing the dynamic range of an audio signal, comprising:
- (a) a system input that accepts an input audio signal;
- (b) an adaptive gain-generation module having an input coupled to the system input and an output that provides a time-varying gain signal based on the input audio signal and a desired output range;
- (c) a multiplier having a first input coupled to the system input, a second input coupled to the output of the adaptive gain-generation module, and an output,
- wherein the adaptive gain-generation module includes a gain computer and a level detector having an input and an output,
- wherein the level detector includes:
- (i) an attack-detection module that determines and provides an indication of whether a transient is occurring in the input audio signal, (ii) a gain-response-time generator that provides an attack gain-response time and a release gain-response time based on the indication of whether a transient is occurring in the input audio signal that has been provided by the attack-detection module, and (iii) a filter that lowpass filters a signal that has been input into the level detector, using the attack gain-response time and the release gain-response time as filtering parameters, and
- wherein the gain-response-time generator shortens the attack gain-response time and increases the release gain-response time in response to a transient detection by the attack-detection module.
Dependencies are inferred from the claim text.