US 6,785,655 B1 · Method for independent dynamic range control

Abstract

Different dynamic range control values are applied to the 2-channel and m-channel outputs without repeating the inverse transform or the windowing of the audio samples. First, m-channel dynamic range control values are applied to audio samples in the frequency domain (“frequency samples” or “frequency coefficients”). The frequency samples are then inverse transformed to generate audio samples in the time domain (“time samples”) and windowed to generate windowed time samples. The windowed time samples are saved and the 2-channel dynamic range control values are applied to the windowed time samples. 2-channel dynamic range control values include 2-channel scale factors that, when multiplied with groups of the windowed time samples, at least partially remove the effects of windowing and the m-ch dynamic range control values applied in the frequency domain and readjust the dynamic range for 2-channel output. Thus, a set of windowed time samples under m-channel dynamic range control values and a set of windowed time samples under 2-channel dynamic range control values are generated without repeating the inverse transform or the windowing, which are computational and/or memory intensive.

Claims34

Dependent claims

A method for controlling the dynamic range of audio samples, comprising:

determining a first dynamic range final scale;
determining a second dynamic range final scale;
determining a first set of scale factors from the first dynamic range final scale and the second dynamic range final scale;
multiplying frequency samples with the second dynamic range final scale to form multiplied frequency samples;
inverse transforming the multiplied frequency samples to form time samples;
windowing the time samples to form windowed samples;
multiplying the windowed samples with the first set of scale factors to form multiplied windowed samples and thereby at least partially removing effects of the windowing and the multiplication of the second dynamic range final scale;
and
downmixing the multiplied windowed samples from the channels of input to the channels of output to form downmixed windowed samples.

6 more elements

A computer-readable medium carrying a program for controlling the dynamic range of audio samples comprising:

a first instruction to determine a first dynamic range final scale;
a second instruction to determine a second dynamic range final scale;
a third instruction to determine a first set of scale factors from the first dynamic range final scale and the second dynamic range final scale;
a fourth instruction to multiply frequency samples with the second dynamic range final scale to form multiplied frequency samples;
a fifth instruction to inverse transform the multiplied frequency samples to form time samples;
a sixth instruction to window the inverse transformed frequency samples to form windowed samples;
a seventh instruction to multiply the windowed samples with the first set of scale factors to form multiplied windowed samples and thereby at least partially removing effects of the windowing and the multiplication of the second dynamic range final scale;
and
an eighth instruction to downmix the multiplied windowed samples from the channels of input to the channels of output to form downmixed windowed samples.

6 more elements

Dependencies are inferred from the claim text.

Method for independent dynamic range control

Life of this patent

Method for independent dynamic range control

Life of this patent

Abstract

Claims34