Signal level limiter

During the restoration process, rounding and overflow errors may cause audible distortions due to signal clipping (described as "pops"). Signal level limiter is a module that prevents clipping by limiting the maximum level of the signal. The threshold value of the limiter is the only parameter set by the user (from -90 to 0 dB). This threshold is converted from decibels to linear value. If the absolute value of signal amplitude (normalized to range from -1 to 1) is below the threshold multiplied by 0.9, the signal is not altered, otherwise the signal is smoothed using the hyperbolic tangent as a threshold function.

It is recommended to use the default threshold value of 0 dB and to change it only if the clipping still occurs.

The signal level limiter is used by default at the output of speech band equalizer, noise gate and clipping restoration modules.

If the signal is already clipped, the clipping restoration module should be used.