Audiokinetic

Wwise Peak Limiter

(See the Wwise Peak Limiter Properties below.)

The Wwise Peak Limiter plug-in effect controls the dynamic range of audio signals. It does this by weakening parts of the audio signal that briefly exceed a pre-defined threshold value as calculated with peak-based detection. To carry out this process, it uses a look-ahead time to check for signal peaks. When the audio signal returns to an acceptable value, the Peak Limiter stops weakening it.

	Caution
	The look-ahead time introduces latency into the output signal.

You can use the Wwise Peak Limiter plug-in effect to limit the overall dynamic range of an audio signal, and therefore increase the overall amount by which the signal can be amplified. As well, you can also use it to even out the gain of multiple audio signals, and prevent clipping. Overall, this should give an impression of increased intelligibility and punch.

	Tip
	To reduce clipping in your overall project, apply the Peak Limiter to the Master Audio Bus.

The following graph represents an audio signal with a peak, x. If the Peak Limiter is not used, peak x will be heard as a loud, sudden noise. Line c on the graph shows the approximate limit of the audio signal. By setting the Peak Limiter to a threshold at line b, you can eliminate the worst of the excess volume without adversely affecting the original audio signal.

A ratio factor determines the extent of the dynamic compression used by the Peak Limiter when the input is above the threshold. For example, a ratio of 4 means that for every 4 dB the input signal is above the threshold, only 1 dB will be observed in the output signal above the threshold.

	General remarks on Wwise dynamic processing plug-ins
There is no interpolation of ratio control (RTPC parameter) for Wwise Compressor, Wwise Expander, or Wwise Peak Limiter. Changing this parameter during playback may lead to signal discontinuities on very clean signals. Sounds with DC offset may alter results of compression/expansion because the sidechain detection algorithm will be offset considerably. DC offset should be removed prior to use in Wwise. The Compressor, Expander, and Peak limiter are non-linear audio processes. This means that order of processing is important. For example, results will be different if you apply gain before or after the Effect. For the first audio buffers, the processing algorithms are said to be in non-steady state. Because the estimated signal power operated by the side chain has no knowledge of the past, its estimate of signal power may be erroneous for a short period of time (but only if the Compressor is already engaged at the start of the sound). A solution to this (if it's a problem at all) is to start the Compressor with a ratio of 1 and shortly after bring it to the desired value. If the Compressor applies some gain reduction and is suddenly bypassed, a signal discontinuity will be heard. A potential solution is to gradually bring the ratio to 1 prior to bypassing the Effect.

General remarks on Wwise dynamic processing plug-ins

There is no interpolation of ratio control (RTPC parameter) for Wwise Compressor, Wwise Expander, or Wwise Peak Limiter. Changing this parameter during playback may lead to signal discontinuities on very clean signals.
Sounds with DC offset may alter results of compression/expansion because the sidechain detection algorithm will be offset considerably. DC offset should be removed prior to use in Wwise.
The Compressor, Expander, and Peak limiter are non-linear audio processes. This means that order of processing is important. For example, results will be different if you apply gain before or after the Effect.
For the first audio buffers, the processing algorithms are said to be in non-steady state. Because the estimated signal power operated by the side chain has no knowledge of the past, its estimate of signal power may be erroneous for a short period of time (but only if the Compressor is already engaged at the start of the sound). A solution to this (if it's a problem at all) is to start the Compressor with a ratio of 1 and shortly after bring it to the desired value.
If the Compressor applies some gain reduction and is suddenly bypassed, a signal discontinuity will be heard. A potential solution is to gradually bring the ratio to 1 prior to bypassing the Effect.

Wwise Peak Limiter Properties

The Wwise Peak Limiter plug-in effect contains a series of properties, many of which can be edited in real-time and mapped to specific Game Parameters using RTPCs.

	Note
	Sounds with a DC offset may alter the results of the Peak Limiter's effect. Make sure to remove the DC offset from your audio file before applying the Peak Limiter in Wwise.

Interface Element

Description

Inclusion

Determines whether the element is included or excluded. When selected, the element is included. When unselected, the element is not included. By default, this applies across all platforms. Use the Link indicator (to the left of the check box) to determine or to set platform-specific customizations.

When this option is unselected, the property and behavior options in the Property Editor become unavailable.

Name

The name of the Effect instance.

Effect instances are a group of effect property settings. They can be one of two types: custom instances or ShareSets. Custom instances can be used by only one object, whereas ShareSets can be shared across several objects.

Effect

The type of effect.

Shared by (Used by)

A list of objects that currently subscribe to the selected ShareSet.

This field is called “Used by” when editing a custom instance of the Effect.

Opens a search field where standard alphanumeric entries filter out unmatching elements from the view. Learn more in Using Tables.

Click the Close icon to the left of the search icon to close the search field and remove the filter.

	Note
	The searches do not include elements in collapsed nodes of the List View, Query Editor, MIDI Keymap Editor, and Reference View.

Returns the Effect property settings to their default values.

This option is only available when editing a custom instance of the Effect.

Notes

Additional information about the Effect.

Effect Settings

Name

The name of the Effect instance.

Effect

The type of effect.

Shared by (Used by)

A list of objects that currently subscribe to the selected ShareSet.

This field is called “Used by” when editing a custom instance of the Effect.

Returns the Effect property settings to their default values.

This option is only available when editing a custom instance of the Effect.

Notes

Additional information about the Effect.

Effect Settings

Threshold

The level of the input value above which the Peak Limiter compressor begins to apply gain reduction.

Default Value: -12
Range: 0 to -96.3
Units: dB

Ratio

The relationship between the input signal and the output signal above a threshold value. This value defines the slope of the output signal above the threshold.

A ratio of 4:1 indicates that for every 4 dB the input signal is above the threshold, only 1 dB will be included in the output signal.

Default Value: 10
Range: 1 to 50
Units: none

Look ahead time

The time offset used to detect upcoming signal peaks. This value is exactly equal to the latency introduced by the Peak Limiter.

Default Value: 0.01
Range: 0.001 to 0.02
Units: seconds

Release

The amount of time it takes for the Peak Limiter to remove the gain reduction as the input level falls below the threshold.

Default Value: 0.2
Range: 0.001 to 0.5
Units: seconds

Output gain

The amount of gain applied to the output signal after the dynamic compression step to make up for potential gain losses caused by the gain reduction process.

Default Value: 0
Range: -24 to 24
Units: dB

Process LFE

Determines whether the Effect is processed in the LFE channel or not. When selected, the Effect is processed in the LFE channel. When unselected, the LFE channel will be delayed to sync up with the other channels affected by the peak limiter, but will not be peak limited.

Channel link

Applies the same gain reduction to all channels. This is implemented by taking the RMS power in the signal of all channels. The threshold is set by scaling the power in dB for the number of channels that are linked.

If this option is not selected, no information is shared between channels, and the Effect is applied on a per-channel basis.

(VU Meters)

A series of meters that display the different levels of the audio signal, including input levels, output levels, and gain reduction levels applied to signal peaks.

To enable the VU meters, you must click the Start Capture button in the Wwise toolbar.

The VU meters only work when the peak limiter effect has been applied to a bus in the Master-Mixer Hierarchy. In the case of a ShareSet, the bus must be selected in the 'Shared by' list of the Effect Editor.

Input

Displays the level of the incoming audio signal.

Gain Reduction

Displays the amount of gain reduction applied to the signal peaks.

Output

Displays the level of the audio output.

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