Audiokinetic

Peak Limiter

(See the Peak Limiter properties below.)

The 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 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.

Note

The following are some general remarks on Wwise dynamic processing plug-ins:

There is no interpolation of ratio control (RTPC parameter) for Compressor, Expander, or 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.

Peak Limiter properties

The 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

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.

(Object Color)

Displays the object's color. Clicking the icon opens the color selector.

Select a color to apply it to the object. When you choose a color for an object, a palette icon appears on the selected square, as well as a yellow triangle in the lower-right corner, as shown.

To inherit the parent object's color, select the square at the far left of the color selector.

Inclusion

Determines whether the element is included in the SoundBanks when they are generated. When selected, the element is included. When unselected, the element is not included.

To optimize your sound design for each platform, you might want to exclude certain elements on certain platforms. By default, this check box applies across all platforms. Use the Link indicator to the left of the check box to unlink the element. Then you can customize the state of the check box per platform.

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

Default value: true

(Show references)

Indicates the number of elements in your project that contain direct references to the object. The icon is displayed in orange when references to the object exist, and in gray when no references exist.

Selecting the button opens the Reference View with the object's name in the References to: field.

Notes

Additional information about the Effect.

Metering

Indicates the name of the object currently being metered.

Allows you to browse for other objects to meter.

	Note
	The metering interface elements only appear in the Effect Editor for Effects that include VU meters.

Sets the display of the Effect Editor's selected tabs. By default, there is one panel displaying only one selected tab. You can, however, click a splitter button to split the panel into two, either side by side or one on top of the other, for two different tabs. The currently selected option is highlighted with a background color.

	Note
	You cannot display the same tab in both panels. If you select the tab that is currently displayed in the other panel, then the other panel will automatically display another tab.

Effect Settings
Threshold	The level of the input value above which the Peak Limiter compressor begins to apply gain reduction. Default value: 0 Range: -96.3 to 0 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
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: s
Release Time	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: 0.1 Range: 0.001 to 0.5 Units: s
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 unaffected. Default value: true
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. Default value: true
(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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