Version
menu_open

Time Stretch

The Time Stretch plug-in can be used to change the speed or duration of an audio signal without affecting its pitch. The plug-in allows for both Time Stretching and time compression with possibly time-varying time scaling ratio during playback. The plug-in is suitable for use on monophonic as well as polyphonic sounds.

[Note]Note

This effect is only available within the Actor-Mixer Hierarchy. It is also possible to use it inside the Interactive Music Hierarchy, but this is not recommended as it will affect the timings in an undesirable manner in the context of interactive music.


[Warning]Warning

Time compression of streamed assets is not recommended and may cause source starvation due to higher throughput required. Time Stretching on the other hand is not a problem for streaming sounds.

Choosing the window size

Choosing the window size parameter is an important step to obtain good quality results. While the default value (2,048) should work well for most content, tuning this parameter is essential for obtaining the best time scaling effect with as little artifacts as possible. While larger window size settings give better frequency resolution, they have less accurate time-domain resolution and thus result in more smearing of transients signal. The window size parameter is thus a compromise between time resolution and frequency resolution.

The ideal window size setting is dependent on audio content where signals with lots of transients (such as punches, drums, and explosions) may benefit from smaller window size settings while harmonic signals with more stable frequency content (such as voices and musical instruments) may work best with larger window size parameter values which provide more accurate frequency resolution.

When planning to make the signal much slower by applying a large Time Stretch setting, larger window size parameter values are often desirable as the frequency resolution gets very noticeable when the sound is playing back very slowly.

Algorithm choice

The Time Stretch plug-in allows you to choose between two time stretch algorithms: the Classic mode from Wwise version 2021.1 and earlier, and the Transient Preserving mode. The Transient Preserving mode further enables controls to fine tune quality level and stereo processing.

Time Stretch properties

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

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.

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

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]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]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.

Time

Time Stretch

Percentage of original sound duration. 100% corresponds to no Time Stretch while 200% is twice as long. Similarly time compression is possible using 50% to get the sound at half the duration. This value supports RTPC and may be smoothly changed during playback without additional artifacts.

Default value: 100

Range: 25 to 1600

Units: % of original duration

Time Stretch Random

Offsets the Time Stretch factor specified by a random amount up to plus or minus the Time Stretch random value. This will be effective for the whole duration of the voice on which the Time Stretch will be applied. RTPC received during the playback will be considered only on the next playback.

Default value: 0

Range: 0 to 200

Units: % of original duration

Pitch

Pitch Shift

The pitch is raised or lowered by the amount specified by this parameter (in Cents). So, +1200 Cents transposes an octave up and -1,200 is an octave down. This value supports RTPC and may be smoothly changed during playback without additional artifacts.

Default value: 0

Range: -4800 to 4800

Units: cents

Pitch Shift Random

Offsets the Pitch Shift amount specified by a random amount up to plus or minus the Pitch Shift random value. This will be effective for the whole duration of the voice on which the Pitch Shift will be applied. RTPC received during the playback will be considered only on the next playback.

Default value: 0

Range: 0 to 4800

Units: cents

Quality

Window Size

Larger window size gives better frequency resolution but more smearing of transients. This parameter is thus a compromise between time resolution and frequency resolution. See section above for a more detailed discussion on how to choose the value for this parameter.

Default value: 2048

Range: 256 to 8192

Units: Sample frames

Stretch Mode

The version of time stretch algorithm to be used.

The following options are available:

  • Classic: Time Stretch uses the algorithm from Wwise version 2021.1 and earlier.

  • Transient Preserving: Time Stretch uses an improved algorithm. With this mode selected, the Quality Level slider allows you to fine tune the performance of the algorithm, and the Stereo Processing control allows for improved handling of complex stereo mixes.

Default value: Classic

Quality Level

Allows fine control of the performance of the improved time stretch algorithm, with the tradeoff of reduced sound quality. This control is only available when Stretch Mode is set to Transient Preserving.

With Quality Level at 100, all parts of the sound are processed. As the level decreases, the CPU demands of the algorithm are reduced, with an impact on sound quality. More specifically, lowering the quality slider will introduce a mild noise floor or phasing effect, as the algorithm skips over portions of the input sound spectrum to save on computation.

It is recommended to fine tune this parameter while watching the CPU % values in the Performance Monitor.

Default value: 100

Range: 0 to 100

Output

Output Gain

The amount of gain applied to the output signal after the dynamic compression that makes up for potential gain losses.

Default value: 0

Range: -24 to 24

Units: dB

Stereo Processing

The method used for handling stereo inputs. This control is only available when Stretch Mode is set to Transient Preserving.

The following options are available:

  • Left Right: Stereo inputs are handled normally.

  • Center Cut: Stereo inputs are split into left, center, and right components before time stretching is applied. They are then reconstructed as left and right channels. Center Cut processing is only applied to stereo (2 channel) inputs.

Since the Transient Preserving time stretch mode has a greater effect on the phase of the sound than the Classic stretch mode, the Center Cut option is provided as a way to better preserve complex stereo mixes.

Default value: Left Right


Was this page helpful?

Need Support?

Questions? Problems? Need more info? Contact us, and we can help!

Visit our Support page

Tell us about your project. We're here to help.

Register your project and we'll help you get started with no strings attached!

Get started with Wwise