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Advanced Authoring Techniques

The Studio desktop app uses its powerful Audio Analyzer algorithm to automatically create rich haptic effects. But you can use additional tools and techniques to further refine and customize haptic experiences.

Adjusting Audio Analyzer Parameters

The default settings for the Audio Analyzer have been tuned to provide the best results for a wide variety of audio content. However, you can adjust the algorithm’s parameters to fine-tune the results. There are controls for the Amplitude Envelope, Frequency Envelope, and Emphasis Detection.

Amplitude Envelope Controls

Amplitude Envelope Parameters

Normalize

Normalization specifies the maximum amplitude that a haptic envelope must achieve. To use this feature, enable the Normalize checkbox. Once you do so, you will be able to adjust the Headroom control. For example, setting the Headroom control to -1.0 dB ensures that the haptic clip amplitude will never go over -1.0 dB.

Headroom

Haptic actuators have a limit on the intensity of vibrations they can create, so the Headroom parameter is calibrated such that 0 dB corresponds to the maximum output of the actuators. You can reduce this value by as much as 12 dB to reduce the strength of the haptic effects, but you can’t turn it up past 0 dB because the actuators wouldn’t be able to produce such strong vibrations.

If you use the same Headroom value when authoring multiple haptic experiences, they will all end up having roughly the same intensity, regardless of any difference in the volumes of the original audio files.

Resolution

The Resolution control sets the resolution of the Amplitude Envelope that is created. The value indicates the number of breakpoints-per-second that are calculated. A higher Resolution setting results in a more detailed Amplitude Envelope. A lower setting results in a more coarse envelope. A coarser envelope produces a smaller haptic clip when exported.

Frequency Envelope Controls

Frequency Envelope Parameters

Upper & Lower Frequency

These two parameters set the upper and lower bounds of the input audio that the Audio Analyzer considers when designing the Frequency Envelope. Setting these bounds for the input audio is important because the Audio Analyzer designs the Frequency Envelope by looking for the most central, strongest frequency at every point along the audio file. If the audio has strong high and low frequency content at the same time, the results might not be ideal.

If you want a haptic effect to follow the shape of the bass frequencies in the audio file, lower the Upper Frequency value. Frequencies above that setting are ignored when the Audio Analyzer designs the Frequency Envelope. If a sound has too much low-end rumble that comes through too strongly in the haptic effect, raise the Lower Frequency value. That way low frequencies are ignored when the Audio Analyzer designs the Frequency Envelope.

Resolution

The Resolution control in this section adjusts the resolution of the Frequency Envelope that is created. The value indicates the number of breakpoints per second that are calculated.

Higher Resolution settings result in a more detailed Frequency Envelope. Lower settings result in a more coarse envelope. A coarser envelope produces a smaller haptic clip when exported.

Emphasis Detection

Emphasis Detection Enable

When the Enable option is checked, the Audio Analyzer will also add Emphasis Points to the resulting haptic it creates. Emphasis Points will usually be placed where the Audio Analyzer detects abrupt increases in amplitude in the audio.

Manually Editing Haptics

The Studio desktop app gives you full control over the haptics you create, enabling you to directly edit the haptic envelopes to achieve your desired results.

Envelopes

The Studio desktop app has an intuitive visual interface that displays envelopes—representations of how the amplitude and frequency values change over time. Envelopes look just like line graphs with time mapped across the horizontal axis.

The Amplitude Envelope represents how the intensity of the haptic changes over time. The intensity is shown in the vertical axis with full intensity at the top (indicated with a value of 1.0) and no vibration at the bottom (indicated with a value of 0.0).

The Amplitude Envelope also includes Emphasis Points which are represented by vertical blue lines within the envelope. Emphasis Points represent an extremely short and sharp sensation, akin to tapping the phone’s screen with your fingernail, which can be used at high amplitudes to increase the impact of a haptic or at lower amplitudes to add a gritty texture to haptics. The height of the blue line indicates the amplitude of the Emphasis Point.

The Frequency Envelope represents how the frequency (the “pitch” or “tone” of the haptic effect) changes over time. Frequency is also represented in the vertical axis, where the lowest frequency is at the bottom (represented with 0.0) and the highest frequency is at the top (represented by 1.0).

Neither the Amplitude Envelope nor the Frequency Envelope represents absolute or exact values. The performance of haptic actuators might be different from one devices model to the next. Lofelt Studio automatically maps these abstract amplitude and frequency ranges to the capabilities of the devices at runtime. This is what allows you to create one haptic clip that is then used by all devices supported by Lofelt Studio.

Envelope Selector

The Studio desktop app designs haptics using the concurrently running Amplitude and Frequency Envelopes, which you can visualize simultaneously in the editor window. Use the Envelope Selector to choose which of the envelopes you want to edit. You can see the Enveloper Selector on the left side of the window after closing the Audio Analyzer.

Envelope Selector

Click on one of the envelopes to select it. You will see the associated envelope move to the foreground in the main editor on the right. The Amplitude Envelope is blue; the Frequency Envelope is yellow.

Each of the selectors also has a small “eye” icon at the right, which enables you to toggle the visibility of the envelopes. To hide an envelope from view, click the eye so that a line is drawn through it. Click it again to make the envelope visible.

The same thing can be done with the “Source Audio” option at the top of the selector. Click its eye icon to toggle the visible state of the source audio waveform in the main editor window.

Above the Envelope window is the Navigator, which sets the view for the Envelope window below it.

Navigator

The Navigator shows an overview of the full length of the haptic envelope you are working on. It also includes a movable frame to select the area visualized in the Envelope window. Click on the center of the frame and drag left or right to move the frame to a different location. Click and drag on the edges of the frame to zoom in and out.

Editing Envelopes

After selecting the envelope you wish to edit using the Envelope Selector, you can then begin to manipulate the selected envelope in the main editor window at the right. You can add, move, and delete breakpoints from the envelopes.

Breakpoints

A breakpoint is a single point in time that has a specific value. When creating two breakpoints next to each other, the Studio desktop app automatically connects those two breakpoints and interpolates values for the time between them. If you delete a breakpoint, the app then fills the gap by creating a connection between the remaining breakpoints on the left and right.

To keep the view of the envelopes clean, breakpoints aren’t normally visualized in the envelopes. However, they become visible when you move the cursor in the editor window. The closest breakpoint to your cursor is shown as an unfilled circle.

Breakpoint Hover

Selecting Breakpoints

To select a breakpoint to edit, simply click on it. A filled circle indicates a selected breakpoint.

Breakpoint Select

Select multiple breakpoints simultaneously by dragging a selection frame around them.

Breakpoint Multiselect

Deleting Breakpoints

To remove breakpoints from an envelope, select one or more breakpoints and then press DELETE on your computer’s keyboard.

Breakpoint Delete

Moving Breakpoints

To move one or more breakpoints, select them, then click-and-drag them, or use the arrow keys on your computer keyboard to make adjustments—this is especially useful when you want to make only small adjustments. You can also constrain movement to the vertical axis only by holding the SHIFT key on your keyboard while dragging.

NOTE: Lateral movement of the breakpoints is limited by any other breakpoints to the left or right of your selection. It is not possible to drag breakpoints over others that already exist.

Breakpoint Moving

Adding Breakpoints

To add new breakpoints, place the cursor where you want the new breakpoint to appear. A small circle with a “+” inside appears on the envelope. Click to create a new breakpoint at that location.

Breakpoint Adding

Editing Emphasis Points

Emphasis Points exist only in the Amplitude Envelope, so be sure to have the Amplitude Envelope visible and unlocked to edit Emphasis Points.

Converting to Emphasis Points

You can convert any breakpoint on the Amplitude Envelope into an Emphasis Point by first selecting it and then pressing CMD(CTRL)+B or selecting the Edit > Emphasis menu item.

Emphasis Menu

Pressing CMD(CTRL)+B or selecting the Edit > Emphasis menu item on a selected Emphasis Point will convert it back to a normal breakpoint.

Create Emphasis Point

Adjusting Emphasis Amplitude

You can edit the amplitude of the Emphasis Point as well as the envelope simultaneously. To edit the Emphasis Point amplitude, click and drag the blue handle at the top of the Emphasis Point up and down. To edit the Amplitude Envelope, click and drag the green breakpoint up and down. Hold SHIFT while dragging to constrain the motion up and down.

Adjusting Emphasis Amplitude

NOTE: The level of the Amplitude Envelope will always be forced lower than the Amplitude of an Emphasis Point.

Selecting the Emphasis Shape

You can change the shape of the Emphasis Point by selecting the Emphasis Point and clicking on one of the three icons that appears above the Emphasis Point. When selecting a single Emphasis Point, the shape will be shown for the currently-selected Emphasis Point only. When selecting multiple Emphasis Points, the shape will be shown for the closest Emphasis Point, however changing the shape will affect all selected Emphasis Points.

Adjust Emphasis Shape

The three shapes are as follows:

Emphasis Blunt

This shape creates a slightly longer and slightly deeper Emphasis, somewhat like a “thud”.

Emphasis Blunt

This shape creates a standard Emphasis.

Emphasis Blunt

This shape creates the shortest and highest Emphasis possible, similar to the precise “tick” from a watch.

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