Audio (parameter behavior)

Audio (parameter behavior)

The Audio parameter behavior performs an analysis of a specific property of an audio track, then applies an animation curve to a parameter of another object in your project based on that analysis. You can apply the Audio parameter behavior to parameters of filters, replicators, shapes, particle systems, lights, text, and even other behaviors to make your visuals pulse in sync to the beat of a soundtrack.

Adjust this behavior using the controls in the Behaviors Inspector:

  • Source Audio: A source well that sets the audio track from which to read audio data. Drag an audio clip or a video clip containing audio into the Source Audio well, or use the pop-up menu to choose a source for audio analysis.

    Note: For the Audio parameter behavior to have an effect on an object, audio must be present in the Audio Timeline at the position of the behavior.

  • Respond To: A pop-up menu that sets the type of audio data analysis to perform. Choose Amplitude or Transients. If set to Amplitude, the behavior responds to peak values of a particular frequency. If set to Transients, the behavior responds to rapid changes in frequency.

  • Graph Range: A pop-up menu that sets the initial range of frequency values to be analyzed by the behavior. There are four options: All Frequencies, Bass, Mid, or Treble. The option you choose affects the frequency range of the Low Frequency and High Frequency parameters (described below).

  • Audio Graph: A graph displaying a visual representation of the Source Audio data analyzed by the behavior per frame.

    Inspector showing Audio Graph

    Click the Play button beneath the Audio Graph to see the selected Source Audio data as it plays back live. If analysis underway, a progress bar appears in the Audio Graph area. The Output level meter shows the amount of audio data from this behavior being sent to the visual effect in Motion. (Output is controlled by the Scale slider, described below.)

    Set Low Frequency, High Frequency, Floor, and Ceiling values by dragging the small tags along the bottom or right side of the graph. Alternatively, you can set these values numerically using the four sliders underneath the graph to isolate specific frequencies and values for analysis:

  • Low Frequency: A slider that sets the low frequency threshold of audio analysis. Only audio frequencies above this value are analyzed. Values range from 1 Hz to 22,050 Hz.

  • High Frequency: A slider that sets the high frequency threshold of audio analysis. Only audio frequencies below this value are analyzed. Values range from 1 Hz to 22,050 Hz.

  • Floor: A slider that sets the minimum value of audio input, below which results are ignored. Values range from 0 to 1.

  • Ceiling: A slider that sets the maximum value of audio input, above which results are ignored. Values range from 0 to 1.

  • Smoothness: A slider (available when Respond To is set to Amplitude) that sets the window size to smooth the result curve. Any value other than 0 triggers a keyframe reduction with an error tolerance of 1%. Values range from 0 to 10.

    Note: Depending on your audio file, Smoothness values greater than 7 may result in audio playing out of sync.

  • Sensitivity: A slider (available when Respond To is set to Transients) that sets the sensitivity of the transient detection. Values range from 0% to 100%.

  • Channel: A pop-up menu that sets the audio channel to analyze. Choose Mix/Mono, Left, or Right.

    Note: With a multichannel audio file used as a source, you must select Mix/Mono for audio analysis to be performed properly.

  • Peaks: A pop-up menu that sets how Motion generates peak curves in the Keyframe editor based on audio analysis data. Changing peak options affects how the Audio behavior is applied to its parent object. There are four menu options:

    • Sharp: Peaks are generated from the maximum amplitude of the audio channels you choose from the Channel parameter and the frequencies you set in the Graph Range. You can adjust which portion of the audio bandwidth is analyzed using the Graph Range pop-up menu and the sliders in the Audio Graph. When Respond To is set to Transients, two keyframes are added before and after each transient keyframe (attack and release), and the transient keyframes are interpolated as linear sharp peaks.

    • Smooth: Peak curves are generated from the average amplitude of the audio channels you choose from the Channel parameter and the frequencies you set in the Graph Range. You can adjust which portion of the audio bandwidth is analyzed using the Graph Range pop-up menu and the sliders in the Audio Graph. When Respond To is set to Transients, two keyframes are added before and after each transient keyframe (attack and release), and the transient keyframes are interpolated as smooth curves.

    • Square: When Respond To is set to Transients, this option appears. Two keyframes are added before and after each transient keyframe (attack and release), and the transient keyframes are constantly interpolated as square peaks.

    • Continuous: When Respond To is set to Transients, this option appears. The transient values are interpolated with no additional processing and appear as is.

  • Attack: A slider (available when Respond To is set to Transients) that modifies the animation curve to the amount of the offset in frames between the peak of the curve generated by the Audio behavior and the first frame of the curve. The number of frames that the curve takes to reach its peak value from its initial value is called the Attack.

  • Release: A slider (available when Respond To is set to Transients) that modifies the animation curve to the amount of the offset in frames between the peak of the curve generated by the Audio behavior and the last frame of the curve. The number of frames that the curve takes to reach its final value from its peak is called the Release.

  • Apply Mode: A pop-up menu that sets the method by which the audio analysis affects the curve. Choose Add, Subtract, Multiply, or Add and Subtract.

  • Delay: A slider that sets a delay in frames to offset the resulting keyframes.

  • Scale: A slider that sets the scale factor to affect the result of the audio analysis.

  • Apply To: A parameter assignment pop-up menu that sets the object parameter to which the audio behavior is applied.

See also
Apply the Audio parameter behavior