Negative Keyframes

In order to voice a particular sound, the mouth needs to be in the appropriate position before any sound is made. In some cases, this causes FaceFX to insert keys at negative times (up to around 300 milliseconds for speech curves and more for gestures). Below are some things to keep in mind with negative keyframes:

• Aggressively Cut Audio - Some games aggressively cut audio so that speech starts right away. Padding audio with some silence can resolve many issues with negative keyframes but this is not always possible so read below for other ways to deal with negative keyframes. On a side note, aggressively cut audio can also cause FaceFX Studio to analyze the audio incorrectly (typically by inserting a silence at the beginning of the file). Some files may produce a warning in the log about "Inadequate leading silence" but they may still analyze correctly. To fix files that are being analyzed incorrectly, use the set command to turn off speech detection prior to analyzing the problematic audio.
• Use FaceFX to Trigger the Sound - The correct way to deal with negative keyframes is to let FaceFX trigger the sound file at time 0 in the animation. See the FaceFX SDK Documentation for more details. Using FaceFX to trigger sounds can have the side-effect of delaying audio playback slightly. In dialogue sequences this may not be a problem, but action-oriented grunts and groans may require the sound to be played immediately.
• Gesture Curves - Gesture curves can take longer to ramp in than speech target curves. As a result, they can have keys pushed furthest into negative time. One way to resolve this issue for time-sensitive animations is to turn off speech gesture generation. This can be done from the Analyze Command or the animation creation wizard.

See Also