Houdini uses the auto-key, auto-commit and Global Set Key options to determine when and where (on which parameters) to add keyframes. These options can be set in the animation preferences or on the playbar.

Auto-key is like having Houdini automatically press K to set keyframes when you change parameters that are in the channel list. When auto-key is turned on, any parameter change is immediately keyed (whether the parameter was previously keyed or not yet keyed), and the changes are reflected in the geometry displayed in the viewport. This lets you scrub the playbar, move objects, pose characters, etc. without having to remember to set keys. However, you can also accidentally create unintended keys/animation.

To turn auto-key on or off in the animation preferences:

1. Choose Edit ▸ Preferences ▸ Animation.

2. Turn on Auto-Key: Add Keyframes on Parameter Change.

Auto-commit is similar to auto-key, but controls whether Houdini automatically saves parameter changes when a key already exists for that parameter at the current frame. When auto-commit is turned on and you change a parameter that has already been keyed at the current frame, the new value is automatically saved as the new keyed value. You do not need to explicitly key the value.

Important: When this option is on and you key the position of an object, you must move the timeline to a different frame before you reposition the object in preparation for setting the next key. If you reposition the object before you move to another frame, you will have changed the keyed values on the first keyframe due to the auto-commit setting.

To turn auto-commit on or off in the animation preferences:

1. Choose Edit ▸ Preferences ▸ Animation.

2. Turn on Auto-Commit: Save Parameter Change at Keyframes.

The Global Set Key preference controls which parameters in the channel list Houdini adds keyframes to. See the animation preferences for the available options.