In a four-point edit, in and out points are marked on both the source clip and record clips. The in and out points on the source clip mark the material that will be used for the edit. The in and out points on the record clip mark where the source material will go.
You can perform a four-point edit as either an insert or an overwrite edit.
With an insert edit, if the source material differs in length from the marked duration of the record clip, the overall length of the record clip changes to accommodate the difference.
With an overwrite edit, the length of the record clip stays the same. The source material timewarps (expands or contracts) to fit into the space between the in and out points on the record clip.
If you do not want to create a timewarp when performing a four-point edit, disable the Auto Timewarp option in the Timeline section of the Preferences menu. Excess source clip frames are brought in as head and tail frames. If there are fewer source clip frames, the source selection only overwrites the equivalent number of frames in the record clip, essentially treating the edit as a three-point edit.
The material between the in and out point on the source clip is used in a fit-to-fill edit between the in and out points of the record clip. A timewarp is applied if their lengths are different.
