After Effects provides different tools for editing layers and editing their time presence is one of the most useful. When we watch a typical advertisement or even a movie sequence we see that the total message is always composed of parts; incomplete parts that nonetheless add their special part of the message. After Effects offers several tools to edit the time window of each layer. A very flexible and friendly one is ‘slip editing’.
When you blend different resources in your composition, especially different videos, you will typically use only portions of them. Exactly how you will blend them together, the timing that makes them work together, and the editing process that helps you make these decisions, all work together to make your composition the final product you want it to be.
Typically as you choose the resources you want, choose the timing you want, the ‘fine tuning’ process can be the most time consuming. You want your transitions to work together, you want them to be seamless, and you want just the right portions of the different entries to make just the right contribution to the total product. This is where slip editing can be a very valuable tool.
To appreciate the simple contribution slip editing provides, choose two or three videos for a composition, reduce their total time window, and place them at your ‘best guess’ interval how they will work together. As you hover your mouse over the beginning and end of each layer, you see the double arrows indicating you can adjust these settings. Notice once you have adjusted the beginning and/or end, the layer bar now has a grey area showing that part of the video time that is no longer being used.
A very useful display to work with these same edits is the time information available on the left side of the timeline. Under your layer resources you see three icons that toggle information displays: overlapping rectangles to display the layer switch information, a circle/square icon toggles transfer controls information, and a set of curly braces show the time information for each layer.
This time information is broken into ‘In, Out, Duration, Stretch’ time settings. While most of us make manual edits to our resources, ‘eyeing’ the changes we make, it is very useful to know the exact times we are creating with our visual adjustments. Everything from synchronizing layer events to keeping the total composition within a predetermined time window will draw on this precise information.
When you make slip edits, this time information will not change. This is a useful reminder of just what a slip edit is. Just like After Effects presents the double arrow icon when you hover over the beginning and end of a layer sequence, once your have reduced this time and hover within the greyed out section, you will see these double arrows with two vertical bars on each end. This tells you that you are in the slip editing mode.
Notice as you slide your time adjusted layer back and forth, your in, out, and duration time do not change. You are not changing any of these values. What you are changing is exactly what portion of this clipped layer will be shown.
Consider that you have finalized the exact time window that works for this layer. You know exactly when it needs to appear (and disappear) in relation to the other layers. You also know exactly how long it can be. Slip editing lets you tune in on its content and exactly what part will appear within this time window. Having this extra degree of control helps you fine tune a bit more, with your focus on the time sensitive content within each layer.