Adobe has introduced a new Warp Stabilizer with the CS5.5 upgrade to After Effects that automatically stabilises jittery hand-held footage. Although the ability to stabilise such footage has been with After Effects for a while, the Warp Stabilizer handles it automatically. Also, it’s far simpler than using Mocha to stabilise a shot. Now the only tweaking you have to do is adjusting the quality of the stabilisation. With DSLRs increasingly being used for video capture, the ability to stabilise quickly in your workflow is a valuable tool. And realising the increasing ubiquity of DSLRs for capture, Adobe has added controls to counteract the Rolling Shutter Effect you get with CMOS sensors.
Import the shaky footage into After Effects and place it on the timeline. The Warp Stabilizer can be applied in several ways – we’ll use the Animation menu and select Stabilize Motion. In previous versions of After Effects this would open the Layer viewer and present the Tracker palette setup for stabilisation.
Now in After Effects CS5.5 it applies the Warp Stabilizer. A message appears telling you it’s analysing the footage in the background and you can continue working on your composition. If you look in the Effects Control palette you’ll see which frame is being analysed and how much time remains.
After Effects is doing some sophisticated pixel-by-pixel analysis, which gets saved with your project file in case it’s needed later. As soon as the analysis finishes, a message tells you the stabilisation is being applied. This does not take as long, and to see the results do a RAM preview.
If you look at your stabilised footage you’ll notice the default settings for the filter have enlarged the footage, and the Stabilizer Control palette will tell you by how much (look at Auto-scale). In this footage it’s 124.1%, and this may not be acceptable.
Each stabilisation is a trade off of enlargement versus stabilisation, and the settings in the Control palette are for the various problems footage presents. The first control to try is Smoothness, set at 50%. You could reduce or increase this to a point where both stabilisation and enlargement are acceptable.
If you open the Advanced options the Crop Less<–>Smooth More slider gives you controls that can reduce the amount of cropping at the expense of stabilisation, without the need to apply a new Stabilisation; it is fine-tuning however and 100% stabilisation effectively locks off the shot.
This clip lends itself to the Synthesize Edges feature. Select this from the Framing menu. Immediately auto-scaling is switched off. In the clip above the sides and bottom edges have been successfully synthesised but the top has not – as seen by the black gap at the top.
To eliminate the gaps, open the Advanced options and experiment with the Synthesis Input Range, measured in seconds either way of the current frame. In this example 5 seconds restored the sky. The Edge Crop is to prevent bad edges in analogue capture being sampled for synthesis.
By default, the stabilisation method is Subspace Warp, which warps areas throughout the clip by differing amounts. This can produce unwanted effects, such as unusual stretching. A simpler method can be chosen from the Method menu: the higher up the menu the simpler the operation.
Warp Stabilizer’s analysis focuses on foreground objects at the expense of background objects. In the above footage the boat has been stabilised but the movement of the opposite riverbank has been exaggerated. This distracts the eye from the boat, thus compromising the stabilisation effect.
Detailed analysis Open the Advanced options and tick Detailed Analysis to solve these problems. And wait – how long depends on the horsepower of your Mac. After an analysis the Stabilizer will try to compensate for background and foreground movement. Because of its speed, keep this option as a last resort.
In scenes where there is predominant horizontal movement at speed, Rolling Shutter Ripples may appear. This is caused by CMOS sensors used in most DSLRs but not by CCD sensors. If the rolling shutter effect is pronounced choose Enhanced Reduction in the Advanced options.
Adding the stabiliser after other Effects evokes a warning box (but only once per session) advising you add your masks and Effects in a pre-composition. Therefore add the Effects first and turn the layer into a pre-comp by selecting Pre-compose from the Layer menu.
In some situations, you may want to lock off the shot completely. To do this, apply the Warp Stabiliser and select No Motion from the Stabilization menu. If you want a small amount of movement select Smooth Motion and increase the Smoothness percentage.
In fast-moving workflows where steadied footage will be edited in Premiere Pro, save time by creating a Dynamic Link. Rather than rendering footage then importing, go to the File menu in Premiere and select Import After Effects Composition (shown above), so you can edit it like standard footage.
Barry Stead is a contributor to our sister publication, Macworld UK.