Какво ще ви е нужно
If you shoot footage using a handheld camera, you will probably end up with shaky shots. Unless this look is intentional, you’ll want to stabilize your shots to eliminate unwanted motion.
Warp Stabilizer VFX in Adobe After Effects CC automatically removes extraneous jitters. When played back, the motion appears smooth because the layer itself is scaled and moves incrementally to offset the unwanted movement. (The Warp Stabilizer VFX effect replaces the Warp Stabilizer effect available in previous versions of After Effects.)
In this excerpt from Adobe After Effects CC Classroom in a Book, published by Adobe Press, you will apply Warp Stabilizer VFX to a shaky clip to see how the stabilization effect works.
About bicubic scaling
In this tutorial, you will scale the video sample. When you scale video footage or an image to a larger size, After Effects must sample data to add information where none existed before. You can choose which sampling method After Effects uses when scaling a layer. For details, see the video, Set scaling quality using bicubic sampling.
In previous versions, After Effects has used only bilinear sampling. Bicubic sampling, new in After Effects CC, uses a more complex algorithm that typically provides better results when color transitions are more gradual, as in nearly all real-world photographic images. Bilinear scaling may be a better option for sharp-edged graphics.
To choose a sampling method for a layer, select the layer, and choose Layer > Quality > Bicubic or Bilinear. Bicubic and bilinear sampling are available only for layers that are set to Best quality. (To change a layer’s quality setting to Best, choose Layer > Quality > Best.)
Setting up the project
As you start After Effects, restore the default application settings for After Effects:
- Start After Effects, and then immediately hold down Ctrl+Alt+Shift (Windows) or Command+Option+Shift (Mac OS) to restore default preferences settings. When prompted, click OK to delete your preferences.
- Click Close to close the Welcome screen.
- After Effects opens to display a new, untitled project.
- Choose File > Save As > Save As.
- Name the project Stabilize.aep, and then click Save.
Importing the footage
You need to import one footage item to start this project. Download the sample tutorial files that accompany this tutorial to follow along.
- Double-click an empty area of the Project panel to open the Import File dialog box.
- Select the flowers.mov file in the sample tutorial files, and then click Import or Open to import the footage into your project (see Figure 1).
Creating the composition
You’ll start by creating the composition.
- Drag the flowers.mov clip in the Project panel onto the Create A New Composition button at the bottom of the panel.
After Effects creates a new composition named Flowers with the same pixel size, aspect ratio, frame rate, and duration of the source clip.
- Click the RAM Preview button in the Preview panel to preview the footage. Press the spacebar to stop the preview when you’ve seen the whole clip. This clip was shot with a handheld camera in the late afternoon. A slight breeze rustles the vegetation, and the camera moves unsteadily.
Applying Warp Stabilizer VFX
Warp Stabilizer VFX starts analyzing footage as soon as you apply it. Stabilization is a background process, so you can work on other compositions while it finishes. How long it takes depends on your system. After Effects displays a blue banner while it analyzes the footage and an orange banner while it applies stabilization (see Figure 2).
- Select the flowers.mov layer in the Timeline panel, and choose Animation > Warp Stabilizer VFX. The blue banner appears immediately.
- When Warp Stabilizer VFX has finished stabilizing, and the orange banner has disappeared, create another RAM preview to view the changes.
- Press the spacebar to stop the preview.
The clip is still shaky, but it’s smoother than it was initially. Warp Stabilizer VFX moved and repositioned the footage. To see how it applied changes, view the effects in the Effect Controls panel. For example, the clip’s borders were scaled up (to about 103%) to hide black gaps that occur when the image is repositioned in the stabilization process. You’ll adjust the settings that Warp Stabilizer VFX uses.
Adjusting the Warp Stabilizer VFX Settings
You’ll change the settings in the Effect Controls panel to make the shot smoother.
- In the Effect Controls panel, increase the Smoothness amount to 75%.
Warp Stabilizer VFX immediately begins stabilizing again (see Figure 3). It doesn’t need to analyze the footage, because the initial analysis data is stored in memory.
- When Warp Stabilizer VFX has finished, create another RAM preview to view the changes.
- Press the spacebar to stop playback when you’re done.
It’s better, but still a little rough. The Auto-scale setting in the Effect Controls panel now displays 103.7%; the effect moved the frames more dramatically, requiring more scaling to eliminate black gaps around the edges.
Rather than change the amount Warp Stabilizer VFX smooths the footage, now you’ll change its goal.
- In the Effect Controls panel, choose No Motion from the Result menu (see Figure 4).
- When the orange banner disappears, create another RAM preview. Press the spacebar to stop the playback.
With this setting, Warp Stabilizer VFX attempts to lock the camera in position. This requires even more scaling. When No Motion is selected, the Smoothness option is dimmed.
Now the camera stays in position, so that the movement you notice is the rustling of the flowers in the wind, not the shakiness of the camera. In order to achieve this effect, Warp Stabilizer VFX had to scale the clip to 112.4% of its original size.
Fine-tuning the results
The default analysis works well most of the time, but sometimes you may need to massage the end results even further. In this project, the clip skews subtly in a few places, most noticeably at about the five-second mark. Casual viewers may not notice the problem, but a keen producer will. You’ll change the method that Warp Stabilizer VFX uses to remove the skew.
- In the Effect Controls panel, choose Position, Scale, Rotation from the Method menu.
- Choose Stabilize Only from the Framing menu.
- Increase the Additional Scale to 114% (see Figure 5).
Note: Scaling a video layer up degrades the image. A good rule of thumb is to keep the Additional Scale value below 115% if possible.
- Create another RAM preview.
Now the shot looks rock-steady. The only movement is that caused by the wind rustling the flowers.
- Press the spacebar to stop the playback when you’re done.
- Choose File > Save to save your work.
- Choose File > Close Project.
Open Stabilize.mov included in the sample tutorial files to see how the final, stabilized footage should look.
As you have discovered, stabilizing a shot is not without its drawbacks. To compensate for the movement or rotation data applied to the layer, the frames must be scaled, which could ultimately degrade the footage. If you really need to use the shot in your production, this may be the best compromise.
Warp Stabilizer VFX settings
This is just a summary of the Warp Stabilizer VFX settings to help you get started.
- Result controls the intended result. Smooth Motion makes camera movement smoother, but doesn’t eliminate it; use the Smoothness setting to control how smooth the movement becomes. No Motion attempts to remove all of the camera motion.
- Method specifies the most complex operation the Warp Stabilizer VFX performs on the footage to stabilize it: Position, which is based on position data only; Position, Scale, Rotation, which uses these three types of data; Perspective, which effectively corner-pins the entire frame; or Subspace Warp (the default), which attempts to warp various parts of the frame differently to stabilize the entire frame.
- Borders settings adjust how borders (the moving edges) are treated for footage that is stabilized. Framing controls how the edges appear in a stabilizing result, and determines whether the effect crops, scales, or synthesizes edges using material from other frames.
- Auto-scale displays the current auto-scale amount, and allows you to set limits on the amount of auto-scaling.
- Advanced settings give you even greater control over the actions of the Warp Stabilizer VFX effect.
Tip: You can use Warp Stabilizer VFX advanced settings to achieve more complex effects, too. To learn more, see Adobe After Effects CC Visual Effects and Compositing Studio Techniques, available from Adobe Press.