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After Effects CS3  |  Go to CS4 Help

Timewarp effect

The Timewarp effect gives you precise control over a wide range of parameters when changing the playback speed of a layer, including interpolation methods, motion blur, and source cropping to eliminate unwanted artifacts. The Timewarp effect works independently of the Frame Blending switch in the Timeline panel.
Note: The Timewarp effect does not work on fields for interlaced footage. To use the Timewarp effect on a layer with an interlaced footage item as its source, double the frame rate in the composition settings. When you render to final output, modify your render settings in the Render Queue panel to set the frame rate appropriate for the output type.

This effect works with 8-bpc and 16-bpc color.

Timewarp effect

Method options

These options determine how interpolated frames are generated:

Whole Frames
Duplicates the last frame shown.

Frame Mix
Creates a new frame by blending existing frames.

Pixel Motion
Creates a new frame by analyzing the pixel movement in nearby frames and creating motion vectors.

Adjust Time By controls

Choose Speed to specify a time adjustment as a percentage. Choose Source Frame to specify a time adjustment by identifying which source frame is to play at which time. If you choose Source Frame for Adjust Time By, then you must animate the Source Frame property to do anything other than freeze on one frame.

Tuning controls for Pixel Motion interpolation

Vector Details
Determines how many motion vectors are used during interpolation. The more vectors used, the longer the rendering time. A value of 100 produces one vector per pixel. If the layer has fast-moving motion, it may look better with a lower Vector Details setting.

Smoothing
These controls affect the sharpness of the image:
Build From One Image
Generates the final output from the closest single frame, as opposed to the closest two frames. The result is a sharper image, but jerkier motion.

Correct Luminance Changes
Equalizes the luminance between frames before calculating motion.

Filtering
The quality of the filtering used to build the interpolated image. Extreme greatly increases rendering time. The Filtering option affects only the sharpness of the final image; use Normal until you’re ready for final rendering.

Error Threshold
Determines the precision of pixel matching from one frame to the next. A higher value results in fewer motion vectors and more blending.
Note: If you see edge tearing in the image, try increasing the Error Threshold for more blending. If the image has heavy grain, try decreasing the Error Threshold so the low-level motion of the grain is ignored.

Block Size
Adjusts the size of the blocks used to calculate the vectors.

Weighting
Controls the weighting of the red, green, and blue channels in calculations used to analyze the image. For example, setting Red Weight and Green Weight to zero means that only the blue channel is analyzed for motion.

Motion Blur controls

Shutter Angle
Determines the intensity of motion blur. The shutter angle is measured in degrees, simulating the exposure caused by a rotating shutter. Simulated exposure time is determined by dividing the shutter angle by the frame rate times 360°. For example, a shutter angle of 90° causes an exposure of 1/96 of a second per frame: 90° / (360° * 24 fps).

Shutter Samples
Controls the quality of the motion blur. A higher value results in a smoother motion blur.

Matte, warp, and crop controls

Matte Layer
The layer to use as a matte for defining the foreground and background areas of the image. White areas in the matte represent the foreground, black areas represent the background, and gray attenuates between foreground and background.

Matte Channel
The channel to use as a matte.

Warp Layer
Allows you to warp the layer to which the effect is applied by applying the motion vectors from the layer that you choose.

Show
Controls the portion of the layer to be time-remapped.

Source Crops
If the image contains unwanted pixels or artifacts at the edges, use Source Crops controls to specify image boundaries. Pixels from the boundaries are repeated to fill the area beyond the boundaries to the layer’s edges.




Comments

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Comments


Jonas Hummelstrand said on May 12, 2008 at 5:20 AM :
This technique is useful for creating slow-motion effects.
No screen name said on Jul 9, 2008 at 9:28 PM :
Does this render faster or slower than frame blending?
Todd_Kopriva said on Jul 9, 2008 at 10:16 PM :
The processing time for the Timewarp effect with a given method (Whole Frames, Frame Mix, or Pixel Motion) is the same as for frame blending of the same sort (off, Frame Mix, or Pixel Motion). The underlying processing is the same. The difference is that the Timewarp effect gives you much more control over how the Pixel Motion blending is performed and how the internal motion blur is calculated. So, it is possible to have the Timewarp effect take more or less time by modifying the settings from the defaults.
No screen name said on Jul 9, 2008 at 10:47 PM :
Hi, thanks for your reply. That helped a lot.
A couple of questions more...

Does it work with 32bit footages?
Is possible to add keyframes in order to swap between Whole Frames, Frame Mix and Pixel Motion?

Best regards

Stefano Virgilli
Todd_Kopriva said on Jul 10, 2008 at 8:22 AM :
> Does it work with 32bit footages?

As the description of the effect says, and as you can see by the '16' on the icon in the Effects & Presets panel, the effect only processes 16 bits per channel. You can still apply the effect to a layer in a 32-bpc project, but you'll lose channel values over 1 and under 0, plus lose some precision in the channel values to quantization. You can use the HDR Compander effect to mitigate the first of these limitations.

> Is possible to add keyframes in order to swap between Whole Frames, Frame Mix and Pixel Motion?

No. If there's no stopwatch next to a property name, you can't add keyframes or expressions to it. If you need to use different methods for different parts of the layer, you'll need to split the layer and apply instances of the effect to each of the resulting layers.

If you want to discuss how best to use this effect, consider bringing questions over to the Adobe After
Effects user-to-user forum:
http://www.adobeforums.com/webx/.ee6b2fe/

Several motion graphics and visual effects professionals help people on that forum with questions like these. I monitor that forum, too, so I can help you to get an answer there.

 

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