Adobe Premiere Pro CS4 - Manual (Page 397)

391 USING ADOBE PREMIERE PRO CS4
Effects and transitions
Last updated 11/6/2011
• Composite In Back Uses the echoes’ alpha channels to composite them back to front.
• Composite In Front Uses the echoes’ alpha channels to composite them front to back.
• Blend Averages the echoes.
Posterize Time effect
The Posterize Time effect locks a clip to a specific frame rate. Posterize Time is useful on its own as a special effect, but
it also has more subtle uses. For example, 60-field video footage can be locked to 24 fps (and then field rendered at 60
fields per second) to give a filmlike look. This effect is sometimes called Strobe in hardware devices.
Animating the value of the Frame Rate slider can give unpredictable results. For this reason, the only interpolation
method allowed for the frame rate is Hold.
Time Warp effect
Time Warp effect
The Time Warp effect gives you precise control over a wide range of properties when changing the playback speed of
a layer, including interpolation methods, motion blur, and source cropping to eliminate unwanted artifacts. Since
Time Warp affects video only, it is usually best to unlink video from audio before applying it to a clip. Reducing the
speed of a clip with Time Warp does not extend the clip’s duration, but instead makes it end on an earlier frame. You
can nevertheless retrim the clip, retaining the Time Warp effect, up to the clip’s full duration. However, during
trimming, the monitors will show the In and Out points of the host clip unaffected by Time Warp. For example, the
end point you might see in the Program Monitor while trimming will not be the end point of the clip when you preview
it with the effect applied. Also, warning bars will not appear on the clip in the Timeline when you trim past the last
frame of available media. Precise trimming of a clip with the Time Warp effect can be tricky. For more information on
using Time Warp, watch the
online training video on the Total Training website.
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.