Time-stretching and time-remapping (2024)

Time-stretching, time-remapping, and the Timewarp effect are all useful for creating slow motion, fast motion, freeze frame, or other retiming results.

For information on the Timewarp effect, see Timewarp effect.

1. In the Timeline or Composition panel,select the layer.

2. Choose Layer > Time > Time Stretch.

3. Type a new duration for the layer, or type a StretchFactor.

4. To specify the point in time from which the layer willbe time-stretched, click one of the Hold In Place options, and thenclick OK.

   Layer In-point

   Holds the starting time of the layer at its current valueand time-stretches the layer by moving its Out point.

   Current Frame

   Holds the layer at the position of the current-time indicator(also the frame displayed in the Composition panel), and time-stretchesthe layer by moving the In and Out points.

   Layer Out-point

   Holds the ending time of the layer at its current valueand time-stretches the layer by moving its In point.

1. In the Timeline panel, move the current-timeindicator to the frame where you want the layer to begin or end.

2. Display the In and Out columns by choosing Columns >In and Columns > Out from the Timeline panel menu.

3. Do one of the following:

   • To stretch the In point to the currenttime, press Ctrl (Windows) or Command (Mac OS) as you click theIn time for the layer in the In column.

   • To stretch the Out point to the current time, pressCtrl (Windows) or Command (Mac OS) as you click the Out time forthe layer in the Out column.

1. Make a note of the time at which the first keyframeappears. (Placing a composition marker is a good way to mark thetime.)

2. In the Timeline panel, click the name of one or morelayer properties containing the keyframes you want to keep at thesame times.

3. Choose Edit > Cut.

4. Move or stretch the layer to its new In and Out points.

5. Move the current-time indicator to the time at whichthe first keyframe appeared before you cut the keyframes.

6. Choose Edit > Paste.

Note:

For bestresults, precompose the layer and then reverse the layer insidethe precomposition. For more information on this process, see Aboutprecomposing and nesting.

1. In a Timeline panel, select the layer you wantto reverse.

2. Choose Layer > Time > Time-Reverse Layer, or pressCtrl+Alt+R (Windows) or Command+Option+R (Mac OS).

1. In the Timeline panel, select a range of keyframesyou want to reverse.

2. Choose Animation > Keyframe Assistant > Time-ReverseKeyframes.

You can expand, compress, play backward, orfreeze a portion of the duration of a layer using a process knownas time-remapping. For example, if you are using footageof a person walking, you can play footage of the person moving forward, andthen play a few frames backward to make the person retreat, andthen play forward again to have the person resume walking. Time-remappingis good for combinations of slow motion, fast motion, and reversemotion.

The Timewarp effect provides similar features withmore control over some aspects of frame blending, but with additionallimitations as a result of being applied as an effect.

When you apply time-remapping to alayer containing audio and video, the audio and video remain synchronized.You can remap audio files to gradually decrease or increase thepitch, play audio backward, or create a warbled or scratchy sound.Still-image layers cannot be time-remapped.

You can remaptime in either the Layer panel or the Graph Editor. Remapping videoin one panel displays the results in both. Each provides a differentview of the layer duration:

• The Layer panel provides a visual reference of the frames you change, as well as the frame number. The panel displays the current-time indicator and a remap-time marker, which you move to select the frame you want to play at the current time.

• The Graph Editor provides a view of the changes you specify over time by marking your changes with keyframes and a graph like the one displayed for other layer properties.

When remapping time in the Graph Editor, use the values represented in the Time Remap graph to determine and control which frame of the movie plays at which point in time. Each Time Remap keyframe has a time value associated with it that corresponds to a specific frame in the layer; this value is represented vertically on the Time Remap value graph. When you enable time remapping for a layer, After Effects adds a Time Remap keyframe at the start and end points of the layer. These initial Time Remap keyframes have vertical time values equal to their horizontal position on the timeline.

By setting additional Time Remap keyframes, you can create complex motion results. Each time you add a Time Remap keyframe, you create another point at which you can change the speed or direction of playback. As you move the keyframe up or down in the value graph, you adjust which frame of the video is set to play at the current time. After Effects then interpolates intermediate frames and plays the footage forward or backward from that point to the next Time Remap keyframe. In the value graph, reading from left to right, an upward angle indicates forward playback, while a downward angle indicates reverse playback. The amount of the upward or downward angle corresponds to the speed of playback.

Similarly, the value that appears next to the Time Remap property name indicates which frame plays at the current time. As you drag a value graph marker up or down, this value changes accordingly and a Time Remap keyframe is set, if necessary. You can click this value and type a new one, or drag the value to adjust it.

The original duration of the source footage may no longer be valid when remapping time, because parts of the layer no longer play at the original rate. If necessary, set a new duration for the layer before you remap time.

As with other layer properties, you can view the values of the Time Remap graph as either a value graph or a speed graph.

If you remap time and the resulting frame rate is very different from the original, the quality of motion within the layer may suffer. Apply frame blending to improve time remapping for slow motion or fast motion.

Note:

Use the information shown in the Info panel to guide you as you work with time-remapping. The ratio given in the units of seconds/sec indicates the current speed of playback—the number of seconds of the original layer being played for each second after time-remapping.

1. In a Composition or Timeline panel,select the layer.

2. Place the current-time indicator on the frame that youwant to freeze.

3. Choose Layer > Time > Freeze Frame.

1. In a Composition or Timeline panel,select the layer that you want to remap.

2. Choose Layer > Time > Enable Time Remapping.

   This command adds two Time Remap keyframes by default,one at the beginning of the layer and one at the end.

3. Move the current-time indicator to where you want themovie to begin.

4. Click the Time Remap property name to select the startand end keyframes.

5. Drag the first keyframe to the current-time indicator,which moves the start and end keyframes. (If you are working inthe Graph Editor, drag the bounding box—not the keyframe or a handle—sothat both keyframes move.)

1. In a Composition or Timeline panel,select the layer that you want to remap.

2. Choose Layer > Time > Enable Time Remapping.

   This command adds two Time Remap keyframes by default,one at the beginning of the layer and one at the end.

   See Also

   3 Easy Ways You Can Speed Up a Video

3. Move the current-time indicator to the frame that youwant to freeze, and set a Time Remap keyframe at the current timeby clicking the keyframe navigator diamond for the Time Remap property.

4. Select the last two Time Remap keyframes (the secondand third keyframes) and drag them to the right.

5. Press F2 to deselect the keyframes, and then click thesecond (middle) keyframe to select it.

6. Press Ctrl+C (Windows) or Command+C (Mac OS) to copythe keyframe.

7. Press Ctrl+V (Windows) or Command+V (Mac OS) to pastethe keyframe at the current time. You should not have moved thecurrent-time indicator since step 3.

8. (Optional) To extend the layer so that its duration isincreased to accommodate the time added by the freeze-frame operation,press the K key twice to move the current-time indicator to thelast Time Remap keyframe, and press Alt+] (Windows) or Option+](Mac OS).

Note:

To switch between GraphEditor mode and layer bar mode, press Shift+F3.

1. In a Composition or Timeline panel, select thelayer you want to remap.

2. Choose Layer > Time > Enable Time Remapping.

3. In the Timeline panel, click the name of the Time Remapproperty to select it.

4. Move the current-time indicator to the time at whichto add a keyframe, and click the keyframe button inthe keyframe navigator to add a keyframe.

5. In the Graph Editor, drag the keyframe marker up or down,watching the Time Remap value as you drag. To snap to other keyframes,Shift-drag.

   • To slow the layer down, drag the keyframedown. (If the layer is playing in reverse, drag up.)

   • To speed the layer up, drag the keyframe up. (Ifthe layer is playing in reverse, drag down.)

   • To play frames backward, drag the keyframe downto a value below the previous keyframe value.

   • To play frames forward, drag the keyframe up toa value above the previous keyframe value.

   • To freeze the previous keyframe, drag the currentkeyframe marker to a value equal to the previous keyframe valueso that the graph line is flat. Another method is to select thekeyframe and choose Animation > Toggle Hold Keyframe, and thenadd another keyframe where you want the motion to start again.

Note:

Before you move a time-remap keyframe,it’s a good idea to select all subsequent time-remap keyframes inthe layer first. This selection will preserve the timing of the restof the layer when you remap time for the current keyframe.

1. Open the Layer panel for the layer youwant to remap.

2. Choose Layer > Time > Enable Time Remapping. Asecond time ruler appears in the Layer panel above the default timeruler and the navigator bar.

3. On the lower time ruler, move the current-time indicatorto the first frame where you want the change to occur.

4. On the upper time ruler, the remap-time marker indicatesthe frame currently mapped to the time indicated on the lower timeruler. To display a different frame at the time indicated on thelower time ruler, move the remap-time marker accordingly.

5. Move the current-time indicator on the lower time rulerto the last frame where you want change to occur.

6. Move the remap-time marker on the upper time ruler tothe frame you want to display at the time indicated on the lowertime ruler:

   • To move the preceding portion of the layerforward, set the remap-time marker to a later time than the current-timeindicator.

   • To move the preceding portion of the layer backward,set the remap-time marker to an earlier time than the current-timeindicator.

   • To freeze a frame, set the remap-time marker tothe frame you want frozen. Then, move the current-time indicator(lower ruler) to the last point in time where the frame will appearfrozen and move the remap-time marker again to the frame you wantfrozen.

The speed graph of the Time Remap propertydirectly relates to the pitch of an audio file. By making subtlechanges to the speed graph, you can create a variety of interestingeffects. To avoid screeching audio, you may want to keep the Speed valuebelow 200%. When the speed is too high, use the Levels controls,located under the Audio property, to control the volume.

Youmay hear clicks at the beginning and end of an audio (or an audioand video) layer after setting new In and Out points in the TimeRemap graph. Use the Levels controls to remove these clicks.

1. In a Composition or Timeline panel,select the layer you want to remap.

2. Choose Layer > Time > Enable Time Remapping.

3. Click the Graph Editor button in the Timeline panel todisplay the Graph Editor, if necessary.

4. Click the Choose Graph Type And Options button at thebottom of the Graph Editor and choose Edit Speed Graph.

5. Move the current-time indicator to the frame where youwant change to begin, and then click the Add A Keyframe button.

6. On the speed graph below the keyframe, drag a marker,watching the Speed value as you drag.

   • To lower the pitch, drag the speed graphmarker down.

   • To increase the pitch, drag the speed graph markerup.

1. If necessary, choose Panel > Audio.

2. In the Timeline panel, select the audio (or audio andvideo) layer to which you applied time-remapping.

3. Expand the layer outline to display the Audio propertyand then the Audio Levels property.

4. Move the current-time indicator to the new In point andchoose Animation > Add Audio Levels Keyframe.

5. In the Audio panel, change the decibel value to 0.0.

6. Press the Page Up key on your keyboard to move the current-timeindicator to the previous frame.

7. In the Audio panel, change the decibel level to -96.0.

8. Move the current time to the new Out point and set thedecibel level to 0.

9. Press the Page Down key to move the current-time indicatorto the next frame.

10. In the Audio panel, change the decibel level to -96.0.

    Note:

    You can change the decibel Slider Minimumvalue in the Audio Options dialog box, which is available from theAudio panel menu.

Aharon Rabinowitz provides a tutorial on the Creative COW website that shows how to use time-remapping to do lip-synching. This same basic concept can be used for many kinds of character animation.

Robert Powers provides a video tutorial on the Slippery Rock NYC website that demonstrates how to use time-remapping to animate a character to synchronize mouth movement with audio (lip synch).

Andrew Kramer provides a video tutorial on his Video Copilot website that demonstrates time-stretching, time-remapping, and frame blending.

When you time-stretch or time-remap a layerto a slower frame rate or to a rate lower than the frame rate ofits composition, movement can appear jerky. This jerky appearanceresults because the layer now has fewer frames per second than thecomposition. Likewise, the same jerky appearance can occur whenyou time-stretch or time-remap a layer to a frame rate that is fasterthan the frame rate of its composition. To create smoother motionwhen you slow down or speed up a layer, use frame blending. Don’tapply frame blending unless the video of a layer has been re-timed—thatis, the video is playing at a different frame rate than the framerate of the source video.

After Effects provides two typesof frame blending: Frame Mix and Pixel Motion. Frame Mix takes lesstime to render, but Pixel Motion provides much better results, especiallyfor footage that has been drastically slowed down.

The Qualitysetting you select also affects frame blending. When the layer isset to Best quality, frame blending results in smoother motion butmay take longer to render than when set to Draft quality.

Note:

When working with a frame-blended layer in Draftmode, After Effects always uses Frame Mix interpolation to increaserendering speed.

You can also enable frame blending forall compositions when you render a movie.

Use frame blendingto enhance the quality of time-altered motion in a layer that containslive-action footage—video, for example. You can apply frame blending toa sequence of still images, but not to a single still image. Ifyou are animating a layer—for example, moving a text layer acrossthe screen—use motion blur.

Note:

You can't apply frame blendingto a precomposition layer (a layer that uses a nested compositionas its source footage item). You can, however, apply frame blendingto the layers within the nested composition if those layers themselvesare based on motion footage items, such as video or image sequences.

1. Select the layer in the Timeline panel.

2. Do one of the following:

   • Choose Layer > Frame Blending > FrameMix.

   • Choose Layer > Frame Blending > Pixel Motion.

A check mark adjacent to the appropriate Frame Blending command (Frame Mix or Pixel Motion) indicates that it is applied to the selected layer. Also, the Frame Blending switch appears in the Switches column for the layer in the Timeline panel. Remove frame blending either by clicking the Frame Blending switch or by choosing the appropriate Frame Blending command again.

Regardless of the state of the layer switches, if frame blending is off for the composition, it is off for all layers in the composition. Set frame blending for the composition by choosing Enable Frame Blending from the Timeline panel menu, or by clicking the Enable Frame Blending button at the top of the Timeline panel.

Note:

Motion blurcan make it harder for Pixel Motion to find discrete objects ineach frame, which makes the calculation of motion vectors less reliable.For better results when using Pixel Motion to create slow motion,use footage with less motion blur.

More like this

• About animation, keyframes, and expressions
• The Graph Editor
• Preview video and audio
• Layer image quality and subpixelpositioning