What is speed?
The speed of a clip is the playback rate compared to the rate at which it was recorded. By default, a clip plays back at its normal, 100 percent speed. (Even if the frame rate of the source footage doesn’t match that of the sequence, the sequence automatically reconciles the difference. It plays back the clip at its proper speed.)
When you change the speed of a clip containing interlaced fields, you can adjust how Premiere Pro treats the fields. Consider making this adjustment especially when the speed drops below 100% of the original speed. (See Create interlaced or non-interlaced clips.)
You can use frame blending to smooth the appearance of a speed effect that changes the time or frame rate of a clip. To enable frame blending, choose Clip > Video Options > Frame Blend. For more information about frame blending, see Blend frames for smooth motion.
What is duration?
Why would I need to change speed and duration of clips?
You typically change the speed and duration of clips either for technical reasons or for aesthetic reasons. Aesthetic reasons include creating a fast-motion effect (speed is over 100 percent) or a slow-motion effect (speed is under 100 percent).
Changing clip speed omits or repeats the source frames during playback, making the clip play faster or slower.
Will changing speed of a clip affect duration?
By default, a change in speed results in a corresponding change in duration, unless the clip is simultaneously trimmed.
However, you can choose to ungang speed from duration in the Clip Speed/Duration dialog box. Then, when you increase the speed, Premiere Pro uses more of the clip to fill the duration between the In point and the Out point. And when you decrease the speed, Premiere Pro uses less of the clip to fill the duration.
You can ungang speed and duration with more than one clip selected. Then, you can change the duration of the clips. For example, you can change the speeds only enough to make all the clips last the same duration.
You can also set clip speed to fill a duration by performing a four-point edit.
How can I view the total duration of selected clips?
In either the Project panel or Timeline panel, select the clips for which you want to know the total duration. The Info panel displays the number of items selected and the total duration of those items. This information is useful if you want to paste clips into a specific area and to know the exact duration of the target area or of the source clips.
If you select contiguous clips in the Project panel, the Info panel displays the total duration of all the clips you select. However, if you select noncontiguous clips in a sequence, the Info panel displays the duration as a range, from In point of the first clip you selected, to the Out point of the last clip you selected. For copying and pasting, the duration of a particular range is more important than the sum of all the clips’ durations. If you copy and paste a noncontiguous group of sequence clips, the pasted clips occupy the range noted on the Info panel and the areas that you did not select will be empty.
You can change the speed and duration for one or more clips at a time. Premiere Pro offers several ways to modify the speed and duration of clips. You can use the Speed/Duration command, the Rate Stretch tool, or the Time Remapping feature.
Note: You can apply Optical Flow only from the timeline or Export Settings dialog box, and not from the Project panel.
You can apply Speed/Duration changes at the Project clip level or at the Sequence clip level. Changes made at the project level will be respected when adding new instances into a sequence. This is different than master clip effects though, because Speed/Duration changes will not be ripped into existing instances of that clip in your sequence(s).
Do any of the following:
- To change the duration without changing the speed of the selected clips, click the gang button so that it shows a broken link. Unganging also allows you to change the speed without changing the duration.
- To play the clips backward, check Reverse Speed.
- To keep the audio at its current pitch while the speed or duration changes, check Maintain Audio Pitch.
- To keep the clips following the changing clips adjacent to them, click Ripple Edit, Shifting Trailing Clips.
- Select a Time Interpolation option for Speed changes: Frame Sampling, Frame Blending or Optical Flow. (For more info about these options, see the sections below entitled Time interpolation using Optical Flow and Frame Blending)
The Rate Stretch tool provides a quick method to change the duration of a clip in the Timeline while simultaneously change the clip's speed to fit the duration.
For example, you might have a gap in your sequence of a specific length and you want to fill that gap with some speed-altered media. You may not care so much about the speed of the video, you just need to make sure it fills that gap at whatever speed it needs to be. Rate stretch takes the guess work out by allowing you to stretch or compress the speed to the per centage needed.
You can change a clip’s speed to fit a duration using the Rate Stretch tool in Premiere Pro. Select the Rate Stretch tool and drag either edge of a clip in a Timeline panel.
See this video tutorial by Andrew Devis on the razor and rate stretch tools.
You can vary the speed of the video portion of a clip. Use Time Remapping to create slow motion and fast motion effects within a single clip.
The playback speed of the video portion of the clip changes and its duration expands or contracts depending on whether its speed is increased or decreased. The audio portion of the clip remains unchanged by Time Remapping, although it remains linked to the video portion.
When you lengthen a clip in a sequence by slowing its speed, it does not overwrite an adjacent clip. Instead, the clip expands until it touches the edge of the adjacent clip. Adobe Premiere Pro then pushes remaining frames into the tail of the lengthened clip. To recover these frames, create a gap after the clip and trim its right edge to reveal them.
Franklin McMahon provides a video tutorial demonstrating time remapping on the Layers Magazine website.
You can speed up, slow down, play backward, or freeze video portions of a clip using the Time Remapping effect. Using speed keyframes, you can change speed numerous times within the same clip. Take a clip of someone walking, for example. You can show him moving forward quickly, slowing suddenly, stopping mid-step, and even walking backward, before resuming his forward motion. Unlike Clip Speed/Duration which applies a constant speed across the entire clip, Time Remapping allows you to vary the speed throughout the clip. Also, you can ease in or ease out speed changes.
You can apply time remapping only to instances of clips in a Timeline panel, not to master clips.
When you vary the speed of a clip with linked audio and video, the audio remains linked to the video, but remains at 100% speed. The audio does not remain synchronized with the video.
You create variable speed changes by applying speed keyframes. You can apply speed keyframes in the Effect Controls panel, or in a clip in a Timeline panel. Applying speed keyframes in either location is like keyframing Motion, Opacity, or any other keyframe effect, with one notable difference: a speed keyframe can be split to create a transition between two different playback speeds. When first applied to a track item, any change in playback speed on either side of a speed keyframe is instantaneous at that frame. When the speed keyframe is dragged apart and spread out beyond one frame, the halves form a speed change transition. Here, you can apply linear or smooth curves to ease in or ease out the change between playback speeds.
It is best to apply time remapping controls to a clip in its own video track, or at least one not followed immediately by other clips. Slowing any portion of a clip makes the duration of that clip longer. If a second clip immediately follows the lengthened clip in the video track, the lengthened clip is automatically trimmed where the second clip begins. To recover the frames trimmed from the lengthened clip, click the Track Select tool, then Shift-drag the second clip toward the right to make room. All clips lying to the right move to the right. Click the Selection tool, then drag the right edge of the lengthened clip to the right, exposing its trimmed frames.
In a Timeline panel, click on the Clip Effect menu and choose Time Remapping > Speed. (The Clip Effect menu appears next to the filename of every clip in a video track. You might have to zoom in to make enough room in the clip to display it.)
- Ctrl-click (Windows) or Command-click (Mac OS) at least one point on the rubber band to set a keyframe. Speed keyframes appear near the top of the clip, above the rubber band in the white speed-control track. Speed keyframes can be split in half, acting as two keyframes for marking the beginning and end of a speed-change transition. Adjustment handles also appear on the rubber band, in the middle of the speed-change transition.
Drag the rubber band on either side of the speed keyframe up or down to increase or decrease the playback speed of that portion. (Optional) Press Shift while dragging to limit the speed change values to 5% increments.
Shift-drag the speed keyframe to the left or right to change the speed of the portion to the left of the speed keyframe.
Speed and Velocity values for the Time Remapping effect are shown in the Effect Controls panel for reference only. You cannot edit these values directly there.
- In a Timeline panel, click the Clip Effect menu and choose Time Remapping > Speed. (The Clip Effect menu appears next to the filename of every clip in a video track. Zoom in, if necessary, to make enough room in the clip to display the menu.)
- Ctrl-drag (Windows) or Command-drag (Mac OS) a speed keyframe (both halves) to the place where you want the backward motion to end. A tool tip shows the speed as a negative percentage of the original speed. The Program monitor displays two panes: the static frame where you initiated the drag, and a dynamically updating frame that reverse playback returns to before switching to forward speed. When you release the mouse button to end the drag, an additional segment is added for the forward playback portion. The new segment has the same duration as the segment you created. An additional speed keyframe is placed at the end of this second segment. Left-pointing angle brackets appear in the speed-control track, indicating the section of the clip playing in reverse.
The segment plays backward at full speed from the first keyframe to the second. Then, it plays forward at full speed from the second to the third keyframe. Finally, it returns to the frame at which the backward motion began. This effect is called a palindrome reverse.
You can create a segment that plays in reverse and doesn't return to forward playback. Use the Razor tool or the Trim tool to remove the segment of the clip with the forward playback section.
- (Optional) You can create a speed transition for any part of the change in direction. Drag the right half of a speed keyframe to the right, or the left half to the left.
A gray area appears between the halves of the speed keyframe, indicating the length of the speed transition. The rubber band forms a ramp between the two halves, indicating a gradual change in speed occurring between them. A blue curve control appears in the gray area.
If the blue curve control does not appear, click in the gray area.
You cannot toggle the Time Remapping effect on and off like other effects. Enabling and disabling Time Remapping affects the duration of the clip instance in a Timeline. In effect, Time Remapping performs an edit. However, you can use the Toggle Animation control in the Effect Controls panel.
To re-enable Time Remapping, click the Toggle Animation button back to the 'on' position. You cannot use Time Remapping with this button in the 'off' position.
- For Still Image Default Duration, specify the number of frames you want as a default duration for a still image.
Changing the default duration of still images does not affect the duration of still images that are already part of a sequence or that have already been imported. You will have to re-import the images after you change the default duration to get a different duration for the images.
The Optical Flow feature in Premiere Pro uses frame analyses and pixel motion estimation to create brand new video frames, resulting in significantly smoother speed changes, time-remapping, and frame-rate conversion.
The Optical Flow option in the Time Interpolation menu (Clip > Video Options > Time Interpolation > Optical Flow) allows you to interpolate missing frames for time remapping and produce better looking and smoother slow motion from conventionally shot footage.
Since the optical flow library cannot sustain real-time playback, as it happens with the existing Frame Blend function, Premier Pro uses the time-consuming Optical Flow only for Time Remapping for high-quality renders. For low-quality or draft rendering, the faster Frame Sample interpolation is used even while the Optical Flow is enabled. You will need to render your sequence to see the optical flow effect. Choose Render In to Out or hit Enter to do that
Optical Flow interpolation is ideal for modifying the speed of clips that contain objects with no motion blur, which are moving in front of a mostly static background that highly contrasts with the object in motion.
The Time Interpolation setting in the Export Settings dialog box (File > Export > Media) allows you to change the frame rate of the exported file by leveraging Optical Flow to interpolate the missing frames. For example, if you have a 30 fps footage that you want to export at 60 fps without repeating every frame, you can export the media with the Optical Flow option in the Time Interpolation drop-down box selected.
In some footage, using Optical Flow for creating smoother motion may not produce the desired results. In such scenarios, you can use one of the other time interpolation options--Frame Sampling or Frame Blending. Frame Sampling repeats or removes frames as needed to reach the desired speed. Frame Blending repeats frames, and it also blends between them as needed to help smooth out the motion.
You can access all the time interpolation methods from within Premiere Pro using one of the following menu options:
- Choose Clip > Video Options > Time Interpolation > Frame Blending | Frame Sampling.
- Right-click on the clip in a sequence and choose Time Interpolation > Frame Blending | Frame Sampling.
- Open the Speed/Duration dialog box and use the Time Interpolation drop-down menu.
- Open the Export Settings dialog and use the Time Interpolation drop-down menu (this method will only apply to exported media).