Understand speed and duration
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.