Video footage is recorded at a fixed rate, so changing the clip speed means changing the playback rate.

For other tips on changing duration and speed, see Pr 101: Changing the Playback Speed of clips.

The so-called time remapping is to map the recording rate to the playback rate. The biggest advantage over using the speed stretch tool and speed/duration is that you can set the gradient transition, and the control is easier and more intuitive.

(1) Create slow motion and fast motion effects in a single clip.

Tip: Mapping to fast motion requires frame extraction (delete), and mapping to slow motion requires frame filling (of course, video recorded by high-speed cameras does not necessarily need frame filling).

(2) The duration of clips will generally change, so try to put clips on an independent track for time remapping.

(3) You can use the time remapping effect to speed up, slow down, rewind, or freeze the video portion of the clip.

Effect demo video

Use time remapping

1. If you want to use time remapping, please try to use video material recorded by high-speed cameras, that is, upgrade shooting, generally reaching 50fps or 60fps and above. Fortunately, most cameras and cell phones can shoot high frame rate video these days;

2. It is more convenient and intuitive to use time remapping in the Timeline panel than in the Effects panel: right click on the clip and choose “Show Clip Key/Time Remapping/Speed”;

3. Zoom in to get enough space for observation.

Tip: When performing time remapping on the timeline panel, you may need to press the “\” key from time to time because the clip may need to be pressed.

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Tip: \

(1) First find the clip point and type the key frame, and then pull the line up and down to speed control; \

(2) Hold down Alt/Option key to drag the keyframe slider; Drag directly to separate the keyframe slider; \

(3) After the keyframe slider is selected, the transition smoothness can be adjusted below;

For high frame rate Footage, it is generally not recommended to drag onto the timeline to change the duration. Instead, right-click on the project panel Footage file and choose “Interpret Footage”.

The duration of the clip may be lengthened or shortened as a result, depending on whether its speed is increased or decreased. While the audio portion of the clip is still linked to the video portion, time remapping keeps the audio portion intact.

5. When using time remapping, to determine the time interpolation algorithm, generally right click on the clip and choose “Time interpolation/Optical flow method”. (See below for details) \

The use of time remapping

Application 1: create slow motion and fast motion effects

Right-click the clip and choose Show clip keyframe/time Remap/Speed. Then, drag the tape up or down to increase or decrease the clip’s speed.

Use two: change speed or direction

For example, a clip of someone walking. You can speed him forward, slow him down suddenly, stop halfway, or even back him up before resuming forward motion.

Tip: \

(1) To stand still (freeze frame), please pull the speed to 1.00%;

(2) To go back, first find the key points and cut the clip, then copy and follow, right click on the copy, check the “speed/duration” in the “speed in reverse”. This will slow down to pause, and then from pause to reverse effect.

Time interpolation method \

There are three time interpolation methods: frame sampling, frame blending and optical flow. The three are different in the algorithm of generating frame complement, so the rendering speed and final effect are also different. In general, the optical flow method is preferred (added after 2017 version). If the effect is not ideal, then try the other two methods.

Action: Right – click on the clip and select one of the three methods under “Time Interpolation”. If speed/Duration is used, select a value in the dialog box.

Optical Flow method

Optical flow method uses frame analysis and pixel motion estimation to create complementary frames, that is, to infer the trajectory of pixel movement according to the upper and lower frames to generate new complementary frames.

Optical flow interpolation is ideal for modifying the speed of clips that include objects that are motion-free, objects that move in front of a largely static background, backgrounds that contrast highly with objects in action, and so on. \

When using time remapping to process normal shooting material into slow motion, the picture will be smoother and smoother.

Tip: Premiere Pro only uses the time-consuming optical flow method for time remapping of high quality renderings when previewing the program window. For low quality or rough rendering, faster frame sampling interpolation is used, even when optical flow is enabled. So, to see the effect of the optical flow, you usually do a rendering.

Frame Sampling \

Repeat or delete frames as needed to achieve the desired speed. Rendering is the fastest and is often used for live preview.

Frame Blend \

Repeat and mix frames as needed, for example, mixing the upper and lower frames to create a complement frame to help improve the flow of the action. The rendering speed and final effect are between optical flow and frame sampling. It is suitable for fast playback because it tends to create a sense of motion blur.

Export high frame rate media \

For example, if you want to export a 30 FPS material to a 60 FPS medium, instead of simply repeating each frame, use optical flow to insert and complement all frames to change the medium frame rate.

In the Export Settings dialog box, select the Optical Flow option from the Time Interpolation drop-down menu to export the media. \