Slow motion is one of the many effects that we see in all kinds of animations. Most video editors have a way to achieve this effect and so does Blender's VSE. So how do we create a slow-motion effect in the Blender VSE?
Select the strip, press N to bring up the properties panel and go to the strip tab, then expand the time section and change the speed factor. A value lower than 1 will slow down the clip and a higher will speed up the clip.
For example, a speed factor of 0.5 will slow down the clip to run for twice as long.
In the rest of this article we'll go into more detail about how we can configure speed control. We'll also go over how to vary the speed of the strip. Finally, we'll go into how to create a freeze frame effect.
Another way to control the speed of a clip is to use an effect strip.
To add a slow motion effect using an effect strip follow these steps:
Related content: Meta strips, scene strips and adjustment layers in Blender VSE
When we're modifying the speed of a video is better to have higher frame rate videos. The reason for this is that when we slow a clip down, we're just changing the time per frame. With a higher framerate we can lower the speed without a noticeable jump between frames.
The effect strip also has a basic interpolation effect. We can use this interpolation effect to smooth out the stretch between frames to help with the jump between frames.
To enable interpolation, select the green speed control effect strip and press N to open the side panel. Go to Strip > Effect Strip and enable the interpolation option.
We can animate the speed control multiplier in the effect strip or the speed facror in the strips time section that we used right at the beginning of the article but let's say that we are using the effect strip multiplier.
To make the strip speed variable first select the speed control effect strip. Press N to open the side panel and then go to Strip > Effect Strip and set Speed control to Multiply.
Drag the playhead to the frame where we want the animation to start slowing down and under speed control there is a multiply value. Next to that value click on the Animate Property circle. We can also insert a keyframe by right clicking on the multiply value and selecting insert keyframe.
Next drag the playhead to the point where we want the animation to be the slowest and then set the multiply value to the speed we want. After we've entered our value insert a keyframe and the scale value will turn yellow showing we've added a keyframe.
In the case that we want the animation to stay at this slower speed for a while we can drag the playhead to where we want the slow motion to start easing back to the original speed and set the multiply value to the same value we used for the first slow motion keyframe and then insert another keyframe.
Finally, to get our speed to ease back to normal speed drag the playhead to the frame we want the slow motion to end and set the scale value to 1 and then insert another keyframe.
While we've used the scale speed control for the example above there is also frame number and length. Length lets us directly control where in the video we are using a 0 - 100% range. Frame number works in a similar way but using frames instead which allows for much more fine control.
While we have the ability to adjust the speed values we may not like the default curves blender creates between keyframes.
To change this we'll need to open up a new window to access the graph editor. To do this go to one of the windows in the video editor workspace and hover the cursor over one of the corners until the cursor turns into a +
Hold down the left mouse button and drag so that a new window pops out and set it to the size we'd like. Set the editor type to graph editor.
Make sure the speed control strip is selected and the keyframe should be visible in the graph editor. Here we can adjust the interpolation curves. We can also select a group of keys and in key > interpolation we can set the interpolation method for the selected keyframes.
For example if we didn't want our speeds to ease into each other we could set the interpolation to linear to have the speed change be constant.
The first thing we'll want to make sure to check is that we have the green speed control effect strip selected. When we don't have it selected we won't be able to find the scale value or insert any keyframe on it.
One issue we may run into when we have keyframes added to our multiply value is that the value keeps being reset to the current frames scale value. We can avoid this by dragging the playhead to the frame we want to insert the value and before we move the playhead.
We may also have trouble finding keyframe in the case we want to remove them. You may have noticed when we added keyframes to the multiply value it turned green or yellow. When the value is green this is an interpolated value between keyframes.
When the value is yellow it shows there's a keyframe on that frame. The animate property dot will also be full white. We can also quickly just between these keyframes without having to do any searching by using the jump to keyframe buttons in the timeline controller.
To get rid of a single frame we can either click on the animate property dot to remove the keyframe or we can right click on the multiply value and select delete keyframe. We can remove all keyframes by right clicking on the multiply value and selecting clear keyframes.
Note that Blender doesn't automatically stretch the clip out to fit the new slowed down size. We'll want to make sure we've made our clip long enough to encompass all of the slowed down clip.
To make the strip speed variable first select the speed control effect strip. Press N to open the side panel and then go to Strip > Effect Strip and set Speed control to Multiply.
Drag the playhead to the frame before we want to freeze frame and then select the speed control effects strip. Open the side panel and in Strip > Effect Strip right click on the speed control value and select insert frame.
Drag the playhead over one frame and then set the multiply value to 0 and again right click and select insert frame. Go to the frame we want the freeze frame to end and insert another frame. finally move the playhead over one frame, set the multiply value to 1 and insert a final frame.
Slow motion effects are quite useful, and Blender's VSE makes it pretty easy to set them up. Whether we just want to stretch a clip out or set it to a certain speed. We can also adjust the speed with keyframes making most slow-motion effects quite easy to setup.
Thank you for your time.
