How do I darken a video smoothly halfway through?

Question

I have a 10 second video clip. At about the 5 second mark, I'm showing a text overlay. I want the video to keep on playing, but I'd like it to be darker when the text is showing.

I don't want an abrupt transition of:

• 0:00: normal video (100% bright), no text
• 0:05: darkened video (50% bright) w/ text overlay

I want a more smooth transition such as:

• 0:00: normal video (100% bright), no text
• 0:04: begin darkening the video
• 0:05: darkened video (50% bright) w/ text overlay

How do I do this in iMovie?

Answer 1

First of all the transition that you are willing to do is according to my knowledge an abrupt transition and according to me dimming 50% of brightness in just 1 second will look less smooth and more immediate than the dimming/reduction of brightness in 5 seconds.

Preferably, I would like you to use Adobe Premiere Pro and/or Adobe After Effects, if you like such transitions, in which "keyframes" do a nice job.

But, in iMovie, you don't have a good keyframe feature. So, what you can do here is answered by AppleMan1958 (quoting it in his own words below):-

Mar 9, 2012, 5:07 AM AppleMan1958 in response to Penfold941

iMovie does not contain keyframes like FCP, but you can simulate it quite a bit. Just drag your mouse from your first "keyframe" to the end "keyframe" within a clip so that you have selected a range of clips. Then right-click within the range and select "Split Clip". Now you can apply a Ken Burns zoom to this section. This works for many effects.

What you cannot do is keyframe the location of a motion graphic to simulate movement, for example.

You may read the full thread here

So, you might have got your answer, if there remains any other confusion, you may ask in the comment section below. But, try this solution out before asking or assuming any confusion. Hopefully, you might get rid of your problem yourself.

Answer 2

As Naved mentioned, you need to split the clip. The most important part, however, is using a Cross Dissolve, which smoothly transitions from one clip to another.

1. Split the two clips in half so you go from [clipA] to [clipA1][clipA2].
2. Modify clipA2 to have whatever effects you want such as darkening the video.

3. Add a Cross Dissolve between the two clips

   (The cross dissolve is so common it has a keyboard shortcut, ⌘T, to add it to both sides.)

In fact these three steps are so common, you can find a one-click solution for doing the same with these effects via the Modify > Fade to menu:

• Black and White
• Sepia
• Dream

A third and final shortcut/tip is even if you want to darken the video, you could use the "Fade to Black and White" feature, then remove the Black and White effect and apply whatever other transformations you want to the video.