When I was beginning to make videos I didn’t know a thing about editing. For my first video (see below) I just shot several scenes in the sequence I wanted for my story, placed my video clips on the timeline of the daunting editing software I was struggling to understand, and pressed the "publish" button, turning that sequence into–eureka–a movie! No trimming of clips, no arranging of clips, no transitions between clips. For a first attempt it wasn’t bad, but of course I knew that continuing to tell my stories this way would be very limiting. I needed to study editing so that I could get rid of "footage" I didn’t need, and move my clips around to see how best to tell my stories; and finally, I wanted to be able to impart different looks to the brief times between scenes, called transitions. Much later I discovered that my video editing application had ready-made transitions which I could drop between clips. They automatically give a certain look to the changes. There are hundreds of transitions in some editing programs, some flashy, even cartoonish, some subtle. This post is about a common subtle transition, the crossfade.
With a digital video editing system one can choose to display the output of files in particular ways, and one of those ways is to fade the output. A fade is a gradual increase or decrease of the visual and audio output of a file. A fade out is the gradual diminishment of the output of a video file. The video goes from strong and clear to fuzzy, then weak, then finally all black or white. The audio goes from full volume to less and less loud. A fade in is the exact opposite: a gradual increase in visual and audio clarity and strength.
In a crossfade the earlier clip fades out and the upcoming clip fades in, simultaneously. The resulting transition shows a subtle morphing of the content of the first scene into the content of the second one, with the subtlety of the change varying according to the length of the crossfade. The shorter the crossfade the less subtle the change.
The video below illustrates crossfades, which are used for most of the transitions:
Some video editing programs have drag-and-drop crossfades that one drops on top of the dividing lines between clips. However, I like editors like Sony Vegas that allow you to make a crossfade by dragging a clip on the timeline over the trailing edge of the clip just before it. When you do this you see an "X" appear in the fade area, indicating that output from the first file is gradually decreasing and output from the trailing file is gradually increasing. Dragging the trailing clip left or right is a very easy way to test the effect of a longer or shorter crossfade.
Why use a subtle crossfade rather than a more dramatic transition? Well, as you tell your story, if you want to mark a major transition in the story flow, perhaps a movement from an introduction to the main body of the film, or from the main body to the conclusion, then you want a fairly dramatic visual transition, to let the viewer know that a significant change is occurring. However, if you just want to mark a minor change from one scene to another, then a subtle crossfade is preferable. Beginning filmmakers often overuse dramatic transitions, distracting their viewers from the content itself. Get used to using more subtle transitions like crossfades and dissolves in order not to eclipse the impact of the story with special effects.