Combining two videos side-by-side is also called a split-screen effect because it separates the single screen into two smaller screens with two separate videos beside each other. You can separate them equally from the middle of the screen or have one video more dominant than the other. You can position and crop them in whatever way you want as long as they fit the rectangular shape of the original screen. Often times, the videos have black backgrounds for spaces not covered by either of the two videos.
Open your video-editing program, then import the two videos you want to use for the split-screen. Some of the most popularly used video-editing programs for combining videos and creating split-screen effects include Adobe Premiere Pro, Final Cut Pro, Sony Vegas and Avid Media Composer. You can also use the native PC and Mac programs Windows Movie Maker and iMovie for the process.
Click on the "Import" button, which is usually located under the "File" menu. Your imported videos will appear on the "Import" or "Project" window. Button names and their locations may vary per video-editing program used, but their basic editing functions remain very similar.
Drag the first video into the first video track of your "Editing Timeline." This timeline is the part where actual editing happens.
Drag the second video into the second video track of your "Editing Timeline."
Finalise your idea on how to combine the two video clips together in your screen. This includes how you should crop each clip and if you intend to reduce or increase its scale to allow the two clips to fit better on the original screen.
Click the first video in your "Editing Timeline" to highlight it. Use the "Crop" selection, which is typically accessible by right-clicking the video clip or selecting the "Crop" button or its equivalent under the program's menu or video-editing tools. Use the "Preview Monitor" to check how your video looks.
Fit your video on one part of the screen. As example and guide for a split-screen, simply combine the two videos together to equally cover the screen with them. For instance, you can position the first video on the left side of the screen. You may also alter its "Scale," which allows you to make the video look larger or smaller. Changing the video's position on screen and its scale are usually options found in the same area where you choose the "Crop" option.
Click the second video in your "Editing Timeline" to highlight it. Scale and crop it the way you did it on the first video, but position it on the right side of the screen.
Make any necessary adjustment on both videos until you see your desired look for your split-screen effect.
Render your edited video to allow the program to generate the final video complete with the effects you made.
Export your video using any popular file format such as MOV, MP4, WMV or AVI.
If you want the two clips side-by-side equally occupying the space on the original screen and you don't want to crop it, expect that there will be a significant black screen serving like a background in your split-screen video. You have to crop your two video clips so they can fit the shape of your original screen if you want to minimise or remove the black background around the split-screen video. Some computers and video-editing programs provide real-time or almost real-time rendering. This rendering process happens on the background, while you continue editing your project. This makes it faster and more convenient for you to see your final video with the applied effects.