How to make a split screen or picture-in-picture video on a Mac
Two clips, one frame. It's the format behind reaction videos, before-and-after comparisons, and the stacked clips that fill Reels and TikTok. The mechanics are simple; the things that make it look right are less obvious.
Pick the layout for the platform, not the footage
Vertical stack: one clip above the other, in a 9:16 frame. This is the social format: talking head on top, gameplay or satisfying b-roll underneath. It only works in portrait, and it's the layout most people actually mean.
Side by side: two clips left and right, landscape. Right for reaction videos, interviews across two cameras, and any genuine comparison where the viewer needs to see both at once at equal size.
Picture in picture: one clip full frame with a small inset. Best when one source is clearly primary, like a screen recording with a webcam corner.
The framing problem nobody warns you about
Two clips of different shapes will not fill their halves neatly. A landscape clip dropped into the top half of a vertical frame either gets cropped hard or leaves black bars, and a portrait clip in a side-by-side layout does the same.
Cropping to fill looks better than bars, but it means losing the sides of the shot, so check that the subject is still in frame after the crop. A talking head framed slightly off-centre is the classic casualty: perfectly composed in the original, half out of frame in the split.
Decide which audio survives
Two clips means two audio tracks, and playing both at once is almost always wrong. Usually one clip carries the voice and the other is silent b-roll, so mute the second entirely. For a reaction video where both matter, lower the source clip well under the reaction so the speech stays intelligible, competing dialogue at equal volume is unwatchable.
Syncing without timecode
If the two clips are meant to line up, two cameras on the same moment, find a sharp sound or a distinct visual event in both and align to that. A clap works because it's a hard spike in the waveform and a visible motion in the picture. Trim both clips to start from that point, then treat them as one.
Doing it in Crisp
- Import both clips.
- Add them to the timeline in the order you want them stacked.
- In the Project panel, find Split screen and pick a Layout: Top and bottom, Side by side, Picture-in-picture, or Grid of four. The first three take exactly two clips; grid takes four, which is the option most guides leave out and the one worth knowing if you are comparing four takes, four angles or four entries rather than two.
- Pick the Audio: from the first clip, both mixed together, or none.
- Press Make a split screen. The result lands in your Media panel; add it to the timeline and export.
It renders on your Mac, so nothing is uploaded and there's no file-size limit beyond your own disk. The free tier does all of this with a small watermark on the export; the $129 licence removes it.
Keeping it watchable
Two moving images compete for attention, which is the point on social and a problem everywhere else. If both halves are busy, the viewer watches neither. Pair an active clip with a calm one, and keep split-screen sections short: a whole video in split screen is exhausting to watch.
Matching two clips that don't match
Footage from two sources rarely agrees on colour. A phone and a camera pointed at the same room will differ in white balance enough that the split looks like two unrelated videos glued together. Nudge the warmer clip cooler, or the cooler one warmer, until skin tones roughly agree. This matters far more than getting either clip objectively correct.
Frame rate mismatch is the other one. A 60fps clip beside a 30fps clip will have visibly different motion, and there's no fixing that in the edit; decide which is primary and accept the difference, or reshoot.
Picture-in-picture: size, position and separation
A picture-in-picture is the same job as a split screen with one clip small. Size. Aim for the inset at roughly a fifth to a quarter of the frame width. A webcam at a tenth of the width is a thumbnail of a face nobody can read expressions on, and most viewers are on a phone. Position. Bottom-right is the default for landscape, because viewers finish scanning there and most on-screen furniture sits there. Move it when the main footage has something important in that corner, or when the platform puts its own interface there: vertical video on social platforms has controls and captions crowding the bottom, so a bottom inset is a bad idea and top-left is usually safer.
The mistake that looks amateur: stretching. A 16:9 webcam squeezed into a square inset, or a vertical phone clip stretched into a landscape box, distorts faces in a way viewers notice instantly even when they cannot say what is wrong. Crop the inset to the shape of the box instead of scaling it: you lose some edges and keep correct proportions, which is always the better trade. Separation. An inset that shares a colour with the region behind it dissolves into the background. A thin border or a subtle drop shadow fixes that in one step and is the difference between “layered” and “pasted on”.