Can you make one side bigger than the other in split-screen dual camera video?
No, not within split screen itself. In DualCam, both split layouts — top and bottom, left and right — divide the canvas into two equal halves, and that ratio is fixed. There is no line to drag and no percentage to set. Each camera gets exactly half the frame, every time.
If what you actually want is for one camera to read as the main subject while the other stays present but smaller, that is not a split-screen problem to solve — it is a sign you want picture-in-picture instead, which is built specifically to make one camera dominant.
Why the split is fixed at half and half
DualCam’s canvas is 1080 pixels wide, either 1920 tall for standard 9:16 or 2340 tall to fill a modern iPhone screen. A split layout divides that canvas in two before either camera image is drawn into it: top-and-bottom gives each camera a full-width, half-height slot, left-and-right gives each camera a half-width, full-height slot. The math behind each camera’s crop — roughly a quarter trimmed off the top and bottom in one split, roughly a quarter off each side in the other — only works out the way it does because the divide is exactly even. An adjustable ratio would mean a different, unpredictable crop every time you moved it, with no way to preview what got cut.
Split screen is also making a specific visual statement: both things in frame matter equally. That is the whole reason to choose it over picture-in-picture for a two-person conversation or a side-by-side comparison. A lopsided split would undercut the one thing the layout is for.
What actually changes which camera dominates
Switch to picture-in-picture
This is the layout built for uneven emphasis. One camera fills the entire canvas and the other floats above it in a small window, with three size steps to choose from and a choice of corner. That is an actual, deliberate size difference between the two feeds — the closest thing DualCam has to a slider, it just lives in a different layout than split.
Swap which camera is the big one
Whether it is a full-frame picture-in-picture background or the larger half of a split, which camera fills the dominant role can be swapped, and in DualCam that swap works mid-recording along with the rest of the layout controls — you do not need to stop and restart to change your mind about which camera should lead.
Zoom in on one camera’s feed
Pinching to zoom changes how much of the scene a camera captures without touching how much canvas space it occupies. Zooming the back camera in tighter on a subject, while the front camera stays wide, makes one half read as more dominant content-wise even though both halves are still exactly the same size on screen.
You do not have to choose before you press record
Layout, the picture-in-picture corner, its size, its shape and the colour filter can all be changed while DualCam is recording, and the file follows the change immediately because the preview and the recording are the same rendered frame. Start in an even split for the part where both people matter equally, then cut live to picture-in-picture the moment one side needs to take over — a real edit performed while the camera is rolling, not something you fix afterward.
Common follow-up questions
Is there a divider I can drag to resize the split?
No. In DualCam, both split layouts are locked at an even 50/50 divide. Dragging only applies to the picture-in-picture inset, which you can move between the four corners.
Do the two split layouts crop the same amount from each camera?
No. Left-and-right split crops roughly a quarter off each side of a source frame to fit a narrow vertical slot; top-and-bottom split crops roughly a quarter off the top and bottom instead, which tends to suit a head-and-shoulders shot better. The full breakdown is in the guide comparing picture-in-picture and split screen.
Can I switch from split to picture-in-picture without stopping the recording?
Yes. Layout changes take effect immediately in DualCam, so you can cut from a split to picture-in-picture, or back, mid-take.
Want to just do this?
DualCam records the iPhone front and back cameras at the same time and writes one finished MP4 while you shoot. Free, no account, no ads, nothing leaves the phone.