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Video Splitter

Four videos, one file. Drop a video into each quadrant and get back the 4K composite the video wall controller expects — each quadrant comes out on its own screen. No Premiere, no export queue: it all happens here, and the file never leaves your computer.

📖 How to use it

What this page is for

The booth has four screens hanging off one video wall controller, and that controller does not take four videos. It takes one 4K video cut into four quadrants and sends each quadrant out of its own socket: whatever sits in the top-left corner of the file leaves through OUT 1, the top-right corner leaves through OUT 2, and so on down. This page builds that file. A useful side effect is that the four screens can never drift apart, because there is only ever one video playing.

OUT 1top left
OUT 2top right
OUT 3bottom left
OUT 4bottom right

Before you start

  • Use Chrome, kept up to date. It is the browser that records straight to MP4, and MP4 is what the fair player reads. If yours cannot, a yellow warning appears under the button rather than handing you a file that dies on the stand.
  • Have the four videos on this computer, in any format Chrome can play — mp4 and mov both work.
  • Set aside as much time as the video lasts, because the render runs in real time. Three minutes of video is three minutes of waiting.

The five steps

  1. Fill the quadrants Drag a file onto a box, or click the box to browse for one. The labels are the controller's own outputs, so the video you put in OUT 1 is the video that comes out of the OUT 1 socket and onto the screen wired to it. Leave a box empty and that quarter of the file stays black, which is exactly what you want when you are running three screens instead of four. The ✕ in the corner takes a video back out.
  2. Check the four settings They open on the values this booth needs, so most days you can walk straight past them. Each one is explained below if you want to change something.
  3. Press Generate video The bar fills in real time and the line underneath counts the seconds. Keep this tab in front while it works: switch away and the render pauses, says so, and carries on from the same point when you come back. Nothing is lost either way, it only takes longer.
  4. Look at the preview, then download The player that appears is the finished composite — check that the four videos are where you meant them to be, then hit Download the file. It saves as videowall-2x2-3840x2160.mp4.
  5. Onto the stick, into the player Copy the file to the USB stick, put the stick in the media player, and set it to repeat. Splitting the picture across the four screens is the controller's job and needs nothing set per screen: it receives one 4K image and cuts it in four by itself.

The four settings, one by one

Resolution
Leave it on 3840 × 2160. Each quadrant is a quarter of the frame, so 4K gives 1920 × 1080 per screen, which is the exact native size of our panels — every pixel lands on a real pixel. The HD option halves that and softens the picture, and it is only there for a quick test when you don't want to wait for a full-size render.
Duration
How long the finished file runs. Clips shorter than that restart on their own to fill the time, so no quadrant ever goes black early. As the longest guarantees every clip is seen at least once through; as the shortest keeps the file small; fixed is for when you want a round number, like a thirty-second loop.
Fit
Fill the quadrant blows the video up until it covers the box and loses whatever hangs over the edges. Show everything keeps the whole frame and pads it with black bars. Filling is right for footage already shot wide; a vertical phone clip loses half its subject that way, and that is when showing everything earns the bars.
Audio from
Which single quadrant keeps its sound, if any. Four soundtracks over three square metres of stand are noise rather than atmosphere, so only one gets through — and the clip you pick has to actually carry audio, or the file comes out silent.

If something looks wrong

  • The bar has stopped moving. The tab went into the background and the render paused itself; the line under the bar says so. Come back to the tab and it resumes.
  • A yellow warning mentions WebM. This browser cannot record MP4, so the file it produces will not play on the fair player without being converted first. Update Chrome and run it again.
  • One quadrant is black in the finished file. That source never loaded, usually because it uses a codec Chrome won't open. Re-export it as an H.264 mp4 and drop it back in.
  • The picture looks soft on the wall. The source was smaller than 1920 × 1080 and got stretched up. Nothing here can invent detail that was never filmed.
  • The file is enormous. 4K at this quality runs to roughly 180 MB per minute. That is normal, and the player handles it without complaint.

The four quadrants

The labels are the controller's outputs: what you put in OUT 1 comes out of the OUT 1 socket and onto its screen. Drag a file in, or click to pick one.

How it gets made

The starting values are already the ones this 2×2 controller wants: 4K in, 1080p per screen.

The render runs in real time: a one-minute video takes one minute. Keep this tab in front while it works, because browsers slow down background tabs — if you do switch away, the job pauses and picks up where it left off. Clips shorter than the chosen duration restart on their own, so every quadrant stays filled to the end.