How to put a countdown timer on an ATEM switcher

The setup takes one computer feeding the switcher and one device for control. Nothing is installed on either.

The list:

• A Blackmagic ATEM switcher — any model with a spare input.
• A computer with HDMI output connected to that input, set to extended desktop mode (not mirrored), so the timer can run fullscreen on the ATEM input while you keep your own screen. On macOS, keep "Displays have Separate Spaces" on if the main screen goes black when you do this.
• ATEM Software Control, on the same computer or another one on the network.
• A MaestroTimer room with a timer in it — created in the browser, no install.

The ATEM sees whatever the connected computer displays, so the first step is filling that display with the timer.

The steps:

1. ✓Create a room in MaestroTimer and add a timer. Set a wrap-up threshold so the display changes color as time runs low — the switcher carries that color change straight to the program feed.
2. ✓Open the room's viewer — every view is a link, so this is just a URL.
3. ✓Drag the viewer window to the display connected to the ATEM and make it fullscreen (F11 on Windows, Cmd+Ctrl+F on macOS).
4. ✓In ATEM Software Control, select that input and confirm the timer is visible.

The fastest way to get the countdown on air is the ATEM's DVE key — a picture-in-picture box pointed at the timer input, cropped down to the digits. No keying, no color sampling, and every color survives exactly as the timer renders it, including the wrap-up change. The box is opaque, so the timer sits on its own background like a broadcast clock bug — which is exactly how most productions want it.

Check one limit before you build it. ATEM Mini models have a single DVE channel, shared between the hardware picture-in-picture button, the DVE upstream keys and Flying Key, so the DVE key is unavailable while PIP is in use. If you need that PIP for something else, use the luma key below or a downstream key instead.

In ATEM Software Control:

1. ✓In the Palettes panel of ATEM Software Control, expand Upstream Key 1 and select the DVE tab.
2. ✓Set the fill source to the timer input. A DVE key needs no key source and no color sampling — the ATEM generates the key internally from the shape of the box.
3. ✓Enable Mask and bring the Top, Bottom, Left, and Right values in until only the countdown is left.
4. ✓Size and position the box with the Position and Size controls — a lower corner keeps it out of the shot's subject. A thin border or a drop shadow, both in the same tab, makes the box read as deliberate.
5. ✓Put the key on air: the ON AIR button above KEY 1 cuts it in immediately, or press KEY 1 in the Next Transition row to bring it in with your next transition.

If the timer should float directly on the picture with no box behind it, use a luma key on the same input. A luma key works from brightness, so it suits the case where your timer page renders light digits on a dark background: the dark part is what gets dropped, and the digits stay.

Set it up in the upstream key panel with the key type set to Luma. Both the Fill Source and the Key Source must be the timer input, and Pre Multiplied Key must be off — with it on, the ATEM assumes the key is already prepared and the tuning controls do nothing.

Then tune with clip, not gain. Lowering the clip level lets more of the underlying video through, so bring clip down until the timer page's background is gone and the digits are still solid. Gain is not a "how much is removed" control — it softens the edge between kept and removed, so touch it last, and only if the edges look harsh.

A luma key trades some edge quality for transparency, and thin fonts suffer first. If the result looks ragged, go back to the picture-in-picture box — it is the same look broadcast uses for clocks, and it never degrades.

Position the keyed timer with the Mask controls inside the same Luma tab — crop it down to the digits exactly as in Method 1 — or enable Flying Key, which adds DVE position and size controls to the key. Flying Key borrows the same DVE channel as Method 1, so on an ATEM Mini it is one or the other.

Two limits worth knowing. A luma key removes all dark pixels, not just the background — a dark-colored element on the timer page fades or disappears, which is another reason the picture-in-picture box is the safer default. And if both upstream keys are busy, a Downstream Key works just as well for a timer: it sits after the upstream transitions, so the countdown stays on screen while you cut between sources — usually exactly what a clock should do.

A speaker-facing countdown often should not be on the program feed at all. Because MaestroTimer runs in the browser, the stage screen does not need the switcher: open the same viewer link on any device driving that screen — a spare laptop, a tablet, anything with a browser — and it stays in sync with what the ATEM shows.

Before doors open, check the room's live connections view. It lists every device attached to the room, so you can confirm the ATEM input computer and the stage screen are both receiving before the show starts.

Control never touches the switcher. Open the controller view on a phone or tablet, and start, pause, and time adjustments appear on the program feed immediately.

Send messages the same way: a bold, colored, or flashing note appears on the viewer next to the countdown — visible in the PiP box on program, or on the stage screen, wherever that viewer is displayed.

For a full rundown, link timers so each segment starts when the previous one ends, or schedule the first timer to start at a set time of day. The switcher operator never has to think about the clock.