Live wallpapers on macOS: video, multi-monitor, and scheduled

How this differs from the wallpaper built into macOS

macOS 14 (Sonoma) introduced Aerial wallpapers: the same slow aerial footage the screen saver uses can be chosen from System Settings > Wallpaper. It is worth knowing how that behaves once it is set. The footage animates around moments such as waking from the screen saver and then settles onto a still frame, so for most of a working day it sits there as a photograph rather than as a moving background. Choosing an Aerial also starts a background download of several hundred megabytes to over a gigabyte, and until it finishes nothing can play it — not System Settings, and not a third-party app either.

Emerald Tools does not replace any of that. It draws its own layer one step below your desktop icons and paints media there, which is why your icons stay exactly where they are and clicks still land on the desktop rather than on the wallpaper. Videos loop through a looping player rather than being restarted, so there is no stutter at the loop point, and playback is muted at all times.

A different wallpaper on every display

macOS can already give each display its own still picture — the Wallpaper settings grow a display selector as soon as a second screen is connected. What it will not do is let those displays differ in kind: a video on the ultrawide, a Photos album on the vertical panel, an Aerial on the built-in screen.

Emerald Tools treats displays separately from the start. Opening Wallpaper from the menu bar shows a card for every display macOS currently reports, under Connected Displays, and each card has its own switch and its own settings page. There is no fixed ceiling on the number of displays: the app creates one wallpaper window per display, however many there are.

Per display you choose:

• The source — a local image or video file, a single photo, a Photos album to cycle through, or an Aerial that macOS has downloaded.
• The framing — rotation from -180 to 180 degrees in 1 degree steps, and scale from 1.00x to 3.00x in 0.01 steps. 1.0x fills the screen exactly at any rotation, and the media cannot be shrunk below that.
• Whether the wallpaper layer is on at all, independently of the other displays.
• Its own schedule, covered in the next section.

Unplugging a monitor does not discard its setup. The settings move to Saved Profiles and are matched back to the display when it is reconnected, so a laptop that meets a different set of monitors at home and at the office does not need reconfiguring twice a day. Profiles for monitors you have retired can be deleted individually or all at once.

Switching wallpapers on a schedule

A schedule entry is three things: which weekdays it applies to, a time range, and the media to show during it. Weekdays are selected as a set, so a single entry can cover Monday through Friday. The time range is set in 30-minute steps, and a range that crosses midnight — 23:00 to 6:00 — is handled as one range rather than two entries.

The schedule is evaluated once a minute, so a wallpaper changes within a minute of its window opening.

Two rules decide what you see when entries meet:

• When entries overlap, the topmost one in the list wins. Entries can be moved up and down, so priority is something you set rather than something you have to work out.
• When no entry matches, the display shows its Default Media — the source you picked outside of any schedule. This makes the default the safe floor of the whole arrangement, rather than a blank desktop.

Schedules belong to a display, like every other wallpaper setting, so two monitors on the same desk can run two entirely unrelated timetables.

An overlay that makes the whole macOS interface look see-through

Everything above puts media behind your windows. Emerald Tools can also put it in front of them.

Overlay draws the media on a layer above every window on that display — Finder, your browser, the menu bar, all of it — at an opacity you choose. Because the layer is translucent rather than opaque, the result is not a video sitting on top of your screen: it is the whole macOS interface taking on a see-through look, with your windows reading through the moving image the way a translucent shell shows what is behind it. Slow footage at a low opacity reads as an atmosphere the entire desktop sits inside, rather than as something in the way.

The layer never takes control away from you:

• Clicks, scrolling and keystrokes pass straight through. The overlay window ignores mouse events outright and refuses to become the key or main window, so every app underneath behaves exactly as it did before. Nothing about how you use the Mac changes.
• Opacity is yours to set — 0% to 100% in 5% steps, with 30% as the default, which is low enough to read text through comfortably.
• It is off until you turn it on, per display, from the same Display Layers card as the wallpaper switch. A display can run the overlay alone, the wallpaper alone, or both at once.
• It follows the schedule. The overlay uses whatever media the display’s schedule has selected, so the atmosphere over your desktop can change by weekday and time in exactly the way the wallpaper does.
• It stays with you across every Space, and is set to remain visible alongside full-screen windows.

This is the part macOS has no equivalent of at all. The Wallpaper settings only ever paint behind your windows; there is no built-in way to put anything translucent in front of them.

Supported formats and limits

Everything below is the behaviour of the current release, not a plan.

• Images: JPEG, PNG, HEIC, GIF, TIFF.
• Videos: MP4, MOV. Audio is never played.
• Reverse loop (forward, then backward): videos of 60 seconds or less. Longer videos fall back to an ordinary loop automatically, because preparing a reversed copy costs time in proportion to the length of the video.
• Rotation: -180 to 180 degrees, in 1 degree steps.
• Scale: 1.00x to 3.00x, in 0.01 steps. 1.0x is screen-filling; there is no shrinking below it.
• Album cycling interval: 30 seconds, 1, 5, 15 or 30 minutes, or 1, 3, 6, 12 or 24 hours.
• Album layouts: Single, Tiled in three densities, or Origami — a non-uniform mosaic that reshuffles its arrangement on an interval of 30 to 600 seconds.
• Transitions: fade or none, with shuffled playback order as an option.
• Schedule granularity: any set of weekdays, with a time range in 30-minute steps, including ranges that cross midnight.
• Overlay opacity: 0% to 100%, in 5% steps. The default is 30%, and the overlay layer is off until you enable it on a display.
• Displays: no fixed limit — one wallpaper window per display macOS reports.
• System requirement: macOS 14.0 (Sonoma) or later.

Photos albums stay current. Changes to the Photos library are noticed, so photos added to an album later join the rotation without any action from you. Photos held only in iCloud are fetched over the network when their turn arrives, which means an album can take a moment to advance on a slow connection.

Aerials are macOS’s own footage, and macOS owns the download. Pick the Aerial you want in System Settings > Wallpaper (or Screen Saver), let it finish downloading, and only then choose Aerial as the source in Emerald Tools; the app shows a reminder about this the first time you select it. The folder macOS keeps downloaded Aerials in has moved between macOS releases, which is why no path is printed here — the file dialog opens in the right place for the version you are running, and you select the .mov file there.