Everything you need to get a picture on the screen, and what to check when something looks or sounds wrong.
Getting started
Screenjack needs one piece of hardware: an HDMI-to-USB capture device, a small adapter with HDMI in on one side and USB out on the other. The what you need section on the home page shows the whole chain. Plug things in this order and the permission prompts arrive at sensible moments. On a USB-C iPad the flow is the same; the On iPad section covers what differs.
1
Plug the capture device into the Mac
Use a USB port on the Mac, or a USB-C adapter or hub. Screenjack picks the device up on its own and asks for camera access, once. Allow it. Until a source is connected you will see "No signal", which is expected.
2
Connect the HDMI cable
From the HDMI out on your game console, single-board computer, camera, or laptop to the HDMI in on the capture device.
3
Turn the source on
The picture appears within a couple of seconds. If audio is switched on (it is by default), Screenjack now asks for microphone access, once. Allow it and sound plays through the Mac.
4
Go full screen
Press ⌃⌘F or click the full screen button in the controls. The menu bar and Dock hide, the picture sits on pure black, and the pointer disappears over live video.
No hardware yet? Choose Help ▸ Show Test Pattern. It feeds a synthetic 1080p picture and a stereo tone through the same video and audio path a real device uses, so you can try every control first.
On iPad
Screenjack is one app for Mac and iPad, and one purchase covers both. On iPad the picture, the aspect modes, and the audio all work exactly as they do on the Mac. What differs is the hardware it needs and how you reach the controls.
What you need. A USB-C iPad on iPadOS 17 or later. Plug the capture device into the iPad's USB-C port, then your source into the capture device with HDMI. An iPad with the older connector cannot read a capture device, so USB-C is required.
Permissions. The first time a capture device connects, iPadOS asks for camera access; once video is live and audio is on, it asks for the microphone. If you declined either, open the Settings app, find Screenjack, and turn Camera (and Microphone) on.
The controls. Tap the screen and the control bar appears along the bottom: the device name, the Fit, Fill, Stretch and Pixel-perfect modes, and mute and volume. Tap the gear for Settings. The bar fades on its own after a few seconds. There are no keyboard shortcuts; every control is a tap.
Always full screen. The picture fills the whole iPad. If you move Screenjack into Split View or Slide Over, it shows a short note and waits, because a live monitor needs the entire screen. Bring it back to full screen and the picture returns.
Settings. The same Video and Audio choices as the Mac: Format, Color range, audio passthrough with the automatic fix for inexpensive sticks, and left and right swap. Under General you can reconnect automatically to the last device and keep the iPad awake while video is showing. The Mac-only items (a separate audio-device picker, Float on Top, and pointer hiding) do not apply.
No hardware yet? On the start screen, tap Show a test pattern to run the whole pipeline with a synthetic picture and a stereo tone, exactly as on the Mac.
Everything in the sections below applies to iPad too, with taps in place of the mouse and menus. Where a fix mentions the menu bar or System Settings, use the on-screen controls and the iPad's Settings app instead.
The controls
Screenjack keeps the picture clean. Move the mouse and a small control bar appears along the bottom edge; leave it alone and the bar fades after two seconds. The window title shows the device name, the resolution, and the frame rate once frames arrive.
Full screen with the controls faded out. Move the mouse to bring them back.
From left to right, the bar holds:
Device menu. Every capture device macOS can see. It reads "No capture devices" until one is plugged in.
Fit, Fill, Stretch, Pixel-perfect. The four aspect modes, explained under Aspect modes.
Mute and volume. The speaker button mutes, the slider sets the level. Muting only silences the output; the audio path stays open.
Full screen. Enter or leave system full screen.
Two things can appear in the bar when they matter: a warning icon when microphone access is missing (click it to open System Settings), and a one-time note when your sound output is a Bluetooth device, because Bluetooth adds delay of its own.
Keyboard shortcuts
These shortcuts and menus are on the Mac. On iPad, every control is a tap; see On iPad.
Action
Shortcut
Enter or exit Full Screen
⌃⌘F
Fit
⌘1
Fill
⌘2
Stretch
⌘3
Pixel-perfect
⌘4
Float on Top
⌘⇧T
Lock Window to Aspect
⌘⇧L
Next Device
⌘]
Mute
⌘⇧M
Volume Up
⌘↑
Volume Down
⌘↓
Settings
⌘,
Show Test Pattern
Help menu
The same commands live in the View, Device, Audio, and Help menus, with a checkmark next to whatever is active.
Aspect modes
Fit shows the whole picture at the largest size that fits, with black bars where the shapes differ. The default.
Fill covers the whole window and crops the edges instead of showing bars.
Stretch matches the window exactly, even if that distorts the picture. Useful for sources that send a squashed signal.
Pixel-perfect scales by whole numbers only (1x, 2x, 3x) with no smoothing, so every source pixel becomes a crisp square. Made for retro game consoles and low-resolution boards. If the source is larger than the window, it falls back to Fit while keeping the unsmoothed sampling.
Lock Window to Aspect (⌘⇧L) keeps the window's shape matched to the source while you resize it. Float on Top (⌘⇧T) keeps the window above everything else, handy for a small live view beside your work.
Settings
Open Settings with ⌘,. Choices that belong to a particular device model are remembered per model, so a second stick of the same kind behaves the same way.
Video
Format. The list of everything your capture device can send. Auto picks an uncompressed format at the highest frame rate available, and only falls back to a compressed one when that is genuinely better. Choosing an explicit format reconnects the device and updates the window title.
Color range.Auto and Full pass the signal through unchanged. Choose Limited when a device sends limited-range video but declares full range, which shows up as washed-out blacks.
Audio
Play audio from the capture device. On by default. Turning it off removes the audio input from the capture session entirely, which also switches off the orange microphone indicator in the menu bar.
Swap left and right channels. For devices that wire the channels the wrong way round.
Fix mono 96 kHz audio. Some inexpensive USB 2.0 sticks report their audio as mono at 96 kHz when it is really 48 kHz stereo. Auto detects and corrects this; On and Off force it either way for the current device model.
Audio device.Auto (paired) uses the audio input that belongs to the selected video device. Pick one by hand if your setup has several.
General
Reconnect automatically to the last device. The device you used last connects on its own at launch and after it is replugged.
Float on top. The same setting as the View menu command.
Keep the Mac awake while video is showing. Stops the display sleeping mid-game. Rendering still pauses when the window is fully covered by other windows.
Hide the pointer over live video. The pointer disappears while it rests over the picture and comes back when it moves.
Troubleshooting
"No signal from your device"
Screenjack sees the capture device but no frames are arriving, and says so after about a second. Check, in this order:
The source is switched on and actually outputting video. Some devices sleep their HDMI port until you press a button.
The HDMI cable is seated at both ends and goes into the HDMI in on the capture device.
The adapter really is a capture device. A USB-C to HDMI display cable sends video out of the Mac; it will never show up as a camera.
Single-board computers and mini PCs sometimes decide at boot whether a display is attached. Restart them with the cable already connected.
Try a different format in Settings ▸ Video, or set the source to a common mode such as 1080p or 720p. Very unusual modes may not be supported by the capture device.
Signal, but the picture is black
Frames are arriving and every one of them is black. After about three seconds Screenjack shows a hint, because the usual cause is copy protection (HDCP) on the source. Game consoles usually let you turn HDCP off in their video or HDMI settings. Streaming boxes and protected video apps generally do not, and those cannot be shown by any capture device.
If HDCP is off and the picture is still black, the source may be sending a mode the capture device cannot handle. Lower the source's resolution or refresh rate and try again.
No audio, or a microphone warning in the controls
Check Settings ▸ Audio ▸ Play audio from the capture device is on, that the speaker button in the controls is not muted, and that the volume slider is up.
A warning icon in the control bar means macOS has not granted microphone access. Click it, or open System Settings ▸ Privacy & Security ▸ Microphone, and switch Screenjack on. macOS applies the change when the app is quit and reopened; the prompt from System Settings offers to do that for you. After the relaunch, audio plays as soon as video is live.
Audio device on the Audio tab should be Auto (paired). If your Mac lists several inputs, pick the one that belongs to the capture device.
Some capture devices have no audio input at all. The controls say so when that is the case; audio would need to come from the source another way.
Check the Mac's own output device in the menu bar sound menu. Screenjack plays through whatever the Mac is set to.
Choppy, crackling, or garbled audio
Audio that sounds sped up, chipmunk-like, or like noise usually means a stick is mis-declaring its format. Set Settings ▸ Audio ▸ Fix mono 96 kHz audio to On.
Crackle or gaps point at USB bandwidth. Plug the capture device straight into the Mac rather than through an unpowered hub, and avoid sharing the same hub with a busy drive.
Try an explicit, lower-bandwidth format under Settings ▸ Video.
Delay rather than crackle? That is Bluetooth. Wired headphones or the built-in speakers keep sound in step with the picture.
Left and right are the wrong way round
Turn on Settings ▸ Audio ▸ Swap left and right channels. If you hear only one side, or the stereo image collapses to mono, the 96 kHz fix above is the setting to try first.
The device was disconnected
The USB link dropped mid-session. Plug the device back in and Screenjack reconnects without asking anything again (as long as Reconnect automatically is on in Settings ▸ General; otherwise pick it from the device menu). If it keeps happening, swap the USB cable or port; some capture sticks are sensitive to long or thin cables.
Camera access was refused
macOS treats a capture device as a camera. If you clicked "Don't Allow", open System Settings ▸ Privacy & Security ▸ Camera and switch Screenjack on. macOS applies the change when the app is quit and reopened; the prompt from System Settings offers to do that for you. After the relaunch, choose the device again from the device menu if it does not connect on its own. The overlay in the window has a button that opens the right pane.
FAQ
Does Screenjack record anything?
No. There is no recording, no snapshots, no streaming, no filters, and no network access. Frames are drawn and discarded; audio is played and discarded. See the privacy policy.
Which capture device should I buy?
Any HDMI-to-USB capture device that your Mac or iPad sees as a camera. Up to 1080p at 60 fps with a USB 3.0 capture device. USB 2.0 models cost less, trade a little resolution or frame rate, and are fine for most uses. We do not recommend specific models, and you do not need an expensive one.
How much delay is there?
Frames go from the capture device to the screen as they arrive and late frames are dropped rather than queued, so the delay is whatever the capture device itself adds. Audio over Bluetooth adds a further delay of its own; wired output does not.
Why does the pointer vanish?
It hides while it rests over live video so it does not sit on top of your game or your camera view. Move it and it comes back. Turn this off under Settings ▸ General.
Can I use a USB-C hub?
Yes. A USB-C adapter or hub works. For USB 3.0 capture devices at 1080p at 60 fps, a powered hub or a port on the Mac itself is the safer choice.
Does it work with a laptop as the source?
Yes, if the laptop has an HDMI output (or a USB-C port that can drive one). The laptop sees the capture device as an ordinary external display.
How do I get a refund?
Purchases are handled by the App Store. Open your purchase history in the App Store app, find Screenjack, and choose Report a Problem.
