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evmux Knowledge Base

Screen Share

Screen Share lets participants (speakers, editors and guests) share their screen during a broadcast. A shared screen appears as a layer in the scene.

Overview

  • Any participant can share their screen
  • Pick a share from a searchable list of participants
  • Filter the list by participant type
  • Remove a background colour with chromakey
  • Spotlight a share to fill the frame

Choosing a screen share

When you add a screen share layer, a chooser panel opens. It contains:

  • A search box that filters participants by name
  • A filter to show or hide Speakers, Editors and Guests
  • One section per participant type; click a section header to collapse or expand it
  • The participants themselves; pick one to add their screen share

Layer features

Chromakey

You can remove a background colour from a screen share. Choose green, red or blue, or pick a custom colour directly from the shared screen with the colour picker, and adjust the range to control how much of the colour is removed.

Spotlight

Spotlight makes the screen share fill the whole frame. Double-click the spotlighted layer to return it to its normal position.

Offline state

The layer shows an Offline label when the participant is not connected or is not sharing yet. If the share is unavailable, the participant’s avatar is shown in its place.

Volume

A screen share can carry audio. Its volume follows the participant’s volume control and the master volume.

Operating-system permission (macOS)

Before the browser can capture anything, the operating system has to allow it. On macOS this is a one-time system permission, and without it screen sharing simply fails: the picker may not open at all, or it opens and the share never starts.

evmux detects this case and shows a dialog with the steps. What you have to do:

  1. Open System Settings (called System Preferences on older macOS).
  2. Go to Privacy & Security → Screen Recording (on older macOS: Security & Privacy → Privacy tab → Screen Recording, after clicking the padlock at the bottom left to allow changes).
  3. Tick Google Chrome (or Microsoft Edge, whichever browser the studio is open in).
  4. Quit and reopen the browser. macOS only applies the new permission to a fresh launch. Then rejoin the studio and start the share again.

Notes:

  • Windows has no equivalent permission. If sharing fails there, the browser picker was dismissed; it is not an OS block.
  • This is a system permission, separate from the camera and microphone permissions the browser asks for when joining a studio.
  • “How do I enable screen recording?” is almost always this permission, NOT the studio’s Recording checkbox, which records the broadcast (see the go-live panel).

Best practices

  1. Ask before adding a share. Make sure the participant is ready.
  2. Test before going live. Check that the share is visible.
  3. Use chromakey with care. It is useful for removing flat UI backgrounds.
  4. Consider bandwidth. Screen shares use more data.
  5. Spotlight for focus. Fill the frame during presentations.