Background effects make the camera video completely black in Firefox on Linux (Teams web)

Question

Background effects make the camera video completely black in Firefox on Linux (Teams web)

Osvaldo Takai 0

Which product: Microsoft Teams — web client (guest/light meetings join link), background effects

Environment

OS: Zorin OS 18.1 (Ubuntu 24.04 base), X11, kernel 7.0.0-34-generic
Browser: Firefox 157.0 (64-bit), default settings (hardware video decoding enabled)
GPU: AMD Radeon 780M (Phoenix, gfx1103), amdgpu driver, Mesa 25.2.8
Camera: Logitech C922 Pro Stream Webcam (046d:085c), UVC/V4L2, works in every other application
Joining through the guest link (light meetings experience): https://teams.microsoft.com/meet/meeting-id?p=redacted&anon=true

Steps to reproduce

In Firefox on Linux, open the guest join link above.
Allow camera access; the pre-join preview shows the camera correctly.
Choose any Background effect — "Standard blur", "Portrait blur", or any background image.
Observe the preview.

Actual behavior

The video turns completely black — both the local preview and the video the other participants receive. It stays black until the effect is set back to None or the page is reloaded. No error message is shown.

Expected behavior

Either the effect is applied (as it is in Chrome, and as it used to be), or — if the effect cannot run — the client keeps sending the unprocessed camera video instead of a black frame. A black frame makes the participant invisible to the meeting, which is worse than not offering the effect at all.

Same machine, same meeting, different browser: works

In Google Chrome 155, on the same computer, the same meeting link and the same camera, background blur and background images apply normally. So the camera, the driver, the GPU and the network are all fine; the failure is specific to the effect pipeline in Firefox.

Control test proving this is not a WebGL/GPU problem (measured on this machine)

A local page that only exercises WebGL, with no camera — same browser, same Firefox profile:

webgl2: OK rgb=102,153,204 | renderer=Radeon R9 200 Series, or similar | vendor=Mozilla
and also OK when the context is requested with failIfMajorPerformanceCaveat: true (i.e. not a software fallback).

The camera itself also works in Firefox in other pages (e.g. Mozilla's WebRTC camera test page). Only the Teams background-effect path produces black frames.

Independent confirmation (same behavior, different user)

IsmaelMartinez/teams-for-linux issue #2599 — https://github.com/IsmaelMartinez/teams-for-linux/issues/2599 ("[Bug]: video background cannot be altered"), where the reporter states: "on firefox, when background picture/blur is selected, video becomes totally dark; with Chromium, it works on background change normally."

Documentation gap

The Microsoft support article "Change your background in Microsoft Teams meetings" — https://support.microsoft.com/en-us/teams/meetings/change-your-background-in-microsoft-teams-meetings — states that "Linux users aren't able to use this feature." In that case the client should not offer the effect on Linux/Firefox at all — offering it and then sending a black video is a functional regression, not a missing feature.

Workaround for affected users

In Firefox, keep Background effects = None (camera works, measured) and use Chrome/Chromium when the background effect is required.

Request

Please investigate the background-effect pipeline on Gecko/Firefox for Linux — the same code path works on Chromium.
As a safety net, fall back to the unprocessed camera track whenever the effect pipeline fails, instead of publishing a black frame.
If the feature is intentionally unsupported on Linux, hide or disable it in the UI on that platform and update the documentation accordingly.

Happy to provide the browser's about:support output, a WebRTC chrome://webrtc-internals-style log, or to run any diagnostic build you suggest.

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1 answer

Your answer

Answer 1

Hi Osvaldo,

Thank you for providing such a detailed report and for documenting the testing you've already performed.

The comparison between Firefox and Chrome on the same system, along with the WebGL and camera validation tests, helps narrow the issue considerably. Based on your findings, this strongly suggests the failure is occurring within the background-effects pipeline used by Teams in the Firefox/Linux guest meeting experience rather than with the underlying camera or graphics stack.

Regarding your requests:

Fall back to the unprocessed camera track whenever the effect pipeline fails instead of publishing a black frame.
Hide or disable background effects on Linux if the feature is intentionally unsupported, and ensure the documentation reflects that behavior.

These are product improvement requests rather than support troubleshooting actions. The best way to ensure they reach the Teams engineering and product teams is to submit them through the Microsoft Feedback Portal. Feedback submitted there is reviewed by the appropriate product groups and can be considered for future improvements and design changes.

When submitting the feedback, I recommend including the reproduction steps, browser and OS details, the Firefox-versus-Chrome comparison, and the expected behavior you outlined above. The suggestion to automatically revert to the original camera feed when effect processing fails would be especially valuable, as it would prevent participants from unintentionally appearing as a black screen during meetings.

In the meantime, the available workaround remains to keep Background effects = None when using Firefox on Linux, or use a Chromium-based browser when background effects are required.

I hope the information I shared earlier was somewhat helpful in addressing your issue. If you have any further questions or updates, please don’t hesitate to share. I’m always happy to assist further if needed.