Screen Sharing Test - Browser Capabilities | Online Tool Box - Mic, Cam, Net Speed, Screen Test

Screen Sharing Capability Test

Test screen capture API. Useful for debugging meeting apps.

Not started

Resolution (desired)

Note: The actual resolution of screen sharing depends on the system/browser/content being shared. These are "ideal values" and may not be strictly valid.

Frame rate (desired)

Note: The actual FPS will be affected by system load, complexity of shared content, and browser limitations. Please refer to the "Measured FPS".

Also request system audio (not supported by some browsers/systems)Grid/Alignment Box

Real-time indicators (auxiliary)

Measured FPS

Recommended ≥ 24fps (when sharing video/animation)

track settings

Clarity (Trend)

0/100

The resolution is low: the window/tab may be shared, or the resolution/bitrate may be limited.

Average brightness (0-255)

The brightness distribution is generally normal (based on the naked eye)

Dark part crop

0.0%

Pixel brightness ≤ 16

Highlight crop

0.0%

Pixel brightness ≥ 240

Current track:Not started

Screen sharing API is not supported in the current environment

Please use a modern browser (Chrome/Edge/Safari/Firefox) that supports `navigator.mediaDevices.getDisplayMedia` and make sure to access it under HTTPS.

Usage suggestions

• Prioritize sharing of "single window/single tab": usually clearer and more stable than "whole screen"

• Check text: Open small font/code/table lines and observe whether there are smears, jagged edges or smearing.

• Check FPS: Play a 60fps video or scroll to see if FPS drops significantly below 15–20

• Sharing is unclear: Prioritize using "Share a single window/single tab" instead, and adjust the content zoom to 100%–125% before comparing screenshots.

• Low frame rate: Watch the Measured FPS, if it drops significantly to 15–20fps while scrolling/playing the video, this is usually due to system load or browser limitations.

• Highlight/Dark Cropping: See "Dark Cropping/Highlight Cropping". If it is too high, it may be a mapping problem caused by night mode/HDR/high contrast themes.

• The setting does not take effect: the resolution/frame rate are "expected values" and are ultimately determined by the system/browser/shared content; it is recommended to use screenshots to compare and verify.

Sharing Guide

Start sharing, check resolution, and FPS.

Step 1

Start screen sharing

about 5 seconds

Click "Start Sharing" and select the screen/window/tab you want to share in the browser pop-up window.

Click "Start Sharing"

In the pop-up window, choose "Window" or "Tab" first (usually clearer and more stable)

After confirming the sharing, you should see the preview screen and real-time indicators begin to change.

Tip: Most browsers require HTTPS to allow screen capture; if the popup doesn't appear, check permissions or browser policies.

Step 2

Apply resolution/framerate settings

about 15 seconds

Adjust the desired resolution and frame rate, and click "Apply settings (restart sharing)" to compare the changes.

Select "Resolution (desired)": Auto/720p/1080p/1440p/4K

Drag "Frame rate (desired)": 30fps is recommended for daily use, and 60fps can be tried for motion effects/videos.

Click "Apply settings (restart sharing)" and compare resolution and FPS on the same content

Step 3

Use screenshots for comparison and verification

about 10 seconds

Screenshots are the most intuitive way to compare: the same screen, different sharing methods/settings, observe the details and compression.

Open pages or documents containing small fonts/table lines/code fonts when sharing

Click "Screenshot" to generate a comparison chart

Test "entire screen" and "window/tab" separately and compare screenshot edges, text clarity, jagged/smudged feeling

FAQ

Have questions? We have the answer! The following are common questions and troubleshooting suggestions about screen sharing detection.

What can be measured on this page?

It can help you confirm whether screen sharing can be started normally (permissions/HTTPS/browser support), and observe the resolution, measured FPS, picture sharpness trend, brightness distribution and cropping in real time during the sharing process. All analysis is done locally in the browser.

Why does "share entire screen" look more blurry?

Common causes are system scaling, browser compression strategies for full-screen capture, and conservative handling of details on shared links. In most cases it will be clearer to share "single window/single tab". It is recommended to take screenshots of the same small font content for comparison.

I adjusted the resolution/frame rate, but there is no actual change. Is this normal?

normal. The resolution/frame rate here is the "ideal value/expected value", and whether it takes effect is ultimately determined by the system, browser implementation, and shared content. It is recommended to compare the "track settings" with the actual look and feel/screenshots.

Why is the "Measured FPS" lower than what I set?

It could be that the system load is high (CPU/GPU busy), the shared content is too complex, the browser has a cap on the capture frame rate, or you are sharing a tab and the background is being slowed down. Close high-load applications, reduce resolution/frame rate, or change browsers for comparison.

Is "clarity (trend)" an accurate indicator?

no. It is a relative trend indicator based on low-resolution sampling. It is more suitable for "same device/same content/same scene" comparison of different sharing methods or settings, but not suitable for absolute scoring across devices.

Why does it prompt "Screen sharing API is not supported"?

Explanation The current environment does not support `navigator.mediaDevices.getDisplayMedia`, or it is accessed under a non-security context (HTTP). Please use a modern browser and open the page under HTTPS.

Will my screen content or screenshots be uploaded to the server?

Won't. Screen preview, indicator analysis and screenshot generation are all done locally in your browser; screenshot downloads are also generated locally and saved to your device.

Can system audio be shared/detected together?

Support for Capture System Audio varies widely between browsers/systems. This page can request system audio, but it will not be played back within the page by default (to avoid echoes). If you only want to check the picture quality, it is recommended to turn off the system audio request.