How to check codec support before an online assessment

An online assessment may require your browser to play video, send camera footage, or handle audio during a proctored session. If a setup check mentions an unsupported codec, it can be hard to tell whether the browser is the problem or whether the message points to something else.

A codec is software used to encode or decode audio and video. You can check what your browser reports, then confirm the device and browser are ready for the assessment. Start with the Browser Info tool, which reports browser details and supported codecs.

Check codec support before the assessment

1. Open Browser Info in the same browser and on the same device you plan to use for the assessment. Find the codec information and note the audio and video formats the browser reports as supported.
2. Compare those entries with the assessment provider's official technical requirements. Check whether they specify a codec, a browser, or a media format. Do not assume a requirement for a file type such as MP4 means the file uses one particular codec.
3. Open System Info and note the browser's available device and system details, such as the operating system, screen, graphics, and network information. These details help you describe your setup if you contact assessment support, but they do not show that a particular codec is working in the assessment itself.
4. If the assessment uses a camera or microphone, check those devices separately with the Camera Test and Microphone Test. Each tool asks for permission before using the device. Confirm that the preview works and that the microphone meter responds to your voice.
5. Run the assessment provider's own compatibility check or practice session, if available. Use the required browser and any required app, because a general browser report cannot confirm how that assessment handles a live audio or video stream.

Run these checks well before the assessment begins. If you need to change a browser, permission, or device, you will have time to verify the change rather than troubleshooting during a timed session.

What the result means

The required codec appears as supported

This is a useful sign: the browser reports that it can handle that codec in at least some supported situations. It does not prove that the assessment will use it, that the service will select it, or that the full camera and audio setup will work. Continue with the provider's compatibility check and a camera and microphone check if those are required.

The required codec is not listed or appears unavailable

The browser report does not show support for that codec. Check the provider's current browser and operating-system requirements, then try a browser they explicitly support. Codec availability can vary between browsers, devices, and operating systems. Do not install a codec pack or change system files based only on a general report.

The codec is supported, but the assessment check still fails

The codec may not be the cause. The assessment could be blocked by a camera or microphone permission, the wrong input device, an outdated browser, a network interruption, or a problem in the assessment service. Follow the exact error message from the provider and test the relevant device separately.

The browser report looks different from the assessment's requirements

Check whether the requirement names a codec or a container. A container, such as MP4 or WebM, packages audio and video together. The codecs inside it determine how those tracks are encoded. A browser can support one codec in a container but not another, so a container name alone may not settle compatibility.

Fix common compatibility problems

1. Use a browser the provider supports. Check the assessment instructions for approved browsers and minimum versions. Update the browser through its own update settings, restart it, and rerun the provider's check. A browser can report different codec support from another browser on the same computer.
2. Allow camera and microphone access. In the browser's site permissions, set Camera and Microphone to allow access for the assessment site, then reload it. On Windows 11, open Settings › Privacy & security › Camera and Settings › Privacy & security › Microphone. Turn on access for the device and desktop apps. On macOS, open System Settings › Privacy & Security › Camera and System Settings › Privacy & Security › Microphone, then allow the browser.
3. Select the intended camera and microphone. If you have a built-in camera, webcam, headset, or USB microphone, confirm the assessment page is using the one you tested. Disconnect unused devices temporarily if the page keeps selecting the wrong one.
4. Close other apps that use audio or video. Quit calling, recording, and camera apps, then try the assessment check again. Another app can keep a device busy or cause the browser to use a different input than expected.
5. Restart the browser and computer. This can clear a device that remains busy after an app closes and ensures a browser update has taken effect. Reopen only the assessment page and its required check before testing again.
6. Contact assessment support with specific details. Share the browser name and version, operating system, the exact codec or error named by the provider, and whether the camera and microphone tests worked. The System Info report can help you describe the device, but avoid sending any personal information the support team does not need.

What a browser codec check cannot confirm

A browser's codec report describes support exposed to the page. It does not reveal every detail of the assessment service's setup, the codec selected for a live call, or whether the remote system will accept the stream. It also cannot guarantee video quality or certify that an assessment will run correctly.

That is why the provider's own compatibility check is important. Treat Browser Info as an early check, not as a substitute for the assessment's official requirements. If the provider says a specific browser is required, use that browser even when another one lists the same codec.

Check the assessment requirements and permissions on the device you will actually use, then run the provider's practice check before exam day.