Fix 'H.264 Not Supported' for Calls and Streams (Run the Codec Test)

Confirm H.264 in the Codec Test

Open the Codec Test. Look for H.264 (AVC) and Hardware decode. A working setup shows "yes" for decode support. If H.264 is missing or hardware decode is "no", keep the tab open and apply the fixes below. Web apps surface this as "H.264 not supported," "video format not supported," or low-resolution fallback.

Fix 1: Update the browser and reboot once

Newer Chromium and Firefox builds ship updated codec bindings.

• Chrome / Edge: Menu > Help > About to pull the latest build, then Relaunch.
• Firefox: Menu > Help > About Firefox and restart after the update.
• After reboot, rerun the Codec Test. Many "H.264 missing" errors disappear after a clean restart because the OS video stack reloads.

Fix 2: Turn hardware acceleration back on

Hardware acceleration unlocks the GPU decode path for H.264 and prevents stutter.

• Chrome / Edge: Settings > System and performance > Use hardware acceleration when available → turn On → Relaunch.
• Firefox: Settings > General > Performance → check Use recommended performance settings and Use hardware acceleration when available.
• If video freezes when acceleration is on, update your GPU driver (see Fix 4) instead of leaving acceleration off.

Fix 3: Install the H.264 codec bundle on Linux

Chromium on Linux may lack H.264 by default.

• Ubuntu/Debian (Chromium): sudo apt update && sudo apt install chromium-codecs-ffmpeg-extra.
• Snap Chromium: sudo snap connect chromium:ffmpeg then restart Chromium.
• Arch/Manjaro: install chromium-ffmpeg or ensure the extra-codecs package is present.
• Restart the browser and recheck the Codec Test. H.264 should now show yes.

Fix 4: Update GPU and media drivers

H.264 decode depends on your graphics stack.

• Windows: install the latest GPU driver from NVIDIA/AMD/Intel. After install, reboot and rerun the test. Outdated drivers are a top cause of disabled hardware decode in Chromium.
• macOS: install pending macOS updates under System Settings > General > Software Update.
• Linux: update Mesa or proprietary drivers from your distro. For NVIDIA, install the current nvidia-driver package and reboot.

Fix 5: Disable software that hooks video

Overlay, capture, or security tools can interfere with media pipelines.

• Close screen recorders (OBS, Loom), streaming overlays, or "game booster" overlays.
• Temporarily pause endpoint security tools that inject DLLs into browsers, then retest H.264. Re-enable afterward.

Fix 6: Reset flags that block proprietary codecs

If experimental flags disabled proprietary codecs, revert them.

• Visit chrome://flags (or edge://flags) and click Reset all. Relaunch.
• In Firefox, ensure media.ffmpeg.enabled and media.ffvpx.enabled remain true. Set media.hardware-video-decoding.enabled to true if you changed it before.

Fix 7: Ensure the OS exposes H.264

On some Windows N editions, the H.264 codec pack is missing.

• Install Media Feature Pack from Settings > Apps > Optional features > Add an optional feature and search for it.
• Restart afterward and run the Codec Test.

Fix 8: Check enterprise policies

Managed browsers can disable proprietary codecs for licensing reasons.

• Chrome/Edge: open chrome://policy or edge://policy and look for HardwareMediaKeyHandlingEnabled or flags that limit proprietary codecs.
• If policy blocks them, only IT can change it. Provide the failing H.264 line from the Codec Test as evidence.

Verify the fix

Run the Codec Test again. You want H.264: yes and ideally Hardware decode: yes. Then open a Meet or Teams call and confirm HD video stays stable. If hardware decode stays off but software decode works, you can still take calls; expect higher CPU usage on older laptops.