Configuring Firefox

Prerequisites:
Hardware acceleration

Fedora KDE uses Wayland by default.

Wayland session
  1. Go to about:support
  2. Ensure that “Window Protocol” is set to “wayland” - if it is not, seek further help on the PC Help Hub or elsewhere as it should be.
  3. Ensure “Target Frame Rate” is set to your display framerate.
  4. Make sure “Hardware compositing” is set to “available”
  5. Open about:config and set widget.use-xdg-desktop-portal.file-picker to 1
X.org session
  1. Go to about:support
  2. Ensure “Target Frame Rate” is set to your display framerate.
  3. Make sure “Hardware compositing” is set to “available”

On non Intel GPUs, you may need to set media.ffmpeg.vaapi.enabled for hardware decoding.

If hardware decoding is disabled with error FEATURE_HARDWARE_VIDEO_DECODING_DISABLE or FEATURE_FAILURE_VIDEO_DECODING_TEST_FAILED, make sure you’ve followed the hardware acceleration setup guide, and set media.hardware-video-decoding.force-enabled to true.

  1. Play a video in Firefox.
  2. Go to about:support
  3. Make sure hardware decoding is supported under “Codec Support Information” Screenshot of Codec Support Information entry

It is normal for Firefox to not support HEVC. Hardware decoding should be supported for H.264, as well as AV1 and HEVC on some GPUs. Audio codecs (AAC, Opus, FLAC, etc) usually do not have hardware decoding support.