FEATURE_HARDWARE_VIDEO_DECODING_NO_LINUX_NVIDIA error in Firefox

[NielsGx]

Hi,

I am running Hyprland on CachyOS, with a RTX 4080.
I have nvidia-open-dkms (580.76.05) and libva (this) installed

my environment variables in hyprland:

env = LIBVA_DRIVER_NAME,nvidia
env = __GLX_VENDOR_LIBRARY_NAME,nvidia
env = NVD_BACKEND,direct
env = MOZ_ENABLE_WAYLAND,1
env = MOZ_DISABLE_RDD_SANDBOX,1

I also have enabled all the things in about:config as specified in your readme

And of course enabled nvidia-drm modeset=1 everywhere (followed hyprland doc for this, and also the grub way)

But I get this in about:support

Before I was getting FEATURE_FAILURE_VIDEO_DECODING_TEST_FAILED until I disabled my iGPU in my BIOS, and now I get this new one above, weird 🤔

(btw it seems to work in Chromium when it shouldn't ?! from chrome://gpu)

[NielsGx]

Hmm, I checked logs (by running MOZ_LOG="FFmpegVideo:5" firefox)
and I saw lots of these when playing a YT video:

[RDD 14015: MediaPDecoder #1]: D/FFmpegVideo FFVPX: Frame decode takes 0.32 ms average decode time 0.25 ms frame duration 41.67 average frame duration 41.67 decoded 186 frames [RDD 14015: MediaPDecoder #1]: D/FFmpegVideo FFVPX: VA-API frame pts=1060750000 dts=1060750000 duration=41666 color space BT709/BT709 transfer BT709

So, is it working or not ? 🤔

[mileslow]

Something that is helpful for me when debugging the drivers is running the following command in the terminal while playing. a video:

watch -n 2 nvidia-smi

This lets you see all the processes on your computer running your graphics card, you should be able to see a noticeable uptick when playing a video in firefox vs. idle firefox, If there is no uptick then its not working.

[NielsGx]

Something that is helpful for me when debugging the drivers is running the following command in the terminal while playing. a video:

watch -n 2 nvidia-smi

This lets you see all the processes on your computer running your graphics card, you should be able to see a noticeable uptick when playing a video in firefox vs. idle firefox, If there is no uptick then its not working.

Apparently the nvidia-open-dkms driver doesn't let you see "Decode" usage in nvidia-smi, so hard to know...
I guess power draw should be lower with hw accel than without, could use a about:config flag to force disable it and see if there's a change with force enabled

But as I said earlier, the log I got with "VA-API frame" is probably showing it works

[itsTyrion]

Install nvtop, it has a DEC load bar that will appear when there is any.

As for FEATURE_HARDWARE_VIDEO_DECODING_NO_LINUX_NVIDIA, I also get that on Fedora 42, however, if I scroll down, support is shown and hw dec is working (I can playback 8k HEVC with like no CPU load)

Codec Name	Software Decoding	Hardware Decoding
H264	Supported	Supported
VP9	Supported	Supported
VP8	Supported	Supported
AV1	Supported	Unsupported
HEVC	Supported	Supported

(My GPU doesn't support AV1 hardware decoding)