nvidia-vaapi-driver

This is an VA-API implementation that uses NVDEC as a backend. This implementation is specifically designed to be used by Firefox for accelerated decode of web content, and may not operate correctly in other applications.

This library requires that the nvidia_drm kernel module is configured with the parameter nvidia-drm.modeset=1

Codec Support

Only decoding video is currently supported.

Codec	Supported	Comments
AV1	⭕	Experimental support. Firefox 98+ is required.
H.264	✔️
HEVC	✔️
VP8	✔️
VP9	✔️
MPEG-2	✔️
VC-1	✔️
MPEG-4	❌	VA-API does not supply enough of the original bitstream to allow NVDEC to decode it.
JPEG	❌	This is unlikely to ever work, the two APIs are too different.

Currently, 10-bit and 12-bit videos are not supported due to the NVIDIA driver not allowing R16 and RG1616 surfaces to be imported. To view which codecs your card is capable of decoding you can use the vainfo command with this driver installed, or visit the NVIDIA website here.

Building

You'll need the gstreamer-plugins-bad library and the nv-codec-headers installed.

Then run the following commands:

meson setup build
meson install -C build

Removing

By default the driver installs itself as /usr/lib64/dri/nvidia_drv_video.so (this might be /usr/lib/x86_64-linux-gnu/dri/nvidia_drv_video.so on some distros). To uninstall the driver, simply remove this file. In addition, this file is usually symlinked to /usr/lib64/dri/vdpau_drv_video.so (or /usr/lib/x86_64-linux-gnu/dri/vdpau_drv_video.so) if the VDPAU to VA-API driver is installed, so this symlink will need to be restored for that driver to work normally again.

Environment Variables

Variable	Purpose
NVD_LOG	This variable can be used to control logging, if it's set to 1 it will log to stdout. If it is set to anything else, it will use that as the filename to append to (or stdout if the file can't be opened).
NVD_MAX_INSTANCES	This variable controls the maximum concurrent instances of the driver will be allowed per-process. This option is only really useful for older GPUs with not much VRAM, especially with Firefox on video heavy websites.
NVD_BACKEND	This variable controls which backend this library uses, either egl (the default), or direct. See below for more details on the direct backend.

Firefox

To use the driver with firefox you will need at least Firefox 96, the following config options need to be set in the about:config page:

Option	Value	Reason
media.ffmpeg.vaapi.enabled	true	Required, enables the use of VA-API.
media.rdd-ffmpeg.enabled	true	Required, default on FF97. Forces ffmpeg usage into the RDD process, rather than the content process.
media.av1.enabled	false	Optional, disables AV1. If your GPU doesn't support AV1, this will prevent sites using it and falling back to software decoding. Hopefully the site will fall back to using a different codec that is hardware accellerated.
gfx.x11-egl.force-enabled	true	This driver requires that Firefox use the EGL backend. If it isn't selecting it by default, it'll need to be forced on using this option or by setting the MOZ_X11_EGL environment variable to 1. It's recommended you try the environment variable method first to test it.
widget.dmabuf.force-enabled	true	Required for NVIDIA 470 series drivers, not required at all on 495+. This option has been shown to help getting decoding working on the 470 driver series. However it should be noted that Firefox isn't coded to allow DMA-BUF support without GBM support, so it may not function completely correctly when it's forced on.

In addition the following environment variables need to be set:

Variable	Value	Reason
LIBVA_DRIVER_NAME	nvidia	This forces libva to load the nvidia backend, as the current version doesn't know which driver to load for the nvidia-drm driver.
MOZ_DISABLE_RDD_SANDBOX	1	This disables the sandbox for the RDD process that the decoder runs in.
EGL_PLATFORM	wayland	This option is needed on FF98+ when running on Wayland, due to a regression that has been introduced.

MPV

Currently this only works with a build of MPV from git master.

There's no real reason to run it with mpv except for testing, as mpv already supports using nvdec directly. The test.sh script will run mpv with the file provided and various environment variables set to use the newly built driver

Direct Backend

The direct backend is a experimental backend that accesses the NVIDIA kernel driver directly, rather than using EGL to share the buffers. This allows us a greater degree of control over buffer allocation and freeing.

Given this backend accesses the NVIDIA driver directly, via NVIDIA's unstable API, this module is likely to break often with new versions of the kernel driver. In addition, this backend has only been testing on a NVIDIA GeForce 1060 6GB, so it's compatibility with other cards is unknown at this point.

This backend uses headers files from the NVIDIA open-gpu-kernel-modules project. The extract_headers.sh script, along with the headers.in file list which files we need, and will copy them from a checked out version of the NVIDIA project to the nvidia-include directory. This is done to prevent everyone needing to checkout that project.

Verifying

To verify that the driver is being used to decode video, you can use nvidia-settings or nvidia-smi:

• nvidia-settings

  By selecting the relevant GPU on the left of the nvidia-settings window, it will show Video Engine Utilization on the right. While playing a video this value should be non-zero

• nvidia-smi

  Running nvidia-smi while decoding a video should show a Firefox process with C in the Type column. In addition nvidia-smi pmon will show the usage of the decode engine per-process, and nvidia-smi dmon will show the usage per-GPU.