Video Acceleration on Gentoo

Posted:: 2023-09-27

Over the past few months, I have found myself gradually spending more time on Youtube videos, both for entertainment and learning. I usually watch them on my laptop, which is equipped with an integrated GPU - AMD Radeon Vega 8. This got me thinking about how I can take advantage of it to reduce CPU load.

The media players that I use the most are Firefox and MPV (for any downloaded Youtube videos). According to the list of video acceleration support across different applications [1], the only method supported by both of them is VA-API, which is

an open source application programming interface that allows applications such as VLC media player or GStreamer to use hardware video acceleration capabilities, usually provided by the graphics processing unit (GPU). [2]

Configurations for Gentoo Portage

In order to enable the VA-API feature on my ADM GPU, the driver "radeonsi" should be added to the list of video cards [3]:

# nano /etc/portage/make.conf
        VIDEO_CARDS="amdgpu radeonsi"

Also, for applications that support VA-VAP, the USE flag "vaapi" can be enabled globally [4]:

# nano /etc/portage/make.conf
        USE="vaapi"

Then, update the whole system to apply these changes:

# emerge -av --update --deep --newuse @world

From now on, let's set up MPV and Firefox to ensure they can work with VA-API when playing videos.

Settings for MPV

To enable VA-API in MPV, either add hwdec-vaapi to its configuration file, or use the option --hwdec=vaapi while launching it:

configure it with the option
$ nano ~/.config/mpv/mpv.conf
        hwdec=vaapi

launch it with the argument
$ mpv --hwdec-vaapi

To check if VA-API is enabled in MPV, play a video and press the key "i" to view its running details. If it shows "hwdec: vaapi" on the top, then VA-API is enabled:

/~an9wer/_static/img/2023/vaapi-mpv.webp

Settings for Firefox

To enable VA-API in Firefox, go to the page about:config, and make sure the below two options are set to true:

gfx.webrender.all             true
media.ffmpeg.vaapi.enabled    true

Note

Strangely, I couldn't find the option media.ffmpeg.vaapi.enable in my Firefox. After channelling my Google-fu, I discovered that:

For ESR,

115 needs the hwcaccel wayland USE flags enabled to get hardware acceleration. X and wayland can be enabled simultaneously.

Since 116, the wayland USE flag isn't needed to get hardware acceleration on supported cards for Rapid. 116 was fixed to have hardware acceleration without wayland support. [5]

As my current version of Firefox was ESR 102, I had to add additional USE flags hwaccel and wayland, and rebuild Firefox:

# nano /etc/portage/package.use/firefox
        www-client/firefox hwaccel wayland
# emerage -av www-client/firefox

To check if Firefox is working with VA-API, run the following command, and if there is any output, then VA-API is enabled:

$ MOZ_LOG="PlatformDecoderModule:5" firefox 2>&1 | grep "VA-API"

/~an9wer/_static/img/2023/vaapi-firefox.webp

Thanks for reading :)