With modern graphics cards, it's often possible to offload the jobs of video encoding and decoding to them from the CPU in order to reduce power usage and make more resources available to the rest of the system. Compared to CPUs, GPUs are much more efficient at the job. However, both hardware as well as software support are required for this offloading, and the latter in particular (at least in the Linux world) has undergone much evolution in recent years. Online documentation is therefore sparse and incomplete, inconsistent, and often outdated. Furthermore, support for hardware video acceleration under Linux world is unfortunately split across different APIs with different levels of support.
Historically, the benefits of hardware acceleration under Linux have been uncertain, but it seems likely that support today has improved drastically. In at least some relatively typical scenarios, the performance gains of using hardware decoding can be huge, with reductions in CPU usage of around 90%.
APIs and Hardware / Software Support
The three main APIs that are in use are VA-API, VDPAU, and NVENC/NVDEC.
VA-API - Supported on Intel, AMD, and NVIDIA (only via the open-source Nouveau drivers). Widely supported by software, including Kodi, VLC, MPV, Chromium, and Firefox. Main limitation is lacking any support in the proprietary NVIDIA drivers.
- VDPAU - Supported fully on AMD and NVIDIA (both proprietary and Nouveau). Supported by most desktop applications like Kodi, VLC, and MPV, but has no support at all in Chromium or Firefox. Main limitations are poor and incomplete Intel support and not working with browsers for web video acceleration.
- NVENC/NVDEC - A proprietary API supported exclusively by NVIDIA. Only supported in a few major applications (FFmpeg and OBS Studio for encoding, FFmpeg and MPV for decoding). Main limitation is limited software and hardware support across the board because of its proprietary nature.
VA-API sees broad software support and is even used by default in applications like MPV when it's available.
For Nouveau and the various AMD drivers, support can be added simply by installing the mesa-va-drivers package.
For Intel, it's split generationally, and into free and non-free drivers. The non-free drivers are necessary to encode media while the free drivers can only decode.
For Gen 8+ Intel hardware, the free driver can be installed with the intel-media-va-driver package. You can find the non-free driver in the intel-media-va-driver-non-free package after adding a non-free component to your apt sources.
For older Intel hardware, the free driver can be installed with the i965-va-driver package. The non-free driver can be installed with the i965-va-driver-shaders package after adding a non-free component to your apt sources. This driver supports up to Gen 9 GPUs. If both drivers are installed, the newer driver from intel-media-va-driver is preferred over i965-va-driver (since Debian 11/Bullseye).
Driver selection can be overridden by setting the environment variable LIBVA_DRIVER_NAME to a specific driver, e.g., LIBVA_DRIVER_NAME=i965 (to use the driver from i965-va-driver on Bullseye) or LIBVA_DRIVER_NAME=iHD (to use the driver from intel-media-va-driver on Debian 10/Buster). See EnvironmentVariables for more details on how to set this environment variable system-wide or per user.
VDPAU faces considerably more limitations compared to VA-API, but nonetheless, it's the only option for some users. Particularly, anyone using the NVIDIA proprietary drivers. It's not supported in any major browser except for GNOME Web but is useful for local playback. MPV is recommended for this.
To enable VDPAU support for the AMD drivers (radeon and amdgpu), along with the open-source Nouveau driver for NVIDIA cards, install the vdpau-driver-all package.
This will also enable VDPAU support over the OpenGL/VA-API backend for Intel GPUs. However, this has severe stability issues and may not work at all on some Intel devices. If possible, you are heavily recommended to use VA-API instead with Intel.
To enable VDPAU support for the proprietary NVIDIA drivers, you must choose the relevant package for your driver version. If you installed the latest drivers via the nvidia-driver package, then you can simply install the nvidia-vdpau-driver package.
NVDEC is supported by the libnvcuvid1 package.
NVENC is supported by the libnvidia-encode1 package.
These are only non-free runtime libraries however. Applications in Debian's main archive, including FFmpeg and OBS Studio, are not compiled with support for NVENC or NVDEC and so the usefulness is limited to third-party binaries not supplied by Debian.
You can find a full report of whether or not VA-API or VDPAU are functional, and what codecs they support, by installing the vainfo and vdpauinfo packages and running their commands. vainfo and vdpauinfo
Application support for hardware acceleration varies, and each application requires individual configuration. Following are details for various applications.
mpv has good hardware acceleration support, although it is not enabled by default. To enable it, use the –hwdec command line switch. It can also be made the default by adding a line like “hwdec” to the mpv configuration file (e.g., $HOME/.config/mpv.conf). [hwdec can also take various values, although ideally supplying the switch with no value should be sufficient. See the mpv manpage for more details (which recommends not to set the switch).]
If hardware acceleration is being used, mpv’s output will contain lines like the following:
libva info: VA-API version 0.39.4 libva info: va_getDriverName() returns 0 libva info: Trying to open /usr/lib/x86_64-linux-gnu/dri/i965_drv_video.so libva info: Found init function __vaDriverInit_0_39 libva info: va_openDriver() returns 0 AO: [alsa] 48000Hz stereo 2ch float Using hardware decoding (vaapi). VO: [opengl] 1920x816 vaapi
Hardware acceleration in VLC is controlled in the GUI via “Tools → Preferences → Input / Codecs → Hardware-accelerated decoding”, or via the CLI option –avcodec-hw value [‘value’ is mandatory].
If hardware acceleration is being used, VLC’s output will contain lines like the following:
libva info: VA-API version 0.39.4 libva info: va_getDriverName() returns 0 libva info: Trying to open /usr/lib/x86_64-linux-gnu/dri/i965_drv_video.so libva info: Found init function __vaDriverInit_0_39 libva info: va_openDriver() returns 0 [00007f082ce97280] avcodec decoder: Using Intel i965 driver for Intel(R) Broadwell - 1.7.3 for hardware decoding
Web video is one of the most important use-cases for hardware video acceleration, as without it, sites like YouTube will cause heavy CPU usage (and therefore power consumption), a particular concern on mobile devices such as laptops and tablets.
VDPAU isn't supported at all in Chromium or Firefox. The only browser that supports it is GNOME Web, available in the epiphany-browser package. GNOME Web leverages GStreamer for this support, also requiring the gstreamer1.0-plugins-bad package for VDPAU support to work properly.