config/graphical-session/graphics-drivers/*: update video acceleration

mesa has changed this recently

Author: classabbyamp

src/config/graphical-session/graphics-drivers/amd.md

@@ -27,4 +27,8 @@ circa 2012.
 
 ## Video acceleration
 
-Install the `mesa-vaapi` and `mesa-vdpau` packages.
+For VA-API, install the `mesa-vaapi` package. To ensure the AMD VA-API driver is
+used, set the environment variable `LIBVA_DRIVER_NAME` to `radeonsi`.
+
+For VDPAU, install `libvdpau-va-gl`. Set the environment variable `VDPAU_DRIVER`
+to `va_gl`.

src/config/graphical-session/graphics-drivers/intel.md

@@ -18,17 +18,19 @@ respectively `vulkan-loader` and `mesa-vulkan-intel`.
 
 ## Video acceleration
 
-Install the `intel-video-accel` meta-package:
-
-This will install all the Intel VA-API drivers. `intel-media-driver` will be
-used by default, but this choice can be overridden at runtime via the
-environment variable `LIBVA_DRIVER_NAME`:
+For VA-API, install the `intel-video-accel` meta-package, which will install all
+the Intel VA-API drivers. `intel-media-driver` will be used by default, but this
+choice can be overridden at runtime via the environment variable
+`LIBVA_DRIVER_NAME`:
 
 | Driver Package       | Supported GPU Gen | Explicit selection       |
 |----------------------|-------------------|--------------------------|
 | `libva-intel-driver` | up to Coffee Lake | `LIBVA_DRIVER_NAME=i965` |
 | `intel-media-driver` | from Broadwell    | `LIBVA_DRIVER_NAME=iHD`  |
 
+For VDPAU, install `libvdpau-va-gl`. Set the environment variable `VDPAU_DRIVER`
+to `va_gl`.
+
 ## Troubleshooting
 
 The kernels packaged by Void are configured with

src/config/graphical-session/graphics-drivers/nvidia.md

@@ -27,6 +27,14 @@ also use the universal `modesetting` driver bundled with Xorg (this is the only
 option on Tegra-based ARM boards). When in doubt, it's a good idea to try
 `xf86-video-nouveau` first. This driver will likely perform better.
 
+### Video Acceleration
+
+For VA-API, install `mesa-vaapi`. To ensure the nouveau VA-API driver is used,
+set the environment variable `LIBVA_DRIVER_NAME` to `nouveau`.
+
+For VDPAU, install `libvdpau-va-gl`. Set the environment variable `VDPAU_DRIVER`
+to `va_gl`.
+
 ### Reclocking
 
 Only first generation Maxwell, Kepler, and some Tesla cards support manual