$ pacman -Qs mesa
local/ati-dri 10.2.1-1
    Mesa drivers for AMD/ATI Radeon
local/mesa 10.2.1-1
    an open-source implementation of the OpenGL specification
local/mesa-libgl 10.2.1-1
    Mesa 3-D graphics library


$ vainfo
libva info: VA-API version 0.35.1
libva info: va_getDriverName() returns 0
libva info: User requested driver 'vdpau'
libva info: Trying to open /usr/lib/dri/vdpau_drv_video.so
libva info: Found init function __vaDriverInit_0_33
libva info: va_openDriver() returns 0
vainfo: VA-API version: 0.35 (libva 1.3.1)
vainfo: Driver version: Splitted-Desktop Systems VDPAU backend for VA-API - 0.7.4
vainfo: Supported profile and entrypoints
      VAProfileMPEG2Simple            :	VAEntrypointVLD
      VAProfileMPEG2Main              :	VAEntrypointVLD
      VAProfileMPEG4Simple            :	VAEntrypointVLD
      VAProfileMPEG4AdvancedSimple    :	VAEntrypointVLD
      VAProfileH264Baseline           :	VAEntrypointVLD
      VAProfileH264Main               :	VAEntrypointVLD
      VAProfileH264High               :	VAEntrypointVLD
      VAProfileVC1Advanced            :	VAEntrypointVLD


$ echo $?
0