gstreamer-vaapi consists in a collection of VA-API based plugins for
GStreamer and helper libraries.

  * `vaapi<CODEC>dec' is used to decode JPEG, MPEG-2, MPEG-4:2, H.264
    AVC, H.264 MVC, VP8, VP9, VC-1, WMV3, HEVC videos to VA surfaces,
    depending on the actual value of <CODEC> and the underlying
    hardware capabilities.  This plugin is also able to implicitly
    download the decoded surface to raw YUV buffers.

  * `vaapi<CODEC>enc' is used to encode into MPEG-2, H.264 AVC, H.264
    MVC, JPEG, VP8, VP9, HEVC videos, depending on the actual value of
    <CODEC> (mpeg2, h264, etc.) and the hardware capabilities. By
    default, raw format bitstreams are generated, so the result may be
    piped to a muxer, e.g. qtmux for MP4 containers.

  * `vaapipostproc' is used to filter VA surfaces, for e.g. scaling,
    deinterlacing (bob, motion-adaptive, motion-compensated), noise
    reduction or sharpening. This plugin is also used to upload raw
    YUV pixels into VA surfaces.

  * `vaapisink' is used to render VA surfaces to an X11 or Wayland
    display. This plugin also features a "headless" mode (DRM) more
    suited to remote transcode scenarios, with faster throughput.

  * `vaapioverlay` is a accelerated compositor that blends or
    composite different video streams.
