Hardware video acceleration

Hardware video acceleration makes it possible for the video card (FIXME: it is not video card) to decode/encode video, thus offloading the CPU and saving power.

v4l2-request
TODO

v4l2m2m
TODO

libvdpau
TODO

VA-API
TODO

Web browsers
There are no browsers with support for v4l2m2m or v4l2-request. Chromium has related code, but it is enabled only for Chrome OS builds

Clapper
https://flathub.org/apps/com.github.rafostar.Clapper can use v4l2-request api

mpv
mpv should be able to do video decoding with v4l2m2m with, but it has been broken for a long time https://github.com/mpv-player/mpv/issues/10701

Testing
'''TODO: Add potential good examples and validate. Potential candidates:'''


 * https://developer.qualcomm.com/qualcomm-robotics-rb5-kit/software-reference-manual/camera-and-video/video-decode
 * https://wiki.postmarketos.org/wiki/Qualcomm_Snapdragon_450/625/626/632_(MSM8953)#Video_Encoder_.2F_Decoder_.28Venus.29
 * (from https://wiki.postmarketos.org/wiki/Xiaomi_Mi_Note_2_(xiaomi-scorpio)#Mainline)
 * for v4l2m2m