In case you cannot get hardware video acceleration to work on your new Intel processor, apart from trying to install the backported kernel, you may also need a newer intel-media-va-driver (as of the current time 21.1.1 is the latest from testing).
In this article, it'll be shown how to backport these yourself (since no backports are available) from testing. Alternatively, you can find prebuild backports from here --
https://drive.google.com/file/d/10rcxvetlJbe4wMUijficd-263S_QYhIj/view?usp=sharing
Extract and install all the debs (dpkg -i *.deb)
To test --
LIBVA_DRIVER_PATHS=/usr/lib/x86_64-linux-gnu/dri/ LIBVA_DRIVER_NAME=iHD vainfo
In case you want to build this yourself, take the following instructions --
Add the following to /etc/apt/sources.list --
deb http://mirror.csclub.uwaterloo.ca/debian-multimedia/ stable main
deb-src http://mirror.csclub.uwaterloo.ca/debian-multimedia/ stable main
#bullseye
deb http://mirror.csclub.uwaterloo.ca/debian/ bullseye main contrib non-free
deb-src http://mirror.csclub.uwaterloo.ca/debian/ bullseye main contrib non-free
deb http://security.debian.org/debian-security bullseye/updates main contrib non-free
deb-src http://security.debian.org/debian-security bullseye/updates main contrib non-free
deb http://mirror.csclub.uwaterloo.ca/debian/ bullseye-updates main contrib non-free
deb-src http://mirror.csclub.uwaterloo.ca/debian/ bullseye-updates main contrib non-free
#sid
deb http://mirror.csclub.uwaterloo.ca/debian/ sid main contrib non-free
deb-src http://mirror.csclub.uwaterloo.ca/debian/ sid main contrib non-free
Next install packages --
aptitude install debhelper=13.3.3~bpo10+1 dwz=0.13-5~bpo10+1 libdrm-dev libgl1-mesa-dev libwayland-dev libx11-dev libxext-dev libxfixes-dev pkg-config build-essential libset-scalar-perl
Generate debs to be installed --
apt-get source --compile libva=2.10.0-1
Install all the resulting debs --
dpkg -i libva-dev_2.10.0-1_amd64.deb libva-drm2_2.10.0-1_amd64.deb libva-glx2_2.10.0-1_amd64.deb libva-wayland2_2.10.0-1_amd64.deb libva-x11-2_2.10.0-1_amd64.deb libva2_2.10.0-1_amd64.deb
Install build-depends of intel-media-driver --
aptitude install debhelper=13.3.3~bpo10+1 dh-sequence-libva cmake libigdgmm-dev=20.4.1+ds1-1 libx11-dev pkg-config
Generate the debs --
apt-get source --compile intel-media-driver=21.1.1+dfsg1-1
And install the generated debs.
Cleanup --
aptitude markauto debhelper dwz libdrm-dev libgl1-mesa-dev libwayland-dev libx11-dev libxext-dev libxfixes-dev pkg-config build-essential libset-scalar-perl libva-dev libva-drm2 libva-glx2 libva-wayland2 libva-x11-2 libva2 dh-sequence-libva cmake libigdgmm-dev libx11-dev pkg-config
apt-get autoremove
