My experimental notes on getting the H.264 hardware decoder to do something useful on MNT Reform: https://community.mnt.re/t/notes-on-building-ffmpeg-and-mpv-to-use-the-hardware-h-264-decoder/305
@mntmn in case you're interested in #gstreamer as well: see https://source.puri.sm/pureos/packages/gst-plugins-bad1.0
fand https://source.puri.sm/guido.gunther/livi for a minimal player that I'm using to validate #hantro/#imx8 accelerated decoding with #gtk4 .
@mntmn I just backported stuff from upstream git to #gstreamer 1.18 so if you don't care about packaging then `gst-build` (https://gitlab.freedesktop.org/gstreamer/gst-build) is even simpler. Once finished gst-play-1.0 --use-playbin3 jellyfish-15-mbps-hd-h264.mkv should be accelerated. The player is only there since i had issues getting accelerated video to work in #gtk3 in some situations and wanted to verify it works with #gtk4 (which it does). If you want to try that building gst-p-b, gtk4 and the player is enough.
@agx thanks!! is it sufficient to build only the gst-plugins-bad? (to be able to build your player).