Comment 19 for bug 1424201

There is no unique nor "official" software path to have hardware acceleration on linux.
Every chip makers have designed their own framework to do so; none of them compatible with one another.

You may want to track bug 1210729 or bug 1210727.

The only GStreamer plugin allowing hardware acceleration decoding was a VAAPI plugin: it was buggy and extremely unstable nor did it provide any significant speed improvement.

You're much better off using ffmpeg