I’ve read several threads on similar topics but I couldn’t make sense of it. Please omit any discussion of Nvidia or AMD, or any discrete GPU solutions; this is purely for intel based IGPUs. Bringing up these other platforms will kind of muddy the waters. It is my understanding that Intel Igpus shouldn’t be affected by Manjaro’s 2022 decision to exclude HW decoding of codecs.
I have Manjaro box as a media player connected to my TV. For further context, it’s an odroid H3+. vainfo reports that the IHD driver is being used, and it lists HEVC as a VAEntrypointVLD, it also says that it’s capable of encoding, but I don’t care about that right now. Further, if I use the Jellyfin player flatpack, HEVC decoding works just fine. So far so good.
However, if I use Chromium or FF as my jellyfin media players, My server has to re-encode to H264. This would be fine, except this feature is buggy in my experience, and if you do anything like skip or rewind, the playback is completely broken. It has been like this for years, and it doesn’t seem to matter what HW I have in the server.
Both browsers claim to be configured to use HW accelerated decoding. In FF, the about:config had this enabled by default. By searching the settings menu for Chromium, it also claims that HW accelerated decoding is enabled by default. Despite all this, both browsers force transcoding if the source is HEVC.
The reason I want the browsers to work is because multiple users use this device, and I don’t trust people to log out of jellyfin. LOL. So, each user gets their own client. 
Any help is appreciated.
TLDR:
- I think that hw decoding is enabled in the system as evidenced by the fact that vainfo reports it so, and the jellyfin flatpack works fine with HW decoding.
- Neither FF or chromium uses HEVC HW decode when run as jellyfin clients despite the fact that they both claim to be configured to do so.
PS:
The system, and all packages are fully up to date.