Changing ffmpeg encoder from libx264 to rkmpp

[Felix_Teil]

Greetings,
I am currently in the process of attempting to run Jellyfin on my Nanopc-T6 SOC
( rk3588 ). I've managed to obtain a functional version of ffmpeg that supports
the encoding codec rkmpp. However, despite using that ffmpeg version within
Jellyfin, the software consistently defaults to using libx264 for encoding. Is
there a method to alter the encoding codec without the necessity of rebuilding
Jellyfin from scratch?
In the event that I do need to compile Jellyfin from its source code, I find the
instructions for this process somewhat unclear. Could someone provide guidance
on how to proceed? Additionally, I'm curious about the necessary modifications
I would have to make. Would it also be imperative to build ffmpeg anew,
specifically tailored for RockChip, even if I intend to use a different version
that already supports RockChip?
Although I have come across numerous posts regarding hardware acceleration for RockChip,
most of them have become inactive and failed to yield any solutions. I'm
hopeful that someone might be able to assist me or at the very least point me
in the right direction. 
I would greatly appreciate any suggestions or insights.

[TheDreadPirate]

I'm not a dev, but my understanding is that the logic to determine what codec to use for transcoding is built into Jellyfin, not ffmpeg. Which almost certainly doesn't include rkmpp.

[Felix_Teil]

That's what I thought, but my understanding is that jellyfin just calls ffmpeg with a set of parameters and im interested in "forcing" it to use rkmpp instead of libx264.

[TheDreadPirate]

If you are asking if there is a setting to do that, there isn't one that I'm aware of. You would need to modify jellyfin's code.

[Venson]

Hey @Felix_Teil

What encoder is used is determined by whenever you enabled hardware acceleration or not. If you do not enable HWA jellyfin will use the software encoder for the requested codec (in your case x264) which is libx264. If you would to enable hardware acceleration for nvidia, it would use h264_nvenc. However i am certain Rockchip is not in the list of supported hardware accelerated devices and would needed to be added in code to be supported which would bring a lot of other issues to be solved with them.

[nyanmisaka]

We still have a lot of work to do before officially adding RockChip RKMPP support in Jellyfin.

See https://github.com/hbiyik/FFmpeg/issues/14

[Felix_Teil]

I hoped it just be a small change and rebuild of jellyfin but kinda figured if it be that easy somebody would have done it already.. thank you for the answers.

[nyanmisaka]

The implementation for Rockchip RKMPP has been completed.
You can try it here and give some feedback.

https://github.com/jellyfin/jellyfin/pull/10748

[deepfriedbutter]

The implementation for Rockchip RKMPP has been completed.
You can try it here and give some feedback.

https://github.com/jellyfin/jellyfin/pull/10748

Running this and so far it is working great. Thanks so much!

Do we need to continue using this specific branch for rkmpp in the future?

[TheDreadPirate]

It was merged into master, so it should already be in the builds we are putting out now. Both docker images and packages. And it will be included when 10.9 is officially released.