Rock PI 4B+ Still missing Driver Support for HDMI PassThrough for Libreelec

#1

Till when will you deliver the most important Audio Feature for a Libreelec running on your Rock PI 4??
There are at least 2 real heavy things, that are still not available for the Rock Pi 4:

Can you give me a perspective on this Topics, or is the Rock Pi 4B+ ready for the trash?!

Thanks

#2

HDMI Audio passthrough are patches LibreELEC has to add for Rockchip devices together with a newer mainline kernel, not Radxa.
There is also currently no HDMI driver for the mainline kernel for Amlogic, Rockchip & Allwinner devices with HDMI passthrough support.
Amlogic, Rockchip, Allwinner all use the same HDMI driver with slight modifications and are all awaiting the mainline kernel HDMI driver developers to add it.
They decided video playback changes were more important before working on HDMI Audio.
So HDMI passthrough might only be supported 6-12 months from now I estimate.

What is wrong with Android Audio Passthrough and Kodi?
It works much better than LibreELEC and always will.

HDMI CEC worked last year when I tried it, not sure if things changed.
LibreELEC with the 4.4 vendor kernel worked great in the past but LibreELEC refused to support older kernels(with all drivers) and only support devices with mainline kernel(with missing drivers) now.

1 Like
#3

Thanks MO for you fast responseā€¦
Since IĀ“m not that deep in that physics, to know who is responsible for the driver support, I asked here, because i thougt it is the HW vendorā€¦ Thanks for clarification!

How ever I tried alot with 2 different Rock PI4+ v1.72.
I tried the latest official Libreelec Images and also the nightlies. And there, I have a several problemsā€¦

A short summary of my major issues:

  • Audio Glitches if I use PCM, since there is no Passthrough available
  • No HDMI CEC, tried different TVĀ“s and AV Receivers, where I have no Problem with Libreelec 10.0.1 on a Raspberry Pi 4 or x64 Windows 10 with Kodi 19.3
  • Only a small Picture in the Middle of the TV with a max. Resolution of 1024x768p when I connect the Rock PI 4 HDMI to the TV via an AV Receiver. With one Sony TV I have the same Issue, when I connect the Rock Pi directly to TV.
    With the same Setup and Cables I have no Problem with Libreelec 10.0.1 on a Raspberry Pi 4 or x64 Windows 10 with Kodi 19.3

Full HD and 4K Video and Menu are running really smooth on the Rock Pi4, if there wherenĀ“t the upper problems.

To answer your question, why I want to use Libreelec native, and not with the Kodi App on Android:
I also tried the Android Image with the Kodi App, but there I have the Issue, that high Bitrate 4K HDR films with HD audio, will no run smooth (hanging / stuttering Video and Audio).
The same problem I have on 2 different Sony Android TVs with Kodi the Kodi Appā€¦

I donĀ“t have any of all upper Issues with the same Setup, Network, Sources, Cables,ā€¦ with Libreelec 10.0.1 on a Raspberry Pi 4 or x64 Windows 10 with Kodi 19.3

So far to my Problemsā€¦

I thought, the Rock Pi4 B+ V1.72 with much better HW Specifications then my well ā€œworkingā€ Raspberry Pi4, will work minimum as good as the Raspberry, but today it isnĀ“t :frowning:

Thanks

#4

Raspberry Pi 4 and Linux/Windows devices are the only ones currently supporting HD Audio Passthrough with LE unfortunately.

Have you tried the latest Kodi with micro stutter fixes?
https://forum.kodi.tv/showthread.php?tid=365127
And also AndroidTV ROM with auto frame-rate switching support and HD Audio Passthrough, it should work much better than stock firmware.
Also see 2nd post.

You could try older LE I made in the past with vendor kernel.
Not sure if this is vendor kernel, otherwise use OP ones.
Not sure if addons will work on older versions.
Only thing not working will be HD Audio Passthrough but the other issues shouldnā€™t exist.

We can only hope they finish audio passthrough for the mainline kernel and LE incorporates it soon.

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#5

IEC958 works in the dw-hdmi driver, at least with Amlogic and Allwinner, and I know Alex was poking support with Rockchip. Iā€™ve just finished watching a 4K HDR (8-bit) movie with pass-through audio on an Amlogic S912 box running my own homebrew LE(11) image :wink:

AFAIK there is still work to be done around controls and some of the higher bitrate formats, and I am not paying any attention to the state of RK images (as itā€™s someone elseā€™s problem) but pass-through is definitely not limited to Raspberry Pi and x86_64 devices!

#6

Who do you mean with ā€œtheyā€?

#7

Is this the same driver situation for the Rock Pi 5 and CEC, HDR + audio pass through support?

#8

Is this still a WIP?
If so, is there some patch that can be applied to the kernel to get this going in the meantime? Or an issue tracking this? Thanks!

#9

There is some old discussions dating back to the original Rock Pi 4 in 2019 and some people managed to apply patches on Linux 4.11 I think. There might have also been someone sharing a script if I recall correctly.

Scattered across the internet there comments which say this will no longer work on Linux 5 and aboveā€¦ my Linux skills arenā€™t good enough to comment sorry. But there are also mentions of patches coming in mainline updates, does anyone know?

Probably like you am puzzled to the status of this and it feels like addressing these issues would mean Rock Pi 4 could be used as an excellent media player with 4K/HDR/audio pass through. Given all the hardware supports this. The workaround is to use the Android image which has these features already.