RK3229 box - can not select SPDIF as passthrough device.

Hansie · September 18, 2020 at 3:05 PM

Hello,

I am trying to set up a MXR 4K box with a RK3229 chip,

I am running community build LE9.20 (Kodi 18.5)

I have a Logitech Z-5450 Speaker/amp set with Dolby Digital (AC3) and DTS support with SPDIF optical and Coax input

I also have a Samsung LCD (2011)

The problem is getting passthrough to work with my SPDIF (COAX) out.

In the audio devices I can select SPDIF and by doing so I can get stereo to work (because the Kodi transcode's the audio to PCM and with SPDIF coax that means I only get two channels (stereo)

The problem is that , at the passthrough options I can NOT select another device (greyed out) also , changing the Audio device itself does NOT change anything at passthrough.

When I enable passthrough now and use my Samsung LCD also to passthrough I can get Dolby Digital to work (goes from Kodi HDMI to my Samsung and than passthrough to the optical SPDIF from my logitech (say's Dolby Digital than)

I can sadly not use that methode for DTS because my samsung (like most TV's) wont passthrough DTS)

What could be the reason I can not select my SPDIF as an output device for passthrough ?

what would cause this to be greyed out ?

I dont think there is anything wrong with the libreelec install since my SPDIF works as normal output device, and passthrough is also working for HDMI, I just cant select any other output for passthrough

I am probably doing something stupid , so have fun pointing that out to me and help me out

thank you,

Hans

Some screenshots ;

mo123 · September 19, 2020 at 4:26 AM

LibreELEC doesn't support passthrough for Rockchip devices.

Hansie · September 19, 2020 at 10:40 AM

Quote from mo123

LibreELEC doesn't support passthrough for Rockchip devices.

Ok, that explains alot

Would be nice if the "passthrough" option would be greyed out than

I am guesing it is do to missing rockchip drivers (from rockchip themselves) and wont be fixed until rockchip brings out drivers ??

thank you for your answer.

tuhajbej6 · November 13, 2020 at 8:54 PM

Quote from mo123

LibreELEC doesn't support passthrough for Rockchip devices.

But what does it mean for future ?
1. no patch for LE is possible
2. it is a matter of patching "rk3399-rock-pi-4.dtb"
3. it is not hardware possible

Please comment - this functionality is really awaited for as it changes sound experience vastly nowadays.

mo123 · November 15, 2020 at 8:24 AM

Quote from tuhajbej6

But what does it mean for future ?
1. no patch for LE is possible
2. it is a matter of patching "rk3399-rock-pi-4.dtb"
3. it is not hardware possible

Please comment - this functionality is really awaited for as it changes sound experience vastly nowadays.

It is hardware possible.

A LibreELEC developer just has to add a working patch for Rockchip devices, test it and build a new image.

Eg. for Allwinner devices these patches add audio passthrough - Allwinner: WIP audio passthrough · jernejsk/LibreELEC.tv@87cbddb · GitHub

So something similar with a few changes could work on Rockchip devices too.

But they first want to improve video playback I heard so audio passthough will likely take the back seat for another couple of months unless independent developers can do tests and create a patch.

tuhajbej6 · November 17, 2020 at 7:07 PM

Quote from mo123

It is hardware possible.
A LibreELEC developer just has to add a working patch for Rockchip devices, test it and build a new image.
Eg. for Allwinner devices these patches add audio passthrough - Allwinner: WIP audio passthrough · jernejsk/LibreELEC.tv@87cbddb · GitHub
So something similar with a few changes could work on Rockchip devices too.
But they first want to improve video playback I heard so audio passthough will likely take the back seat for another couple of months unless independent developers can do tests and create a patch.

Thanks for clarifying.

I see it was commited in July.. So nobody willing took care of it yet for Rockchip?
Not sure how the development goes - where can we put request in this case ?

lmorand · January 30, 2022 at 8:36 PM

A bit late to the party, but I just wanted to share that simply changing the S/PDIF card name from ROCKCHIP,SPDIF to SPDIF in the devicetree was enough to get passthrough to work for me. I attached the modified dtbs, in case anyone wants to try them.