Cannot get audio pass-through of DTSHDMA or TrueHD with new x86 thin client box

Hi,
I've been using OpenELEC/LibreELEC for a few years with various small x86/x64 boxes to stream my BluRay rips and other locally stored programming. I recently ran into a problem that I can't figure out.

Originally, I was using a Chromebox with great success. Later I discovered how cheap some recent model Dell/HP thin clients sell for on Ebay. So last year, I tried LibreELEC on a cheapo Dell/WYSE 5010 (uses AMD G-T48 "Brazos" dual core) and it worked great. It was able to pass-through all the lossless audio formats to my receiver (Display Port>HDMI cable to Yamaha A-3010 receiver). However, it struggled with HEVC programming (both cores at 100% and lots of dropouts), so I thought I'd try to find a newer quad core version to perhaps help with HEVC decoding. This brings us to the current problem.

Last week, I picked up an HP T-620 thin client ($30 shipped!). It has an AMD GX-415GA quad core embedded SOC (Kabini?). According to all that I can find, this AMD should support pass-through of the lossless (this is the document I found: 52259_KB_G-Series_Product_Data_Sheet.pdf )

I installed the latest LibreELEC, everything goes fine, I set all the settings similar to what I've used before, but I get no sound from any of my DTS-HD Master, DD+, or Dolby TrueHD/ATMOS soundtracks! It is frustrating. I have tried various combinations of settings, tried both Display Port outputs, but nothing seems to work. I also tried to install the latest version of Plex Embedded and it has the same problem. I upgraded the BIOS on the T-620 to the latest, but that had no effect. I have checked BIOS settings, and there doesn't seem to be anything in there that would affect audio out.

Any ideas or should I just give up on this little box? It does play the HEVC quite smoothly (about 50% on the CPU, split across all 4 cores), so I would like to use it. Right now, I don't have much HEVC, but over time, it will probably increase.

Thanks,
BW

Quote from blueribb

Have you tried installing Windows to see if it supports all the HD Audio modes ?

Not yet...It came with a Windows Embedded key. I might try it just to make sure there isn't some hardware limitation. I'm sure the performance would suck though> the SOC only has a passmark of 1900.

Trying to test with Windows is proving difficult. I had to try about 4 different versions of Windows Embedded until I found one that matched the certificate in BIOS. After that, I found out that Kodi doesn't install on embedded Windows permanently. Every time you reboot, it wipes it. I need to figure out how to have it installed with write privileges. I gave up after about 5 hours of messing with it. I'll get back to it in a few days.

OK> I finally figured out how to get Kodi to permanently mount to Windows 7 Embedded Standard (W7ES).

I just had to turn off the write protection that HP had enabled by default.

I set all the Audio/Video settings as usual and Kodi on W7ES was able to pass DTSHDMA and TrueHD/ATMOS. So, it appears this is a shortfall somewhere in the linux drivers with LibreELEC? Not sure at this point. Need some help.

Also, trying to run HEVC/H265 on Kodi through W7ES pegs the CPU and it is not smooth like it was under LibreELEC, so ultimately, I would like to get this sorted out and be able to run either LibreELEC or Plex Embedded on this HP T620.

BTW, the actual AMD video is identified as Radeon 8330E through Windows/Kodi.

On a whim, I tried to install an older 7.x version of LibreELEC. Same issue. I was also going to try OpenELEC, but the installer is crap. It repeatedly leaves me with an unbootable SSD.

Quote from blueribb

If no one can help you here, maybe you could try posting this issue over at the Kodi forums in General Support / Linux.

Kodi | Open Source Home Theater Software

I suspect it has more to do with something lacking in LibreELEC drivers. When I get a chance, I'm going to install a desktop version of Ubuntu 14.04, load the official AMD Linux drivers for this embedded chip (14.04 is the last they support) and then see how it works.

Overall, I could probably learn to live with letting Kodi convert to PCM 7.1 channel, but over the years, I've really come to enjoy seeing the receiver display light up with DTS HD Master or TrueHD.

Not much luck getting things to work better with Ubuntu. A day of tinkering, I was able to get Ubuntu 14.04.2 with AMD proprietary drivers installed, but Kodi runs terrible and the only audio options are with Pulseaudio. I might need to go back and try it with server version or just give up and accept PCM. I'll probably try the Milhouse 9.0 releases too.

chewitt , can you point me toward the most effective way to report the issue 'upstream' to the Devs?

Finally got the chance to install the latest Milhouse release. It still does not pass DTS-HD MA or TrueHD/ATMOS.

So, I made a discovery tonight. After trying some of the Milhouse builds, including one that is based on Linux 4.15.y (which adds AMDGPU DC). Still no luck and I was getting tired of messing.

So, I rolled it back to an official build (8.2.4?). I didn't spend to much time in the settings. I was prepared to have Kodi convert to PCM for the lossless tracks.

To my amazement, it was all of a sudden passing DD+, DTS-HD MA and TrueHD!

What was the difference? It took me awhile of checking settings,

and some additional testing, but I finally realized that the difference is if I select to automatically switch playback rate (to 24p) for my bluray rips. If I keep it at 60p, it will pass-through the lossless codecs, if I have it switch to 24p, it doesn't pass the lossless.

I have ALWAYS had my Kodi boxes set to switch to native 24p when playing back bluray sources. So, there is something still not right with the drivers or Kodi. It should be able to pass lossless no matter what the frame rate. It should be EASIER for the box to send 24p. No reverse pulldown, no frame interpolation, etc.

Any thoughts?

Quote from milhouse

I would recommend posting this information on the Kodi forum that's why LE9.0 test builds are supported there - this may need someone like @fritsch or @fernetmenta to comment as they handle the AudioEngine side of things and might be able to explain what is happening.

Thanks for the advice, I will post there. However, did you notice that I said I'm back to running an official version (LE8.2.4)?

When the LE9.0 didn't help, I reverted back to official build. I was able to get it passing the lossless codec on the official version, just with the strange limitation of having to keep the display refresh rate at 60p.

So, I haven't had any response over at the Kodi forum under the LE9.0 thread.

Just to be clear, I'm using an official LE8.2.4 build, it passes DTSHD-MA/Dolby TrueHD, but only when "Adjust display refresh rate" is disabled. I do not use "Sync Playback to Display."

Quote from grom_e30

yeah i had the same problem on my nuc6cayh in the millhouse builds, hd pass through only works when "adjust refresh rate" was off i did bring this up before but i didn't go anywhere. i haven't checked any recent builds to see if this is still the same though

Have you tried using the Official 8.2.x builds? If so, does HD audio pass-through work with "adjust refresh rate" with any of them?