[fezster]

I posted this on LibreElec forums but not had any replies. Hoping someone here can point me to how to debug/diagnose this further.

I have a Optiplex 3050 which has both a DisplayPort 1.2 (capable of 4k) and HDMI 1.4 (capable of 1080p only).

I'm using LibreElec 11 stable (although tried 12 nightly too) and I cannot get HD audio to work on the DP using a Benfei DP->HDMI adapter (reading around, seems to be a common problem with NUC's as well). DD/DTS work fine.

I can, however, get HD audio working over the HDMI 1.4 connection.

If it is a limitation of the DP itself, I'd like to understand why.

Here's my findings:

HD Audio (TrueHD and DTS HD MA) from HDMI 1.4 works - log here:

https://paste.kodi.tv/tevameminu

HD Audio (TrueHD and DTS HD MA) from DP 1.2 DOES NOT work - log here:

https://paste.kodi.tv/ijiziposic

In both cases, it first tries to create a 2 channel output stream:

Sample Rate : 44100
Sample Format : AE_FMT_S32NE
Channel Count : 2
Channel Layout: FL, FR

and then an 8 channel output stream:

Sample Rate : 192000
Sample Format : AE_FMT_S16NE
Channel Count : 8
Channel Layout: RAW, RAW, RAW, RAW, RAW, RAW, RAW, RAW

I suspected perhaps the DP 1.2 does not support 192000khz with 8 channels, but if I run a speaker-test command, it works fine:

LibreELEC:~ # speaker-test -D hdmi:CARD=PCH,DEV=0 -c 8 -r 192000 -b 9600 -p 2400 -F S32_LE

speaker-test 1.2.8

Playback device is hdmi:CARD=PCH,DEV=0
Stream parameters are 192000Hz, S32_LE, 8 channels
Using 16 octaves of pink noise
Rate set to 192000Hz (requested 192000Hz)
Buffer size range from 8 to 131072
Period size range from 4 to 65536
Requested period time 2400 us
Requested buffer time 9600 us
was set period_size = 461
was set buffer_size = 1844
 0 - Front Left
 4 - Front Center
 1 - Front Right
 7 - Rear Right
 3 - Rear Right Center
 2 - Rear Left Center
 6 - Rear Left
 5 - LFE
Time per period = 23.984268

If I turn off passthrough in Kodi settings, LPCM 7.1 is sent fine via the DP for all 8 channel HD audio streams.

Any guidance on what I can check next?

[fezster]

Found this thread: https://forum.kodi.tv/showthread.php?tid=297918

So it seems 8 channel, rate 192khz - works on HDMI 1.4, but not on DP 1.2.

At 48Khz, it works on DP 1.2 (but both DTS-HD and TrueHD require 192Khz).

[fritsch]

Then simply disable DTS-HD-MA, TrueHD passthrough. Those are the only two needing that format in order to get all the bits IEC packed.

[Krobar]

Found this thread: https://forum.kodi.tv/showthread.php?tid=297918

So it seems 8 channel, rate 192khz - works on HDMI 1.4, but not on DP 1.2.

At 48Khz, it works on DP 1.2 (but both DTS-HD and TrueHD require 192Khz).

The latest DRM Tip kernel fixes being unable to bitstream TrueHD and DTS HD MA for me with a VMM7100 Displayport to HDMI 2.1 convertor, might help you too.
https://gitlab.freedesktop.org/drm/i915/...sues/10819

To try if this works for you

1. Install the latest Ubuntu Desktop
   
2. Install Kodi (It will be an older version if you use the Ubuntu supplied one but should be fine for testing)
   
3. Install todays drm-tip kernel packages: https://kernel.ubuntu.com/mainline/drm-t...-22/amd64/
   
4. Disable Pulseaudio
   
5. Start Kodi forcing the Alsa Audio Engine
   

FYI @fritsch

[fritsch]

That's awesome news - after all those years. nice!