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+---- Thread: HD Audio from DisplayPort - no sound (HDMI works) (/showthread.php?tid=375819)
HD Audio from DisplayPort - no sound (HDMI works) - fezster - 2024-01-17
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:
Quote:https://paste.kodi.tv/tevameminu
HD Audio (TrueHD and DTS HD MA) from DP 1.2 DOES NOT work - log here:
Quote: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:
Quote: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?
RE: HD Audio from DisplayPort - no sound (HDMI works) - fezster - 2024-01-17
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).
RE: HD Audio from DisplayPort - no sound (HDMI works) - fritsch - 2024-01-17
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.
RE: HD Audio from DisplayPort - no sound (HDMI works) - Krobar - 2024-05-22
(2024-01-17, 19:00)fezster Wrote: Found this thread: https://forum.kodi.tv/showthread.php?tid=297918The 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.
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).
https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/10819
To try if this works for you
- Install the latest Ubuntu Desktop
- Install Kodi (It will be an older version if you use the Ubuntu supplied one but should be fine for testing)
- Install todays drm-tip kernel packages: https://kernel.ubuntu.com/mainline/drm-tip/2024-05-22/amd64/
- Disable Pulseaudio
- Start Kodi forcing the Alsa Audio Engine
RE: HD Audio from DisplayPort - no sound (HDMI works) - fritsch - 2024-05-24
That's awesome news - after all those years. nice!