Audio cuts with 192 khz 8 channel 16 bit (Dolby TrueHD/Atmos) and 24p
Linux-Hardware: Asrock J4105-ITX with Celeron J4105
AVR: Denon 2800H
Kernel: Linux 6.2.0-custom #'6 SMP PREEMPT_DYNAMIC Mon Mar 6 23:14:32 CET 2023 x86_64 x86_64 x86_64 GNU/Linux
OS: Ubuntu 22.10
Background: A Kodi standalone system is used as media center directly connected to a Denon 2800H via HDMI.
Issue: If the refresh rate is fixed to 24 Hz during 4k playback with 192 khz 8 channel 16 bit audio (Dolby TrueHD/Atmos), audio cuts occur frequently. Depending on the kernel used, the effect is different:
- Ubuntu Standard Kernel 5.19: small but audible cuts every 10-30 seconds
- drm-tip Kernel 6.20: very significant cut only after 2 minutes and then every 10-30 seconds. The disruption is much more severe than with the 5.19 kernel so that sometime even the AVR recognises an audio signal loss
The AVR can be configured in two modes for 4k video:
- Standard: 60 Hz, 4:2:0, 8 Bit
- Extended: 60 Hz, 4:4:4, 8 Bit or 60 Hz, 4:2:2 10 Bit
Steps to reprodcuce:
- Set Denon Receiver to "Extended" mode
- Set refresh rate to 24 Hz
- Playback TrueHD audio and 24 Hz video
The issue can be reproduced every time.
Further insights:
- The issue does not occur when the Denon is configured in "Standard" Mode
- The issue does not occur when 60 Hz is set as fixed refresh rate
- The issue does not occur on other sourround tracks like DD 5.1
- The issue does not occur with a dedicated UHD Bluray Player connected to the Denon
- The issue does not occur if I connect the system directly to the TV and use eARC back to the Denon
Together with the Kodi developers I could exclude any external or application layer root cause. There are literally no audio video errors/drops/skips/corrections reported by Kodi (discussion). A low-level HDMI protocol or clock issue seems to be more likely.
In extended mode, the TV receives an RGB 12 Bit video.
In standard mode, the TV receives an RGB 8 Bit video.
Are the audio registers / clocks differently programmed whether it is 8 or 12 Bit?
Logs:
As it works in standard mode but not in extended mode I pulled the dmesg logs in both cases:
- dmesg log with Denon AVR in "extended" configuration, i.e. with sound glitches dmesg_extended_debug_Denon_tip
- dmesg log with Denon AVR in "standard" configuration, i.e. with no sound glitches. dmesg_standard_debug_Denon_tip
*Other users are reporting this issue as well, also on newer Intel hardware, e.g. ASRock H670M-ITX/ax, with a Intel Core i5-12500.
Please let me know in case further information is required.
Thanks a lot!
Chris aka Flachzange