ADL 2160p @ 23.976 Hz passthrough HD Audio dropouts
Short audio dropouts with screen resolution 2160p @ 23,976 Hz in 12 bit if the audio is HD (for 19 out of 20 BD/4k remux i tested).
To reproduce you need
- Kodi 20 or 21
- AVR with decoding capabilities for TrueHD, DTS-HD
- Alder Lake GPU (checked with N100, NUC i7-1270P)
- using HDMI GPU -> AVR -> TV
- remux of BD / UHD BD with HD audio (i used makemkv)
- using Alsa HDMI audio passthrough
- kernel 6.1 or 6.6
- playback resolution needs to be 3840 x 2160 @ 23.976 Hz in 12 bit
It happens mostly within 5 minutes at least once.
Tested with
- LibreELEC 11.0.6 GBM kernel 6.1.74
- LibreELEC 12 GBM kernel 6.6.14
- Ubuntu 23.04 Wayland kernel 6.5.0 (very short test, after finding out how to use passthrough)
- full story so far https://forum.libreelec.tv/thread/27886-intel-alder-lake-2160p-23-976-hz-passthrough-hd-audio-dropouts-i7-1270p-n100/
used Hardware
- TV LG OLED55E6D
- AVR Denon X6700H
- MiniX Z100-0db with N100
uname -a
Linux twang 6.1.74 #1 SMP Sat Jan 27 04:56:55 CET 2024 x86_64 GNU/Linux
Linux twang 6.6.14 #1 SMP Mon Jan 29 02:31:41 UTC 2024 x86_64 GNU/Linux
lspci -vnn -d :*:0300
00:02.0 VGA compatible controller [0300]: Intel Corporation Alder Lake-N [UHD Graphics] [8086:46d1] (prog-if 00 [VGA controller])
DeviceName: Onboard - Video
Flags: bus master, fast devsel, latency 0, IRQ 124
Memory at 6000000000 (64-bit, non-prefetchable) [size=16M]
Memory at 4000000000 (64-bit, prefetchable) [size=256M]
I/O ports at 4000 [size=64]
Expansion ROM at 000c0000 [virtual] [disabled] [size=128K]
Capabilities: [40] Vendor Specific Information: Len=0c <?>
Capabilities: [70] Express Root Complex Integrated Endpoint, MSI 00
Capabilities: [ac] MSI: Enable+ Count=1/1 Maskable+ 64bit-
Capabilities: [d0] Power Management version 2
Capabilities: [100] Process Address Space ID (PASID)
Capabilities: [200] Address Translation Service (ATS)
Capabilities: [300] Page Request Interface (PRI)
Capabilities: [320] Single Root I/O Virtualization (SR-IOV)
Kernel driver in use: i915
reproduced with drm.debug=0xe log_buf_len=4M ignore_loglevel
running LE12 nightly-20240129-40b8914
2x times there where dropouts playing makemkv remux of EAN 4010232073624 mpls 00800
dmesg-LE12-20240129-40b8914.log.gz
cat /sys/kernel/debug/dri/0/i915_vbt >vbios.dump vbios.dump
workarounds that fix the audio problem (hints / patch to find / workaround from smp at the libreelec forum)
- switch playback to 24 Hz not 23.976, then there are frame jumps every now and then, but that is expected
- restrict playback to 10 bit with proptest from libdrm (attached the LE12 version) proptest.gz
PORT=$(grep -l '^connected$' /sys/class/drm/*/status | awk -F/ '{ print $5 }' | sed -e 's|^card[^-]*-||')
CONNECTOR=$(./proptest | awk "/(${PORT})/{ print \$2 }")
systemctl stop kodi.service
./proptest $CONNECTOR connector 191 10
systemctl start kodi.service
then it plays absolut perfect with or without HDR10 for any of my 1080p or 2160p (UHD) BD remux i tested
- patched kernel to restrict playback to 10 bit
linux-999-adl-max-10-bit.patch.gz
then it plays absolut perfect