No HBR Audio with LSPCON - Trying to collect information

    Recently it seems quite a few people have had issue with no HBR Audio when an LSPCON is used. For NUCs this is often a case of update the LSPCon firmware but this is not always the solution / an option.

    For anyone reading this and wondering what an LSPCON is or does my setup use one; an LSPCON converts from Displayport to HDMI in this case. Older Intel 7000/8000/9000 CPU motherboards with an HDMI 2.0 port will be using an LSPCON. If you are using an "Active" Displayport to HDMI converter then your setup will also be using an LSPCON. HBR audio is DTS HD Master Audio or Dolby TruedHD with the bitstream option enabled in Kodi (You need to switch to Expert mode and make sure DTSHD and Dolby TrueHD are enabled too).

    My experience of this issue is PCM 7.1 and legacy SPDIF Dolby Digital and DTS work fine. I'm interested in hardware and other info from people who have had similar issues of no HBR audio with an LSPCon in the chain.

    Below are my findings. Before anyone mentions an immediate firmware update for the LSPCon some of these adapters are known to have firmware which work with HBR audio and they also work fine in Windows. Ultimately I would like to raise an appropriate bug but I need more results in order to spot any pattern (Other than using an LSPCON); I'm not sure if this issue is only when using Intel graphics.

    CPU: Intel I3-8300S
    Chipset: Intel C246
    Video Card: Integrated
    LSPCON: Paradetech PS175
    LSPCON Type: Integrated on motherboard
    LSPCON Firmware Version: 0x2C
    General Operation: OK
    HDR: OK
    HBR Audio: Broken (Silence)
    Notes: All OK in Windows

    CPU: Intel I3-8300S
    Chipset: Intel C246
    Video Card: Integrated
    LSPCON: Paradetech PS175
    LSPCON Type: Integrated on motherboard
    LSPCON Firmware Version: 0x40
    General Operation: Problematic - No 24/50Hz 4K support
    HDR: OK
    HBR Audio: Broken (Silence)
    Notes: HBR Audio ok in Windows but same 24/50Hz issues as Libreelec.

    CPU: Intel I3-8300S
    Chipset: Intel C246
    Video Card: Integrated
    LSPCON: VMM7100
    LSPCON Type: External Adapter (CAC-1087)
    LSPCON Firmware Version: 7.02.120
    General Operation: OK
    HDR: OK
    HBR Audio: Broken (Silence)
    Notes: All OK in Windows. Linux seems to uniquely offer 120hz support with this combination (Assume it is 4K/120/4:2:0 to 4:2:2 conversion).

    CPU: AMD 7600X
    Chipset: AMD X670E
    Video Card: Nvidia RTX3080
    LSPCON: VMM7100
    LSPCON Type: External Adapter (CAC-1087)
    LSPCON Firmware Version: 7.02.120
    General Operation: No display after splash screen
    Notes: Using required Generic Legacy image.

    CPU: AMD 7600X
    Chipset: AMD X670E
    Video Card: Integrated Graphics
    LSPCON: VMM7100
    LSPCON Type: External Adapter (CAC-1087) via USB-C passive cable
    LSPCON Firmware Version: 7.02.120
    General Operation: OK at 4K/60 but not at 4K/24
    HDR: Broken (Black screen)
    HBR Audio: Broken (Intermittent)
    Notes: PCM audio has slight interruptions. SPDIF/legacy bitstream has same interruptions as HBR audio.

    sky42 I saw you mentioned the same issue when you tried a Displayport to HDMI adapter; can you provide further info?

    Edited once, last by Krobar (April 1, 2024 at 3:56 PM).

    Just tested the same external Displayport to HDMI adapter with AMD integrated graphics. The results are different to Intel, HBR audio is intermittent instead of completely silent.

    If you start to poke around in the Gitlab issue log for the Intel DRM driver you'll see reports and triage that reveal the problem isn't simple like LSPCON vs. no-LSPCON; as there are different LSPCON chips (different chip vendors) with different properties, and even identical LSPCON chips can have rather different implementations (different electrical properties, resulting in different bandwidths available on internal connections) on different boards. In some cases firmware changes can tweak voltages and such that drive the LSPCON chip differently so achieve improvements. In other cases the LSPCON implementation is more fundamentally wrong and no tweaking can get the right result. Most of the issue reports are focused on graphics performance; but the underlying issue is related to bandwidth and thus HBR audio (needing more bandwidth) suffers similarly to higher resolution and refresh rate and colour depth graphics (needing more bandwidth). TL/DR; /shrug

    Quote from chewitt

    If you start to poke around in the Gitlab issue log for the Intel DRM driver you'll see reports and triage that reveal the problem isn't simple like LSPCON vs. no-LSPCON; as there are different LSPCON chips (different chip vendors) with different properties, and even identical LSPCON chips can have rather different implementations (different electrical properties, resulting in different bandwidths available on internal connections) on different boards. In some cases firmware changes can tweak voltages and such that drive the LSPCON chip differently so achieve improvements. In other cases the LSPCON implementation is more fundamentally wrong and no tweaking can get the right result. Most of the issue reports are focused on graphics performance; but the underlying issue is related to bandwidth and thus HBR audio (needing more bandwidth) suffers similarly to higher resolution and refresh rate and colour depth graphics (needing more bandwidth). TL/DR; /shrug

    Thanks for the tip. I understand your point but the same external adapter and internal LSPCon I list above work fine with Windows for HBR audio which means I know this is a Linux software issue. This is a recurring theme with a lot of these LSPCon issues too; works fine with Windows but broken in Linux. Whilst a sample of one does not mean much the fact the same external DP to HDMI adapter produces some HBR audio with AMD means this might actually be an Intel Graphics driver issue/quirk but I'm hoping for more feedback from others to help confirm or deny this theory.

    I realise that this is not a Libreelec specific issue and these problems likely lie in the kernel / firmware but I suspect a high proportion of those that are affected by LSPCON HBR audio issues are Libreelec users so I hope you don't mind me posting this topic here.

    Todays build of drm-tip that contains the patch above fixes the issue for me:

    LSPCon - No HBR Audio - Same kernel, DP to HDMI adapter and HDMI hardware works with AMD (#10819) · Issues · drm / i915 / kernel · GitLab
    I am using Kernel 6.6.26 in Libreelec nightly build. Intel hardware is I3-8300 on Supermicro motherboard using Intel C246 Chipset. Working AMD platform is…
    gitlab.freedesktop.org

    FYI fezster

    I guess it will be some time until this fix makes it way into drm-tip to drm-next to a stable kernel.

    Maybe the root cause of your 4.0 channel issue is the same like this issue:

    Post

    RE: Only 6.1 LPCM for 7.1 sources with Raspberry Pi

    When you open a HDMI audio device on the RPi the kernel automatically chooses a channel map based on the number of channels (eg 8 in this case) and the speaker allocation from the EDID.

    The hdmi-codec driver has an ordered list, sorted by preference, and will choose the first entry that's supported by HDMI for the given number of channels and is supported by the AVR as well (all channels of that entry must also be present in the EDID speaker allocation block).

    In this table the 6.1 entry with RC…
    HiassofT
    May 2, 2024 at 11:10 AM
    Quote from HarryH

    Maybe the root cause of your 4.0 channel issue is the same like this issue:

    Post

    RE: Only 6.1 LPCM for 7.1 sources with Raspberry Pi

    When you open a HDMI audio device on the RPi the kernel automatically chooses a channel map based on the number of channels (eg 8 in this case) and the speaker allocation from the EDID.

    The hdmi-codec driver has an ordered list, sorted by preference, and will choose the first entry that's supported by HDMI for the given number of channels and is supported by the AVR as well (all channels of that entry must also be present in the EDID speaker allocation block).

    In this table the 6.1 entry with RC…
    HiassofT
    May 2, 2024 at 11:10 AM

    It could be driver related if the Intel Linux driver does not support that channel layout or it could be a bug in the older version of Kodi included with Ubuntu. 4 channel PCM is a bit awkward as effectively 4 channel mappings are used:
    FL + FR + SL +SR
    FL + FR + SBL + SBR (This is in fact still the only official Windows preset config)
    FL + FR + C + SW ("3.1")
    No mapping given

    With Windows Wasapi all are supported in my config although SBL+SBR is mapped to SL+SR (Not sure if this is done by the driver or the AVR).

    Quote from Krobar

    Todays build of drm-tip that contains the patch above fixes the issue for me:
    https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/10819

    FYI fezster

    I guess it will be some time until this fix makes it way into drm-tip to drm-next to a stable kernel.

    Hi Krobar. This sounds great.

    Is there any documentation on how to use this patch and apply to Libreelec?


    Ignore - I see your post on https://forum.kodi.tv/showthread.php?tid=375819. If it cant be used on LibreElec, I'll leave for now. For me, multichannel LPCM is working fine (and I dont have Atmos speakers), so not critical for me to get this working until it's more readily available. Great find though!

    Quote from fezster

    Hi Krobar. This sounds great.

    Is there any documentation on how to use this patch and apply to Libreelec?


    Ignore - I see your post on https://forum.kodi.tv/showthread.php?tid=375819. If it cant be used on LibreElec, I'll leave for now. For me, multichannel LPCM is working fine (and I dont have Atmos speakers), so not critical for me to get this working until it's more readily available. Great find though!

    I tried to patch Libreelec but there were far too many other code changes in drm-tip and although the patch applied the compile failed due to other missing elements referenced in the patch. I'm not in a big hurry for now and will use Windows until the patch hopefully makes it to Kernel/Libreelec.

    I reported a bug that Kodi wouldn’t play quad (4.0) pcm files on Android. The fix was to send 5.1 (4.0 with two silent channels: L, R, s, s, Ls, Rs). That was implemented in Kodi 21 Android builds back in February and tested on Firestick 4K Max.

    AudioTrack: Simplify Channel selection by fritsch · Pull Request #24554 · xbmc/xbmc
    All major Android devices have issues opening more "fine grain" audio channel configurations besides Stereo, 5.1 or .7.1 - use AE's feature to silently add…
    github.com
    Quote from Krobar

    I tried to patch Libreelec but there were far too many other code changes in drm-tip and although the patch applied the compile failed due to other missing elements referenced in the patch. I'm not in a big hurry for now and will use Windows until the patch hopefully makes it to Kernel/Libreelec.

    Krobar Help me understand the post here: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/10819

    Quote

    It has already been picked up by v6.6 and v6.8


    LibreElec 12 is based on Kernel version 6.6.x. Should this fix not already be included?

    Thanks - same issue for me though using DTS-HD MA audio.

    Debug log here:

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    This log might be more relevant:


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    To summarise working (non-HD passthrough) vs not working (HD passthrough):

    Quote

    To confirm I'm using Chewitt's build:

    2024-05-24 11:24:00.724 T:916 info <general>: -----------------------------------------------------------------------
    2024-05-24 11:24:00.724 T:916 info <general>: Starting Kodi (21.0 (21.0.0) Git:21.0-Omega). Platform: Linux x86 64-bit
    2024-05-24 11:24:00.724 T:916 info <general>: Using Release Kodi x64
    2024-05-24 11:24:00.724 T:916 info <general>: Kodi compiled 2024-05-24 by GCC 14.1.0 for Linux x86 64-bit version 6.6.30 (394782)
    2024-05-24 11:24:00.724 T:916 info <general>: Running on LibreELEC (chewitt): 12.80.0 13.0, kernel: Linux x86 64-bit version 6.6.30

    Quote from chewitt

    This image contains the patch from drm-tip (which was no issue to backport onto the LE kernel sources) and the channel allocation reorder patch that was suggested with RPi recently: https://chewitt.libreelec.tv/testing/LibreE…_64-12.80.0.tar

    Let me know if the issue is resolved and/or whether the 4.0 > 5.1 workaround is required?

    chewitt Thank you for the build. This build also fixes HBR audio bit streaming for me. Atmos, DTS:X, hi-res HBR and every bit stream format I tried worked perfectly so that is a big step forward for this setup. sky42 I saw you tested LSPCon DP to HDMI 2.1 adapters and had what sounded like the same HBR audio issue as me, does Chewitt's build above fix the issue for you?

    I need to get some time with Libreelec versus Kodi on Windows. TVHeadend switching and general use is snappier whilst CPU usage is somewhat lower than Windows as well as of course no issues with forced Windows updates so already quite a few advantages. Not likely to do with Libreelec but right now any refresh rates below 50hz don't work (50, 59.94 and 60 work well); I need to try some different LSPCon firmwares. Will likely start a new thread once I have solved any problem I can by myself.

    The PCM issues are not just with 4.0 and seem to be at least partly Kodi related as the selection behaviour is plain bad. Both 4.0 and 5.0 playback as 7.1 and even if they are not supported by Linux choosing 7.1 is wrong (Should pick 5.1). I confirmed 5.1 PCM works. 44, 48, 88, 96, 176 and 192Khz sampling rate all work nicely but it seems multi channel PCM right now is limited to 5.1 and 7.1.

    Quote from Krobar

    chewitt Thank you for the build. This build also fixes HBR audio bit streaming for me. Atmos, DTS:X, hi-res HBR and every bit stream format I tried worked perfectly so that is a big step forward for this setup. sky42 I saw you tested LSPCon DP to HDMI 2.1 adapters and had what sounded like the same HBR audio issue as me, does Chewitt's build above fix the issue for you?


    Interesting. So maybe the Optiplex 3050 / Benfei adapter I am using are not the same LSPCon chipset?

    Benfei adapter I have: https://www.amazon.co.uk/gp/product/B07…e?ie=UTF8&psc=1

    The way I tried Chewitt's build was to create a standard LibreElec bootable USB and then copied the files from the tar onto the USB stick. I definitely get his version and name on startup in the top right hand corner, so pretty certain I've done that part right.


    Just to be sure, I applied the tar file using the .update folder. However, got the same result. I've attached below the dmesg output and lspci output. Let me know if there's any other useful info I can pull.


    dmesg:

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    lspci -vvv:

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    Edited once, last by fezster (May 25, 2024 at 1:31 PM).