No HBR Audio with LSPCON - Trying to collect information


    So the adapter I tested with is using a newer VMM7100 HDMI 2.1 converter and yours is an HDMI 2.0 adapter so they are definitely not the same chipset. I believe Sky42 has Megachips HDMI 2.1 converters. When I get time I will try with the much older Paradetech PS175 HDMI 2.0 converter which is built-in to the motherboard. Before this neither could do HBR audio but from memory the PS175 also had trouble with HDR which the VMM7100 based adapter does not.

    Your problem on the surface sounds identical. You can check the build in System -> Librelec, Chewitt is mentioned in the build name if you have the right one.

    Quote from fezster

    I had that same thought, so have ordered this (uses VMM7100 chipset):

    https://www.amazon.co.uk/gp/product/B08…0?ie=UTF8&psc=1


    Arrives tomorrow. Will report back if it makes any difference.

    I'm using the Club3D version currently with the latest Cable MAtters firmware but AFAIK they are identical.

    Let me know if yours works with 4K/24 and 4K/30 (Currently mine does not). Best test with the default firmware before upgrading too.

    Quote from HomerJau

    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.

    https://github.com/xbmc/xbmc/pull/24554

    Would this affect Linux / Alsa? Support for PCM channels / mapping in Linux has definitely gone way down hill with current builds. 3 years ago I was testing changes by a Kodi dev and Linux support was excellent, it even supported odd channels (eg. 3.0 and 5.0) which Windows WASAPI does not. You can see discussion on that here:
    PCM 3.0 Output from HDMI (kodi.tv)

    Right now PCM multichannel support in Linux/ALSA is bad. It only seems to support 5.1 & 7.1 and on any mismatch is just uses 7.1 which is also bad behaviour (I assume that would be bad behaviour for Android too).

    Quote from Krobar

    I'm using the Club3D version currently with the latest Cable MAtters firmware but AFAIK they are identical.

    Let me know if yours works with 4K/24 and 4K/30 (Currently mine does not). Best test with the default firmware before upgrading too.


    Got the CableMatters adapter. Below info is using Chewitt's build. With the standard build, I lose picture if I try to play any HD audio stream. I can still stop the video and it returns to the GUI. With my Benfei adapter, I still got picture and garbled audio with HD audio streams.

    First off - It works with 4k/24 refresh rate switching.

    Also, both DTSHD-MA and TrueHD do passthrough. However, seeing some oddities and maybe need to play around a little bit more. After stopping a movie, it randomly* (see note below) loses audio, even when back in the Kodi GUI. So far, nothing but a reboot seems to fix it (EDIT - I can do "systemctl restart pulseaudio" to get audio back without rebooting).

    *note - It has only lost audio when I've turned off refresh rate switching. I.e. used 4k/60, but I will try it some more at 4k/24 permanently.

    The log where it's normal and audio works:


    The log when I lose audio (bolded the relevant part):


    So some success, at least.

    Edited 3 times, last by fezster (May 26, 2024 at 11:32 AM).

    Quote from fezster

    Been playing around and so far not had the loss of audio issue again - perhaps because I'm not using 4k60 anymore.

    Appreciate the build chewitt.

    So much for consistency mine wont run <50hz but audio is perfectly stable when auto switching 50/59.94/60.0hz. Do you know which firmware your Cablematters is running? I have tried 7.02.130 (Actually the oldest) and 7.02.120.

    I checked the firmware first and it was already on the latest version (or at least, the version was the same as is available for download - 7.02.120).

    Well, it seems firmwares for LSPCon all have bugs for me, just a matter of which. The good news is the patch fixed HBR audio in all cases on my setup (No audio at all with HBR bitstream on any of the combinations below before the patch but all work afterwards).

    Paradetech PS175 - 0x2C:
    Linux Working Refresh - All
    Windows Working Refresh - All
    HDR Linux - No
    HDR Windows - No (Does work in early Win 10 versions but not later)
    PCM < 5.1 Linux - Yes

    Paradetech PS175 - 0x40:
    Linux Working Refresh - 24/30/60 only (Rest are misaligned)
    Windows Working Refresh - 24/30/60 only (Rest are misaligned)
    HDR Linux - Yes
    HDR Windows - Yes
    PCM < 5.1 Linux - Yes

    VMM7100 - 7.01.130:
    Linux Working Refresh - 50/59.94/60 only (Rest give no display)
    Windows Working Refresh - All
    HDR Linux - Yes
    HDR Windows - Yes
    PCM < 5.1 Linux - No

    VMM7100 - 7.02.120:
    Linux Working Refresh - 50/59.94/60 only (Rest give no display)
    Windows Working Refresh - All
    HDR Linux - Yes
    HDR Windows - Yes
    PCM < 5.1 Linux - No

    The refresh rate issues may be dependent on other things (The firmware Fezster used would be interesting to know)

    Firmware is 7.02.120 (ie. Same as latest download). So I did not need to update it.

    Are you sure the refresh is not a limitation of your graphics card/chipset?

    Quote from fezster

    Firmware is 7.02.120 (ie. Same as latest download). So I did not need to update it.

    Are you sure the refresh is not a limitation of your graphics card/chipset?

    It could be a limitation of the graphics card bios rom/VBT side however one LSPCON in the same setup has other problems but all of the refresh rates work in Linux. Equally your VMM7100 works with other refresh rates so it seems is likely a combination of more than one factor.

    Would be interesting to know if your setup works with PCM 2.1/3.0/4.0/4.1/5.0. I think that issue might be a plain bug in the VMM7100 firmware.

    I've ordered a Megachips Mcdp2900 based adapter and a Paradetech PS176 based adapter. Aside from finding a fully working adapter for my own setup I hope to put a kind of working capabilities table in the first post to help others.

    Edited once, last by Krobar: Merged a post created by Krobar into this post. (May 27, 2024 at 7:52 AM).

    Tried FLAC 3.0/4.0/5.0/6.1.

    LFE is always active in all scenarios.

    All speakers map correctly. In the case of 6.1, it maps the 2 rear surround speakers as rear centre.

    Quote from fezster

    Tried FLAC 3.0/4.0/5.0/6.1.

    LFE is always active in all scenarios.

    All speakers map correctly. In the case of 6.1, it maps the 2 rear surround speakers as rear centre.

    I dont know what brand AVR you have but what does it detect as input for each? If it shows 7.1 for each input then you have the same problem. I suspect it does because when it is working properly 3.0/4.0/5.0 wont show LFE input on Linux.

    Quote from Krobar

    I dont know what brand AVR you have but what does it detect as input for each? If it shows 7.1 for each input then you have the same problem. I suspect it does because when it is working properly 3.0/4.0/5.0 wont show LFE input on Linux.

    Denon AVR-X2700H

    Quote from fezster

    Denon AVR-X2700H

    20240527-101132.jpg

    Thanks, That is correct behaviour. I'm going to test with the same set of files but this might be differences in the AVR (I'm using an Arcam AV40-8K). The fact it works with the Paradetech LSPCon though again suggests it is some sort of difference in the LSPCon causing the issue for me.

    fezster Can I ask one more thing; does the behaviour change if you use the 8K Input on your Denon AVR?

    Edited once, last by Krobar: Merged a post created by Krobar into this post. (May 27, 2024 at 10:56 AM).

    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 I am currently building 12.0.0 and would like to apply the drm-tip patch myself. Would you be able to tell me the steps to do this?

    EDIT - Found your post here: What is the right way to apply a patch to a dts while building

    Seems I can download the patch and put it under projects/Generic/linux/patches. Will give this a go when my build completes.

    Edited once, last by fezster (May 27, 2024 at 12:20 PM).