Posts by mytbyte

    kszaq:


    can you please take a look at this post from OSMC forum:


    https://discourse.osmc.tv/t/4k-hdr-videos-too-dark-on-non-hdr-tv/54220/18


    the poster talks about the intention of implementing additional parameters to am_vemc that could resolve the too dark HDR->SDR conversion with OSMC, I presume. Can this somehow be implemented, i.e these parameters added to Libreelec based on that work?


    I apologize for linking to another forum, but I had no idea how else to do this...

    Haven't upgraded LE in my beelink minimxIII II for a while and got to it just yesterday, trying to install this build, but box wouldn't boot after SMB upgrade. As I missed to put the latest device tree in Upgrade dir, I thought I'd do a full SD reinstall, adding the latest 2GB device tree downloaded from supplied links but it still wouldn't boot...I finally got it to boot with device tree already included in img.gz so I'm hesitant to try upgrading to 9 since using device trees from the said link cause my box not to boot into LE


    BUT, MORE IMPORTANTLY, I wished to share the fact that HDR to SDR conversion now seems to behave properly - a great success, so I was wandering what exactly has been done to achieve that? If it was a targeted fix, perhaps I could be so bold to suggest minor corrections/additions: while 0 black level is now as it should be, there is still some black crushing in darker scenes (perhaps a fix to HDMI ranges full vs studio/limited is required) + non-HDR UHD BT.2020 media is still not converted from BT2020 to Rec709 color.


    perhaps it looks as if I'm nit-picking but LE is all about video (and audio) so it deserves to allow for the best presentaton of media...


    Thanks for the great work

    Which version of LE are you using? I'm still on the latest 7.xxc... I succeeded controlling HDR on/off via ssh but it's either no effect with off and light blacks with on


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    I played those very 60+ mbps releases over 100 mbps powerline adapter from a Windows PC (smb) as well as wifi ac from my mobile phone (copied some samples to it) and after the initial buffering, playback went smoothly, buffering at roughly the same rate as playback... I measured over 80 Mbps in both cases with ookla (perhaps not the most accurate method)...
    Off-topic: I'm not sure of the technical validity of those HDR releases, if they indeed are the ones I think they are . I'm not sure you can capture HDR metadata to a file, it was probably inserted after capture with generic or assumed values.


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    Cool. Thanks to all three...On SDR TVs it looks wrong, washed-out black and compressed gamma...I'd hoped the s905x boxes would do HDR->SDR and BT2020->BT709 conversion but they don't, they just pass them out to HDMI with descriptors for the TV to take care of it...so, if you happen to aquire or start accumulating some HDR and UHD material for, say, future switch to UHD HDR display, there is no way to watch them on legacy displays now...

    Stige: can you absolutely confirm that you get proper-looking HDR input from the box on your HDR TV and that the TV reports it's receiving HDR signal? That would confirm that the box is not doing HDR-SDR conversion but is configured for native HDR output... That would explain light blacks on SDR TV's, but why then it even attempts to alter the look when all it needs is send picture as is, with added HDR metadata...


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    It's not a Kodi thing, but in Android system, amlogic library calls probably, it's system-wide, works with any player, and Kodi for Android respects that deep color setting via mediacodec subsystem, as I understand it... Probably could be made as libreelec setting option, not Kodi settings... It's just a HDMI output flag switch/metadata, probably...


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    Beside the HDR problem, there is the non-HDR related BT.2020 problem: the chipset doesn't pass regular BT.2020 color to the UHD TV so colors are wrong - desaturated and sickly... Of course, also there is no conversion from bt.2020 to rec. 709 going on inside the box...Don't know what data I should enclose as guideline for BT.2020 implementation... The feature works in android with Deep Color set to "on"


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    kszaq: there is an option (switch) in Android 6.0 screen resolution settings called Deep Color that activates 10-bit output but also BT.2020 wide color gamut support. Without BT.2020 support, 10-bit UHD video looks pale and green because colorspace of UHD video as per standard is wider than usual TV colorspace (rec.709)...so, a UHD TV needs to know that incoming HDMI video is in BT.2020 colorspace and it's up to the TV box to signal that by activating the Deep Color feature...


    Hope this clears it up...I suppose you need to tackle into android source to locate the deep color option...


    A very late P.S. :D - HDR is broken, as described above, in Android as well, so I would concentrate on BT.2020 Deep Color support first, that is more important...


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    May I raise the issue of BT.2020 support. I somehow have a feeling that we are too easily getting over trying to properly activate full 4K support these s905x boxes have...I have tested Libreelec in terms of BT.2020 support and it doesn't work...the box does not signal BT.2020 colorspace to the UHD TV while it does so in Android via Deep Color option (a misnomer actually, Deep Color doesn't have much to do directly with BT.2020 but it gets it activated)...


    I'm in a way being very insisting on this because BT.2020 is THE standard for 4K video, both broadcast or UHD Bluray, and here we are, owning true 4K boxes but we don't get the right colors (we get dull greenishly discolored excuse for a picture)...


    there also seems to be trouble with HDR support in both Android and Libreelec in the way that HDR is not converted properly for SDR TVs, but since I don't have a HDR TV, I can't tell with certainty whether it's broken or the option is really not meant for HDR->SDR conversion and actually works correctly when connected to a HDR TV...


    kszaq: please can you try looking into this or explain why we can't have it, I can help as much as I can with whatever I know about this matter in color science terms and termonology, but I have no programming knowledge...


    Cheers

    Thanks for the link. Yup. Works smooth for me too. That's quite some capable hardware for cheap!


    I suppose a YouTube app or add-on will be able to detect if the online YT video is HDR according to the metadata associated with the clip on YT servers, not from metadata embedded in the video so picture should appear correct but somehow I think 4K HDR YT will never happen on these boxes, at least not in android, at least not officially... It's officially available only on Chromecast ultra, AFAIK, everyone else is in waiting...



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