RPi4 testbuild with HDR support

    I think there's a lesson here for me, a clean build is invariably the way to go! I did a clean install of the most recent nightly and everything works perfectly. I'll pop the other SD card in tomorrow and run pastekodi, but I suspect it's not going to tell us much.

    Thanks again Hias.

    The "flip done" / "blank display" issue unfortunately is rather intermittent - I haven't got it here yet but others (including RPi devs) run into it more frequently.

    Just keep an eye on it (whether you use the freshly installed nightly or the other SD card) and if something odd happens just ssh in, run "pastekodi" and post the URL.

    so long,

    Hias

    hi,

    using Libreelec 10.0.1 on Raspberry Pi 4 with my LG OLED C9 and 4K/HDR looks fantastic! No problems so far.

    I wonder what this means

    • 10/12-bit video output isn’t implemented yet, 10-bit video is displayed in 8 bits

    My movies come with HDR10. So Libreelec plays thos files with 8 bits?

    Thanks

    Yes, video decoding is working at 10bits but display output only in 8. BTW: this is already fixed in development builds, next LE10 release will have it, too.

    so long,

    Hias

    Quote from HiassofT

    Yes, video decoding is working at 10bits but display output only in 8. BTW: this is already fixed in development builds, next LE10 release will have it, too.

    so long,

    Hias

    okay. great! do you know when next LE10 will release? Or is there are soruce for nightly builds?

    Quote from heinzgruber

    hi,

    using Libreelec 10.0.1 on Raspberry Pi 4 with my LG OLED C9 and 4K/HDR looks fantastic! No problems so far.

    I wonder what this means

    • 10/12-bit video output isn’t implemented yet, 10-bit video is displayed in 8 bits

    My movies come with HDR10. So Libreelec plays thos files with 8 bits?

    Thanks

    Yes - in this case the video is output as 8-bit (usually RGB), but accompanied with an HDMI flag to tell your TV that the video isn't to be displayed in SDR but is instead in a PQ HDR dynamic range (which is what HDR10 content uses), and that triggers your TV into an HDR mode. You may see banding that you wouldn't see with a full 10-bit path.

    More recent nightly LE 11 builds will ensure the full 10-bit source is preserved and output, and remove the 8-bit bottleneck.

    Quote from noggin

    Yes - in this case the video is output as 8-bit (usually RGB), but accompanied with an HDMI flag to tell your TV that the video isn't to be displayed in SDR but is instead in a PQ HDR dynamic range (which is what HDR10 content uses), and that triggers your TV into an HDR mode. You may see banding that you wouldn't see with a full 10-bit path.

    More recent nightly LE 11 builds will ensure the full 10-bit source is preserved and output, and remove the 8-bit bottleneck.

    I can attest that it is indeed working beautifully!

    Does HDR10+ pass through with these latest builds? (it's hard to search for HDR10+ - as the '+' tends to get excluded from search queries).

    I'm using the LE10 test build provided earlier, but my TV says it's only outputting HDR.

    I am using a BDMV backup, rather than mkv though...

    Quote from chewitt

    The concept of "pass-through" doesn't exist for video.

    Precisely this - whilst HD Audio can bit bitstreamed/passed-through retaining the source compression, video is always decompressed from a lossy compressed format (h.264/AVC, h.265/HEVC, VC-1, MPEG2, AV1 etc.) to an uncompressed stream of RGB or YCbCr (ignoring Dolby Vision) carried over HDMI (or similar)

    It's the equivalent of MP3 or AAC being decoded to PCM.

    If you didn't decode the video you wouldn't be easily able to overlay a GUI etc. (unless you sent two video streams over HDMI and your TV composited them together)

    When it comes to HDR PQ / HDR HLG / SDR (*) EOTF and Rec 601, Rec 709 and Rec 2020 Gamut signalling, and then static and dynamic EOTF metadata - different codecs will do this in different ways (I think some codecs have multiple options in some cases?), and each will need to be then decoded, and converted into a format that HDMI Infoframes etc. can carry to a display. This is driver specific AIUI - so different HDMI output systems on different platforms will have different ways of doing this?

    Edited 2 times, last by noggin (February 8, 2022 at 11:39 AM).