[S905/S905X][LE 8.0.x] 4k picture quality issues

    There are multiple post scattered among the release threads about these issues, but I haven't found any solution that works for me yet. So here's a seperate threads where people will hopefully post solutions to these issues.

    The list of issues I've encountered myself so far:

    • Picture quality in 4k is worse than 1080p, this is easy to spot when switching the UI to 4k and looking at the clock in the top right corner; 1080p has crisp numbers, 4k has smudged numbers. This happens on both s905 (AVR says it's doing 4k50/yuv420) and s905x (AVR says it's doing 4k50/yuv444). The suggested solution of switching to RGB mode using sysfs doesn't seem to work, same smudgy clock. In fullscreen video this smudging affects things like the BBC logo.
    • Screenshots made in 4k mode are corrupted and show a different buffer e.g. end credits of the previous 1080p video.
    • H265/HDR gives horrible banding on s905x. The TV does show the 'HDR' popup.
    • VP9.2/HDR doesn't make the TV show the 'HDR' popup. Only tested with one sample by pointing youtube-dl to a hdr clip.

    I'm also curious about workarounds, I wouldn't mind having a knob to disable HDR in kodi or a knob to disable switching to 4k. If people want to test I can provide a 1 minutes/100MiB clip of h265/hdr footage, contact me via PM for that.

    At the time of writing, these bugs show up with 8.0.1h.

    Edited once, last by koenkooi (April 27, 2017 at 12:51 PM).

    Quote from koenkooi
    • Picture quality in 4k is worse than 1080p, this is easy to spot when switching the UI to 4k and looking at the clock in the top right corner; 1080p has crisp numbers, 4k has smudged numbers. This happens on both s905 (AVR says it's doing 4k50/yuv420) and s905x (AVR says it's doing 4k50/yuv444). The suggested solution of switching to RGB mode using sysfs doesn't seem to work, same smudgy clock. In fullscreen video this smudging affects things like the BBC logo.


    The last time I connected my boxes to a 4k monitor, kodi would run in 1080p for any content <=1080p and would only switch to 4k content >1080p, leaving any scaling from 1080p to the 4k display to the display. To my knowledge, it is not recommended to use kodi to scale SD, HD or FHD content to 4k.

    Quote
    • Screenshots made in 4k mode are corrupted and show a different buffer e.g. end credits of the previous 1080p video.

    No idea about that. Most likely a result of kodi on amlogic using the video path of the cpu and using the framebuffer only for the gui.

    Quote
    • H265/HDR gives horrible banding on s905x. The TV does show the 'HDR' popup.

    Kodi Krypton, for whatever reason maps 10bit content to a 8bit output, while Kodi Jarvis keeps it 10bit.

    Quote
    • VP9.2/HDR doesn't make the TV show the 'HDR' popup. Only tested with one sample by pointing youtube-dl to a hdr clip.

    No idea again.

    Quote


    I'm also curious about workarounds, I wouldn't mind having a knob to disable HDR in kodi or a knob to disable switching to 4k. If people want to test I can provide a 1 minutes/100MiB clip of h265/hdr footage, contact me via PM for that.

    At the time of writing, these bugs show up with 8.0.1h.

    Quote from mmpp


    The last time I connected my boxes to a 4k monitor, kodi would run in 1080p for any content <=1080p and would only switch to 4k content >1080p, leaving any scaling from 1080p to the 4k display to the display. To my knowledge, it is not recommended to use kodi to scale SD, HD or FHD content to 4k.

    Having kodi upscale mdeia to 4k is not my goal, setting the GUI to 4k is just a fast way to check for this issue. I've turned off all 'enhancements' the TV can do for upscaling, so the smudged look in 4k shouldn't be the TVs doing. A chromecast ultra hooked up the the same AVR gives very crisp 4k picture on the TV.

    Not sure re: vp9 hdr metadata (never tested), but you should really downgrade to one of the nougat kernel jarvis builds with the 4:4:4 patch if you care about 10 bit output and 2160 picture quality.

    Slightly OT: I started building LE master + kodi-agile builds with kszaq's changes merged in because I was curious about the state of development, but the krypton PQ regressions aren't fixed.